physicsworld.com Volume 23 No 10 October 2010

Nuclear powerThe road ahead

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Frontiers 4The constant that might not be so constant ● Solar cells repair themselves ● Watchingblack holes merge ● The incredible shrinking Moon ● Novel electronic nose

News & Analysis 6CERN faces budget cuts ● Germany targets nuclear expansion ● Changes needed atthe IPCC ● China expands Antarctic observatory ● Fermilab weighs up acceleratoroptions ● Upgrade for cosmic-ray lab ● Pakistan science budget slashed ● Dawn of the memristor ● Japan tests new form of hydropower ● Astronomy photographer of the year ● Carlo Rubbia: nuclear pioneer ● Uncertain times for Yucca Mountain

Feedback 19Studying gender bias, plus comments from physicsworld.com

Nuclear powerNuclear power: yes or no? 24Barry Brook says nuclear power is the cornerstone for a carbon-free society, while Ian Lowe argues for renewable sources

The lost leader 26Geoff Allen wonders how the UK can regain its global lead in nuclear power

Nuclear fear revisited 28Worries about nuclear power continue to dog the industry: Robert P Crease asks why

Nuclear’s new generation 30Edwin Cartlidge examines the six most promising designs for “generation-IV” nuclear power plants

Beyond the envelope 36Physics World highlights four reactor concepts with radically different designs

A world of difference 38A global map showing the haves, have-nots and want-nots of nuclear power

Enter the thorium tiger 40Matthew Chalmers tours India’s nuclear-research labs to find out about the country’sgrand three-stage vision for nuclear power that exploits its vast thorium reserves

Hot fusion 46Steve Cowley explains why the multinational ITER facility is expected to reach the hotnew regime required for commercial fusion power

Reviews 52The dangers of radiation ● The future of nuclear waste ● Web life: Nuke Power Talk

Careers 60Playing it safe with reactors Mike Yule ● Once a physicist: John Hemming MP

Recruitment 65Graduate recruitment

Lateral Thoughts 76The rise and fall of nuclear naivety Margaret Harris

Totally thorium – India’s nuclear dream 40–45

Physics World is published monthly as 12 issues per annualvolume by IOP Publishing Ltd, Dirac House, Temple Back, Bristol BS1 6BE, UK

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Physics World (ISSN 0953-8585) is published monthly by IOP Publishing Ltd, Dirac House, Temple Back, Bristol BS1 6BE,UK. Annual subscription price is US $585. Air freight and mailingin the USA by Publications Expediting, Inc., 200 Meacham Ave,Elmont NY 11003. Periodicals postage at Jamaica NY 11431.US Postmaster: send address changes to Physics World,American Institute of Physics, Suite 1NO1, 2 Huntington Quadrangle, Melville, NY 11747-4502

On the cover

Nuclear power (Photolibrary) 23–51

Saying no to nuclear – a legacy of fear 28

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physicsworld.com Contents: October 2010

1Physics World October 2010

PWOct10contents 20/9/10 14:37 Page 1

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Send copies to all the pompousnincompoops it will offend. They willsell it for youRobert Park from the University of Maryland in hisWhat’s New bulletinPark was commenting on the marketing tactics forStephen Hawking’s new book The Grand Design,which caused a media storm last month by arguingthat science can explain the origin of the universewithout invoking God.

To close it would make us aninternational laughing stockAstronomer Patrick Moore quoted in The TimesWith the UK government looking to cut sciencefunding in its spending review this month, Moorewarns against slashing cash for the Jodrell Banktelescope in Cheshire.

It would be madness, vandalismeven, at every levelParticle physicist and broadcaster Brian Cox

quoted in the GuardianWith possible cuts of about 25% planned for thescience budget, Cox says that pulling out of CERNor mothballing new facilities such as the Diamondsynchrotron would cause irreparable damage tophysics in the UK.

Until I work out how I fit into all of this,I will just continue washing his pantsTV producer Gia Milinovich quoted in the GuardianMilinovich, who is married to the Manchesterphysicist Brian Cox, says she used to present showson science and technology but that since Cox’sstardom following his hit TV series Wonders of theSolar System she has taken a back seat.

Peer review is largely hokum

Nigel Hawkes, director of Straight Statistics,quoted in the IndependentHawkes says that peer review seldom detects fraudor even mistakes and is biased against women andless-famous institutions, adding that once a paperis rejected from one journal, authors just send it toanother lower down the pecking order.

I have always loved physics –quantum physics is really just afascinating areaAmerican singer-songwriter Jewel quoted in theToronto SunGrammy-nominated Jewel says that if she were nota pop and folk star, she would have gone back toschool to study physics.

For the record

Quanta

The model in role modelPhysicists might not be known for theirdress sense, but that has not stoppedLondon-based fashion company L K Bennett recruiting a physicist to modelfor it. Anna Dawson, a 26-year-oldgeophysicist, was selected to pose for thelabel’s recently launched autumn/winter2010 collection. The new ads featureprofessional women photographed goingabout their everyday lives and includeDawson standing on a rocky shoreline atKlive Beach in Somerset, UK, wearing an L K Bennett dress and with a pair ofbinoculars in one hand and a suitcase ofequipment on a rock behind her. Dawsonobviously has the model looks, as sherecalls on L K Bennett’s website that on herway from Los Angeles to Tokyo “a guycame running up to me and asked if I wasone of the Baywatch women!”. Apparently,the fashion firm is asking prospectivemodels for their next campaign to get intouch – so what are you waiting for?

Geek chicSpeaking of fashion, the former Englandfootballer David Beckham has apparentlyturned to promoting dark matter – themysterious, invisible substance believed tomake up more than 80% of the matter inthe universe. Beckham was recentlyspotted wearing a T-shirt from designerDavid Lindwall’s latest collection thatexplores “the element of technology inrelation to the human mechanism”.Written across the garment, which costs acool £70, are the words “constraints on thedark matter” and “black matter may domore than just weigh” together with adiagram underneath that, as for as Physics World can tell, has absolutelynothing to do with dark matter. “The shirtis my artistic interpretation of a fewdifferent scientific equations concerningblack matter and time travel,” Lindwalltold the Guardian. Right…

Bend it like CarlosStill on football, many consider the goalscored from a free kick by Brazilian fullbackRoberto Carlos against France in 1997 to beone of the best ever. When the São-Paulo-born defender struck the ball about 35 mfrom the French goal, it was initiallyheading so far wide that it made a ball boy,who was standing a few metres to the rightof the goal, duck. But at the last momentthe ball curved strongly to the left and justsnuck into the net. Theories for this effectrange from the material of the ball, theunusually dry conditions on the night toeven a gust of wind. Now, 13 years on,Guillaume Dupeux and colleagues at theEcole Polytechnique in Palaiseau, France,say they can finally explain the physicsbehind the curve (New J. Phys. 12 093004).By firing and tracking tiny polymer spheresthrough water, the researchers witnessed a“spinning-ball spiral” effect where thefriction exerted on a ball by its surroundingsslows it down enough for the spin to takeover in directing the ball’s trajectory. Theresearchers say that before the ballsmashed into the back of the net it followedsuch a spinning-ball spiral. The researchhas been a big hit, with a PDF of the paperbeing downloaded 10 790 times within twodays of being published. And the institutionthat downloaded the paper the most? Yep, you guessed it, São Paulo University.

Case dismissedWalter Wagner, the Hawaiiresident who set his sightson stopping the LargeHadron Collider (LHC) atCERN, has finally lost hislegal battle. Wagner,

together with his colleague Luis Sancho,filed a federal lawsuit in the US DistrictCourt in Honolulu in 2008 to prevent theLHC from starting up. In the lawsuit,Wagner and Sancho claimed that if theLHC were switched on, then the Earthwould eventually fall into a growing microblack hole, thus converting our planet intoa medium-sized black hole, around whichthe Moon, artificial satellites and theInternational Space Station would orbit.But Wagner’s court battle ended in lateAugust when a judge from Hawaii threwout the case, finding that Wagner had nostanding before the court. The judge saidWagner and his cohort failed to show a“credible threat of harm”, and, as the USgovernment does not control the operationof the LHC, it was not the correct party tobring action against the collider. Phew.

Seen and heard

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A group of physicists in Australia has madethe controversial claim that billions of yearsago the strength of electromagnetic in-teraction differed across the universe. Bystudying light from ancient quasars, theresearchers believe that the “fine-structureconstant”, known as α, has changed in spaceand time over the age of the universe.

The fine-structure constant, which isapproximately 1/137, is a measure of thestrength of the electromagnetic interactionand quantifies how electrons bind withinatoms and molecules. But despite beingdubbed a constant, there are good theoret-ical reasons why α might be a variable. Achanging α could, for example, help solve thebiggest mystery of physics – how to formu-late a single unified theory that describes thefour fundamental forces of nature.

For more than a decade, John Webb,

Victor Flambaum and colleagues at the Uni-versity of New South Wales have been look-ing for evidence of variations in α in lightcoming from distant quasars in the northernhemisphere. Radiation from these extremelybright objects has travelled for billions ofyears before reaching the Earth and will havepassed through ancient clouds of gas alongthe way. Some of the light is absorbed at spe-cific wavelengths that reveal the chemicalcomposition of the gas. By analysing theposition of absorption lines in the chemicalspectra, the researchers were able to extractα from hundreds of quasars, finding that bil-lions of years ago α was about one part in100 000 smaller than it is today.

Now, Webb and colleagues have analysed153 additional quasars in the southern skyusing the Very Large Telescope (VLT) inChile, and have made the startling discoverythat α was about one part in 100 000 bigger10 billion years ago than it is today. Thisasymmetry in the two hemispheres – dubbedthe “Australian dipole” by the researchers –has a statistical significance of about 4σ,meaning that there is only a one in 15 000chance that it is a random event (Phys. Rev.Lett. at press).

This spatial variation in α is further evi-dence that the electromagnetic interactionmay violate Einstein’s equivalence principle– one of the cornerstones of relativity thatstates that αmust be the same wherever andwhenever it is measured. Such a violation isgood news for those seeking unificationbecause many leading theories also violatethe equivalence principle.

Researchers at the Massachusetts Instituteof Technology (MIT) have fabricated a pho-tovoltaic cell that mimics the self-healingsystem naturally found in plants, which cap-ture sunlight and convert it into energy dur-ing photosynthesis. Although researchershave been trying to replicate this processwith synthetic materials, this has proved dif-ficult, in part because the Sun’s rays gradu-ally destroy solar-cell components overtime. Plants, in contrast, have developed anelaborate self-repair mechanism to over-come this problem that involves constantlybreaking down and reassembling photo-damaged light-harvesting proteins to ensurethey always work like “new”.

Michael Strano and colleagues have mim-icked this process by creating light-harvest-ing complexes made up of proteins, isolated

from the purple bacterium Rhodobactersphaeroides, that contain a light-reactioncentre comprising bacteriochlorophylls andother molecules. When the centre is exposedto solar radiation, it converts the sunlightinto electron–hole pairs (excitons) thatshuttle across the reaction centre and sub-sequently separate again into electrons andholes. The complexes also contain single-walled carbon nanotubes (SWNTs), whichact as wires channelling the electrons and soproducing a current.

Strano’s team found that it can control thisprocess by spraying the system with a solu-tion of soap molecules. The liquid initially“jumbles” the surface of the solar cell, butwhen removed it rejuvenates the reactioncentres. In doing so, the researchers wereable to increase the efficiency by more than300% over 164 hours of continuous illu-mination compared with a non-regeneratedcell (Nature Chemistry 10.1038/nchem.822).

Solar system older than we thoughtThe solar system is up to two million years moreancient than previously thought, according to apair of researchers in the US who have dated ameteorite to be 4568.2 million years old. Labelled“Northwest Africa 2364”, the space rock has amass of 1.5 kg and was bought by a private dealerin Morocco in 2004. The researchers acquired asample of the rock and used the decays ofuranium-238 into lead-206, and uranium-235 intolead-207, which have half-lives of ~4.47 × 109

years and ~704 × 106 years, respectively, to pindown its age. An older solar system would lendweight to the theory that the Sun and planets did not form in isolation but instead were seededby the remnants of a supernova explosion (Nature Geoscience 10.1038/ngeo941).

Graphene transistor breaks speed recordsResearchers in the US have developed a new wayof making transistors from graphene – the materialhailed as a potential rival to silicon within thesemiconductor industry. The device consists of athin film of graphene – a sheet of carbon just oneatom thick – with a gate just 140 nm long madefrom a cobalt-based nanowire. The researchersthen placed a thin layer of platinum on top of thenanowire, thus dividing the graphene film into twoseparate zones that form the electrodes. Thisprocess helps to minimize the number of defects inthe material, which have hindered previousgraphene-based transistors. The finished devicesboast a number of record-breaking properties,including an electron mobility of 20 000 cm2 pervolt-second, which is roughly two orders ofmagnitude better than that of similarly sizedcommercial silicon transistors (Nature 10.1038/nature09405).

Proteins swarm in packsSwarms of insects and flocks of birds are examplesof natural systems in which individual componentsact independently yet together display complexcollective motion. Now, a group of biophysicists inGermany has recreated this behaviour in thelaboratory. The researchers studied the motion ofactin filaments – a common protein that makes upthe skeleton of biological cells, which aretransported and divided by myosin proteins. Bypreparing a sample of actin and myosin immersedin water, the researchers observed that filamentsmove around randomly in samples with an actindensity less than about five per square micron. Butabove this critical density, the filaments formdistinct clusters 20–500 μm in width that movearound erratically and endure for several minutes(Nature 467 73).

Fine structure may not be so constant

Self-healing solar cells

In brief

Read these articles in full and sign up for freee-mail news alerts at physicsworld.com

View from the south The European SouthernObservatory’s Very Large Telescope (VLT) in theAtacama Desert in northern Chile.

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Sniffer dogs may soon find themselves out of a job,thanks to a new type of electronic “nose” beingdeveloped by researchers in the US. The device,made from sheets of graphene coated in DNA,could be capable of detecting a variety ofmolecules, from chemical weapons to toxic waste.

Like their biological counterparts, electronicnoses are sensitive to a large number of differentmolecules, and to achieve this they usually consistof hundreds, or even thousands, of sensors on thesame chip. Each sensor reacts to a specificmolecule, just as the receptor proteins in mammalnoses do. However, the need to fabricatethousands of different sensors – and thechallenges of converting chemical reactions intoelectronic signals – can make electronic nosesexpensive and complicated devices.

Now, Charlie Johnson of the University of Pennsylvania and colleagues Ye Lu, Brett Goldsmith and Nick Kybert have devised asimple way of sensing chemicals by showing thatthe electronic properties of DNA-coated graphenechange when exposed to certain molecules.Johnson’s team based its devices on graphenetransistors made using the standard “sticky tape”method, which involves exfoliating individualatomic layers of carbon from graphite. Eachtransistor was then soaked in a solution of aspecific sequence of the four bases (A, G, C, T) ofsingle-stranded DNA, which self-assembles into apattern on the surface of the graphene.

Each sequence interacts differently with volatileorganic chemicals because of its varying shapeand pH, and this has a unique effect on thegraphene’s electrical resistance. This change,which can be as large as 50%, can easily bemeasured by applying a 1 mV bias voltage and azero gate voltage across the sensor and observinghow the current changes when the device isexposed to different chemicals. And, because this is a direct electronic measurement, it is veryfast – complete responses can be seen in lessthan 10 s and the sensors recovers in about 30 s(Appl. Phys. Lett. 97 083107).

The team’s next big challenge is to scale upproduction of its sensors. “We need to test moreDNA sequences, fit more devices on a chip andmake sure we understand all the signals when abig array of sensors is exposed to a mixture ofchemicals,” says Johnson. “We have high hopesfor these sensors but there are still lots of hurdlesto overcome. Eventually, we would like to put dogsout of the chemical-sensing business, and, withproper development, sensors like ours might beable to do that.”

Electronic nose sensessweet smell of success

Lurking at the centre of nearly every galaxy and gobbling up stars in their vicinity, supermassive black holescan grow to become thousands, or even millions, of times more massive than our Sun. Now, aninternational team of astronomers has offered an explanation for why legions of these galactic monsterswere born during the early history of the universe. Lucio Mayer at the University of Zurich, working withcolleagues in Chile and the US, believes the high birth rate is caused by the merger of two or more primordialgalaxies, which creates the right conditions for black-hole formation. These images, created by computersimulations involving more than three million hours of processing, show the density of dust and gas atdifferent length scales as two young galaxies come together and spiral about a central disk (1 pc is about4000 years). For galaxies above a critical size, more than 100 million solar masses of dust can bechannelled towards the centre within just 100 000 years, creating a disk-like nucleus at the centre thateventually collapses to form the seed of a black hole. After running the model for the equivalent of108 years, the researchers found that the black hole had grown to a billion solar masses. This model of rapidgrowth would explain why large numbers of mature supermassive black holes were already present withinthe first billion years of the universe. Researchers had previously thought the objects would take muchlonger to develop, forming once huge dying stars and collapsed in on themselves (Nature 466 1082).

Innovation

Freshly discovered scars on the face of theMoon reveal that this rocky satellite isshrinking at a relatively rapid pace, sayresearchers in Germany and the US. Theimages were collected by NASA’s Lunar Re-connaissance Orbiter, which includes threedifferent cameras that can take both narrow-and wide-angle high-resolution photo-graphs. This high level of detail revealed 14 lunar landforms known as lobate scarpsthat are similar to the thrust faults on Earththat result from compressional forces suchas plate tectonics.

Lobate scarps occur when the surface of abody experiences a compressional force,causing one part of the upper surface to foldand fracture above the other. In the absenceof significant lunar tectonics, the researchersbelieve the faulting is caused by cooling ofthe Moon’s core; as it cools it also shrinks,applying stress throughout the interior of theMoon towards the brittle lunar crust andcausing it to rupture and split. This theory isbacked up by the observation that the lobatescarps are globally distributed, which indi-cates contraction of the whole Moon.

On relatively small planetary bodies, suchas Mercury, the Moon and possibly some ofthe icy satellites, it has long been thoughtthat the original cooling of the body veryearly in its history could cause a global con-traction in its size. However, in the case ofthe Moon, this faulting appears to have beendelayed. By analysing how the scarps inter-act with other nearby surface features ofknown age, including craters, the research-ers infer that the Moon has contracted radi-ally by 100 m in the past one billion years ofits 4.5 billion year history. This is in keepingwith the “crisp, un-degraded appearance” ofthe scarps, which provides yet further evi-dence of their young age (Science 329 936).

“There is a general impression that theMoon is geologically dead – that everythingof geologic significance that happened to theMoon happened billions of years ago,” saysThomas Watters of the Smithsonian Institu-tion’s National Air and Space Museum andlead author of the paper. “Our results sug-gest this is not the case. The Moon may begeologically and tectonically active, and stillcontracting today.”

Facial scaring reveals that the Moon is shrinking

Supermassive black holes spawned by galactic merger

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News & Analysis

The CERN particle-physics lab nearGeneva is to slash about 7260m($340m) from its budget for 2011–2015. The cut, which was approved by CERN’s council last month, will re-quire the lab to scale back researchinto future particle accelerators. How-ever, CERN boss Rolf-Dieter Heuerinsists that the reduction will not affectthe operation of the Large HadronCollider (LHC) or force CERN tolose any of the 2000 or so staff that it currently employs.

The 7260m cut is most likely to hit future upgrades and accelerators,which will now “proceed at a slowerpace”. Also cut in the new budget –dubbed the medium-term plan – is the operation of CERN’s acceleratorsduring the planned year-long shut-down of the LHC in 2012, when thelab will prepare the collider to gostraight to maximum-energy 14 TeVcollisions. A few of CERN’s acceler-ators were planned to be used duringthe shutdown period to study newdetector techniques, but now nonewill operate in 2012.

“All our member states are makingsignificant budget cuts at the nationallevel, and it is difficult to argue whyintergovernmental organizations suchas CERN should be exempt,” says

Heuer in a memo to staff. Worst hitcould be work on the Compact LinearCollider (CLIC) – CERN’s own blue-print for a future electron–positroncollider – that could be built once the LHC reaches the end of its life.Although research on CLIC and a“higher-energy proton machine” willcontinue, CERN’s contribution toCLIC will be held at about 716m andnot be increased as was previouslyproposed. “In the present financialand political climate, I think it was

inevitable that CLIC would be amongthe programmes to suffer,” particletheorist John Ellis told Physics World.

Ellis says that resources alreadymade available by CERN will, how-ever, allow an upgrade to the CLICtest facility to go ahead. But the bud-get cut means that an engineering de-monstration facility called CLIC0,which would have to be constructedbefore CLIC could be approved, willnot now happen unless external fundsare sought. CLIC0 is supposed todemonstrate beam acceleration toabout 6.5 GeV.

Some are taking the news as anexpected consequence of countriesaround Europe tightening their belts.“In the current financial climatethese cuts are not unexpected andwhile they will slow down some of thelonger-term projects, they will not putin jeopardy any of CERN’s scientificobjectives,” says Mark Lancaster, aparticle physicist from UniversityCollege London who works on theCompact Muon Solenoid detector at the LHC. Ellis notes that the re-cent decision to open membership toCERN to countries outside Europecould mean that the extra funds areinstead provided by these nations.Michael Banks

CERN faces 7260m budget cuts

Germany’s coalition government ledby Chancellor Angela Merkel has con-troversially agreed to extend the life of the county’s 17 nuclear reactors.Under a new bill, plants constructedbefore 1980 could be allowed to runfor an additional eight years, whileplants built after that could operate for an extra 14 years. Some observers,however, have questioned the legalityof the plan and believe the decisioncould ultimately be thrown out byGermany’s constitutional court.

Under the current nuclear-plantphase-out plan, which was agreed in2001, Germany’s four nuclear oper-ators – Vattenfall, Energie Baden-Württemberg, RWE, and E.On – arerequired to shut down their reactors

by 2022. Merkel insists that the exten-sion of nuclear power will not affectthe German government’s commit-ment to renewable energy, but thatmore time is needed to make theswitch. “We see nuclear and coal-firedpower plants as an indispensablebridge towards this goal,” Merkel said at a press conference in Berlin on5 September to announce the plan.

Several of Germany’s 16 states are,however, against the bill. They say it is unconstitutional because it wascrafted to require only the approvalof the Bundestag, Germany’s lowerhouse of parliament, where Merkelholds a majority. Normally, Bun-destag-approved bills also need afinal stamp of approval from the Bun-

desrat, the upper house, which re-presents Germany’s states and whereearlier this year Merkel’s ruling coali-tion lost its majority control.

Dietrich Pelte, a physicist at theUniversity of Heidelberg, told PhysicsWorld he believes that most physicistsin Germany would favour extendingthe life of the country’s nuclear plants.But with German public sentimentoverwhelmingly opposed to nuclearenergy, Pelte says the bill’s passagethrough the Bundestag is not guar-anteed. “Even if it does pass, the op-position will appeal to the courts tohave it removed,” he says. Indeed, ifthe Bundestag approves the extensionbill, opponents have vowed to fightthe legality of the plan in court, withthe Greens and the centre-left SocialDemocrats saying they would kill theextension should they regain power in2013 federal elections.Ned Stafford

Hamburg

Nuclear power

Reactors thrown an extended lifeline

In the firing line

CERN’s CompactLinear Collider – aplanned electron–positron collider –could be hit by thelab’s budget cuts.

The extensionof nuclearpower will notaffect theGermangovernment’scommitment to renewableenergy

CERN

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The heat is on

The InterAcademyCouncil has called for changes to theway that theIntergovernmentalPanel on ClimateChange works.

The Intergovernmental Panel on Cli-mate Change (IPCC) must signifi-cantly improve the management,rigour, transparency and communi-cation of its climate assessments ifthese reports are to continue to havean impact. That is the verdict of theInterAcademy Council, a grouping of national science academies fromaround the world. It was commis-sioned by the United Nations and theIPCC to review the panel’s reports inthe light of controversies surroundingtheir accuracy and impartiality.

The IPCC has been producingperiodic assessments of the under-lying causes, impact and mitigation of changes to the Earth’s climate formore than 20 years. The controversysurrounding this process has inten-sified recently, particularly when itemerged in January that its mostrecent assessment report, from 2007,controversially stated that the Hima-layas could lose their glaciers by 2035.

The new report says that minim-izing the risk of future errors willpartly involve changing the IPCC’smanagement structure. In particularit recommends that the chair of the 194-member IPCC only serve one six-year term – rather than the currentlimit of two six-year terms – and callsfor the setting up of a new group ofindividuals from both inside and out-

side the IPCC to oversee its day-to-day decision making.

The chairman of the 12-memberreview committee – the economistHarold Shapiro of Princeton Univer-sity – told Physics World that the one-term limit is not designed specificallyto unseat the IPCC’s current chair,Rajendra Pachauri, who has comeunder fire for his handling of theHimalayan error, but to reflect therapid pace of change within climatescience. “Our thinking was that it isuseful to have a new face every five orsix years,” says Shapiro.

Shapiro’s team also says that theIPCC must be more transparent, par-ticularly regarding the criteria forselecting the scientists who take partin the assessment process. In addition,it recommends that those scientistsediting the reports should do more toensure that all review comments areaccounted for, and calls for more ex-plicit guidelines regarding the use ofnon-peer-reviewed literature (whichprovided the spurious glacier data).

The committee also points out thatthe three IPCC working groups eachuse a separate definition of “uncer-tainty” and calls for these to be re-placed by a single definition. And itwants the panels’ understanding of atopic to be qualified by describing theamount of evidence available and thedegree of agreement among experts.

Shapiro acknowledges that thecomplexities of climate science, suchas levels of uncertainty, can be dis-torted when the main assessment re-ports are condensed into summariesfor policymakers. Interests, “whetherconscious or not”, he says, can affectthe content of these summaries, ex-plaining that the inevitable emissionof nuances from the detailed reportsis subject to “to-ing and fro-ing”. Heinsists, however, that this processdoes not affect the panel’s key find-ings regarding the effect of humanactivity on the climate. The Inter-Academy Council report is due to beexamined by the IPCC’s member gov-ernments at a meeting in South Koreathis month.Edwin Cartlidge

Science academies urge IPCC revamp

Astronomers in China are planning to construct two telescopes in Antarc-tica that will search for planets outsideour solar system and study the natureof dark matter and dark energy. Thetelescopes will join the existing Chi-nese Small Telescope Array – a set offour 14.5 cm telescopes – at Dome Aon the Antarctica plateau, which is lo-cated 1200km inland and is thought tobe one of the coldest places on Earth.

The plans have been submitted bythe Chinese Academy of Sciences(CAS), which wants to start con-structing a 2.5 m optical/infrared tele-scope and a 5 m telescope operating

in the terahertz range next year. Ac-cording to Lifan Wang, director of the Chinese Center for Antarctic As-tronomy and an astronomer at TexasA&M University in the US, the 5 mterahertz telescope will study the for-mation of stars in distant galaxies.The 2.5 m optical and near-infraredKunlun Dark Universe Telescope, incontrast, will focus on dark matter,dark energy and exoplanets.

“The observatory is a great op-portunity for the development ofChina’s astronomy and physics,” saysJi Yang, director of the CAS’s PurpleMountain Observatory in Nanjing.

Yang adds that Antarctica has manyadvantages over other telescope sites,such as Mauna Kea in Hawaii, be-cause of its very dry atmosphere,which means that it is more transpar-ent to terahertz wavelengths.

The two telescopes are the firststep in plans to expand observationsat Antarctica’s Dome A. Astron-omers in China also hope to subse-quently build a 6–8 m optical/infraredtelescope, as well as a 15 m terahertztelescope. These will study blackholes and the origin of universe, andalso provide a long-term monitoringplatform for transient objects, such assupernovae and gamma-ray bursts.“These telescopes are expected toplay a unique and important role inastronomy,” says Yang.Jiao Li

Beijing

Facilities

Chinese astronomers target Antarctica

Down south

The Kunlun DarkUniverse Telescopebased in Antarcticawill hunt forexoplanets and study dark matter.

CAS

Climate change

NO

AA

physicsworld.com News & Analysis

7Physics World October 2010

PWOct10news 20/9/10 16:46 Page 7

A recommendation that Fermilabshould continue operating its Tevatroncollider until 2014 has left laboratoryofficials with a dilemma: keep huntingfor the Higgs boson, or focus on a ser-ies of neutrino experiments that thelab’s director has called the “long-term future of our laboratory”?

Proponents of the first option re-ceived a boost last month when thelab’s Physics Advisory Committee(PAC) strongly endorsed a three-yearextension for the collider, which iscurrently scheduled to close in Sep-tember 2011. The committee’s viewsare not binding, however, and Fermi-lab director Pier Oddone’s publiccomments have been lukewarm.While acknowledging the Tevatron’s“remaining promise for the future”,he also called the recommendation“very problematic for us”, since an ex-tension could hinder the lab’s trans-ition towards projects on the so-calledintensity frontier.

One such project is NOvA, which isdesigned to study neutrinos producedwhen a 700 kW beam of protons fromFermilab’s Main Injector acceleratorcollides with a graphite target. If theTevatron, which collides protons and

antiprotons, is still running whenNOvA starts in 2013, the availablebeam power will drop to about400 kW, thereby sharply reducing theamount of data NOvA collects in itsfirst 18 months. However, the PACconcluded that this “would not meanrobbing NOvA of a discovery”, sayscommittee member and University ofRochester particle physicist ReginaDemina, adding that competitors likeJapan’s T2K are already better placedto make early progress in the field.

Still, a delay for NOvA would be ablow to the neutrino community, saysDavid Wark, a physicist at ImperialCollege London who is part of the

T2K collaboration. “Of course, Iwould like T2K to make any discov-eries first, but from a broader per-spective it is critical to have multiplecomplementary experiments,” hesays. T2K spokesperson Takashi Ko-bayashi agrees, noting that NOvA willbe able to measure some things –such as which flavour of neutrino islightest and which is heaviest – thatT2K cannot.

A similar argument could, how-ever, be made for the Tevatron and itscompetitor, CERN’s Large HadronCollider (LHC). If the Higgs boson is heavier than about 140 GeV, it ismore likely to decay into pairs of W orZ bosons, and the LHC should beable to detect this signal easily in thedebris of proton–proton collisions. Alighter Higgs is more likely to decayinto pairs of b-quarks, which wouldfavour the Tevatron. Ultimately, theTevatron’s future rests with Oddoneand officials at funding agencies suchas the US Department of Energy,who also need to decide whether tocover the collider’s $60m-a-year op-erating costs. A decision is not ex-pected until early 2011.Margaret Harris

Fermilab officials weigh up options for Tevatron

Decisions, decisions

Researchers at theNOvA neutrinoexperiment arehoping any extensionto the life ofFermilab’s Tevatroncollider will not impacton their plans.

Ferm

ilab

A prototype for a new generation of cosmic-ray detectors is to be in-stalled at the Pierre Auger Obser-vatory in Argentina later this month.The Buried Array Telescope at Auger(BATATA), which has been designedand built by researchers at the Na-tional Autonomous University ofMexico (UNAM), will allow the en-ergy spectrum of these energetic par-ticles to be studied down to 1017 eV.This is an order of magnitude lessthan was possible before, which willenable researchers to better study the“cut-off” period in the spectrum ofultrahigh-energy cosmic rays, wheretheir numbers drop dramatically.

The Pierre Auger Observatory con-sists of 1600 water tanks distributedover an area of 3000 km2 high in theAndes. It can detect the electrons andmuons created from the “shower” ofparticles that are formed when high-energy cosmic rays strike the nuclei

of gases in the Earth’s atmosphere.When an incoming particle hits anelectron or nuclei of water, a chargedparticle is produced that moves fasterthan the speed of light in water to cre-ate light known as Cerenkov radiationthat can then be detected. Here, theamount of light produced by a parti-cle shower can reveal how energeticthe cosmic ray is.

Unfortunately, while these detec-tors measure all particles in a cosmic-ray shower, they cannot distinguish

between muons and electrons. How-ever, BATATA will be able to pick outthe muons via plastic scintillator rodsburied between depths of 30 cm and2.5 m underground. These rods ab-sorb the energy of the muon and thenproduce a flash of visible light, whichis detected.

“BATATA is a unique experiment,which will form part of the largestcosmic-ray observatory in the world”,says BATATA lead investigator Gu-stavo Medina-Tanco, a physicist atUNAM’s Nuclear Sciences Institute.BATATA will be integral to an up-grade to the observatory called AugerMuons and Infill for the GroundArray of the Pierre Auger Observa-tory (AMIGA). This is expected toconsist of Cerenkov-radiation detec-tors on the surface working togetherwith the buried muon counters.Gabriela Frías Villegas

Mexico City

Astronomy

Mexican scientists build novel cosmic-ray detectorGoing underground

Researchers at theNational AutonomousUniversity of Mexicohave beenconstructing thedetector arrays for the Buried ArrayTelescope at thePierre AugerObservatory.

ICN

-UN

AM

Particle physics

physicsworld.comNews & Analysis

8 Physics World October 2010

PWOct10news 20/9/10 16:46 Page 8

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R010_108_Ad_YI0403EB_210x140.indd 1 15.01.08 17:55:43Untitled-2 1 07/09/2010 09:17

US tops the classThe US has seven of the top 10 universitiesin the world, according to a league tablecompiled by the Times Higher Education(THE) newspaper. Harvard is top, followedby the California Institute of Technology,the Massachusetts Institute of Technology,Stanford and Princeton. Cambridge in sixthis the top non-US university in the list,followed by Oxford, University of California,Berkeley, Imperial College London andYale. Together, US and UK universities takethe top 14 places, with the Swiss FederalInstitute of Technology in Zurich being thebest institution from a non-English-speaking nation in 15th place. Cambridgeand Oxford universities, however, whichwere second and fifth in last year’srankings, have fallen in the standingsbecause of a change in rankingmethodology. Education-services firm QS,which until last year compiled the rankingstogether with THE, published its own listlast month that put Cambridge in top spot,followed by Harvard and Yale.

Sun explorer tools upNASA has selected five instruments thatwill go on Solar Probe Plus – the spaceagency’s next mission to the Sun. The fiveinstruments include a camera that will take3D images of Sun’s corona, while twomass spectrometers will study theelements in the solar atmosphere. Anotherprobe will measure the electric andmagnetic fields that pass through theSun’s atmospheric plasma, while the fifthinstrument will study particles in the solarwind. Solar Probe Plus is due to belaunched by 2018.

Judge rejects climate ‘fraud’ caseA judge has rejected demands by Virginia’sattorney general Kenneth Cuccinelli for theUniversity of Virginia to hand overdocuments about grants awarded to theclimatologist Michael Mann between 1999and 2005. A critic of global warming,Cuccinelli has suggested that Mann mayhave “manipulated” some of his data tofavour the existence of climate change(see Physics World June p6). But Judge Paul Peatross ruled that Cuccinellihad not shown sufficient “reason tobelieve” that the university possessed anydocuments indicating fraud. “It is not clearwhat [Mann] did that was misleading, falseor fraudulent in obtaining funds from theCommonwealth of Virginia,” Peatrosswrote. The judge, however, noted that theattorney general is within his rights toinvestigate research grants funded bytaxpayers, and Cuccinelli has said that hewill now issue new demands for data.

Sidebands

IT giant Hewlett-Packard (HP) an-nounced last month that it will beginmass-producing “memristors” – a newkind of electronic component firstdiscovered in 2008 – in a move thatpromises to revolutionize memory inelectronic devices. HP said it was plan-ning to team up with Korean-basedchip-manufacturer Hynix Semicon-ductor to make memory chips frommemristors, which could be bothfaster and able to store more data thanconventional memory.

A circuit can be created using threestandard components: a resistor,which opposes the flow of charge; aninductor, which opposes any changein the flow of charge; and a capacitor,which stores charge. In 2008 research-ers at HP announced they had beenthe first to build a memristor – afourth fundamental element in integ-rated circuits first predicted by elec-tronics engineer Leon Chua fromUniversity of California, Berkeley –that can “remember” the amount ofcharge that has flowed through it andas a result change its resistance.

The memristors, made from a layerof titanium dioxide, will now be in-

cluded in silicon chips for resistiverandom access memory (ReRAM),which can store data even when theirpower supply is off. ReRAM couldeventually replace the flash memorythat is currently used in a range ofdevices from mobile phones to USBdrives. “We are going into this todisrupt the memory market,” saysStanley Williams of Hewlett PackardLabs in Palo Alto, California, who wasinvolved in producing the first mem-ristor. “Memristors are surprising uswith their capability and we still do not know everything that can be donewith them.” HP and Hynix aim tobring out the first memristor productsby 2013.Michael Banks

Hewlett-Packard brings ‘memristor’ to marketIndustry

Everlasting

memories

Hewlett-Packard,which firstannounced that ithad made amemristor in 2008,will now use it inmemory chips.

Sharp cuts in Pakistan’s science budget

have provoked condemnation from some

of the country’s top officials. Science

minister Azam Khan Swati attacked his

own government’s “myopic vision”, while

Higher Education Commission (HEC)

executive director Sohail Naqvi deplored

“a basic lack of appreciation of why

science, research and development, and

higher education are important to the

development of a country”.

The government’s budget for new

science projects has been cut by almost

20% to Rs 35.6bn (about £266m). This

figure includes funds allocated to atomic

energy, telecommunications and

agricultural research, as well as to the

HEC and the Ministry of Science and

Technology (MOST). The deepest cuts

have come at MOST, which saw funds for

new projects almost halved to Rs 1.64bn.

Civilian nuclear-science projects will also

receive about 25% less for capital

expenditure this year because of cuts in

the Atomic Energy Commission’s budget.

The picture is more complicated at the

HEC, which spends 70% of its budget on

scientific research and training. Ministry

of Finance figures indicate that the HEC’s

development budget for 2010–2011 will

be 15% lower than the amount earmarked

for similar projects last year. However,

only half of the funds promised in the

previous budget were ever released, Naqvi

says. As a result, “the big things are all

impossible now”, although some projects

with budgets of less than £65 000 will go

ahead, and the 9000 PhD students

supported by the HEC will still receive

their scholarships.

With large swathes of Pakistan

suffering from the effects of severe

flooding, some might question whether

the science budget should be a priority.

But Naqvi vehemently rejects that view.

“The flood problem is gigantic, but we are

only talking about a little money to

support us,” he says. “The irony is that the

flood problem was greatly aggravated by a

lack of science. Had proper satellite data

been used and controlled flooding been

done on a scientific basis, then we would

not be in the situation we are in.”

Margaret Harris

Funding

Pakistani officials denounce budget cutsThe irony is that the floodproblem was greatlyaggravated by a lack of science

HP

physicsworld.com News & Analysis

11Physics World October 2010

PWOct10news 20/9/10 16:47 Page 11

The Japanese government has an -nounced it is to build a hydroelectricoffshore power plant to test a varietyof ways of generating electricity fromwater. In addition to using waves orwater currents to power turbines inthe sea, the new facility will examinewhether the temperature differencebetween the upper and lower areas of the ocean can be used as a powersource. The technique will also beable to produce fresh water by de sa -lin ation and accumulate lithium foruse in batteries. The Japanese econ-omy, trade and industry ministry isnow seeking ¥1bn (£7.5m) in its 2011budget to begin construction, with atotal of ¥13bn earmarked for the pro-ject over the five years to 2015.

The project is based on ocean ther-mal energy conversion (OTEC) – atechnique that has been pioneered byengineer Haruo Uehara from theOrganization for the Pro motion ofOcean Thermal Energy Conversionin Saga. Based on the Uehara cycle,which he invented in 1994, the pro-posed plant would pump cold seawater at a temperature of about 5 °Cfrom 800 m below the surface into acondenser to liquidize ammonia. Thisfluid would then be sent into an evap-orator, situated a few metres below

sea level, which is heated to about25 °C with warm sea water. The vapor-ized ammonia gas could then be sentto a turbine to generate electricity. Itis estimated that the cost of this kindof power generation would be about¥8–20 per kilowatt-hour – similar tothat of wind power.

The steam that turns the turbinecould also be condensed and collectedas fresh water for human consump-tion, leaving only salt-water crystals asa by-product. According to Ue hara,once the system is up and running, thefresh water produced by the systemcosts less than $1 per cubic metre(1000 l). The OTEC system could alsocollect lithium – a material widelyused in batteries – via an absorption

column that gathers lithium fromdeep seawater. Lithium accounts for0.2 parts per million in seawater.

Interest in the technology is beingshown by the Pacific islands, whichcannot economically afford – or shun– using fossil fuels but which have verydeep local ocean locations with suf -ficient temperature differences. “Itworks well, especially in the southernPacific region where the tempera turedifference between the oceans sur-face and deep seawater is as much as24 °C,” says engineer Yasuyuki Ike -gami from Saga Univer sity, who hascarried out theoretical and experi-mental studies on OTEC.

Indeed, in February an OTEC pro -cess based on the Uehara cycle waschosen for use in a 10 000 kW plant to be built in the South Pacific islandof Tahiti. The Republic of Palau in the Western Pacific is also currentlyworking with researchers at SagaUni versity to construct a system thatcan produce enough drinking waterto meet the needs of some 20 000 resi -dents while also producing electri city.Saudi Arabia has also showed in -terest and is due to send a delegationto the university.Fred Myers

Tokyo

Energy

Japan trials power and fresh water from the oceansOcean power

Japanese engineerHaruo Uehara is theman behind theocean thermal energyconversion system.

Photographers shine a light on the universe

US photographer Tom Lowe has beatenhundreds of amateur and professionalphotographers from around the globe to winthe Astronomy Photographer of the Year 2010award run by the Royal Observatory inGreenwich and Sky at Night magazine. Lowe’swinning shot, “Blazing bristlecone”, whichsecured him the top prize of £1000, wastaken on 14 August 2009 and shows the star-riddled Milky Way arching over an ancientbristlecone pine tree, which can live to be5000 years old. The photo was taken in White Mountains, California, with a Canon 5DMark II camera and an exposure time of 32 s.The competition received in excess of 400 entries from more than 25 countries andwas split into three categories – Earth andspace, our solar system, and deep space –together with the young photographer award,which was won by Dhruv Arvind Paranjpye, 14,from India. Selected images are on show in afree exhibition at the Royal Observatory, whichruns until 27 February 2011.Michael Banks

Tom

Low

ephysicsworld.comNews & Analysis

12Physics World October 2010

Forthcoming institute conFerences December 2010 – september 2012

2010

14–16 December

condensed matter and materials

physics (cmmp10)

University of Warwick, Coventry, UKOrganised by the IOP Condensed Matter and Materials Physics Division

2011

4–7 April

iop nuclear and particle physics

Divisional conference

University of Glasgow, Glasgow, UK Organised by the IOP Nuclear and Particle Physics Division

4–7 April

iop Annual plasma physics conference

2011

Macdonald Marine Hotel and Spa, North Berwick, UKOrganised by the IOP Plasma Physics Group

4–7 April

microscopy of semiconducting

materials 2011 (msm-XVii)

Churchill College, Cambridge, UK Organised by the IOP Electron Microscopy and Analysis Group

4–7 April

18th interdisciplinary surface science

conference (issc-18)

University of Warwick, Coventry, UK Organised by the IOP Thin Films and Surfaces Group

10–14 April

13th international conference on

electrostatics

Bangor University, Wales, UK Organised by the IOP Electrostatics Group

13–15 April

Dielectrics 2011

University of Kent, Canterbury, UK Organised by the IOP Dielectrics Group

10–14 July

petrophase 2011

London, UK Organised by the IOP Liquids and Complex Fluids Group

11–13 July

the 9th international conference on

Damage Assessment of structures

St. Anne’s College, Oxford, UK Organised by the IOP Applied Mechanics Group

8–12 August

rutherford centennial conference

University of Manchester, Manchester, UK Supported by the IOP Nuclear Physics Group

4–9 september

14th european conference on

Applications of surfaces and interface

Analysis (ecAsiA)

Cardiff City Hall, Cardiff, Wales, UK Supported by the IOP Ion and Plasma Surface Interactions Group

6–9 september

electron microscopy and Analysis

group conference (emAg 2011)

University of Birmingham, UK Organised by the IOP Electron Microscopy and Analysis Group

12–14 september

physical Aspects of polymer science

University of Surrey, Guildford, UK Organised by the IOP Polymer Physics Group

12–14 september

sensors & their Applications XVi (s&A)

Clarion Hotel, Cork, Ireland Organised by the IOP Instrument Science and Technology Group

31 october – 4 november

27th general Assembly of iupAp

(2011)

Institute of Physics, London, UK Organised by the International Union of Pure and Applied Physics

2012

3–7 september

24th general conference of the

condensed matter Division of the

european physical society (cmD-24,

ecoss-29, ecscD-11)

Edinburgh, UK Organised by the EPS Condensed Matter Division

See www.iop.org/conferences for a full list of IOP one-day meetings

The conferences department provides a professional event management service to the IOP Groups and Divisions and supports bids to bring international physics events to the UK.

Institute of Physics, 76 Portland Place, London W1B 1NT, UK Tel +44 (0)20 7470 4800 E-mail conferences@iop.org

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Periodic Table of the Elements

1

2

3 4 5 6 7 8 9 10 11 12

13 14 15 16 17

18

1.00790.090-252.87

Hydrogen

H1

6.9410.54180.5

Lithium

Li39.01221.851287

Beryllium

Be4

22.9900.9797.7

Sodium

Na1124.3051.74650

Magnesium

Mg12

39.0980.8663.4

Potassium

K1940.0781.55842

Calcium

Ca20

85.4681.5339.3

Rubidium

Rb3787.622.63777

Strontium

Sr38

132.911.8828.4

Caesium

Cs55137.333.51727

Barium

Ba56

[223]––

Francium

Fr87[226]5.0700

Radium

Ra88

138.916.146920

Lanthanum

La57140.126.689795

Cerium

Ce58140.916.64935

Praseodymium

Pr59144.246.801024

Neodymium

Nd60[145]7.2641100

Promethium

Pm61150.367.3531072

Samarium

Sm62151.965.244826

Europium

Eu63157.257.9011312

Gadolinium

Gd64158.938.2191356

Terbium

Tb65162.508.5511407

Dysprosium

Dy66164.938.7951461

Holmium

Ho67167.269.0661497

Erbium

Er68168.939.3211545

Thulium

Tm69173.046.57824

Ytterbium

Yb70

[227]10.071050

Actinium

Ac89232.0411.721842

Thorium

Th90231.0415.371568

Protactinium

Pa91238.0319.051132

Uranium

U92[237]20.45637

Neptunium

Np93[244]19.816639

Plutonium

Pu94[243]–

1176

Americium

Am95[247]13.511340

Curium

Cm96[247]14.78986

Berkelium

Bk97[251]15.1900

Californium

Cf98[252]–860

Einsteinium

Es99[257]–

1527

Fermium

Fm100[258]–827

Mendelevium

Md101[259]–827

Nobelium

No102

44.9562.991541

Scandium

Sc2147.8674.511668

Titanium

Ti2250.9426.111910

Vanadium

V2351.9967.141907

Chromium

Cr2454.9387.471246

Manganese

Mn2555.8457.871538

Iron

Fe2658.9338.901495

Cobalt

Co2758.6938.911455

Nickel

Ni2863.5468.921084.6

Copper

Cu2965.397.14419.5

Zinc

Zn3069.7235.9029.8

Gallium

Ga3172.645.32938.3

Germanium

Ge3274.9225.73816.9

Arsenic

As3378.964.82221

Selenium

Se3479.9043.12-7.3

Bromine

Br3583.803.733-153.22

Krypton

Kr36

10.8112.462076

Boron

B512.0112.273900

Carbon

C614.0071.251-195.79

Nitrogen

N715.9991.429-182.95

Oxygen

O818.9981.696-188.12

Fluorine

F920.1800.900-246.08

Neon

Ne10

26.9822.70660.3

Aluminium

Al1328.0862.331414

Silicon

Si1430.9741.8244.2

Phosphorus

P1532.0651.96115.2

Sulphur

S1635.4533.214-34.04

Chlorine

Cl1739.9481.784-185.85

Argon

Ar18

4.00260.177-268.93

Helium

He2

88.9064.471526

Yttrium

Y3991.2246.511855

Zirconium

Zr4092.9068.572477

Niobium

Nb4195.9410.282623

Molybdenum

Mo42[98]11.52157

Technetium

Tc43101.0712.372334

Ruthenium

Ru44102.9112.451964

Rhodium

Rh45106.4212.021554.9

Palladium

Pd46107.8710.49961.8

Silver

Ag47112.418.65321.1

Cadmium

Cd48114.827.31156.6

Indium

In49118.717.31231.9

Tin

Sn50121.766.70630.6

Antimony

Sb51127.606.24449.5

Tellurium

Te52126.904.94113.7

Iodine

I53131.295.887-108.05

Xenon

Xe54

174.979.841652

Lutetium

Lu71178.4913.312233

Hafnium

Hf72180.9516.653017

Tantalum

Ta73183.8419.253422

Tungsten

W74186.2121.023186

Rhenium

Re75190.2322.613033

Osmium

Os76192.2222.652466

Iridium

Ir77195.0821.091768.3

Platinum

Pt78196.9719.301064.2

Gold

Au79200.5913.55-38.83

Mercury

Hg80204.3811.85304

Thallium

Tl81207.211.34327.5

Lead

Pb82208.989.78271.3

Bismuth

Bi83[209]9.20254

Polonium

Po84[210]–302

Astatine

At85[222]9.73-61.85

Radon

Rn86

[262]–

1627

Lawrencium

Lr103[265]––

Rutherfordiu

m104

[268]––

Dubnium

Db105[271]––

Seaborgium

Sg106[272]––

Bohrium

Bh107[270]––

Hassium

Hs108[276]––

Meitnerium

Mt109[281]––

Darmstadtium

Ds110[280]––

Roentgenium

Rg111[285]––

Copernicium

Cn112[289]––

Ununquadium

Uuq114

Solids�& Liquids (g/cm3)�Gases(g/l)

€

Melting�point�(Solids�&�Liquids)�•�Boiling�point�(Gases)

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Element Name

SymbolAtomic�weight

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AtomicNo.

advent-rm.comAdvent�Research�Materials�Ltd�•�Eynsham�•�England�OX29�4JA

ADVENT

[284]––

Ununtrium

Uut113[288]––

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Uup115[293]––

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Uuh116

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RESEARCH MATERIALS

[–]––

Ununseptium

Uus117[294]––

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For more information see:

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Speakers include:Prof. John Barrow FRS, Dr William CarrollDr George Coyne SJ, Prof. George Ellis FRS, Prof. Michał Heller, Revd Dr Rodney Holder, Prof. Helge Kragh, Prof. Dominique Lambert, Prof. Don Page, Revd Dr John Polkinghorne KBE FRS, Prof. Paul Shellard, Dr William Stoeger SJ, Prof. Keith Ward FBA

Celebrating Lemaître: cosmologist, priest and father of the Big Bang theory

What is your view on the current

energy situation?

Energy is a major problem for societyas a whole. Today, we use 10 times asmuch primary energy as we did whenI was born – and this cannot go on in-definitely. We will have to adapt. Butit takes a very long time to changehabits and things are becoming ur-gent. Everybody, including the oil in-dustry, is wondering what will happenwhen there is no oil and no natural gasleft – and no uranium either.

How do you see things developing?

A planet without any oil at all is prob-ably a long way off. But before then,we may be faced with a situation inwhich the demand for energy – mainlybecause of the growing needs of de-veloping nations – vastly exceeds sup-ply, thus triggering a serious ongoingfinancial crisis with oil prices risingout of control. Things will then getvery bloody because people will notaccept a situation of major need.Novel forms of energy will thereforebe necessary.

So where will we get our energy from?

In the long term there are only twoprimary sources that can meet ourdemands. One is the Sun – either di-rectly, for instance with concentratedsolar power, or indirectly throughwind, biomass or waves. The other isnuclear. But nuclear cannot be con-ventional nuclear energy based onuranium, which makes up only 6% ofprimary energy. If we carry on in thesame way, there will be no more en-ergy from nuclear than from oil ornatural gas. New methods to produceenergy from nuclei must be pursued.

But how can we boost investment in

energy research?

Pulling a barrel of oil out of theground in the Middle East costs just a few dollars, but the oil companiessell it for anything up to $100 or more.Governments then put huge taxes on top, sometimes doubling petrolprices. But what fraction of thatmoney goes back into energy re-search? Almost zero. Even ITER [thefusion facility being built in southernFrance, see p46] is costing us just a few

billion euros over 20 years, which istiny when you think that about thesame amount went on dealing withthe recent BP oil spill off the US coast.If even 1% of the money our govern-ments get from fuel taxes was investedinto research for new forms of energy,that would make a great difference.

Why are you so interested in thorium?

Simply because it involves nuclear re-actions that are much more effectivethan those in conventional nuclearreactors. For instance, to produce1 GW of electrical power in one yearfrom an ordinary reactor you needabout 200 tonnes of natural uranium.But to produce the same amount ofpower from thorium you need justone tonne of it. And thorium is aboutthree times more abundant on Earththan uranium; it is about as abundantas lead. Another advantage of thor-ium is that it is less of a proliferationthreat – there is a uranium bomb anda plutonium bomb, but no thoriumbomb can be produced.

How would an energy amplifier work?

The use of thorium has received a lotof attention from many scientists,such as Alvin Weinberg and Ed Teller.But the main drawback with thoriumis that you need two neutrons, ratherthan the one in ordinary uranium-powered reactions, to produce onefissile nucleus. It is a problem thatdemands new solutions and my con-tribution, which I first proposed about15 years ago, was to come up with apractical way of producing these addi-tional neutrons with the help of an

accelerator. In my energy amplifieridea, what you need to do is to fireneutrons – produced by bombardingprotons from an accelerator into aheavy-metal target – into thoriummetal or oxide. This converts thor-ium-232 nuclei into thorium-233. Itthen undergoes two beta decays tobreed uranium-233 – which is fissileand can produce energy.

So why has thorium not been more

successful so far?

One of the reasons is that the energyamplifier involves combining fissionwith accelerator physics. But theseaccelerator-driven systems have nowbecome a reality – there are hundredsof people around the world workingon them.

Does thorium have any other advantages?

Burning uranium creates plutoniumand long-lived minor actinides such asamericium, neptunium, curium andso on, which last for millions of years,as well as fission fragments, like stron-tium and caesium, which have a half-life of about 30 years. The actinideswill be a serious problem for futuregenerations. But thorium machinesburn all the actinides completely sincethey become the seeds of the next stepof the fission. For the theoretical caseof a well-conceived energy amplifier,the actinides would be completelyburned until all the thorium has goneand all you are left with as waste areshort-lived fission fragments. Theywould be hot for just a few centuriesand, after storing them in a “secular”repository under surveillance andnear the surface, they could be re-turned to the environment after theyhave fully decayed.

So would energy amplifiers remove

the need for long-term underground

waste repositories?

Today’s nuclear reactors have pro-duced – and will continue to produce– a huge amount of waste, particularlyplutonium. But with an energy ampli-fier, the accumulated plutonium couldinstead be used at the start of the cycleto activate the thorium-driven reactor.The energy amplifier would thereforealso be a net plutonium destroyer.

Accelerating ahead

Carlo Rubbia hasproposed a practicalway of generating theneutrons needed toburn thorium.

The actinidescreated byburninguranium will be a seriousproblem forfuturegenerations,but thoriummachines willburn all theactinidescompletely

Matin Durrani catches up with Nobel-prize-winning particle physicist Carlo Rubbia to find out progresson his plans for an “energy amplifier” that can extract energy from thorium

Q&A

Burning ideas of a nuclear visionary

Mat

in D

urra

ni

physicsworld.com News & Analysis

15Physics World October 2010

PWOct10news 20/9/10 16:47 Page 15

Rising abruptly out of the flat barrenNevada desert 160 km northwest ofLas Vegas lies a long ridge that stret-ches for several kilometres. The ridge,which is about a kilometre high, wascreated by eruptions from a calderavolcano – a cauldron-like featureformed by the collapse of land follow-ing a volcanic eruption. Known asYucca Mountain, the formation iscomposed entirely of a rock madefrom consolidated volcanic ash calledignimbrite or “tuff”.

While the violent volcanic eruptionsthat formed the mountain ended anestimated 12 million years ago, thearea has more recently been troubledby threats of a different kind. Lying a few kilometres away from YuccaMountain is the Nevada Test Site area,where the US military conductedsome 904 atomic bomb tests between1945 and 1992. And for the last 30years the mountain has been the primechoice for a US national repository tostore radioactive waste from the coun-try’s 104 nuclear reactors.

First proposed in the 1970s, theYucca Mountain nuclear repositorycould – if it were built – store about77 000 tonnes of nuclear waste via 100 kilometres of tunnels – each 7.5 mwide dug into the base of the moun-tain. The US government has so farspent some $9.5bn on the YuccaMountain repository – about 15% ofthe project’s total estimated cost.Most of this money has gone on con-structing a 8 km U-shaped test tunnelthat was excavated to conduct experi-ments on the hydrology and geologyof the site.

But despite soaking up so muchcash, the project has endured a roughride politically (see box). A big hitchcame in the 2009 US budget, whichsaw President Barack Obama allo-cating just $68.6m to the nuclear-repository programme, run by theDepartment of Energy (DOE). Thisfigure was £49m less than in 2008 andeffectively sounded the death knellfor Yucca Mountain, with US sec-retary of energy Steven Chu quotedas saying that the repository was “offthe table”. Obama has now set up a“blue ribbon” commission to lookinto long-term storage options fornuclear waste. These politically inde-

pendent commissions are often ap-pointed by the government to reporton a controversial subject.

Yet Yucca Mountain still remainsthe only site in the US that is goingthrough the process of gaining a li-cence to store waste from nuclear re-actors in a deep geologic repository.Indeed, some say the licensing is nownot based on site suitability alone butmore on the politics of nuclear-wastemanagement. “The original decisionto select the Yucca Mountain site andthe recent decision to take it off thetable were both political,” says Rich-ard Lester, head of the department ofnuclear science and engineering at the Massachusetts Institute of Tech-nology (MIT) and director of its In-dustrial Performance Center. “It isunfortunate that politics has driventhese important decisions to this ex-tent,” he says.

Rod Ewing, a geologist at the Uni-versity of Michigan who in the 1990swas asked by the DOE to study hownuclear spent fuel at Yucca Mountainrepository would interact with itsenvironment, says the project is be-tween the proverbial rock and a hardplace. “At the moment no-one reallyknows what is going to happen toYucca Mountain, even the long-termdisposal of nuclear waste in the coun-try is up in the air,” he says. Politiciansmay think they have some breathingspace as existing waste can sit at reac-tor sites for decades, but it is expectedthat by 2020 the US will already havecreated more nuclear spent fuel at itsreactors than the Yucca Mountain re-pository could handle in total, even ifit were built.

Testing timesThe US has a total of 57 000 tonnes of high-level nuclear waste, which isstored at most (although not all) ofthe country’s reactor sites. This high-level waste consists of fission productsand transuranic elements – those thatare heavier than uranium and canhave half-lives from a few to millionsof years. It is stored in dry casks – 4 m-high steel cylinders that are sur-rounded by concrete and filled withan inert gas such as argon. Inter-mediate-level waste, such as fuelcladding, and low-level waste, such asgloves and clothing worn by workersat nuclear plants, is in contrast mostlystored in canisters and put in shallowunderground storage facilities.

Yucca Mountain would only dealwith spent nuclear fuel and high-levelwaste, specifically from commercialnuclear reactors. This fuel, whichwould initially be put into stainless-steel containers and stored in engin-eered vaults or wet storage pools onthe reactor sites, would be trans-ported by rail from the various re-actors around the country to YuccaMountain. When it arrives, the wastewould then be transported by a systemof robotic railcars and cranes that feedthe waste into the tunnels for storage.

Any nuclear waste destined forYucca Mountain would first be storedat the site of the reactor that producedit for about 40–60 years before beingtaken to Nevada. This is because thespent fuel is initially very radioactive,and possibly “hot” enough to boilgroundwater. If the waste were to beplaced underground straight away,then this could create steam thatopens cracks in the rocks – particularlyimportant at Yucca Mountain giventhat tuff is slightly permeable to water.

But even if Yucca Mountain weregiven the go-ahead now, many believethat there are still lots of technical is-sues that need to be studied. As Lesterpoints out, there has been volcanicactivity in the area over timescalescomparable to that of the regulatorycompliance period. “At Yucca Moun-tain it is a challenge to understand thebehaviour of spent fuel in an oxidizingenvironment,” says Ewing.

There are also plenty of politicalchallenges too. Indeed, given the cur-rent political impasse, any required li-censing to operate a repository wouldcome up against stiff opposition,especially from senate majority leaderand Democrat Harry Reid from Ne-vada, who claims that Yucca Moun-tain is not a safe site and that it wouldthreaten the health and safety ofNevadans. “As long as senator Reid is

A wasted opportunity?As US President Barack Obama axes funding for a national nuclearrepository at Yucca Mountain in Nevada, Michael Banks looks at whatlessons have been learned for nuclear-waste storage

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Waste ground

The US governmenthas already spent$9.5bn on the Yucca Mountainnuclear-wasterepository in Nevada.

Why should wedelay and thenmake futuregenerationsclean up our mess?

physicsworld.comNews & Analysis

16 Physics World October 2010

PWOct10news 20/9/10 16:48 Page 16

repositories dotted around the coun-try that could be about the same sizeof WIPP rather than a large one suchas Yucca Mountain. “Waste is a bigissue for the nuclear industry and weneed to show that we are makingprogress,” says Macfarlane. “Whyshould we delay and then make futuregenerations clean up our mess?”

Indeed, whatever the outcome ofthe blue-ribbon commission, the USstill needs a site, which will take manyyears of further political bargaining.Both Macfarlane and Forsberg saythat any future repository would needthe support of local residents whoneed to be involved at all times.Others warn the saga has hit not justthe public’s opinion of Yucca Moun-tain, but of nuclear-waste manage-ment in general, which could hamperfuture plans to put a repository else-where. “It is not so much that YuccaMountain has now been lost,” saysEwing. “But rather the whole credi-bility of the process.”

in office, then the project will not goforward,” says Lester. “But in the endthe need to have a nuclear repositorywill far outlast Reid’s career.”

Setting examplesYucca Mountain is not the first nuc-lear repository in the US. The DOEalready operates the Waste IsolationPilot Plant (WIPP), located 42 kmeast of Carlsbad, New Mexico, whichis licensed to store transuranic wastefrom the research and production ofnuclear weapons by the US Depart-ment of Defence. At WIPP, waste isplaced in rooms located 650 km un-derground in a salt mine. Operationbegan in 1999 and the repository hasa regulatory period of 10 000 yearswith disposals until 2070.

The technical lessons of WIPP forYucca Mountain, however, may befew and far between, as WIPP is con-structed within a salt formation ratherthan in volcanic tuff. But what is lostin technical lessons is gained in po-litical ones. The state body of NewMexico was widely consulted beforeconstructing WIPP, as were local resi-dents. In contrast, many lament theway the US Congress announced in1987 that a repository would be lo-cated in Nevada, which does not haveany reactors, without consulting thepublic first. “What is hoped is that the government has learned that youcannot force these repositories onpeople,” says MIT nuclear engineerCharles Forsberg, who is also execu-tive director of MIT’s nuclear-fuel-cycle study. “This is why the US isbehind in long-term storage of nuc-lear waste.” Forsberg adds that otherrepositories in Europe have involvedthe public more readily, notably the Olkiluoto repository in Finland,which is under construction and ex-pected to start taking waste in 2020.

Allison Macfarlane, a geologistfrom George Mason University whois serving on the blue-ribbon commit-tee, says there are differences in howEuropean nations and the US havegone about implementing nuclear-waste repositories. “In the US, statesare very powerful and in most caseshave had the final say,” says Mac-farlane, who would not comment onthe specifics of the Yucca Mountainsite. “But let’s not kid ourselves, othercountries have also had their hiccupsalong the way.”

Fuel cycles for the futureThe remit of the 15-member blue-ribbon committee, which is set toreport its findings in 2012, may disap-point some as it will not be looking at

alternative repository sites to YuccaMountain. Instead, the committee isexpected to examine different optionsfor long-term storage, for example dif-ferent rock types. It will also conducta “comprehensive review of policiesfor managing the back end of thenuclear fuel cycle”, which will includestudying alternatives for the storage,processing and disposal of civiliannuclear waste.

The commission may recommendattempting to recycle some of thespent fuel before it is put into long-term storage. At the moment all of thespent fuel would be buried, but de-pending on the reactor type, up to 80–90% of the original uranium oxidecould be recycled, with some reactortypes, such as fast-breeder reactors,breeding their own fuel. This wouldmean that the only waste that needsto be stored would be long-lived ac-tinides. Another option, which hasbeen suggested by energy secretaryChu, could be to have many smaller

It was in 1982 that the US Congress established anational policy to solve the problem of nuclear-wastedisposal. The Nuclear Waste Policy Act made nuclear-power companies pay a 10th of a cent for everykilowatt-hour of energy their reactors generated into anuclear-waste trust fund, which the government woulduse to build a long-term storage facility. The act alsomade the US Department of Energy (DOE) responsiblefor finding a site for a geological repository. In 1986 theDOE began looking into Yucca Mountain as a storagefacility along with two others – Hanford in Washingtonand Deaf Smith County in Texas. In 1987 Congressamended the Nuclear Waste Policy Act to designateYucca Mountain as the sole repository to be studied.

In 1997 a 8 km U-shaped test tunnel was excavatedto conduct experiments on the hydrology and geologyof the site. The site was then recommended by the DOEto President George W Bush in 2002 and in 2006 theDOE proposed that the facility would be ready in 2017to begin accepting waste. But following the 2009 USbudget, which cut the DOE’s budget for its nuclear-repository programme by £49m, the DOE then

withdrew its licence application to build and operatethe repository at Yucca Mountain. This caused a seriesof lawsuits to be filed by the nuclear industry, as well asstates including Washington state. The cost of delays tostoring the waste is now costing the US governmentabout $500m every year.

The latest twist in the 30-year saga came in Junewhen a panel of judges at the Nuclear RegulatoryCommission (NRC), which carries out reactor licensingand oversees nuclear-waste management, ruled thatthe DOE could not withdraw the licence. The project hasalso been dogged by other controversies. In 2006criminal charges were brought against threegovernment researchers who allegedly falsifiedresearch data on how water infiltrates within Yucca Mountain. The investigation, which waseventually dropped, focused on e-mails in whichresearchers wrote about using “fudge factors” and thekeeping of multiple sets of notebooks, one to keepauditors happy and one for themselves. Thecontroversy caused DOE to delay the project anddouble-check the research.

The rocky road to Yucca Mountain

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physicsworld.com News & Analysis

17Physics World October 2010

PWOct10news 20/9/10 16:48 Page 17

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Seeking hard data on gender biasI am disappointed that Physics World treatsAmy Bug’s research on unconscious biasagainst female physicists as “significant”and able to provide “hard data” on genderbias in physics. Her article “Swimmingagainst an unseen tide” (August pp16–17)describes an experiment in which fouractors – two male, two female – gaveidentical lectures and then had theirteaching ability rated by 126 students.

But however identically actors arecoached, their teaching ability in thiscontext will still be distributed in some(possibly narrow) range. If we start with thenull hypothesis that men and women showan equal distribution of teaching abilities,we can then treat the four individuals asindependent and identical draws from thisunknown teaching-ability distribution.

There are thus six equally likely rankingsfor teaching ability: MMFF, MFMF,MFFM, FMMF, FMFM and FFMM,where in each case the actors are rankedfrom strongest to weakest and M and Frepresent “male” and “female”. The firsttwo outcomes would indicate that menwere stronger teachers, while the last twowould indicate that women were stronger;conclusions drawn from the others woulddepend on the details of the distribution.

The principles of basic statistics indicatethat any outcome in this experiment canonly provide a p-value (roughly, a measureof how much evidence we have against thenull hypothesis) of greater than or equal to33% (2/6 for a two-tailed test). This is not ap-value that is typically thought to bedistinguishable from random chance, sowith this sample size we would not be ableto reject the null hypothesis that theteaching abilities of men and women areidentically distributed.

The experimental procedure described isinteresting, but many more actors will needto be recruited, trained and tested beforethe experiment provides strong evidencefor a gender bias in teaching ability.Edward Ratzen

Cheltenham, UK

Amy Bug (abug1@swarthmore.edu) replies:

We considered using more actors, but as wewere designing our study, we learned thatthis type of experiment characteristicallyuses only one actor of each “type”. Forexample, a recent study on customer-service representatives (D R Hekman et al.2010 The Academy of Management Journalat press) used one white man, one whitewoman and one black man. The reason forthis is that, statistically speaking, feweractors means a smaller “error variance”.

Our experimental design precluded anydifference in the knowledge of physicsexhibited by the “professors”, and anydifference in the words spoken or symbolschalked on the board. This eliminatedvariability in the lecture’s intellectualcontent. By using actors of the same race,matched for attractiveness and quality ofacting CV, and rehearsing them in a groupsetting, we tried to homogenize someperformative aspects of their lectures aswell. As a result, our null hypothesis wasthat student responses would be statisticallyindistinguishable among actors.

This null hypothesis was, in fact, upheldfor the three summary questions aboutoverall quality – but only for the femalestudents. According to them, both thelecture and lecturer were of uniformquality, irrespective of the actor’s gender.The male students disagreed, preferringthe male actors. The fact that opinionswere divided sharply along gender linessuggests that a distribution of teaching/acting ability among the actors is not acompelling explanation for our results.

Our statistical tools for demonstratingthis are common ones in the socialsciences: the t-test and the analysis ofvariance (ANOVA). These do notcalculate the likelihood that an ordering ofpreferences, like MMFF, will occur bymere chance. Instead, they test how likelyit is for the group means (in our case the

scores given to a professor averaged overthe number of students who saw him/her)to differ quantitatively by the amount seenif the null hypothesis is true. These testsdeliver a p-value, which shows that if wetried the experiment many times with newsubjects, then we would expect differencesof this magnitude to emerge by chanceonly in a fraction p of the trials.

From the t-test we saw that professorgender had a marginally significant( p = 0.10) effect on mean score. However,the effect became highly significant( p < 0.01) when only male studentresponses were included. This suggesteduse of our second tool, the ANOVA, whichrevealed that the independent variables ofprofessor gender and student gender“interacted” to a significant degree. Inother words, the value of one of thesevariables meaningfully influenced whattranspired when the other was varied.

Other studies have shown that the resultsof real-world evaluations are sometimesconfounded by many factors, not justgender. For example, in 2003 a pair ofresearchers at University of Texas at Austinfound that students considered a better-looking man to be a better professor (D S Hamermesh and A M Parker 2003Working paper 9853, National Bureau ofEconomic Research). So does an attractivephysical presence merely enhance the“performance” aspect of teaching? Or aremore attractive people truly capable ofproducing better intellectual content, viasome interplay between genetics and lifetrajectory? Our study effectivelyeliminated the latter as a possibleexplanation – but in the context of gender,rather than beauty.

Finally, the ranking orders we found inour study – MMFF when male studentswere queried or MFMF when all studentswere queried – might strike some readersas suggestive, and others as statisticallyunimpressive. Both notions are defensible.Yet analysing the rank order was not part ofour procedure. Furthermore, no singlestudy like ours can guarantee that gender isa causative factor rather than, say, theblond hair of our most popular male versusthe black hair of our least popular female.Such determinations can be made, though,as a body of research grows. This is howscience progresses. When our results arepublished in full, we sincerely hope thatthey will make a useful contribution.

Correction

We stated in September (p8) that theastrophysicist Giovanni Bignami was thefirst European to be elected president ofthe Committee on Space Research(COSPAR). He was in fact the firstEuropean to be elected as COSPARpresident in a contest that was also open toAmericans and Russians.

Letters to the Editor can be sent to Physics World, Dirac House, Temple Back, Bristol BS1 6BE, UK, or to pwld@iop.org. Please include your address and a telephone number. Letters should be no more than500 words and may be edited. Comments on articlesfrom physicsworld.com can be posted on the website;an edited selection appears here

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19Physics World October 2010

PWOct10feedback 17/9/10 10:03 Page 19

Oh, God. Yes, the debate about science and

religion has kicked off once again, this time

thanks to Stephen Hawking and Leonard

Mlodinow’s new book The Grand Design

(2 September “God and the god particle”;

3 September “Talking Hawking and God”;

8 September “M-theory, religion and science

funding on the BBC”). The book is chiefly about

M-theory, but as one astute commenter pointed

out (thanks Balajee) “the media does not have

the slightest clue about the mind-boggling

mathematics involved in even considering this

theory”. So, most reports have focused on the

authors’ claim that M-theory makes belief in God

unnecessary. Are they right? Wrong? Or are

Hawking and Mlodinow just trying to sell books?

The majority of scientists today adhere to Karl Popper’s dictum that all scientific propositionsought to be falsifiable. Thus the statement “Godexists” as well as its opposite “God doesn’t exist”do not constitute scientific propositions becausethey are both non-falsifiable. They simply representpersonal opinions or beliefs. Why should the beliefof a famous scientist enjoy such publicity, whereasa famous footballer’s should not? I am afraid whatwe are talking here is simply high-stakes businessand, if so, I ask myself: who pays for all of this?Dionysios G Raftopoulos

There’s absolutely no scientific evidence for M-theory, the anthropic principle or the multiverse.These are speculative hypotheses with as muchsupporting evidence as heaven and hell and thesweet baby Jesus. This isn’t science versus religion,this is M for moonshine.John Duffield

All you smart people seem to forget one thing. M-theory didn’t just come about because a bunchof physicists looked up at the sky and decided thatit felt right, or that it was the only thing that madesense. Many years of research went into this. Whatboggles my mind is how vehemently the religiousand semi-religious among you are willing to attackHawking and his theories, but no-one wants to dothe same to religious beliefs that have more holesin them than any scientific theory.Santino Barile

The “God” hypothesis (it doesn’t begin to qualify asa theory) makes no predictions, lacks internalconsistency and has never explained any aspect ofour existence in a non-tautological way.Duwayne Anderson

I am pretty sure that Hawking is well aware thatthere is little experimental evidence to back up M-theory. But communicating science is not justabout disseminating only the well-established facts– it is about informing people about cutting-edgeresearch, often speculative and uncertain, wherescientists themselves disagree. And this is the mostexciting thing about it.Alex

Most Christians accept that humans came intobeing through evolution, and were thus the indirectresult of an earlier creative act. If that is accepted, I don’t see how it is a significant threat to religiousfaith to have God create the space–time continuumand let matter and energy be created indirectly, asthe natural result of a vacuum fluctuation.John Savard

Hawking is a physicist, not a theologian. I will readhis book to find out why he has settled on M-theoryas fact. I shan’t worry about his views on God.Tom of the Sweetwater Sea

Elsewhere on physicsworld.com, commenters

preferred to focus on the truly important things

in life – like why so many films are full of bad

physics. Judging from the online response, our

review of the website Insultingly Stupid Movie

Physics (Physics World September p45) brought

back plenty of fond and not-so-fond memories.

I was always disturbed by pictures of Supermanwith his arm stretched out, holding up an enormousweight. I can conceive that someone might bestrong enough to lift such a weight, but to avoidfalling over, Superman would need almost infiniteweight himself.andrew.hooper, UK

And isn’t it wonderful how computers [in films] bootup instantly and the hero knows every availableprogram and can type faster than a whirlwind?robertdevos

Science fiction is absolutely accurate. I know howto get into all NORAD and NATO computers atlightning speed via dial-up modem with no userguide and no training. Hey, I can even get into theplans for every building in our city and interpretthem to permit rescue of the hostages! With myskills and expertise, why do we need universities?Errol, Australia

I think this is what is meant by artistic liberty.jamesroy

Even if current physics says an effect is nonsense,you cannot use that to say the effect cannot occur.Recent steps in metamaterials with negativerefractive indices show that some things that wereonce “obviously” impossible are not impossible atall. Also, I had an MRI done long ago by one of thethen brand-new devices. It sounded exactly like thesound effects in the movies Gog and Earth VersusThe Flying Saucers – the magnetic generators didindeed generate those “cheesy” sci-fi soundeffects. I will never doubt a sci-fi movie again!Nathan Okun, US

Read these comments in full and add your own atphysicsworld.com

Comments from physicsworld.com

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20Physics World October 2010

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Nuclear power

This special issue of Physics World examines the challenges in store for nuclear power

From breathless early excitement at an energy source that could be “too cheapto meter” to the fear and suspicion following the accidents at Three Mile Islandand Chernobyl, nuclear power has always aroused strong feelings. Some see it asthe ideal carbon-free energy source – a proven technology that will play a key rolein our future energy supply. Others, however, regard nuclear power as dirty, dan-gerous, costly and uneconomic, as our special debate makes clear (p24). And, ofcourse, it has always had to live – fairly or unfairly – in the shadow of the nuclearbomb (p28).

But there are signs that nuclear power could make a dramatic comeback. Coun-tries such as Germany, Italy, Sweden and the UK (p26) are dusting off nuclearplans, extending the lifetime of existing plants, or reversing previous decisions tohalt any new stations, which could be good news for physicists looking for a job(p60). In the short term, any new plants are most likely to be pressurized-waterreactors – the most common current variety of light-water reactor (p38). But longerterm, the nuclear industry is eyeing up a range of six alternative reactor designs,going under the banner generation-IV (p30). Technically fascinating, the reactorspromise much, although hurdles remain before any are ever built.

This special issue of Physics World also examines the prospects for energy fromfusion, focusing on the ITER facility being built in southern France (p46). Weweigh up India’s ambitious “three-stage” nuclear vision, which seeks to exploit thecountry’s vast reserves of thorium as an alternative to uranium (p40). And online,check out physicsworld.com for upcoming video interviews with ChristopherLlewellyn Smith – former chair of ITER’s council – and with Melanie Windridge,who is spreading the message of fusion via this year’s Institute of Physics’ SchoolsLecture. Our view is that, despite the challenges, particularly of waste (p15, p16and p55), nuclear power deserves a significant place in the energy mix.Matin Durrani, Editor of Physics World

The contents of this magazine, including the views expressed above, are the responsibility of the Editor. They do not represent the views or policies of the Institute of Physics, except where explicitly stated.

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The road ahead

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23Physics World October 2010

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There are no universal truths in a complexquestion such as the future role of nuclearpower. Each country has a unique energysupply and demand pattern. At one extreme,France gets over 80% of its electricity fromfission reactors, so the country would find italmost impossible to do without nuclearpower on any realistic timescale. At the otherextreme, countries such as Australia, Por-tugal and Norway have no commercial re-actors and limited capacity to develop thetechnology quickly, so it would take decadesfor them to develop a nuclear-power in-dustry. Most countries belonging to the Or-ganisation for Economic Co-operation andDevelopment, such as the UK, are some-where between those two extremes.

The only reason anyone would even con-sider building nuclear power stations in anation that does not already have any is therecognition that climate change is a seriousthreat to our future. A decade ago, nuclearpower was widely seen as a failed technol-ogy. Originally hailed as cheap, clean andsafe, after the Chernobyl accident it wasseen as expensive, dirty and dangerous. Thepeak of nuclear-power installation hap-pened more than 20 years ago. Since then,cancellations and deferments have out-numbered new constructions.

If nuclear power were the only effectiveway of slowing climate change, then I wouldsupport it. However, we would have to put ahuge effort into managing nuclear waste.That problem is, in principle, one that wecould eventually solve. Storing the currentwaste is a technical problem, while it is poss-ible in principle to design reactors that couldburn materials that are now seen as waste.But even if it were solved, I would remaindesperately worried about the proliferationof nuclear weapons, as this is a social andpolitical problem with no apparent prospectof a solution. Fortunately, we may not haveto face that terrible dilemma as there areother, much better, ways of moving to a low-carbon future.

Nuclear-waste risksNuclear power is certainly not a fast enoughresponse to climate change. In Australia, forexample, a strongly pro-nuclear governmentcommittee concluded that it would take 10–15 years to build one nuclear reactor fromscratch. It proposed a crash programme of25 reactors by 2050 but then calculated thatthis would not actually reduce Australia’scarbon-dioxide emissions; it would only slowthe growth rate.

Nuclear power is also expensive. In mostcountries, there have to be direct or indirect

public subsidies to make the nuclear optionlook competitive. Applying a carbon priceof about £30 per tonne of carbon dioxideemitted by fossil-fuel power stations wouldmake fossil-fuel electricity more expensiveand make nuclear look more attractive, butit would also improve the relative economicsof a wide range of renewable supply options.It might be true, as optimists assure us, thata promised new generation of reactorscould deliver cheaper electricity, but we can-not afford to delay tackling climate changefor decades.

While modern nuclear power stations donot have the technical limitations of theChernobyl reactor, there will always remainsome risk of accidents. There is communityanxiety about nuclear energy because anaccident at a nuclear power station poses amuch more serious risk than an accident atany form of renewable-energy plant. Sincenobody has yet demonstrated the safe andpermanent management of radioactivewaste from nuclear power stations, we canonly give the public assurances that the prob-lem will be solved in the future.

There also does not seem to be any realprospect of stopping the proliferation of

nuclear weapons. Only five nations hadnuclear weapons when the Non-Prolifer-ation Treaty was drafted in 1970. Today,however, there are nearly twice as many,while a further group of countries has thecapacity to develop weapons. The morecountries that use nuclear technology, thegreater is the risk of fissile material beingdiverted for weapons. Indeed, MohammedEl Baradei, the former head of the Inter-national Atomic Energy Agency, told theUnited Nations that he faced the impossibletask of regulating hundreds of nuclear in-stallations with the budget of a city policeforce. His agency documented countless ex-amples of attempts to divert fissile materialfor improper purposes. There is a real riskof unaccountable military regimes, roguedictators or even terrorists having eitherfull-scale nuclear weapons or the capacityto detonate a “dirty bomb” that could makean entire city uninhabitable.

The fundamental point is that there arebetter alternatives. Australian, Europeanand global studies have concluded that wecould reduce demand dramatically – not byturning out the lights, but simply by impro-ving the efficiency of turning energy intoservices such as lighting – and get all ourelectricity from a mix of renewables by 2030. That is a more responsible approachto tackling climate change. The clean-energy strategy is quicker, less expensiveand less dangerous and there is no risk fromterrorists stealing solar panels or wind-turbine blades! A mix of renewable supplysystems would decentralize energy produc-tion, thus making societies more resilientand better insulated against natural disas-ters or terrorist action. We also know how todecommission wind turbines and solar pan-els at the end of their life, at little cost andwith no risk to the community. So the ques-tion for pro-nuclear advocates is, as Austra-lian political analyst Bernard Keane put it,“Why should taxpayers fund the most ex-pensive and slowest energy option when somany alternatives are significantly cheaperand pose less financial risk?”

● Both authors contributed to a new bookWhy vs Why: Nuclear Power outlining the case for and against nuclear energy(2010, Pantera Press)

Nuclear power: yes or no?

Ian Lowe is president of the AustralianConservation Foundation and aclimate scientist at Griffith University,e-mail i.lowe@griffith.edu.au

Decision time Is nuclear power the best idea?

There is no risk fromterrorists stealingsolar panels or wind-turbine blades

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physicsworld.comNuclear power: The big question

24 Physics World October 2010

PWOct10forum1 16/9/10 15:14 Page 24

As China, India and other populous de-veloping nations expand their economies,with the very human aim of improving theprosperity and quality of life enjoyed by theircitizens, the global demand for cheap, con-venient energy is growing rapidly. If thisdemand is met by fossil fuels, then we areheading for both an energy-supply bottle-neck and, because of the associated massivecarbon emissions, a climate disaster.

Ironically, if climate change is the “incon-venient truth” facing high-energy-use, fossil-fuel-dependent societies such as the US,Canada, Australia and many countries in theEuropean Union, then the inconvenientsolution staring back is advanced nuclearpower. The answer does not principally liewith renewable energy sources such as solarand wind, as many claim. However, thesetechnologies will likely play some role.

There is a shopping list of “standard ob-jections” used to challenge the viability ordesirability of nuclear fission as a clean andsustainable energy source. None of thesearguments stands up to scrutiny. Opponentsclaim that if the world ran on nuclear energy,then uranium supplies would run out in thecoming decades and nuclear power plantswould then have to shut down. This is false.Uranium and thorium are both more abun-dant than tin; and with the new generationof fast-breeder and thorium reactors, wewould have abundant nuclear energy formillions of years. Yet even if the resourceslasted a mere 1000 years, we would haveample time to develop exotic new futureenergy sources.

Going nuclearCritics argue that past nuclear accidents suchas Chernobyl mean that the technology isinherently dangerous. However, this simplyignores the fact that nuclear power is alreadyhundreds of times safer than the coal, gas and oil we currently rely on. A study of 4290energy-related accidents by the EuropeanCommission’s ExternE research project, forexample, found that oil kills 36 workers perterawatt-hour, coal kills 25 and that hydro,wind, solar and, yes, nuclear, all kill fewerthan 0.2 per terawatt-hour. Moreover, innuclear reactors the passive safety featuresdo not rely on engineered intervention andso remove the chance of human error, ma-king it impossible to have a repeat of seriousaccidents. For example, in an emergency in the core cooling tank of a Westinghouse AP-1000 third-generation nuclear powerplant, water is channelled into the reactorcore by gravity, rather than by electric pumps.

Some contend that expanding commer-

cial nuclear power would increase the riskof spreading nuclear weapons. First, this hasnot been true historically. Furthermore, themetal–fuel products of modern “dry” fuelrecycling using electrorefining, which aredesigned for subsequent consumption infast reactors, cannot be used for bombsbecause it is not possible to separate pureplutonium from the mix of uranium andminor actinides. Potential bomb-makerswould get only a useless, dirty, contamin-ated product in a mix of heavy metals.Indeed, burning plutonium in fast reactorsto generate large amounts of electricitywould take this material permanently out ofcirculation, making it the most practical andcost-effective disposal mechanism imagin-able. Those opposed to nuclear energy alsoclaim that it leaves a legacy of nuclear wastethat would have to be managed for tens ofthousands of years. This is true only if we donot recycle the uranium and other heavy“transuranics” metals in the waste to extractall their useful energy.

At present, mined uranium is cheap. Forlight-water reactor technology, the total fuelcosts – including mining, milling, enrich-ment and fuel-rod fabrication – is £13m agigawatt per year. In unit-cost terms, thatworks out at 0.13p a kilowatt-hour foruranium oxide at a price of £45 per kilo-gram. However, in the longer term a once-through-and-throw-away use of nuclear fuelmakes no economic sense. This is becausesuch “open” fuel cycles not only leave a leg-acy of having to manage long-lived actinidewaste, but they also inefficiently extract lessthan 1% of the energy in the uranium. Feed-ing nuclear waste into fast reactors will use all of the energy in uranium, and liquid-fluoride thorium reactors will access theenergy stored in thorium, which works outas an 160-fold gain!

After repeated recycling, the tiny quantity

of fission products that would remain wouldbecome less radioactive than natural gran-ites and monazite sands within 300 years. Toclaim that large amounts of energy (thusgenerating greenhouse gases) would be re-quired to mine, process and enrich uranium,and to construct and later decommissionnuclear power stations simply ignores awealth of real-world data. Authoritative andindependently verified whole-of-life-cycleanalyses in peer-reviewed journals have re-peatedly shown that energy inputs to nuclearpower are as low as, or lower than, wind,hydro and solar thermal, and less than halfthose of solar photovoltaic panels. That istoday’s reality. In a future all-electric society– which includes electric or synthetic-fuelledvehicles supplied by nuclear power plants –greenhouse-gas emissions from the nuclearcycle would be zero.

Embracing nuclear energyFinally, when all other arguments have beenrefuted, critics fall back on the claim thatnuclear power takes too long to build or istoo expensive compared with renewableenergy. These arguments are perhaps themost regularly and transparently false argu-ments thrown up by those trying to blocknuclear power from competing on a fair andlevel playing field with other energy sources.Many environmentalists believe that the bestlow-carbon solution is for governments toguide us back to simpler, less energy-con-suming lives. Notions like that are unrealis-tic. The world will continue to need energy,and lots of it. But fossil fuels are not a viablefuture option. Nor are renewables the mainanswer. There is no single solution, or silverbullet, for solving the energy and climatecrises, but there are bullets, and they aremade of uranium and thorium – the fuelsneeded for nuclear plants.

It is time that we embraced nuclear en-ergy as a cornerstone of the carbon-freerevolution we need in order to address cli-mate change and long-term energy securityin a world beyond fossil fuels. Advancednuclear power provides the technologicalkey to unlocking the awesome potential ofthese energy metals for the benefit of hu-mankind and for the ultimate sustainabilityof our society.

The world is caught between providing enough energy for its citizens and fighting climate change byburning less fossil fuel. Ian Lowe says that climate change can only be tackled by using renewableenergy sources, while Barry Brook argues that nuclear power offers the only alternative to fill thisimpending energy gap

Barry Brook holds the Sir HubertWilkins chair of climate change at theUniversity of Adelaide’s EnvironmentInstitute in Australia. He also runs the popular climate-change blogBraveNewClimate.com, e-mail barry.brook@ adelaide.edu.au

There is no silverbullet for solving theenergy and climatecrises, but there arebullets, and they aremade of uraniumand thorium

physicsworld.com Nuclear power: The big question

25Physics World October 2010

PWOct10forum1 16/9/10 15:15 Page 25

The UK has long been a pioneer in nuclearenergy. It became the first nation to adopt –and then implement – a plan to supplant coalwith atomic energy. It opened the world’sfirst full-size nuclear power station in 1956at Calder Hall in Cumberland, which was agas-cooled, graphite-moderated “Magnox”reactor using fuel rods of natural uraniummetal encased in finned, magnesium-alloycans. Flushed by that early success, nineother Magnox plants were ordered by thethen generating boards for various sites,which came online in the early 1960s. Produ-cing some 10% of the country’s electricity,these reactors promised much for the future.

The natural successor to the Magnox sta-tions was the advanced gas-cooled reactor(AGR) designed by the UK Atomic EnergyAuthority (AEA). But by the late 1960s, theUK seemed to have lost the political will andorganizational ability to tackle large projectssuccessfully. The AEA’s design team wasbroken up and replaced by five private en-gineering consortia, which proved a disas-ter. The lead AGR station – Dungeness B –was ordered in 1965 but only began operat-ing in 1983, some 13 years later than plan-ned. Meanwhile, further restructuring in themid-1970s left the UK back where it began,with just one design team (British NuclearDesign and Construction) as the main con-tractor. The lack of progress was not thefault of the AGR technology, but simply oneof administration.

By the time that a second power pro-gramme involving seven AGRs was com-pleted in 1988, the nuclear industry wassupplying more than 20% of the UK’s elec-tricity. But by then, pressurized-water reac-tors (PWRs) were the technology of choicearound in the world, with France, for ex-ample, having long moved away from AGRtechnology and begun a massive programmeto build 58 PWRs. In many ways PWRs aresuperior to AGRs, being largely factory-built, which means they are up to 30%cheaper to construct than an AGR of thesame capacity because major componentscan simply be transported ready-made towhere they are needed.

Eventually, the Central Electricity Gen-erating Board (CEGB) – the UK’s state-

owned power-generating company – decidedto follow suit and go down the PWR route.But in the absence of a UK-designed PWR,it opted instead for a US-designed version,drawing up plans to build 23 such reactors on UK soil. However, the oil crisis and eco-nomic downturn of the early 1970s temperedthis enthusiasm, the anticipated demand forelectricity was not realized, and such a largeexpansion of the nuclear programme wasdeemed unnecessary.

In the end, the UK only built one PWR –the Sizewell B station in Suffolk, which even-tually opened in 1995 after a lengthy publicenquiry. The point of this inglorious story is that, rather than choosing – and stickingwith – one design, as France and many othercountries have done, the UK dabbled in toomany different options. The CEGB eventoyed with the idea of building a fleet of fast-breeder reactors or steam-generating heavy-water reactors, all of which came to naught.

Filling the gapThe question facing the UK today is how tofill the massive gap in our electricity suppliesthat is looming large as the last of the age-ing Magnox stations are forced to close –Oldbury-on-Severn in 2012 and Wylfa (innorth Wales) in 2014. That these plants con-tinue to be pressed into service more than40 years after they were built is itself testi-mony to the superb – and sadly largely un-recognized – engineering that went intotheir construction and design.

The UK’s energy needs are rising yearly aspurchases of electrically powered equipment

(electric cars, domestic appliances, etc) con-tinue to increase and as the government seeksto build an additional 200000 new homes peryear. Yet the country continues to rely onimported coal for almost 40% of its energysupply, while its various domestic coal-firedpower stations are scheduled to close at theend of 2015. Of course, there is wind power,but its supply is intermittent and the amountof electricity generated by the UK’s 3000existing wind turbines account for a mere 2%of the country’s energy requirement.

Thankfully, nuclear power is back on the agenda, and the UK energy ministerCharles Hendry has revealed that a NationalPolicy Statement to pave the way for a newgeneration of nuclear reactors will be pre-sented to parliament next spring. HinkleyPoint in Somerset has been earmarked to bethe first in the new wave of reactors, withenergy giant EDF having submitted a plan-ning application to build two massive plantsat Hinkley C. However, these are unlikely to be in operation until well after 2018 – even assuming that planning permission isgranted. Similarly, there is very little opti-mism that the Horizon plan – a joint venturebetween energy companies E.ON UK andRWE npower to construct a nuclear plant at Oldbury – could generate energy before2025. Moreover, it is inconceivable that theUK will revert to the plethora of nuclearreactors that it had in the 1970s. Instead,these will probably be of one type – the PWR– built by different firms.

The problem for the UK nuclear industryis that, with the CEGB having been dissolvedin 1990, only two of the six firms currentlysupplying electricity to homes – Centricaplus Scottish and Southern Energy – are UKowned. British Energy belongs to France’sEDF, which also controls InternationalPower, while Scottish Power has gone toSpain’s Iberdrola and npower has fallen toGermany’s RWE. While the nationality ofthe owners does not, in principle, matter, theproblem is that these firms will, where poss-ible, use their own staff and reactor designs,leaving the UK’s nuclear expertise trailingand without the infrastructure to build itsown indigenous nuclear plants.

Still, the French seem to be extremely goodat nuclear power; the question is, can they doit in the UK?

With the UK having let its once-proud lead in nuclear technologyfritter away, Geoff Allen looks athow the country can make themost of a bad situation

The lost leader

What next? The Sizewell B pressurized-water reactor isthe only UK nuclear power station to have opened inthe last 20 years.

Geoff Allen is an AWE William PenneyFellow at the Interface Analysis Centre,University of Bristol, UK, and hasworked in the nuclear industry since1970, e-mail g.c.allen@bristol.ac.uk

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26 Physics World October 2010

PWOct10forum2 16/9/10 15:32 Page 26

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In 1988 the science historian Spencer Weartpublished a groundbreaking book calledNuclear Fear: A History of Images, which ex-amined visions of radiation damage andnuclear disaster in newspapers, television,film, literature, advertisements and popularculture. In his analysis, Weart noticed some-thing odd about nuclear-disaster scenarios:we have seen them all before. He found thattheir imagery and plots eerily resemble thoseof pre-nuclear and even pre-technologicaldisaster scenarios.

In involving arrogant scientists who playGod by probing nature’s secrets with specialmachines before unleashing powers that theycannot control to destroy the world, theseplots are suspiciously similar to earlier storiesinvolving magicians or alchemists who playGod by probing nature’s secrets with specialdevices or processes before eventually un-leashing world-destroying powers that theycannot control.

Tales of witches unleashing magicalpowers, Weart noted, have much to do withanxieties about socially disruptive classes of people. Likewise, fictional tales of tech-nological apocalypse have much to do withanxieties about modern civilization, the roleof technology and the social authority of sci-entists. The plot is what Weart calls “Faust’ssin of prideful power divorced from moralresponsibility”; the new nuclear technologymerely feeds the image by giving the dan-gerous scientist more expensive and flashierhardware to do it with.

Nuclear fear, Weart concluded, has less todo with our knowledge of atomic structureand its exploitation than with psychology,history and culture. His book explained whypublic discussions of nuclear power tend notto centre on issues but to be derailed by pas-sions having nothing to do with either thetechnology or the wisdom of its use.

Has nothing changed? Weart raises thisquestion in a forthcoming revision of his1988 book and in the article “Nuclear fear1987–2007: Has anything changed? Haseverything changed?”, which appears in the new book Filling the Hole in the NuclearFuture edited by Robert Jacobs (2010, Lex-ington Books). Weart’s surprising answer,

backed up by polls, surveys and media analy-ses, is that nuclear fear declined in the wakeof two events of 1986. One was the start ofdétente after that year’s Reykyavik summitbetween presidents Reagan and Gorbachev.“A significant part of the fear of nuclear reac-tors is displaced fear of nuclear war,” Wearttold me. “With the ending of the Cold War, itwas natural for this general fear of being ir-radiated and blown up to diminish.”

The other event was the Chernobyl reac-tor disaster, coming seven years after theThree Mile Island accident. “[I]n a seemingparadox,” Weart writes in his recent article,“the worst civilian nuclear disasters in his-tory ultimately brought a decline in publicconcern about nuclear power.” By silencingthe utopian claims of nuclear-power pro-ponents, fostering more cautious technol-ogies, and curtailing reactor start-ups, theaccidents leached energy from the anti-nuclear movement.

Those born after 1986, says Weart, “didnot grow up in a world where talk of nuclearwar, radiation, nuclear reactors and so forthshowed up frequently in the news, and evensometimes in personal relations, in a con-text full of anxiety”. Indeed, nuclear reac-tors are now prosaic enough to be mockedin cartoons. “How many have first met anuclear reactor in the introductory se-quence of the perennially popular cartoonshow The Simpsons, featuring a lovable butamusingly incompetent reactor operator?”

Changes afootSo has everything changed? No. Nuclear fearis still potent, losing none of its old asso-ciations and gaining new outlets. “Nuclearterrorism”, Weart writes, “does trump all.”

When the Bush administration wanted tomobilize public opinion for its 2003 invasionof Iraq, for example, its most effective toolwas an appeal to (imagined) Iraqi weaponsof nuclear, rather than biological or chemi-cal, destruction. Nuclear threats are still theterrorist weapon of choice, both in popularculture – films and computer games – andalso in the real world. “The complex ofimagery walks in the real world, to no goodresult,” Weart writes.

Last summer, a right-wing blogger publi-cized a 2.5 minute video of Shirley Sherrod,a Department of Agriculture official in theObama administration, seeming to admit tohaving mistreated a white farmer. The ugly,racist portrait that the video created was so repugnant that Sherrod was fired imme-diately, before even being consulted. Theblogger, it turned out, had sharply edited a20-minute speech to make it emotionallyrepellent. Anyone who listened to the entirespeech understood that Sherrod’s messagewas about the need to treat everyone equally.It was a lesson in image manipulation. Sher-rod was offered her job back afterwards,when her message was considered coolly andin context.

Reactors, too, are vulnerable to what one might call “Sherroding”. Nuclear fearcannot be switched off, for the associativeand affective reasons that Weart identified.Until recently, the anti-nuclear movementhad skilfully wielded powerful images ofworst-case scenarios, mushroom clouds andgenetically damaged children to create a“cultural hysteresis” in which nuclear re-actors are equated with Chernobyl, andnuclear disasters with Hiroshima. Weartmay be right to see a diminution of nuclearfear, but activists can still inflame it. Hiswork helps lessen our dependence on his-torical events and, by giving us an under-standing of the deep non-scientific roots ofnuclear fear, helps us address it.

Given the planetary threat posed by globalwarming, and the possible use of nuclearpower as an alternative to ultimately dan-gerous fossil-fuel technologies – which storetheir wastes in the atmosphere, for free –optimally addressing global safety requiresthe ability to debate reactor technology, itsstrengths and weaknesses, independently ofthat cultural hysteresis. Otherwise, theremay be no afterwards in which to consider it coolly.

Robert P Crease is chairman of the Department of Philosophy, Stony Brook University, and historian at the Brookhaven National Laboratory, US,e-mail rcrease@notes.cc.sunysb.edu

Nuclear fear revisitedWith a revised edition of alandmark book about the publicimage of nuclear power due outsoon, Robert P Crease explainswhy its central message is stillrelevant more than 20 years on

Public image Examining the culture of the nuclear age.

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22452-71-Rediscover Physics world Ad 2.indd 1 15/9/10 10:17:55

After a 20-year slump following accidents at ThreeMile Island in the US and Chernobyl in the formerSoviet Union, the power of the atom is making a come-back. In the past two years alone, China has begun con-structing 15 new nuclear power stations, while Russia,South Korea and India are also initiating major expan-sions in atomic power. Some Western countries lookset to join them: at the end of 2009, licence applicationsfor 22 new nuclear plants had been submitted in theUS, while the Italian government has said that it willreverse a ban on nuclear power and start constructingreactors by 2013.

The reasons for this resurgence are not hard to spot.One is the political importance of fighting anthro-pogenic global warming: nuclear reactors do not emitgreenhouse gases during operation, and are more reli-able than other low-carbon energy sources such as solaror wind power. The other is energy security: govern-ments are keen to diversify their energy sources anddistance themselves from politically unstable suppliersof fossil fuels. As a result of such pressures, a reportpublished in June this year by the International EnergyAgency (IEA) and the Organisation for Economic Co-operation and Development’s Nuclear Energy Agencyanticipated that the world’s total nuclear generatingcapacity could more than triple over the next four dec -ades, rising from the current 370 GW to some 1200 GWby 2050.

However, the agencies believe that countries mustdevelop more advanced nuclear technologies if thisform of energy is to continue to play a major role be -yond the middle of the century. Today’s reactors aremostly “second generation” facilities that were builtin the 1970s and 1980s. The “third generation” facil -ities that are gradually replacing them often incorpor -ate additional safety features, but their basic designs

remain essentially the same. Moving beyond theseexisting technologies will require extensive researchand development, as well as international co-oper-ation. To this end, in 2001 nine countries set up theGeneration-IV International Forum (GIF), whichaims to foster the development of “fourth generation”reactors that improve on current designs in four keyrespects: sustainability, economics, safety and reliab -ility, and non-proliferation.

Since then, the forum has expanded to 13 members(including the European Atomic Energy Community,EURATOM) and it has identified six designs that meritfurther development. The hope is that one or more ofthese will be ready for commercial deployment in the2030s or 2040s, having proved their feasibility in de -monstration plants in the 2020s. But the scientists andengineers working on these designs have many for -midable technical challenges to overcome, and mustconvince funders that the advantages of these advancedreactors over existing plants will be worth the billionsneeded to deploy them.

A slow (neutron) start

Nuclear-fission reactors generate energy by splittingheavy nuclei, with each splitting giving off neutrons thatgo on to split further nuclei. This process creates astable chain reaction that releases copious amounts ofheat. The heat is taken up by a coolant that circulatesthrough the reactor’s core and is then used to producesteam to drive a turbine and generate electricity. Mostexisting nuclear plants are “light-water reactors”, whichuse uranium-235 as the fissile material and water as both the coolant and moderator. A moderator isneeded to slow the neutrons so that they are at the optimum speed to fission uranium-235 nuclei.

Of the six designs for generation-IV reactors (seetable on page 32), the closest to existing light-waterreactors is the “supercritical water-cooled reactor”.Like light-water reactors, this design uses water as thecoolant and moderator, but at far higher temperaturesand pressures. With the coolant leaving the core at temperatures of up to 625 °C, the reactor’s thermo -dynamic efficiency – the ratio of power generated aselectricity to that produced in the fission reactions –can reach as high as 50%. This compares favourably tothe 34% typical of today’s reactors, which operate atjust over 300 °C. Moreover, because the cooling waterexists above its critical point, with properties betweenthose of a gas and a liquid, it is possible to use it to drivethe turbine directly – unlike in existing designs, wherethe coolant heats up a secondary loop of water thatthen drives the turbine.

Physicists are designing new types of nuclear reactor that could be cheaper, greener, safer and more secure than existing plants. But as Edwin Cartlidge discusses, these designs must overcomemajor technical and financial hurdles if they are ever to see the light of day

Edwin Cartlidge

is a science journalistbased in Rome, e-mail edwin.cartlidge@ yahoo.com

Nuclear’s new generation

The scientists working on theseadvanced reactors have manyformidable technical challenges to overcome, and must convincefunders that the advantages of thesedesigns will be worth the billionsneeded to deploy them

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30Physics World October 2010

Challenges ahead

The next generation of nuclear reactorswill be difficult toimplement, bothtechnically andfinancially.

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Both of these improvements would reduce the costof nuclear energy. However, a number of significanttechnological hurdles must be overcome before theycan be implemented, including the development ofmaterials that can withstand the high pressures andtemperatures involved, plus a better understanding ofthe chemistry of supercritical water.

Another generation-IV option, the “very-high-tem -pera ture reactor”, uses a helium coolant and a graphitemoderator. Because this design uses a gas coolant ra -ther than a liquid one, it could operate at even highertemperatures – up to 1000 °C. This would boost effi-ciency levels still further and also allow such plants togenerate useful heat as well as electricity, which couldpotentially be used to produce hydrogen that is neededin refineries and petrochemical plants (figure 1).

Some elements of this concept for a very-high-tem-perature reactor have already been investigated atlower temperatures in prototype gas-cooled reactorsbuilt in the US and Germany. A number of countriesare also developing reactors that operate at interme-diate temperatures of up to 800 °C. Until recently, oneof the most advanced intermediate-temperature pro-jects was South Africa’s “pebble-bed modular reactor”,which was designed to use hundreds of thousands offuel “pebbles” – cricket-ball-sized spheres each con-taining about 15 000 kernels of uranium dioxide en -closed inside layers of high-density carbon to confinethe fission products as the fuel burns. The reactor corewould also contain 185 000 fuel-free graphite pebblesto moderate the reaction.

Packaging the fuel in this way confers two majorpotential advantages over the fuel rods used in con-ventional light-water reactors. One is that pebble-bed-type reactors could be refuelled without shutting themdown; the pebbles would simply fall to the bottom ofthe reactor core as their fuel burned and then be re -inserted at the top of the core, thus allowing the reactorto supply energy continuously. Pebble-bed reactorscould also be designed to be “passively safe”, meaningthat any temperature rise due to a loss of coolant would

reduce the efficiency of the fission process and bringthe reactions to an automatic halt.

However, in July the South African governmentdecided to end its involvement in pebble-bed research.Jan Neethling, a physicist at the Nelson MandelaMetro politan University in Port Elizabeth who hasworked on developing the fuel pebbles, believes thatfollowing elections in 2009, the new government de -cided that the country’s urgent energy needs would bebetter met with coal and conventional nuclear plants –rather than with a potentially more efficient and saferbut untried and problematic alternative.

One factor that may also have played a role in theSouth African government’s decision to abandon thepeeble-bed idea is a 2008 report by Rainer Moormannof the Nuclear Research Centre at Jülich, Germany,which operated a small pebble-bed reactor between1967 and 1988. The report indicated that radiation mayhave leaked out of the pebbles, making repairs andmaintenance of pebble-bed reactors potentially morecostly than previously envisaged. Also, customers andinternational investors never really got behind theSouth African project, mirroring the Jülich centre’searlier failure to sell their pebble-bed technology toRussia. “We had a very good flagship project that com-bined the work of many scientists and engineers,” saysNeethling, “but more time and money is needed tocommercialize this concept.”

Opinion is divided on the significance of the SouthAfrican project’s termination. Stephen Thomas, anenergy-industry expert at the University of Greenwichin London, calls it a “major setback” for the develop-ment of very-high-temperature reactors, since, he says,South Africa’s efforts appeared to be more advancedthan research being carried out elsewhere. However,Bill Stacey, a nuclear engineer at the Georgia Instituteof Technology in the US, disagrees with this assess-ment, adding that South Africa was “just one of manyplayers and not one of the major ones”. China, Japan,France and South Korea are also developing technol-ogy for high-temperature reactors, some of which is

Design How it works Advantages Disadvantages

Supercritical water-cooled reactor Water is heated to above its critical point High efficiencies; reduced plant cost New materials needed to withstand high(where it has both liquid and gas properties) due to a simpler heat- exchange system temperatures and pressures; chemistry and used to drive a turbine directly of supercritical water poorly understood

Very-high-temperature reactor Uses helium as a coolant, allowing the reactor Very high efficiencies; potentially able to New fuels and reactor components to reach temperatures of up to 1000°C; produce heat and hydrogen as well needed for such high temperaturesfuel is contained in pebbles or blocks to as electricityimprove safety and refuelling

Sodium-cooled fast reactor Builds on existing sodium-cooled reactors, Potential to breed plutonium fuel and Reactivity and radioactivity of sodiumwhich use “fast” rather than burn radioactive waste, thus “closing” coolant complicate operation and “thermal” neutrons fuel cycle upkeep, and increase plant cost

Gas-cooled fast reactor Fast reactor with helium coolant Fuel breeding and waste burning; Helium is much poorer coolant potential to provide heat and hydrogen; than sodium uses inert coolant

Lead-cooled fast reactor Fast reactor with liquid-lead coolant Fuel breeding and waste burning; Corrosion of other metals in reactorinert coolant

Molten-salt reactor Uses nuclear fuel dissolved in a circulating No need to fabricate fuel; could be used Chemistry of molten salt not wellmolten-salt coolant; could use either fast or to breed fissile thorium understood; corrosion is a problemthermal neutrons

Reactors for a new generation – promises and problems

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32Physics World October 2010

also designed to use pebbles.For its part, the US is pursuing a variant of the

pebble-bed design known as the Next GenerationNuclear Plant (NGNP). Intended to reach tempera-tures of 750– 800 °C, the NGNP will allow for differentfuel configurations, with the coated fuel kernels heldeither in pebbles or hexagonal graphite blocks. Ac -cording to Harold McFarlane, technical director ofGIF and a researcher at the Idaho National Labor -atory, the US Congress approved the construction of aprototype NGNP in 2005 but has so far awarded fund-ing only for preliminary research and development.The US De partment of Energy is now trying to set upjoint funding for the project with industry. The reactoris unlikely to be completed by its original target date of2021, McFarlane says, and where it will be built stillneeds to be determined, although speculation so farhas concentrated on sites along the Gulf Coast.

Faster neutrons

Both the supercritical water-cooled reactor and thevery-high-temperature reactor would use uranium-235as fuel. However, less than 1% of naturally occurringuranium comes in this form: the remaining fraction isuranium-238, which ends up as “depleted uranium”after uranium ore is enriched to produce reactor-gradefuel (typically about 5% uranium-235, 95% uranium-238). Significant amounts of uranium-238 are also discarded as waste after the fissile fraction of reactor-grade fuel has been consumed. Many nuclear expertstherefore believe that this “open fuel cycle” is a wasteof resources. It would be better, they say, to recycle theuranium and plutonium that make up the bulk of spent

fuel as well as the depleted uranium in what is known asa “closed fuel cycle” (figure 2).

The most efficient way of doing this is to use “fastreactors”, which do not moderate the speed of fissionneutrons. Such reactors require a far higher concen-tration of fissile material, usually plutonium-239, togenerate sustained chain reactions than moderated, or“thermal”, reactors do. But they are far better at con-verting non-fissile uranium-238 into plutonium-239 via neutron absorption. In fact, fast reactors can bemade to produce more plutonium-239 than they con-sume – a process known as “breeding” – by surroundingthe reactor core with a “blanket” of uranium-238.Using uranium-238 in this way would extend the life-time of the world’s uranium resources from hundredsto thousands or even tens of thousands of years, assu -ming no increase in current nuclear generating capa -city. Fast reactors could also be made to burn some ofthe long-lived, heavier-than-uranium isotopes (knownas “transuranics”) that make up spent fuel, convertingthem to shorter-lived nuclides and thereby reducingthe volume of nuclear waste that needs to be stored in long-term geological repositories (see review of Into Eternity on p55).

All four of the remaining generation-IV reactordesigns could be configured to work as fast reactors.The main difference between them is in their coolingsystems – an aspect of fast-reactor design that seemsto offer plenty of scope for innovation. So far, nearlyall of the world’s fast reactors have used sodium as acoolant, taking advantage of the material’s high ther-mal conductivity. Unfortunately, sodium reacts vi -olently when it comes into contact with either air or

Significantamounts ofuranium-238are discardedas waste after the fissilefraction of reactor-gradefuel has beenconsumed

pump

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Very-high-temperature reactors could generate the heat required to produce hydrogen by splitting water molecules.

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water. As a result, at least two sodium-cooled reactorshave been shut down for significant periods due tofires. One of them, Japan’s Monju prototype fast re -actor, experienced a major sodium–air fire in 1996 andonly restarted earlier this year, almost a decade and ahalf later. Even without such incidents, the very factthat sodium and air need to be kept apart means thatrefuelling and repairs are more complicated and time-consuming than for water-cooled reactors. The onecommercial-sized fast reactor built to date, France’sSuperphénix (figure 3), was shut down for more thanhalf the time it was connected to the electrical grid(between 1986 and 1996).

Sodium also becomes extremely radioactive whenexposed to neutrons. This means that sodium-cooledfast-reactor designs must incorporate an extra loop ofsodium to transfer heat from the radioactive sodiumcooling the reactor core to the steam generators; with-out it, a fire in the generators could release radio activesodium into the atmosphere. This extra loop adds sig-nificantly to the cost of such reactors. Indeed, accord-

ing to a recent report from the International Panel onFissile Materials (IPFM) – a group promoting armscontrol and non-proliferation policies – the fast re -actors constructed so far have typically cost twice asmuch per kilowatt of generating capacity as water-cooled reactors.

Scientists working on generation-IV sodium fast re -actors are aiming to make them cheaper through im -proved plant layout and steam generation. They arealso experimenting with more inherent safety fea-tures, such as arranging the reactor vessel and othercomponents so that if the system overheats, the so -dium na turally transports the excess heat out of thesystem, not back into it. Researchers in both Franceand Japan hope to start operating new sodium reac-tors that in corporate such advanced features at somepoint in the 2020s.

The three non-sodium-cooled fast-reactor designsbeing explored by the GIF each have their own ad -vantages, but major technological hurdles mean theyare more of a long-term prospect. The “gas-cooled fast

Scientistsworking ongeneration-IVsodium fastreactors areaiming to makethem cheaperthroughimproved plant layoutand steamgeneration

An illustration of a “closed” fuel cycle where fast reactors are employed to generate energy from plutonium and uranium-fission by-products.

thermalreactor

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new fuel

recycled fuel

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2 More fuel, less waste

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reactor”, like its thermal equivalent, would operate athigh temperatures (up to 850 °C), generating electri -city more efficiently than a sodium plant and raisingthe possibility of producing hydrogen or heat as well.Unfortunately, although the helium gas coolant in sucha plant would be inert, helium is a much poorer coolantthan sodium. Given the high concentrations of fissilematerial needed in a fast-reactor core, this makes gas-cooled designs extremely challenging to implement.

No less challenging is the “lead-cooled fast reactor”.Like helium, lead does not react with air or water,which would potentially simplify the plant design.Unfortunately, a liquid-lead coolant would corrodealmost any metal it touched, so new kinds of coatingswould be needed to protect the reactor’s componentsfrom corrosion.

The final and most ambitious generation-IV conceptis the “molten-salt reactor”. This design calls for thenuclear fuel to be dissolved in a circulating molten-saltcoolant, the liquid form doing away with the need toconstruct fuel rods or pellets and allowing the fuel mix-ture to be adjusted if needed. Such a reactor could useeither fast or thermal neutrons, and could also be usedto breed fissile thorium (see “Enter the thorium tiger”on p40) or burn plutonium and other by-products.How ever, the chemistry of molten salts is not wellunderstood, and special corrosion-resistant materialswould need to be developed.

Thinking ahead

In addition to the considerable research and develop-ment needed to implement each of the individual fast-reactor designs, new kinds of plants for reprocessingand refabricating the fuel would be required to com-mercialize the technology. Beyond this, however, liesan even bigger problem associated with fast reactors:the freeing up of weapons-grade plutonium duringreprocessing. According to the IPFM, there is cur-rently enough plutonium in civilian stockpiles to maketens of thousands of nuclear weapons, and the con -tinued development of fast reactors would only add to this. Advocates of fast reactors have proposed keep-ing the reprocessed plutonium bound up with some ofthe transuranics inside spent fuel, which would in the-ory make it more difficult to steal because the mixedplutonium–transuranic packages would be more ra -dioactive than plutonium alone. However, panel co-chair Frank von Hippel of Princeton Univer sity in theUS points out that radiation levels in such packageswould still be lower than those found in spent fuelbefore reprocessing. A report produced last year by agroup of nine scientists working at the US’s na tionallaboratories did not find that this transuranic bundlingwould significantly reduce the risk of proliferation, von Hippel adds.

Edwin Lyman of the Union of Concerned Scientistsin Washington, DC, agrees. “Fast reactors should notbe part of future nuclear generating capacity at all,” hesays. “Around $100bn has been wasted on this technol-ogy with virtually nothing to show for it. Research anddevelopment on nuclear power should instead befocused on improving the safety, security and efficiencyof the once-through cycle without reprocessing.”

This view is not shared by Stacey. Although he ack -

nowledges that the technical challenges in commer-cializing fast reactors are “sobering”, he believes thatthe arguments in favour of closing the fuel cycle arestill compelling. “You can’t provide nuclear power for a long time using 1% of the energy content of ura-nium,” he says, referring to the tiny fraction of naturaluranium that is fissile. “And as it is, the spent fuel isstacking up and at some point we are going to need todo something about it. We can bury it but we wouldneed sites that can contain it for a million years. Thatstretches credibility.”

Whether or not any of the generation-IV designs arecommercialized will depend on a broad range of issues,including those beyond the purely technical. Theseinclude the need to build up a skilled workforce andmaintain safety standards at existing plants, as well asthe political problem of what to do with nuclear waste.The industry’s progress on constructing third-genera-tion plants will also influence what follows them.

But as William Nuttall of Cambridge University’sJudge Business School points out, perhaps the mostimportant factor is economics. Nuttall, an energy-pol-icy analyst specializing in nuclear power, says it is stillnot clear how far governments are prepared to go inimplementing policies such as carbon taxes that couldmake nuclear energy cost-competitive with fossil fuels.As for fast reactors, higher prices for uranium couldmake them more attractive in the future, he suggests, aslong as their capital costs and reliability measure up.

“The question is what the scale of the nuclear re -naissance will be, especially in Europe,” says Nuttall.“If it means simply replacing nuclear with nuclear, then there is probably no need to go beyond light-waterreactors. But if you want to, say, replace coal with nu -clear, then there could be room for generation-IV.”The important thing, he believes, is to keep the optionopen. “We don’t want to be in a position 20 years downthe line when we wish we could have done it, but findwe can’t,” he says. ■

The world’s only commercial-scale fast reactor, France’s Superphénix, suffered a range ofmaintenance problems and frequent shut-downs during its 11-year lifetime.

3 No phoenix rising

Yann

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Beyond the envelopeHow it works

Conventional fission involves a self-sustainingnuclear chain reaction, with the neutronsproduced in one reaction going on to split morenuclei, and so on. Once a chain reaction isestablished, then the reactor is said to be“critical” and must be carefully controlled toensure that the number of neutrons does notescalate and result in “super-criticality”. If, onaverage, fewer than one neutron goes on to splitmore nuclei, then the reaction is “sub-critical”and the fission will eventually die away.Accelerator-driven sub-critical reactors (ADSRs)are purposely kept sub-critical. The reaction issustained by actively supplementing the reactorcore with extra neutrons using an externalaccelerator. It fires beams of protons at a heavy-metal target within the reactor, where neutronsare chipped off to maintain fission. The chainreaction keeps going as long as the acceleratoris still firing protons; to put an end to thereaction, the proton beams are simply turned off.It is proposed that the reactor could burnthorium as a fuel and use lead as the coolant.Who is behind it?

First suggested by the Nobel-prize-winningphysicist Carlo Rubbia, the idea has since beentaken on by various research organizations,

including the Belgian Nuclear Research CentreSCK•CEN, which has funding for a test reactor.The Thorium Energy Amplifier Association(ThorEA) in the UK has called for a public–privatepartnership in which a public investment of£300m would finance a five-year period ofresearch and development, which it says wouldstimulate £1.5–2bn of commercial support.Plus points

The design is inherently safe, and thorium hasmany advantages over uranium as a nuclear fuel(see “Enter the thorium tiger” on p40). Thoriumis three times as abundant as uranium and,

moreover, breeder reactors such as ADSRs useall the fuel, meaning supplies will lastthousands, rather than hundreds, of years. As asideline, excess neutrons from the heavy-metaltarget could be used to convert waste fromconventional reactors into isotopes that aremuch less radioactive.Drawbacks

At present, existing accelerators are just tooexpensive – each accelerator costs in the regionof a billion dollars. Also, accelerators withsufficient reliability – i.e. making sure that theproton beam remains turned on – have not yetbeen demonstrated. This means that severalpricey accelerators are required, not just one.Little ADSR research has so far been carried out.Prospects

One promising idea for delivering a reliable beamof high-power protons is the non-scaling fixed-field alternating-gradient accelerator (nsFFAG). A prototype nsFFAG called EMMA has been builtat the Daresbury Laboratory in the UK to test theconcept, and is now conducting experiments.ThorEA expects that the technologies required forADSRs will be developed, and functioningdemonstrations delivered, within five years andthat a privately funded prototype could be builtand commissioned by 2025.

Accelerator-driven sub-critical reactor

How it works

The core of this reactor is essentially a log ofdepleted uranium several metres in length with asmall amount of enriched uranium at one end.The enriched uranium is used to kick start afission reaction, which then moves very slowlyalong the log. This “travelling wave” of fissionwould reach the other end of the log after about40–60 years. Depleted uranium does notundergo fission itself, but add a fast-movingneutron and it will convert via neptunium intoplutonium, which then fissions to release energy.As the 40 cm-wide wave moves through thereactor it breeds plutonium fuel at the front, usesthis as fuel for fission and then leaves behind by-products and unused fuel. The heat istransported away using liquid sodium.Who is behind it?

Microsoft founder Bill Gates, who describes it asa possible “energy miracle”. Gates is one of thekey investors in TerraPower, a company seekingto commercialize this technology. TerraPower isa spin-off from Intellectual Ventures, which isheaded by ex-Microsoft chief technology officer

and former physicist Nathan Myhrvold (PhysicsWorld March 2007 pp12–13). Microsoft hasprovided much of the supercomputing requiredto model the reactor design and fuel cycle.Plus points

The reactor would help to dispose of nuclearwaste, since depleted uranium is its mainresource. The reaction is self-sustaining, sorefuelling is not required beyond its 40–60 year

lifetime, and it is also self-limiting – good from asafety perspective. The risk of proliferation is lowbecause the enrichment step is only done onceto produce the small amount of enricheduranium needed to initiate the reaction.Drawbacks

This technology is novel, and no prototype hasyet been built to prove that the principle works,which could mean the licensing is a long way off.Another criticism is that research anddevelopment should focus on near-termapplications, not divert resources away fromtechnologies that are known to work.Prospects

The conceptual design for a gigawatt-scalereactor has already been completed andpatented by Intellectual Ventures. Plans are nowunder way to design a small modular unit thatcan generate 500 MW. TerraPower boss John Gilleland claims that its operation can bedemonstrated in less than 10 years, andcommercial deployment can begin in less than15 years, costing several billion dollars perpower plant.

Travelling-wave reactor

Round and round The EMMA proof-of-principleprototype accelerator can now store a particle beam.

Travel log This quirky design has the valuable financialand public support of Bill Gates.

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Out of thousands of proposed new reactor designs, only a select few have gathered enough momentumto even stand a chance of seeing the light of day. Physics World looks at four that, despite not being inthe “generation-IV” collection, are developing under their own steam

How it works

Hyperion Power Generation, Inc. – a US firmbased in Denver, Colorado – unveiled the firstdesign for its Power Module in November 2008.Two different versions now exist, but the mainselling point is the same for both: the units aresmall – about the size of a hot tub – andtherefore transportable, making them useful forremote locations such as the Alberta oil sands,military facilities and rural areas in thedeveloping world that need electricity for cleanwater. The first Power Module design wouldhave no moving parts. The idea is to fuel areactor core with uranium hydride (UH3) at afactory, before transporting and then installing itunder the ground. Heat pipes would transfer theheat to water above ground for powergeneration. The neutrons released in uraniumfission would be moderated by the hydrogen. Ifthe UH3 gets too hot, then the hydrogen wouldbe driven out of the uranium metal and thereaction would stop. But as the container issealed, the hydrogen could then return to allowthe reaction to resume. The second design,unveiled in 2009, is a less-adventurous liquid-metal-cooled fast reactor (see “Nuclear’s newgeneration” on p30). Hyperion says it brought inthis more conventional design to meet customer

demand in the short term, but that it willcontinue to develop the more elegant uranium-hydride design.Who is behind it?

Otis Peterson, then at the Los Alamos NationalLaboratory (LANL), designed the uranium-hydride reactor together with colleagues.Hyperion Power Generation, Inc. was set up in2006 to commercialize this technology, andPeterson left LANL to join the firm as chiefscientist. The venture-capital company Altira Group has invested several million dollarsin Hyperion.

Plus points

The Power Modules can be transported by rail,heavy hauler or barge in licensed nuclear-fueltransport containers. Their small size also meansthat companies and organizations canrealistically afford to buy them. Useful in remotelocations where connecting to the electricity gridis not an option, Hyperion says the reactor isthen buried underground, making it lessvulnerable to human incompetence or hostiletampering. Also, the fuel is manufactured insuch a way as to make it much less of aproliferation concern than industry-typicalnuclear fuel.Drawbacks

Each Power Module would need replacing every10 years. This would mean installing a secondunit while the first is still running in order tomaintain continuity of the power supply.Prospects

The US Nuclear Regulatory Commission hasstated that the Power Module will require3–5 years of review. By early 2009 Hyperionsaid that it had secured more than 100 ordersfor the original design. Deliveries for its $50m2009-vintage reactors are scheduled for late2013. Hyperion plans to build manufacturingfacilities in the US, the UK and Asia.

The Hyperion Power Module

How it works

As the name suggests, hybrid fusion–fissionreactors would combine nuclear fusion andfission in a single device. They would resemble afusion reactor, with a hot ball of plasma(magnetic-confinement fusion) or a series ofexploding fusion targets (inertial-confinementfusion) at the centre. The problem with currentfusion reactors is that they cannot generatemore power than they consume. One of the mainstumbling blocks, especially for magnetic-confinement fusion, is temperature: getting theplasma hot enough will require very largereactors. Any commercial fusion reactor will alsorequire a reactor wall and “blanket” that canwithstand immense heat and neutronbombardment (see “Hot fusion” on p46). Ahybrid fusion–fission reactor might solve thisproblem by using a layer of fissioning material asthe blanket, which would absorb the high-energyneutrons produced in fusion and protect theouter reactor wall. In magnetic-confinementfusion the fission blanket would in turn provideheat to the fusion reaction.

Who is behind it?

Originally conceived in the 1950s, the conceptis now being pursued by scientists at theNational Ignition Facility (NIF) at the LawrenceLivermore National Laboratory (LLNL) in the US,and at the University of Texas at Austin. If NIFsucceeds in using lasers to ignite fusion anddemonstrate a net energy gain, then the likelynext focus at the LLNL will be LIFE: a project to

ignite fusion within a reactor, or a sub-criticalfission-reactor blanket.Plus points

The deuterium fuel, found in seawater, ispractically unlimited, while the tritium fuel isderived from lithium, a common mineral. Theblanket could burn a range of fuels, includingspent nuclear fuel and thorium. The fissionwould be sub-critical and so relatively safe.Drawbacks

This technology is decades away. The concept ofcombining fission with fusion has never beentested experimentally, so it is not clear how theenergy balance would work out – and, crucially,whether there would be a net power gain.Prospects

Steven Chu, the US Energy Secretary, has saidthat hybrid fusion–fission is a means to bothmake power and to break down nuclear waste.Earlier this year, Paul Drayson, then the UKScience Minister, also called for research intohybrid fusion–fission reactors. China’s Instituteof Plasma Physics has gone one step further andplans to build a prototype by 2020.

Fusion–fission reactors

Stronger together A fusion–fission hybrid reactor suchas LIFE could combine the best of both worlds.

Nuclear hot tub These diminutive reactors would beburied underground for a decade at a time.

LLN

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35.937.437.839.5434548.651.753.575.2

A world of difference

Unlike other sources of energy, the use of nuclear power variesconsiderably around the world. A total of 30 countries currently havenuclear power plants and this map shows the percentage of each ofthose nation’s electricity generated from nuclear reactors in 2009,ranging from red (the highest) to light yellow (the lowest). France is thebiggest fan of fission, with 75.2% of its electricity coming from nuclear,followed by Slovakia with 53.5% and Belgium with 51.7%. However,many nations are nuclear-free, shown here in pale blue, includingalmost all of Africa plus Australia and New Zealand.● Data from the International Atomic Energy Agency

The whole ofAfrica is

nuclear-free,except for

South Africa

The UK hasidentified

10 potentialsites for new

nuclear reactors

The US ispledging $8bn in

federal loanguarantees for

new plants

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38 Physics World October 2010

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CanadaSpainRussiaUKRomaniaTaiwanGermanyJapanFinlandCzechRepublic

SouthKorea

Bulgaria

14.817.517.817.920.220.620.726.128.932.933.834.835.9US

≤ 7

ArgentinaSouth AfricaMexicoNetherlandsBrazilPakistanIndiaChina

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a further 24

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has 23% of theworld’s uranium

deposits

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A road trip through Mumbai is a survival course incoping with fumes and traffic, but amid the bafflementand mass of humanity, it is impossible to ignore thevast scale of construction taking place in India’s mostpopulous city. Concrete office blocks and apartmentsspring from impossible spaces, some draped in tar-paulins long before they are completed to give squat-ters shelter from monsoon rains. The scenes aretestament to the dynamism of India’s economy, whichis currently growing by about 8% each year. But forthis growth to continue, India needs a similar expan-sion in its energy supply, with the country’s per-capitaconsumption of electricity expected to soar to seventimes its current value by 2050. More than 300 millionpeople – 40% of India’s population – are not yet con-nected to the electricity grid.

India is therefore backing another type of construc-tion that is relatively rare in Europe and the US thesedays: new nuclear power stations. India currently has19 operational nuclear reactors, which generate 3% ofthe country’s electricity (the global average is about15%). But it is also building eight more reactors and,according to the World Nuclear Association, is eyeingat least a further 35 on top of that. India’s near-termnuclear growth is topped only by that in China.

That India sees nuclear power as vital to its energymix is nothing radical. Many countries faced with grow-ing energy demands, a desire for increased energysecur ity, and the need to reduce greenhouse-gas emis -sions are turning or returning to the nuclear option.The UK government, for example, has identified 10potential sites on which vendors can bid to build whatwould be the first reactors in the country since SizewellB was switched on in 1995. In the US, meanwhile, theObama administration has pledged loans that wouldsee the first orders for new-build nuclear reactors sincethe early 1980s. Italy, Sweden and others are also dust-ing off their nuclear plans or reversing previous de -cisions to halt nuclear construction.

But the Indian government’s plans are bolder thanmost. Not only does it want to increase its nuclear con-tribution from its current 5 GW to 28 GW in the next10 years, but the reactors generating this power are thefirst stage of a unique “three-stage” nuclear vision. Firstformulated back in the 1950s, this vision would seeIndia producing 270 GW of electricity from nuclearsources by 2050 – a quarter of the country’s projectedpower needs and two-thirds of today’s global nuclearcapacity. India could then find itself as a leading ex -porter of an alternative nuclear technology that is moreefficient than today’s uranium–plutonium fuel cycle,produces less and shorter-lived radioactive waste prod-ucts, and that offers resistance against malevolent use.It is a technology based on thorium.

One vision

Two large portraits dominate Srikumar Banerjee’swood-panelled office in downtown Mumbai. One is ofAlbert Einstein. The other is of Homi Bhabha: thephysicist and founder of India’s nuclear programmewho, more than 40 years after his death, remains verymuch alive in the minds of those working on that effort.As the secretary to India’s Department of Atomic En -ergy (DAE) – a post first occupied by Bhabha in 1954 –Banerjee shares his predecessor’s vision, insisting thatIndia is planning not just for the next 100 years but forthe next 1000. “Growth will come from fast-breederreactors, sustainability from thorium,” he says.

Bhabha was also the founding director of what is now the Bhabha Atomic Research Centre (BARC),which lies on the outskirts of Mumbai. Set among geo-metrical flower-beds and thick forest looking out overElephanta Island in the Arabian sea – it is said thatBhabha desired a sea view from his office – BARC isthe hub of India’s nuclear programme. Surrounded byheavy security, it currently employs some 16 000 staffacross 20 groups and 90 divisions, although severalthousand other researchers are based at the handful ofother DAE labs around the country.

Having studied at Cambridge University in the UKin the late 1920s and early 1930s, and made break-throughs in cosmic-ray and quantum physics, Bhabhareturned to India in 1939 – befriending future Indianpremier Jawaharlal Nehru on the voyage home – andsoon began work on his grand three-stage plan fornuclear power. The plan was, and still is, rooted in adesire for energy security, given that India has fairlymeagre amounts of uranium – the fuel powering theworld’s 440 existing commercial reactors. AlthoughIndia is aggressively searching for more uranium,known supplies are only sufficient to generate about

India has a unique vision for a secure nuclear-energy future based on thorium. As the UK enters a new era of civil nuclear collaboration with India, Matthew Chalmers tours India’s nuclear labs with a British High Commission team helping to bring physicists from both countries together

Matthew Chalmers

is a science writerbased in Bristol, UK, e-mailmdkchalmers@googlemail.com

Enter the thorium tiger

India could find itself as a leadingexporter of an alternative nucleartechnology that is more efficient thantoday’s uranium–plutonium fuelcycle and produces less and shorter-lived radioactive waste products

physicsworld.comNuclear power: Thorium

40Physics World October 2010

10 GW of electricity if burned in the usual “once-through” fuel cycles.

Locked up in monazite in the sands of India’s south-ern and eastern beaches, however, are some of theworld’s largest reserves (at least 225 000 tonnes) ofthorium – uranium’s lighter and at least three timesmore abundant neighbour in the actinide series. Thor -ium is not technically a nuclear fuel because it is not“fissile” – that is, it cannot sustain a chain reactionwhereby neutrons released from the disintegration ofone thorium nucleus go on to split another. But ifbathed in an external supply of neutrons, a thorium-232 nucleus can capture a neutron before undergoinga couple of beta decays and transmuting into uranium-233, which is fissile.

It is analogous to the conversion of uranium-238 intoplutonium-239 in conventional reactors. However, thebalance between neut ron-induced fission and neutron-capture events in the thorium cycle is more favourablethan for the uranium– plutonium cycle, enabling moreuseful energy to be ex tracted from the thorium. An -other benefit of thorium is that it has a lower atomicmass than uranium, which means that it produces lesslong-term waste in the form of plutonium and long-livedminor actinides such as americium, although otherlong-term hazards such as protactinium are still present.

In the early days of nuclear power, several other

coun tries (including Germany, the former SovietUnion and the US) tried using thorium to expand theirfissile inventories – uranium-233 being one of just a fewfissile isotopes, along with uranium-235 and plutonium-239. But by the 1970s the uranium–plutonium cycle –given a head start by the initial military objective ofbreeding plutonium for weapons – had conquered thecommercial power market. Given that uranium is theonly naturally occurring fissile material and it seemedplentiful, choosing thorium instead “is a bit like tryingto build a fire with fresh green shoots that blow smokeinto your eyes rather than use some dry, dead woodlying nearby”, as Vijay Kumar Raina, BARC’s reactor-group director, puts it.

New deal

As well as possessing far more thorium than uranium,India has had another reason to stick with thorium:more than 30 years of isolation from mainstream uran -ium technology, which came about after the countrydetonated a nuclear device in 1974. That isolationinevitably hampered India’s nuclear programme, yettoday it boasts some of the world’s best performingpressurized heavy-water reactors (PHWRs), plus top-of-the-range research facilities. “Progress could wellhave been quicker were it not for international poli-tics that resulted in India having to plough a lonely

In its own hands

India envisages a new range ofnuclear powerstations fuelled bythorium pellets.

Palla

va B

agla

/Cor

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furrow,” admits former Indian government scientificadviser Vallam padugai Arunachalam, who is chair ofthe Centre for Study of Science Technology and Policyin Bangalore.

However, in October 2008 India and the US reacheda landmark agreement on civil nuclear co-operationthat led members of the Nuclear Supplier Group –which represents 46 nations, including Canada, China,Russia, the UK and the US – to open up trade in ura-nium technology. At the time, India’s prime ministerManmohan Singh said that the deal would not ad -versely affect India’s three-stage programme. In fact,senior researchers at BARC say that no government in50 years has interfered with its thorium vision, which isquite a feat given that India – the world’s largest de -mocracy – is and has been run by coalition governmentsof more than a dozen parties.

The final step of the deal – the legal framework forliability in the event of an accident – was thrashed out inthe Indian parliament in late August. It lets India, inprinciple, import fuel and reactors that will help it meetnear-term energy demands while adding to its fleet ofindigenous PHWRs, which make up the first stage ofthe country’s three-stage plan. These reactors burn uranium while irradiating thorium oxide to produceplutonium and uranium-233, respectively. In stage two,reprocessed plutonium fuels “fast reactors” that breedfurther uranium-233 and plutonium from a thoriumand uranium “blanket”, respectively, while also help-ing to plug a 400 GW deficit in electricity productionpredicted by 2050. In stage three, advanced heavy-water reactors (AHWRs) with lifetimes of a centurywill burn uranium-233 while converting India’s vastreserves of thorium into further uranium-233 in a sus-tainable “closed” cycle. All three stages are taking placein parallel, and each has been demonstrated on alaboratory scale.

Not surprisingly given its ambitions, India is theworld’s biggest producer of scientific papers on thor -ium, and it has an enviable nuclear road map. Indeed,following a trip to the subcontinent in September 2009,

three UK nuclear experts – Tim Abram of ManchesterUniversity, Mike Fitzpatrick of the Open Universityand Robin Grimes of Imperial College London –wrote that India has “a national strategy of develop-ment and deployment of nuclear-power technologiesthat, frankly, puts current UK policy to shame”. IfIndia’s senior nuclear scientists are to be believed, itsthree-stage programme is bang on track, which meansthat Bhabha’s plan will be realized by the middle ofthis century.

Bhabha’s legacy

Each year since 1957 a couple of hundred graduatephysicists, chemists and engineers, drawn from morethan 10 000 applicants, are tutored in the ways ofIndia’s indigenous nuclear-power programme – mostof whom then go on to be employed at India’s govern-ment labs. Indeed, those who work on India’s nuclear-power programme talk about themselves and theircolleagues as if they are “eggs” hatched to carry for-ward Bhabha’s vision, each knowing their own (andtheir colleagues’) “batch number”. “Bhabha’s masterstroke was to set up the BARC training school,” says C S Sundar, who graduated as part of batch 17 in 1974and is now director of materials science at the IndiraGandhi Centre for Atomic Research (IGCAR) inChen nai – the DAE’s other main lab.

It is hard not to sense Bhabha’s presence at BARC,not least thanks to the portraits – some of which are setin what look like shrines. As one is guided around afood-irradiation laboratory, where genetically modi-fied seeds are developed and distributed to farmers toimprove their crops, a giant collage of Bhabha madefrom different shades of mutant beans suddenly ap -pears. But his real legacy is the infrastructure, such asBARC’s 100 MW uranium-fuelled research reactorcalled Dhruva and an older reactor called CIRUS,where the first and third stages of India’s thorium visionwere and are being played out.

Standing next to the humming Dhruva device, Rainaexplains how, for example, thorium was irradiated in

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India’s energy gap (Left) India currently gets about 75% of its power from fossil fuels (mostly coal), 20% from hydroelectricity and the rest from nuclear and renewables.Although the country currently produces just 5% of global carbon-dioxide emissions, continuing to rely on coal is not an attractive environmental option. Unless it importslight-water reactors and reprocesses spent fuel from those reactors, India sees itself ending up with a 400 GW “power deficit” by 2050 that could only otherwise be filled byimporting 1.6 billion tonnes of coal. (Right) The growth in installed capacity of electricity generated by nuclear reactors in India will be taken up by its pressurized heavy-water reactors (purple), plutonium–uranium fast-breeder reactors (yellow) and thorium-fuelled reactors (red). Source: Department of Atomic Energy

Founding father

India’s three-stagenuclear-energy planwas formulated in the1950s by thephysicist HomiBhabha (1909–1966), who remainsits inspiration morethan 40 years afterhis death.

physicsworld.comNuclear power: Thorium

42Physics World October 2010

CIRUS back in the 1960s and the resulting uranium-233 was first separated from irradiated thorium atBARC in 1970. In the next 18–24 months, he says, all the necessary steps for starting construction of aBARC-designed 300 MW AHWR will be completed –a technology demonstration for a thorium–uranium-233 plant. The reactor physics of the AHWR is alreadybeing validated in a separate “critical facility” reactorcommissioned in 2008.

With Dhruva busily transmuting uranium into plu-tonium in the background, and India being one of justeight nations known to possess nuclear weapons, ner-vous laughter erupts among our tour group when Rainaseems to say – while describing some of the condensed-matter research that takes place at Dhruva – that “mis-siles” have been studied in one of the many neutronbeam lines emerging from the off-yellow cylindricalreactor. (In fact, he had said “micelles” – an aggre -gation of molecules dispersed in a liquid.) Yet duringlunch with new BARC director Rata Kumar Sinha, whotook over from Banerjee in May, the BARC boss makesno mention of what India terms its “strategic” (i.e.weapons) programme as he reels off all the additionalactivities taking place at BARC. On being asked, hereplies that it involves a tiny minority of staff spreadacross its many programmes.

As a result of the Indo-US deal, CIRUS will closedown at the end of this year, while 14 of India’s reac-tors will come under the auspices of the InternationalAtomic Energy Agency (IAEA). No longer the nuclearoutsider, India is open to civil nuclear collaborationwith other countries, including the UK. Soon, followingmore than two years of efforts by the British HighCommission in New Delhi, Research Councils UK andthe DAE to forge links between researchers in bothcountries, a dozen or so postdocs will swap countries

under a £1.2m research grant from the Engin eeringand Physical Sciences Research Council and similaramounts from the DAE (see box above). India has alsosigned co-operation deals with France, Russia and Can -ada to allow nuclear trade between the two nations.

Fast reactors

A two-hour internal flight from Mumbai brings you to Chennai on the south-east coast of India, and toIGCAR – the laboratory enacting stage two of India’snuclear-power programme. Security is less severe thanat BARC, and, being 15 years younger, the large leafycampus has a fresher feel to it. Sipping tea in directorBaldev Raj’s office beneath photos of Bhabha togetherwith Nehru, IGCAR chiefs talk of their pride in seeingvarious reactors grow and evolve with home-growntechnology. As for what other countries such as the UKhave to offer India, chemistry group director VasudevaRao says collaboration in areas such as materials,mechanics and computational fluid dynamics should“enhance the economics, performance and safety” ofIndia’s three-stage nuclear programme.

IGCAR’s 40 MW Fast Breeder Test Reactor (FBTR)makes India one of just four countries, along withRussia, Japan and China, to have an operational fastreactor. These devices, which use highly energetic neut -rons to cause fission in isotopes such as uranium-238,differ from thermal reactors in that they can breed morenuclear fuel than they consume. They do this by usingtheir higher neutron flux to convert fertile material tofissile material in breeder blankets, which can then be reprocessed to produce new uranium–plutoniummixed oxide (MOX) fuel and fed back into the reactor.Two of the main challenges of fast reactors are to extractheat safely and efficiently from the core and to designfuel that can withstand the high neutron flux and “burn

During a visit to India in late July, the UK Prime Mini ster David Cameron signalled a newera in nuclear trade between the two countriesbased on a joint declaration of civil co-operationsigned in February. While new businessopportunities for companies such as Rolls Royce and Serco hit the headlines, in thebackground five nuclear-research proposalsworth more than £2m were jointly funded by theUK’s Engineering and Phys ical SciencesResearch Council (EPSRC) and by India’sDepartment of Atomic Energy.

Robin Grimes of Imperial College London, whojoined the prime-ministerial trip as an adviser,says such collaboration is not without itssensitivities given that India is outside theNuclear Non-Proliferation Treaty. But he says thatthe deal presents a “marvellous opportunity” forthe UK’s nuclear sector, which has been in slowdecline since the mid-1980s, to get involved withIndia’s national programme and to takeadvantage of its expertise and facilities.

UK nuclear researchers are particularly keento use facilities such as India’s full-scale sodium

cooling loop in its Fast Breeder Test Reactor(FBTR) in Chennai. Materials engineer Mike Fitzpatick of the Open University, forexample, who is about to take up one of the fivejointly funded proposals, is eyeing up India’sresearch reactors. “The facilities that previouslyexisted in the UK have gone, and although theNational Nuclear Laboratory has great potential,we don’t yet have access to a place where wecan test our irradiation models,” he says.

Indian researchers, meanwhile, are keen toget beam time at the UK’s ISIS neutron sourceand Diamond synchrotron to characterize theproperties of materials such as the glasses usedto store long-term waste and those used to makemetallic fuel for fast reactors. UK universitiesand companies also have modelling,engineering and materials expertise that will beuseful, for example, to develop the welding forthe high-pressure joints in fast-reactor plumbing.

Three further joint proposals are in thepipeline. “We want Indo-Anglo grants to bebusiness as usual,” says EPSRC’s power andenergy manager Stephen Elsby. And despitedifferent scientific cultures and national nuclearambitions, both sides are brimming withenthusiasm. “I’ll be honest, I wasn’t expectingmuch commonality when I went over,” saysFitzpatrick of his first trip to the Bhabha AtomicResearch Centre (BARC) in Mumbai. “But when Igot there, I was amazed at the ambition andresource behind India’s nuclear programme, andhow much UK researchers could benefit frombeing associated with it.”

Indo-Anglo collaboration

IGCA

R

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43Physics World October 2010

up” rates.Based on a French design and operational since 1985,

India’s FBTR removes heat from the core via a liquid-sodium loop and runs on a unique uranium–plutonium–carbide fuel because of India’s historical lack of accessto enriched uranium (fast reactors need fuel with ahigher fissile content). This has provided “burn up” – ameasure of the total energy extracted from a fuel – of165 GWd per tonne (where 1 GWd = 24 × 106 kWh),which is 20 times that of a typical PHWR. Recently,IGCAR researchers loaded mixed-carbide fuel pelletscontaining material reprocessed from spent FBTR fuelback into the reactor, thereby “closing” the fuel cycle.

Driving along sandy roads towards IGCAR, onepasses the construction site of the 500 MW PrototypeFast Breeder Reactor (PFBR), the foundation pit ofwhich was flooded when the Indian Ocean tsunamistruck the Kalpakkam coast in 2004. Due to switch onin 2012, the PFBR is the stepping stone to six 500 MWfast reactors that will be the workhorses of India’s

nuclear-power programme from about 2020. Initially,India’s fast reactors will burn MOX fuel with a thoriumand uranium blanket, but, gradually, advanced metal-alloy fuels that increase the plutonium breeding ratiowill be introduced. Before then, however, the PFBRhas to demonstrate the safety of India’s fast reactors,particular its sodium cooling loop.

Described by Raj as a “mega-challenge”, In dia’s fast-reactor programme will involve, some time after2020, rolling out a fleet of 1 GW metal-fuelled fast re -actors that will increase uranium-233 stocks for use inthe third stage of the thorium fuel cycle in multipleAHWRs. IGCAR already has the world’s first and onlyuranium-233-fuelled reactor, the 30 kW KAMINI re -actor built in conjunction with BARC, which demon-strates the transition to stage three – its fuel beingproduced from thorium irradiated in India’s PHWRsand reprocessed at IGCAR.

21st-century fuel

India’s three-stage plan may be unique, but it is not theonly way to exploit thorium (see box left) and neitheris it necessarily the quickest. There are also tough chal-lenges ahead for the scientists and engineers goingthrough BARC’s training programme, particularly inseparating thorium and uranium-233 from spent fast-reactor fuel. “Slowly, some experience is being ac -cumulated in low-level irradiation of thorium fuel inPHWRs and reprocessing to recover uranium-233,”says Arunachalam, “but the third stage of India’s pro-gramme is quite some decades away.”

The problem with uranium-233 is that it comes inti-mately bound with uranium-232 – a short-lived isotopethat has among its decay products isotopes that emitdangerous levels of gamma radiation. On the otherhand, the presence of uranium-232 makes it hard to useuranium-233 for a bomb because the material has to behandled remotely and cannot be easily concealed froma radiation detector. Although this increased resistanceto proliferation is billed by its proponents as one ofthor ium’s greatest assets, a report published in Augustby the UK’s National Nuclear Laboratory (NNL) – an in dependent nuclear-technology service providerowned by the UK government – suggests that suchclaims have been overstated. The NNL recommendsthat uranium-233 poses a proliferation risk compar -able to enriched uranium-235, and points out that “significant though reduced” amounts of plutoniumwill always be produced when burning thorium in any-thing other than a breeding cycle.

The NNL also treats claims about thorium’s im -proved waste characteristics with caution. It says thatregardless of the reactor system, uranium and pluto-nium will remain an integral part of the thorium fuelcycle unless the uranium-233 is fully recycled. As far asthe commercial utilities are concerned, NNL says thepotential savings that thorium fuel offers and otherclaimed benefits are insufficiently demonstrated andtoo marginal to justify the technical risk. “The reasonthat uranium is still and will continue to be the fuel ofchoice for decades to come is that it is proven, relativelyinexpensive and abundant for some years,” say NNL’sAndrew Worrall and Kevin Hesketh. “Why would any-one wish to move to a new, unproven, risky venture that

Unlike uranium-235, which makes up about 0.7% of natural uranium, thorium is notfissile and so it needs an initial “inventory” of fissile material to achieve criticality in areactor core. India’s ultimate aim is to utilize uranium-233 and thorium in a closed,self-sustaining cycle (see main text). However, India is also maintaining an interest inanother approach called an accelerator-driven system (ADS), which may allow thecountry’s vast thorium reserves to be exploited sooner than its “third stage” AHWRs.

The ADS or “energy amplifier” proposed by particle physicist Carlo Rubbia andothers in the early 1990s produces neutrons by firing a beam of high-energy protonsat a spallation target, usually lead or tungsten, in the reactor core. The advantage ofthe ADS is that it is inherently protected against reactor power excursions becauseshutting down the reactor is just a matter of switching off the proton accelerator. Itcould also be used to transmute existing high-level waste – something common to allattempts to use thorium but for which the ADS offers greater scope.

Although there is a large push in the UK from the Thorium Energy AmplifierAssociation (ThorEA), which envisages a privately built 600 MW prototype ADS reactorgenerating electricity by 2025, the energy amplifier is unlikely to be commercializedany time soon, partly because there is not yet a particle accelerator reliable enough tobe hooked up to a national grid. “You’re trying to marry complex particle-acceleratortechnology with complex fast-reactor technology,” says Tim Abram of the University ofManchester in the UK. “France looked into ADS in great detail and concluded thatconventional fast reactors were a better solution for large-scale power generation.”

Another vision for a thorium utopia is the molten-salt reactor (MSR). Firstdemonstrated in 1965 as part of an attempt by the US military to build a nuclear-powered aircraft, today it is being resurrected in the form of liquid-fluoride thoriumreactors (LFTRs). Rather than use fuel rods, which become degraded in efficiency asmore reaction products build up, LFTRs would use a liquid form of thorium saltdissolved in a bath of lithium and beryllium fluoride salts. The LFTR concept does not need a particle accelerator to maintain criticality or expensive pressure-containment vessels to house the reactor core, and, say proponents, it can be shutdown safely and passively with human intervention.

Elsewhere, the US firm Lightbridge is developing a fuel with Russia’s KurchatovInstitute that burns uranium-233 bred from thorium in situ, and is intended for once-through cycles in light-water reactors. Lightbridge’s fuel would extend the lifetime ofexisting LWRs, cut the volume of waste by about 40% and slash long-term radio-toxicity of used fuel by up to 90%. Meanwhile, Thor Energy in Norway – a country richin thorium but with no commercial reactors – is also developing a thorium– plutonium-oxide fuel for light-water reactors, although a 2008 government-commissioned reportsaw no impetus to start a national thorium programme. Similarly motivated by healthythorium reserves, Atomic Energy of Canada is developing single-use thorium-basedfuel for use in its CANDU and other heavy-water reactors.

Thorium utopia elsewhere

physicsworld.comNuclear power: Thorium

44Physics World October 2010

will not be available for some decades?”But India’s three-stage vision has very much been

about security of supply and less about the cost per kilo-watt-hour, says Grimes, who adds that the economicarguments even for conventional reactors are not en -tirely settled. Moreover, he argues, it is not even clearwhat the winning ticket for nuclear power is: massiverecycling with MOX fuel, fast reactors or thorium.“What is clear”, he says, “is that the silly claims of the1960s, when people talked about energy too cheap tometer, remain positively silly.”

Cultural power

Back in downtown Mumbai, one thing Banerjee doesnot see as a hurdle to India’s nuclear future is anti-nuclear groups – not because India does not have them,but because the DAE runs projects to show the benefitsof nuclear power. He also thinks there is less protestbecause India has such pressing energy needs. “Atti -tudes towards nuclear power in the UK would soonchange after a week of power cuts,” he says.

In a modern context, Bhabha’s nuclear vision is partof a wider goal for clean, affordable energy also in theform of solar, wind and hydroelectricity – all of whichIndia is investing in heavily. India’s nuclear programmecould even one day encompass nuclear fusion, with thecountry already a partner in the ITER project currentlybeing built in France. Indeed, despite its large coalreserves, Raj thinks India might one day opt out of thefossil-fuel race altogether, saying that an intensive andconsumption-rich materialistic lifestyle is not advo-cated by traditional Indian values.

That said, I find myself sitting across a table from C S Sun dar in a beach resort a short drive along thecoast from IGCAR talking about the all too realprospect of Indian car ownership rising 25-fold thiscentury. Sundar describes India as a chaotic systemfrom which everything somehow always seems to turnout okay. Earlier in the day, with his hands behind hisback strolling along a thick-carpeted and sunlit cor -ridor at IGCAR, passing another portrait of Bhabha,he had turned and asked “Who is the father of yournuclear programme?”. ■

Planning ahead Set to open in 2012, the Prototype Fast Breeder Reactor at theIndira Gandhi Centre for Atomic Research is the forerunner to a series of Indian fast-breeder reactors to open from about 2020.

Pres

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CCFE

physicsworld.comNuclear power: Fusion energy

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It has to be one of the greatest public lectures in the his-tory of science. Indeed, the presidential address byArthur Stanley Eddington to the 1920 meeting of theBritish Association in Cardiff is still worth reading forthe simplicity and clarity of the arguments alone. Butit is his extraordinary vision that stands out nearly a century later. Until Eddington’s lecture, it was widelyaccepted that the Sun was powered by gravitationalcontraction, converting gravitational potential energyinto radiation. Some 60 years earlier, Lord Kelvin hadargued that this mechanism means that the Sun can beno more than 20–30 million years old. But using sim-ple arguments based on a wide range of observations,Eddington showed that the Sun must be much olderthan Kelvin’s estimate and that stars must draw onsome other source of en ergy.

It was fortunate that just prior to Eddington’s addresshis Cambridge University colleague Francis Aston hadmeasured the masses of hydrogen and helium to be1.008 and 4, respectively. Eddington argued that theSun is being powered by converting hydrogen to helium– by combining four hydrogen nuclei (protons) withtwo electrons and releasing energy in the process. Theexact details were wrong of course – the process is morecomplicated and involves deuterium, positrons andneutrinos, for example – but the basic idea was correct:the Sun is indeed converting hydrogen to helium.

The energy released in this transformation can be cal-culated using E = mc2 and the measured masses ofhydrogen and helium. From this, Eddington estimatedthat the Sun has enough energy to shine for 15 billionyears – remarkably close to modern estimates of ap -proximately 10 billion years from formation until theSun enters its red-giant phase, when it will have ex -hausted the hydrogen fuel in its core. He had deducedthe existence of what we now call nuclear fusion. Al -though Eddington cautioned about being too certain ofhis conclusions, he realized that the potential was stag-gering and he immediately saw the enormous benefitsfusion could bring society. As he told his audience inCardiff, “we sometimes dream that man will one daylearn how to release it and use it for his service”.

Eddington’s vision is now within our reach, althoughit has not been easy getting this far. Along the way wehave needed to develop the field of plasma physics,which studies gases heated to the point where the elec-trons separate from their atoms. Despite the struggles,it is fair to say that scientists have now captured theSun’s power.

Steve Cowley is Chief ExecutiveOfficer of the United KingdomAtomic EnergyAuthority at theCulham Centre forFusion Energy andprofessor of plasmaphysics at ImperialCollege London, e-mail steve.cowley@ccfe.ac.uk

Hot fusionDespite more than 50 years of effort, today’s nuclear-fusion reactors still require more power to run than theycan produce. Steve Cowley says the next step is to get thefusion plasma to generate its own heat – to make itselfhotter than the centre of the Sun

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47Physics World October 2010

From dream to reality

The modern fusion programme really began in theclosing moments of the Second World War at Los Ala -mos in the US, when Enrico Fermi and other membersof the team that built the first atomic bombs speculatedthat a fusion reaction might be initiated in a plasmaconfined by a magnetic field. In May 1946 GeorgeThomson and Moses Blackman of Imperial CollegeLondon applied for a patent for a magnetically con-fined fusion device in which powerful magnets couldbe used to hold a plasma in place while it is heated tohigh temperatures.

By the early 1950s it was clear that the easiest fusionreaction to initiate is that of two isotopes of hydrogen –deuterium and tritium. To initiate significant fusion, a plasma of deuterium and tritium must be heated to temperatures of about 150 million kelvin. Some 10times hotter than the centre of the Sun, this was a

daunting goal. However, in 1997 scientists achieved it ina magnetically confined plasma at the Joint EuropeanTorus (JET) at the Culham Centre for Fusion Energy inthe UK. JET produced 16 MW of fusion power whilebeing driven by 25 MW of input power.

Eddington would no doubt be pleased with the sci-entific progress on his vision. But despite the successes,we are not yet at a point where we can generate com-mercial electricity and fusion’s home stretch still in -volves significant challenges. Exactly what needs to bedone to make a commercial fusion power source?What are the key scientific issues? How should coun-tries position themselves to participate in a futurefusion economy? These are essential questions. Beforeturning to them, however, it is worth addressing themost important question of all: why bother? Perhapsother energy sources would be simpler options. In real-ity, there are worryingly few long-term energy sourceswith sufficient resources to replace the roughly 80% ofour energy that is generated by fossil fuels.

In the coming decades, current nuclear-fission tech-nology will play a critical role in generating low-carbonelectricity. But in the long term, aside from fusion, onlysolar and nuclear fission with uranium or thoriumbreeders (advanced reactors that breed nuclear fueland so extend the resource of fission fuel) have thecapability to replace fossil fuels. These technologiesstill need extensive research before they are ready tobe deployed on a large scale. But despite this potential,it is clear, however, that no energy source offers theextraordinary promise of fusion: practically unlimitedfuel; low waste; no carbon-dioxide production; attract -ive safety features and insignificant land use. These arecompelling reasons to develop fusion even if success isnot fully assured.

Self-heating fusion reactors

What then needs to be done to capitalize on JET’sachievement of significant fusion power? The nextstage is clearly to demonstrate that a plant producinga net amount of electricity can be constructed – some-thing that JET was not designed to achieve. The ratio of fusion energy produced to the electrical energy consumed to initiate and sustain the reaction must be increased. This requires a self-heated plasma – oneheated by the energetic helium nuclei produced in deuterium–tritium fusion (figure 1).

The National Ignition Facility (NIF) at the Law renceLivermore National Laboratory uses a different ap -proach to fusion than the magnetic-confinementmethod discussed here. The facility is designed to con-centrate 500 TW of power onto a millimetre-scale fuelpellet using an array of 192 lasers. The fusion energyproduced is expected to be roughly 10 to 20 times whatthe laser driver delivers as light. This would be a signi -fi cant demonstration of fusion “burn”, i.e. self-heat-ing. However, the NIF laser is less than 1% efficientand thus the facility is still short of the critical demon-stration that net energy production is possible.

For magnetically confined fusion, the crucial demon-stration is at hand. Seven international partners –China, the Euro pean Union, Japan, South Korea, In -dia, Russia and the US, together representing morethan half the world’s population – are now, after years

Deuterium (heavy hydrogen) and tritium (superheavy hydrogen) fuse to make helium and aneutron – releasing 17.6 MeV of energy as fusion power. This is the easiest fusion reaction toinitiate since it has a high reaction rate at low temperature (where “low” means 100–200million kelvin). Tritium does not occur in nature as it decays with a short 12-year half-life tohelium-3. Thus it must be “bred” from lithium using the neutron produced in thedeuterium–tritium fusion reaction. Here, the neutron causes a tritium-breeding reaction withthe isotope lithium-6, which comprises roughly 7.5% of naturally occurring lithium. The fuels forthis fusion reaction are therefore deuterium and lithium, which are plentiful in seawater.

1 Deuterium–tritium fusion

● Fusion power has the extraordinary promise of practically unlimited fuel, nocarbon-dioxide production, good safety and insignificant land use

● Controlled fusion was realized in the 1990s by the Joint European Torus (JET) andthe US Tokamak Fusion Test Reactor. JET needed more energy to run than itproduced – 25 MW input power to the plasma produced 16 MW of fusion power

● We could reach net electricity production by building a reactor that can support thehot burning-plasma regime, where fast-moving fusion products self-heat thereaction, so that less input power is required

● Simulations and measurements predict that the ITER facility being built in Francewill reach this regime by having a less turbulent fusion plasma and a greater volume– therefore making more fusion and losing less energy – than its predecessors

● For commercial fusion, a wall and “blanket” for the reactor must be engineeredthat can withstand many years of heat and radiation without weakening

At a Glance: Fusion energy

deuterium

tritium

tritium

helium (3.5 MeV)

helium

lithium-6

neutron (14.1 MeV)

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of delays, building a self-heated device called ITER atCada rache in southern France (figure 2). Like JET, thisexperiment will have a magnetic configuration denotedby the Russian acronym “tokamak”. ITER will be com-pleted in 10 years and a few years after that is expectedto be producing roughly 500 MW of output power fromless than 50 MW of input power – a 10-fold amplifica-tion, or “gain”, at least. One-fifth (roughly 100 MW) ofthe fusion power will be released as energetic heliumnuclei, which get trapped by the magnetic field and self-heat the plasma. The target is to sustain this power levelfor a duration of 400 s or more. However, recent experi -ments using JET and other machines, coupled withdetailed modelling, show that it should be possible tosignificantly increase that duration – and the gain. Evenwithout these increases, ITER will generate industriallevels of fusion power while being largely self-heated;this is the burning-plasma regime. This demonstrationof the scientific feasibility of high-gain fusion is a crit icalstep on the road to fusion power.

But how do we know that ITER will reach these per-formance levels? The key physics parameter is the“energy confinement time”, τE, which is the ratio of theenergy in the plasma to the power supplied to heat theplasma, where the latter is both the self-heating due tothe fusion-produced helium (one-fifth of the fusionpower, Pfusion/5) and the external heating (Pheat). Theenergy confinement time parametrizes how well themagnetic field insulates the plasma – it might bethought of as roughly the time it takes the heat put into the plasma to work its way back out. The plasma issustained for many energy confinement times (in prin-ciple indefinitely) by the heating. Clearly, a larger τEmakes a fusion reactor a better net source of power.The energy gain is defined as Q = Pfusion/Pheat. The deuterium–tritium fusion power produced per cubicmetre of plasma at a given temperature and density(the fusion power density) can be calculated using the measured fusion cross-section (the reaction ratefor a given fusion collision). In the temperature range100 × 106– 200 × 106 K, the fusion power density is ap -proximately 0.08p2 MWm–3, where the plasma pres-sure, p, is meas ured in atmospheres.

At high pressure the fusion power is large and theplasma is entirely self-heated (Pheat = 0 and Q → ∞) –this is termed “ignition”. Heating the plasma externally(supplying Pheat) reduces the net output and compli-cates the reactor design. Therefore, high gain is essen-tial. The gain of a fusion device depends on the state ofthe plasma – specifically the fusion product, pτE, andthe plasma temperature, T. Ignition occurs roughlywhen pτE > 20. In ITER the central plasma pressurewill reach about 7 atmospheres and the confinementtime is expected to be in the range 3.5–4 s (recall thatITER’s plasma will be sustained for more than 400 s –perhaps thousands of seconds). A plot of piτE versus Tenables a performance comparison for different toka-maks, where pi = p/2 is the ion pressure in the centre ofthe toroidal plasma (figure 3).

Predictions of high power at ITER

The most challenging technical question faced by thefusion community is determining what the confinementtime is and how we can be sure that it will reach 3.5–4 s.

We know that the loss of heat from magnetically con-fined plasmas is controlled by small-scale turbulence.The turbulence consists of plasma-density and elec-tromagnetic-field fluctuations that cause little swirls of plasma flow – eddies. The turbulent fluctuations are essentially unstable sound waves driven by the tem-perature gradient in the plasma. Like convection in asaucepan, eddies transport hot plasma out and coldplasma in. Progress in tokamak performance over thelast 40 years has been achieved by increasingly sup-pressing the turbulent convection of heat and therebyincreasing τE. One of the scientific triumphs of the lastdecade has been the ability to calculate this turbulenceusing high-performance computers to provide state-of-the-art simulations (figure 4).

Detailed comparisons of the simulations and meas-urements show that in many cases the calculations are indeed correctly capturing the complex dynamics.There is, however, still room for improvement, espe-cially in the intriguing cases where the simulated tur-bulence is almost entirely suppressed. The analyticaltheory of this turbulence is complicated and is onlynow just beginning to be understood. However, a qual-itative understanding of the turbulent transport canbe obtained from a simple random-walk argumentbased on the characteristics of the unstable soundwaves that form the eddy structures. This argumentyields the estimate τE ∝ L3B2T–3/2, where L is the size

Now being built at Cadarache in southern France, ITER will contain roughly 830 m3 of hotplasma inside a toroidal-shaped cavity. Confinement is provided by a magnetic field ofapproximately 5.2 T created by a niobium–tin superconducting coil at a temperature of 4 K.The plasma will be heated to fusion temperatures by radio waves and energetic neutralparticles that are injected into the plasma. Once at fusion temperatures (about 200 millionkelvin) ITER is expected to produce about 500 MW of fusion power for more than 400 s and belargely self-heated – such plasmas are termed burning plasmas. ITER is designed to have a“duty cycle” of at least 25% – i.e. the gap between burning-plasma shots is less than threetimes the shot duration.

2 ITER

ITER

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of the device, B is the magnetic field strength and T isits temperature. Clearly, bigger devices should per-form much better due to the steep L3 scaling. Indeed,empirical scaling derived from many experiments differs only a little from the simple estimate. ITER’senergy confinement time has been predicted in twoways: first, by extrapolation from the existing machinesusing the empirical scaling; and second, using so -phisticated local-transport models derived from si -mulations. These predictions are expected to be veryaccurate, with confinement times in the range 3.5–4 s.This prediction is the basis of our confidence thatITER will reach the self-heated burning-plasmaregime. We can get a qualitative feel for the extrapo-lation using the simple random-walk scaling: JETachieves roughly τE ~ 0.5–1 s confinement times andtherefore ITER (which will be roughly twice as big,30% hotter and have a field approximately 30% lar -ger) will have roughly τE ~ 4 s.

Blanket engineering

Given our current knowledge, it is more than reason-able to assume that ITER will achieve its goal of aburning plasma in the mid-2020s. However, as anyengineer will confirm, there is much more to com-mercial power generation than simply proving a designis scientifically feasible. Indeed, several componentsof any future fusion reactor – in particular the systems

that breed tritium from lithium (the second reactionin figure 1) and convert neutron power to electricalpower – have yet to be tested at any scale. The neut -rons produced in deuterium–tritium reactions, whichcarry four-fifths of the fusion power, are not confinedby the magnetic field and therefore leave the plasmaand pass through the surrounding wall. Inside the wallthere must be a complex system that absorbs the neut -rons, extracts heat and “breeds” tritium from lithium– this is known as a “blanket”.

There are many blanket designs but they all have afew things in common: they are typically 0.5–1 m thick,separated from the plasma by a steel wall and boundedon the outside by a steel shield. The blanket containslithium, which absorbs neutrons from fusion to breedtritium (figure 1) that is then fed back into the plasmaas fuel. Also in the blanket are neutron multipliers anda coolant used to flush out tritium and heat, which isused to power a turbine and generate electricity.

The blanket must satisfy some key requirements: tobe economically viable it should operate robustly athigh temperature in a harsh neutron environment formany years; and for tritium self-sufficiency it mustbreed more tritium than the fusion reactions consume.The technologies of the blanket, as well as the wall, arebecoming a major focus of the fusion programme andwill represent much of the intellectual property asso-ciated with commercial fusion. These reactor-systemtechnologies are critical for a future fusion economy– we cannot wait for ITER’s results in order to startdeveloping them.

A prerequisite for a viable blanket–wall system isrobust materials. Structural materials, breeder ma -terials and high-heat-flux materials are needed. In typical reactor conditions the atoms in the first few cen-timetres of the wall facing the plasma will get moved, ordisplaced, by neutron bombardment more than 10times per year. Each displacement causes the localstructure of the solid wall to be rearranged. Often thiswill be benign but sometimes it can weaken the struc-ture. Materials must therefore retain structural in -tegrity in these very challenging conditions for severalyears. To minimize the environmental impact of fusion,the walls must also be made of elements that do notbecome long-lived radioactive waste following high-energy neutron bombardment.

We do not know for certain whether such materialsexist, but several promising candidate materials havebeen proposed. For example, various special steelshave been shown to have suitable structural propertiesin theoretical calculations and ion-beam tests under-taken at Culham and UK universities. But we will notknow for sure until samples have been subjected to afusion-type neutron-radiation environment. The Inter -national Fusion Materials Irradiation Facility (IFMIF)is an accelerator-driven neutron source being devel-oped by the international research community to testsmall samples of the promising materials; its designteam is based in Japan as part of the deal that broughtITER to Europe. The neutron spectrum of IFMIF willmimic the high-energy neutron spectrum of a fusionreactor. Samples will be irradiated in a beam of neut -rons for several years to evaluate the changes in theirstructural properties.

Selected data from different tokamaks demonstrate substantialprogress over recent decades, with ion temperatures of more than100 million kelvin now routine. With JET, an energy gain (Q) of about0.7 has been reached – this is labelled as “breakeven” in thisdiagram. The Japanese experiment JT60 ran without tritium but if ithad been using tritium, then the gain would have been 1.25. ITER isexpected to obtain an energy gain of more than 10 – commercialreactors would need more than 20.

10

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3 Progress towards the promised land

Given ourcurrentknowledge, it is more thanreasonable toassume thatITER willachieve its goalof a burningplasma in themid-2020s

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50Physics World October 2010

We need a testing facility

If, as expected, ITER proves to be successful, thenblanket development is probably the critical path forfusion. Blanket designs are being developed and testedwith weak sources of neutrons, and it appears that thesedesigns will breed tritium efficiently enough to be self-sufficient. But they must be tested at full neutron powerbefore we can ensure a reliable commercially viablesystem. Although test-blanket modules will be placedin the walls of ITER in the later stages of operation,definitive tests require a continuous neutron flux of 1–2 MW m–2 for several years, which will not be techni-cally possible at ITER. Thus I believe that a “compo-nent test facility” (CTF) that can deliver reactor-levelneutron flux over many square metres is needed to significantly accelerate the development of blanket and wall structures. For such a device to be affordableit must be compact with low power consumption.

Researchers at Culham have pioneered a compactdevice called the spherical tokamak that is a primecandidate for a CTF. Indeed MAST (the MegaAmpSpher ical Tokamak) has achieved impressive plasmaconditions at a very modest scale. Calculations andmeasurements suggest that MAST achieves good con-finement by suppressing the turbulence by spinningthe plasma at supersonic speeds. The National Spher -ical Tokamak Experiment (NSTX) at Princeton in theUS also operates at about the MAST scale.

Results from these devices suggest that the sphericaltokamak is an ideal candidate for a compact and afford-able fusion device – i.e. a suitable candidate for a CTF.Culham and the Oak Ridge National Laboratory in the

US have therefore developed conceptual designs ofCTFs based on spherical tokamaks. These facilitiescould test whole components of the blanket and wall atfull power for many years. Both Princeton and Culhamare upgrading their machines to prove the viability ofthese conceptual designs. The MAST upgrade willdeliver near-fusion conditions, sustained plasmas anda test of the new exhaust system for gaseous plasma-burn products – the Super-X divertor.

If the MAST upgrade confirms the viability of aspherical CTF, then one could be built during the earlyyears of ITER’s operation. Wall and blanket develop-ment on the CTF coupled with ITER’s programmecould enable the construction of the first demonstra-tion reactors in the 2030s. The current internationalprogramme has no plans to build a CTF – but surely itis essential if we are to deliver commercial fusion whenit is needed.

It seems inevitable, given what has been achieved,that Eddington’s dream will come true eventually – butwhen? Although we cannot say for sure, for a worldthat is hungry for energy, a reduction of the time tocommercial fusion by even one decade could have anenormous impact. ■

More about: Fusion energyITER: www.iter.orgNIF: https://lasers.llnl.govK Ikeda et al. 2007 Progress in the ITER physics basis NuclearFusion 6 47R Pitts, R Buttery and S Pinches 2006 Fusion: the way aheadPhysics World March pp20–26

Fluctuations of plasma density caused by turbulence, as simulated for the DIII-D tokamak at General Atomics in La Jolla, California, using acomputer code called GYRO. Magnetic field lines lie on nested doughnut-shaped surfaces – toroidal surfaces. In this image we can see two suchsurfaces, the turbulence between them and two cuts across the surfaces. The hot middle of the plasma is omitted. The field lines are not shownbut the fluctuations are elongated along the magnetic field lines and are thus visible as the red and blue streaks along the toroidal surface.Turbulent flow is roughly along lines of constant colour and is perpendicular to the magnetic field lines. As can be seen from the cuts across thesurfaces, the swirls – eddies – are shorter in scale across the field (they are a few times the width of the helical orbit of the ions about the fieldlines). GYRO solves kinetic equations for the rings of charge formed by the helical motion of particles around the magnetic field lines. The fieldsare calculated from Maxwell’s equations using the calculated charge and current.

4 Heat loss through turbulence

Jeff

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Reviews

Just how dangerous is radiation? Sci-entists have been debating this ques-tion for decades yet, despite extensivestudies, there is still controversy. Theworking assumption, which is cur-rently accepted as the basis for regu-lation and legislation, is that radiationraises the risk of cancer at a rate thatis directly proportional to dose at alldose levels. A consequence of this“linear no threshold” (LNT) model isthat it assumes that there is no safelevel of radiation dose. The otherpossibility is that below a certainthreshold level, radiation is essen-tially harmless: any damage done byionization and the consequent radio-chemical and radiobiological effectsis effectively and quickly repaired bythe human body, with neither lastingharm nor elevated risk of cancer.

Conclusive evidence in favour ofone model or the other would be ofenormous interest. Scientists whodesign and operate nuclear powerplants and radioactive-waste repos-itories would benefit from greaterclarity. Medical physicists, who rou-tinely weigh up the benefits of diag-nostic tests and radiation treatments

against the risks to patient health,would be on firmer ground – as wouldthe politicians who approve the ne-cessary regulations. But any changesin policy or clinical practice must bedriven by data. Bold claims that radi-ation-protection regulations are afactor of 1000 too cautious may beappealing, but they should be dis-missed out of hand unless they aresupported by both a reasoned argu-ment and unequivocal data.

In Radiation and Reason: TheImpact of Science on a Culture of Fear,Wade Allison, a physicist at the Uni-versity of Oxford, sets out a reasonedargument in favour of the thresholdmodel, and against the LNT assump-tion outlined above. To support thisargument, Allison provides examplesfrom engineering and biology wherethere are indeed thresholds for ir-reparable effects. For example, anindividual who suffers a bruise orlaceration will recover completelyfrom such a minor injury, but beyonda certain threshold, laceration is irre-parable and possibly life-threatening.Why, Allison asks, should radiationcarcinogenesis be different? After all,

we know that damaged DNA can berepaired, and that in some cases ir-reparably damaged cells can be elim-inated by apoptosis, or programmedcell death. Surely this is evidence thatthe LNT model is flawed?

In the course of researching thisself-published book, Allison clearlybecame convinced that the radiobio-logical processes underlying carcino-genesis are well enough understoodthat the LNT assumption can be dis-missed. However, the reader shouldbe aware that the data he uses to sup-port this argument have also been re-ported and discussed extensively byresearchers in the field, and their con-clusions were rather different. No-tably, the L H Gray Conference inJune 2008, which brought togetherinternational experts in radiobiology,epidemiology and risk assessment,concluded that “at the present time,although the possibility of a low-dosethreshold cannot be ruled out, currentthinking on radiation protection sug-gests it is likely that low doses of radi-ation will carry some risk”.

The threshold hypothesis set out in Radiation and Reason is based onobservations from human popula-tions. In particular, data on survivorsof the Hiroshima and Nagasakiatomic bombings and those exposedto radiation in the aftermath of theChernobyl incident show that thenumber of “excess” cancers is lowerthan would be expected from the LNTmodel. However, the evidence fromradiotherapy patients, who Allisonclaims are safely exposed to dosesmany orders of magnitude higher thanradiological-protection dose con-straints, is not completely appropriatein this context, nor is it complete.

In radiotherapy, the volume of tis-sue irradiated to very high doses istypically less than 1% of the wholebody. A much higher volume of tissuereceives dose levels that can producefunctional side effects (such as dam-age to the integrity of the skin orblood vessels, or reduced saliva pro-duction) rather than carcinogenesis.Allison correctly cites the repair pro-cesses for these side effects as being

Peter Williams

Absence of evidence

Reviews

Radiation and

Reason: The Impact

of Science on a

Culture of Fear

Wade Allison2009 Wade AllisonPublishing£15.00/$23.00pb216pp

A warning sign

Debating the realdanger of radiation.

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the mechanism whereby therapeutic-ally effective doses can be delivered totumours without doing irreparabledamage to normal tissue.

Repairing functional damage is,however, very different from the re-pair at the molecular level that is ne-cessary to reverse the genetic damagethat leads to cancer. Moreover, thereis also an unavoidable whole-bodydose associated with radiation ther-apies – typically 4 mSv per day fromleakage and scattered radiation. (Incomparison, the average annual dosefrom background radiation is ap-proximately 2.4 mSv.) This scatteredradiation is known to induce “secondcancers”, which can occur far awayfrom the regions of high dose. Forexample, a large study of men withprostate cancer demonstrated anincreased subsequent risk of lung can-cer for those treated using radiother-apy compared with a matched cohorttreated by surgery. Although the ap-pearance of such cancers does notpreclude the existence of a threshold,it does undermine the grounds forrejecting the LNT model on the basisthat radiotherapy is risk-free.

The bottom line is that the scien-tific debate on the existence of athreshold cannot be resolved bypopulation studies alone, simplybecause the data are so sparse (thank-fully, since they stem largely fromnuclear wars and accidents). As theold saying goes, “absence of evidenceis not evidence of absence”. Resolu-tion of the threshold question, if it is possible, will be indirect and willdepend on quantitative basic radio-biology rather than epidemiology.

While the book draws on data frommany applications of radiation, it is the nuclear-power industry thatwould, its author believes, benefitmost from relaxed regulation. Yet Al-lison acknowledges that most of thevast expense involved in designingsafe reactors and appropriate storagesystems is directed at avoiding orreducing the risk of major incidents;as such, these costs do not depend on

the existence of a threshold dose. Thenecessary storage time for fissionproducts and other medium-half-liferadioactive waste would be influ-enced by the level of a threshold, andby public and scientific acceptance ofit. However, the costs of constructinga waste-storage facility will not bevery sensitive to the threshold dose,nor to the timescale required. A facil-ity built to last 500 years is unlikely tocost three times as much as one de-signed to last 150 years – another ex-ample of nonlinearity.

Radiation and Reason also posesquestions of a sociological and polit-ical nature. Why, Allison asks, is radi-ation perceived as being particularlyharmful? Can that perception bechanged to ensure that nuclear powercan be made more affordable andavailable, leading to worldwide so-cietal benefits? In exploring thesequestions, the author suggests thatoverzealous regulation has persuadedthe public to believe that radiation ismore dangerous than it actually is. Heargues that this has produced an ever-tightening spiral of constraints, whichothers have described as the “ratchetof radiation protection”. Perhaps, hesays, the time has come to release it.In this respect, Allison may have apoint: a relaxation of constraints mayindeed be in order, and it should cer-

tainly be on the agenda.However, such sensible thinking is

undermined by Allison’s statementsregarding would-be nuclear terror-ists. In particular, his suggestion thatterrorists will be deterred if regu-lations on the storage and use of ra-dioactive materials are relaxed, inresponse to evidence of reduced risk,strikes me as fanciful. For one thing,it wrongly assumes that terrorism isbased on rational behaviour. It alsoignores the fact that if radiation wereknown to carry a lower risk than cur-rent thinking suggests, then terroristswould simply need to steal a biggerflask of radioactive material to causethe same effect.

So is this a book about science, thepublic understanding of science, orpolitics? Perhaps all three, but theauthor’s emotive language in statingthat “the public need to know thetruth” implies that in the past theyhave been told lies. This puts the mat-ter squarely in the political domain.For scientists, the threshold debate is not about truth or lies; rather, it isabout how to deal with facts in a worldof uncertainty, where decisions haveto be made on the basis of the balanceof probabilities. Allison is acerbic inhis criticism of international bodiessuch as the International Commissionon Radiological Protection, but theirconservatism is not, as he says, “anabrogation of scientific responsibil-ity”. Rather, it is a recognition thatscientists have a responsibility tomake judgments as well as reportingtheir results. Until the radiobiologi-cal and radiological-protection com-munities reach a consensus, it wouldbe unreasonable to expect legislatorsto relax regulation and undertake anexperiment that will take generationsto mature.

Peter Williams retired as director of medicalphysics at the Christie Hospital in Manchester,UK, in October 2009 and is a past-president of the Institute of Physics and Engineering inMedicine, e-mail peter.williams@physics.cr.man.ac.uk

Allison suggeststhat overzealousregulation haspersuaded thepublic to believethat radiation ismore dangerousthan it actually is

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The archaeologists who excavated thetombs of the pharaohs were lucky.When they stumbled upon the re-mains of an ancient civilization, theyfound gold and valuable artefacts.Their descendents will not be so for-tunate. When explorers go digging for our last remains, what they findmay be valuable, and it will certainlytell them something interesting aboutour culture. But it could also kill them,because the longest lasting monu-ments of our civilization will probablybe our nuclear-waste repositories,and the radioactive “treasure” theyharbour will remain dangerous forthousands of years.

What does this say about us? This is the central question posed by thefilm Into Eternity – a fascinating andtroubling documentary about a wasterepository in southwest Finland calledOnkalo, a name that means “hidingplace”. Currently under construction,Onkalo is due to receive its first con-signment of radioactive waste in 2020.When it is completely full, sometimein the early 22nd century, its entrancewill be sealed. Its designers hope thatit will remain that way for at least100 000 years. But no human-builtstructure has ever lasted a 10th of thistime, so every decision made aboutOnkalo rests on uncertain ground.

Subtitled “A film for the future”,Into Eternity explores this uncertaintyin detail. The film, which will get itsUK première in Sheffield at theDoc/Fest event in November, discus-ses the physics of radioactivity, thepracticalities of interim and perma-nent storage, the requirements of thelaw, and the vexed question of how to keep our descendents safe fromOnkalo. Between interviews with vari-ous Finnish and Swedish officials,filmmaker Michael Madsen takes usround the Onkalo site, including theunfinished tunnel, which will eventu-ally stretch for 5 km and reach depthsof more than 450 m.

The tunnel is a surreal place, cov-ered in unintelligible markings andsuffused with a dim blue light. Oneinterviewee – a workman called SamiSavonrinne – likens it to a time cap-sule. We hear Savonrinne’s words ashe crouches on the tunnel floor, alonely figure in a high-visibility jacketpreparing to blast away the next sec-tion of bedrock (see image). It is astriking image, one of many in thissurprisingly beautiful film. The musicis also well chosen, with a multina-tional soundtrack featuring music bythe Finnish composer Jean Sibeliusas well as Arvo Pärt, Kraftwerk and –to great effect, in the film’s final scene

– Edgard Varèse.Such artistry would be wasted if

the interviews did not provide contentto match. Fortunately, Madsen hasput together a remarkably candidbunch of experts – some affiliatedwith Onkalo, others not – and they allhave interesting things to say. One ofthe most fascinating discussions con-cerns the chances of Onkalo beingfound, and the consequences of anysuch “human intrusion”. The expertsgenerally agree that the repositorywill, at some point, be forgotten – cer-tainly by the next predicted ice age in60 000 years, and probably well beforethen. As a result, says Onkalo’s seniormanager of communications TimoSeppälä, “My personal belief is thatno human intrusion will take place atany timescale ever.”

Timo Älkäs, the facility’s vice presi-dent for engineering, is more equi-vocal. Someone might break intoOnkalo, he concedes, but if they did,they would have tools to measure theradiation. One of the external experts,Peter Wikberg of Sweden’s NuclearFuel and Waste Management Com-pany, elaborates on Älkäs’ point: anycivilization advanced enough to diginto Onkalo, he says, would also beadvanced enough to know what it wasdealing with.

That is a comforting thought, buthis colleague Berit Lundqvist imme-diately casts doubt on it, noting that16th-century Swedish miners wereable to dig several hundred metresbelow the surface even though theywere unfamiliar with steam engines,let alone radioactivity. Over such animmense stretch of time, we cannotassume that humankind will becomeever more technologically advanced;any number of events could send ourdescendents back to the Middle Ages.The moderate-technology societythat might follow is a nightmare sce-nario for Onkalo’s designers, onewhere “people may drill but may notunderstand”, concludes Mikael Jen-sen, an analyst with Sweden’s Radi-ation Safety Authority.

Would it help to warn them? Poss-ibly – but there is no guarantee that awarning would be understood. Even ifit is, the advice might not be heeded.As the film points out, one Norwegianrune stone, carved less than 1000yearsago, bears a warning that it “should

Margaret Harris

A problem for the future

Into Eternity: A Film

for the Future

Michael Madsen2009 Magic HourFilms, 75 min,www.intoeternitythemovie.com

Burying the future

Inside the Onkalonuclear-wasterepository in Finland.

Mag

ic H

our

Film

s

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not be touched by misguided men”.The stone was found lying face down.

Yet Finnish law states that the fu-ture must be informed, so it will be –in Finnish-language archives that areunlikely to last more than a fraction ofOnkalo’s useful life. In the film, thetask of explaining this legal lunacyfalls largely to Esko Roukola, prin-cipal advisor for regulation at Fin-land’s Radiation and Nuclear SafetyAuthority. He looks distinctly uncom-fortable about it. Asked if he trustsfuture generations, at first he squirmsand waves the camera away. Even-tually, he stammers “I cannot say thatI trust but I cannot say that I don’ttrust.” It is one of the film’s best lines,succinctly capturing the problem On-kalo’s builders face.

There are a few gaps in the film,mostly on the technical side. For aplace that is meant to be stable andunchanging, the Onkalo tunnel ap-pears to contain an awful lot of run-ning water. It would have been niceto hear at least one expert explain inmore detail how waste is to be keptsegregated from groundwater overthe next several thousand years. Amore nuanced approach to the facil-

ity’s 100 000-year lifespan would alsohave been welcome. Half-lives beingwhat they are, at some point Onkalo’swaste, though still hazardous, will nolonger pose an immediate threat tolife. How long will that take? 500years? 1000? 10 000? The film doesnot say.

On a related note, it is a pity thatMadsen’s interviewees give shortshrift to the possibility of transmutingwaste into less hazardous substanceswith shorter half-lives. Although Ju-hani Vira, Onkalo’s senior vice presi-

dent for research, accurately pointsout that transmutation would notmake all the waste disappear, it wouldcertainly reduce the total volume andperhaps the required isolation period.This is not a small advantage. Buildinga handful of Onkalos to last 1000yearswould be a manageable engineeringproblem. Building several hundred tolast 100 000 seems dangerously closeto a crime against the future.

Unfortunately, there does not seemto be an alternative: if we want nuc-lear power, we will get nuclear waste.Indeed, we have accumulated morethan 200 000 tonnes of waste already,so even if we shut down all our nuclearpower plants tomorrow, we would stillhave a massive problem. Places likeOnkalo represent an implicit promisethat we can keep this waste safe – notonly in our own time, but for whatmight as well be an eternity. So arethey the solution? Into Eternity has noanswers, but it is a beautiful film aboutan ugly problem, and anyone inter-ested in nuclear power should see it.

Margaret Harris is Reviews and Careers Editorof Physics World, e-mail margaret.harris@iop.org

Any civilizationadvanced enoughto dig into Onkalowould also beadvanced enoughto know what itwas dealing with

URL: http://nukepowertalk.blogspot.com

So what is the site about?Nuke Power Talk is primarily a forum for discussingimportant issues related to the nuclear-powerindustry. You’ll find information here about newreactor designs and recent conferences, pluscommentary on speeches by major figures in theindustry. What really distinguishes this blog,though, is the insightful way that it connectsnuclear power with the bigger picture. For example,an entry posted shortly after the BP DeepwaterHorizon oil-rig disaster discusses how safetyprocedures that were developed for the nuclearindustry are now being applied in other fields. Otherentries focus on how nuclear power fits into theenergy industry as a whole, and how it stacks up incomparison with solar and wind power.

Who is behind it?Blog author Gail Marcus has an impressive string ofprevious appointments on her CV, including a stintas president of the American Nuclear Society anddeputy directorships at the Nuclear Energy Agencyand the US Department of Energy’s Office ofNuclear Energy, Science and Technology. Now anindependent consultant on nuclear power andtechnology, Marcus started blogging in 2009 after“seeing a lot of information in news articles or onthe Web that was only telling part of the story”, shetold Physics World. Although clearly a supporter ofthe industry, she is sometimes critical as well, andtries hard to maintain a balanced viewpoint. Hergoal, she says, is to be “a voice of reason in a sea ofrhetoric” about nuclear power.

Who is it aimed at?Nuclear insiders will appreciate Marcus’s postsabout news she picks up from attending meetingsand reading various specialist publications. Othersmay be drawn more to entries where she dissects,in clear and intelligent language, the policy issuessurrounding nuclear power.

Can you give me a sample quote?In a post about “unintended consequences”,Marcus writes “I’m not completely sure why thescientists and engineers have not been able todevelop the ability to try to project suchconsequences. I do realize it is difficult…We’ve got to anticipate ways that people will misuse

appliances. We’ve got to anticipate all conditionsunder which a system may operate – rain, snow,heat, humidity. We’ve got to anticipate theresource requirements, competition with otherneeds, etc, when a new technology grows fromlimited to large-scale use…For example, questionsare raised from time to time about the impacts ofthe increased use of nuclear power. Will there beenough uranium? What will the land impacts be ofmining lower-grade ores? The questions are goodones, and will need better answers if we are torealize a nuclear renaissance.”

Are there any other nuclear blogs that areworth investigating?Absolutely. Dan Yurman’s Idaho Samizdat(djysrv.blogspot.com) is a great site for the latestnuclear-industry news and gossip, and it coversnon-proliferation issues as well. Energy FromThorium (energyfromthorium.com) is morespecialized, offering an in-depth look at…well…deriving energy from thorium (see “Enter thethorium tiger” on p40). Blogging About theUnthinkable (sovietologist.blogspot.com) is a bit offthe beaten track. The author, a historian with aninterest in Soviet atomic culture, has recentlyposted photos from a field trip to Chernobyl –including several taken in the Unit 1 reactor controlroom, which looks exactly as it did in 1986, whenthe neighbouring Unit 4 reactor melted down. Withan incredibly diverse community of nuclear bloggersout there, though, this is just the tip of the iceberg.

Web life: Nuke Power Talk

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INSTITUTE OF PHYSICS AWARDS 2011The Institute of Physics Awards Committee is now seeking nominations for the Institute Awards 2011, and we need your help to nominate the most outstanding physicists in their respective fields.

The awards exist to recognise and reward outstanding achievements by physicists in their respective fields, working in industry, business or research. In 2008 the awards portfolio expanded, so we now have 27 medals that span all areas of physics as well as contributions made to physics outreach, physics education, the application of physics and physics-based technologies. We particularly welcome nominations for women and people from ethnic minorities who are often under represented in the nominations we receive.

Closing date: 10 January 2011Full details of the awards, eligibility, terms of reference and the nomination procedure are available on the website. Go to www.iop.org and select Awards. Alternatively, contact the secretary to the Awards Committee (tel +44 (0)20 7470 4800; e-mail awards@iop.org).

For the Awards 2011 we are seeking nominations for the following medals and prizes:

International medal Isaac Newton medal.

International bilateral medalsBorn medal; Holweck medal; and Occhialini medal.

Gold medals Business and Innovation medal; Dirac medal; Faraday medal; and Glazebrook medal.

Education and outreach medals Bragg medal and Kelvin medal.

Early career medals Maxwell medal; Moseley medal; and Paterson medal.

Subject medals Chadwick medal; Joule medal; Payne-Gaposchkin medal; Mott medal; Tabor medal; Rayleigh medal; and Young medal.

History of an uneasy elementAmong the Bemba people of centralAfrica, the word “shinkolobwe” isslang for “a man who is easy-goingon the surface but who becomesangry when provoked”. It is also thename of the Congolese uraniummine that yielded raw material forthe atomic bomb that flattenedHiroshima. As historicalcoincidences go, this one seemsalmost too good to be true. Still, one can hardly blame author Tom Zoellner for seizing upon it inUranium: War, Energy and the Rockthat Shaped the World, a veryreadable (if somewhat chaotic)history of how this normally easy-going element has provoked angeron five continents. After a scene-setting visit to the Shinkolobwemine, Zoellner’s description of theManhattan Project will contain fewsurprises for anyone who has readmore comprehensive histories. Onenotable exception is his explanationof how the scientists got the uraniumfor the bomb. This tale of costlyenrichment programmes, dubiousmiddlemen and colonialskulduggery has importantramifications for the entiresubsequent history of uranium. Inchasing this history, Zoellner goes toan impressive amount of trouble totell some of the less-heralded storiesof the uranium age, talking toprospectors from Darwin, Australia,to Moab, Utah, and to one of the lastsurvivors of an East Germanuranium gulag, where politicalprisoners dug the ore that built theSoviet nuclear arsenal. The pricethey paid was high – thousands diedfrom radiation, non-existent safetyprecautions and maltreatment – butit was scarcely lower for miners inthe West, where labour was unforcedbut just as hazardous. Theuniversally cavalier attitudes toradiation during this period aresobering to contemplate. The book’sfinal chapters cover a grab-bag oftopics from endemic fraud inCanadian uranium stocks to thequestion of whether terrorists couldget enough uranium to build a bomb.It is not a question Zoellner cares toanswer directly, but some may feelthat the facts speak for themselves:on his visit to Shinkolobwe, he foundthe still-productive mine almostcompletely unguarded.● 2010 Penguin £11.99/$16.00pb368pp

Questioning the cosmosAs a means of conveying scientificinformation, the “question andanswer” format has a lot torecommend it: it is simple,straightforward and easy to follow.The downside is that books in thisstyle tend to misjudge theiraudiences – after all, how do theauthors know which questionsreaders want answered? For thisreason, A Question and AnswerGuide to Astronomy is a pleasantsurprise. Written by engineer Pierre-Yves Bely and astrophysicistsCarol Christian and Jean-René Roy(and recently translated from theoriginal French into English), thebook claims to give “simple butrigorous explanations” in “non-technical language”, and it doesexactly what it says on the tin. Splitinto 10 sections, it answers hundredsof questions in fields ranging fromplanetary science (“What is thegreenhouse effect?”) to astronomyand cosmology (“How do starsdie?”). It also tackles trickierconcepts such as “Can anything gofaster than the speed of light?” andvarious big mysteries, including“What was there before the Big Bang?”. All the explanations arewell expressed and usually aided by a full-colour illustration orphotograph. Within explanations,the authors helpfully have embeddedcross-references to other pages thatmay help to explain commonconcepts, allowing readers to skimthrough the questions focusing onthe areas that interest them most.Towards the end, the book becomesmore specialized, with 30 or soquestions on telescopes followed bya propaganda-like section on how toget involved in astronomy. Despitethis, the majority of the guide isinformative, and by successfullytackling ideas that are oftenmisunderstood, it makes for aworthwhile and enjoyable read.● 2010 Cambridge University Press£18.99/$28.99pb 294pp

First you have to look for themThe ever-expanding catalogue ofworlds discovered outside our ownsolar system contains all sorts ofplanets: hot, cold, icy, rocky – youname it. But what about wateryplanets? Or those lovely, not-too-cold, not-too-hot “Goldilocks” oneswith an active geology and perhaps abiggish moon nearby, just to keep

things interesting? In How to Find aHabitable Planet, James Kastingbegins by describing various factorsthat geophysicists, astrobiologistsand others have deemed necessary(or at least desirable) for producingplanets capable of supporting life.He then examines the evolutionaryhistories of the planets we know best– the Earth, Venus and Mars – in anattempt to determine why theydeveloped the way they did. Thebook’s second half looks at ways offinding new planets using indirectmethods (like measuring the tinygravitational wobble imparted to astar when a planet passes nearby)before moving on to the challengesassociated with detecting themdirectly. Being able to separate thefaint reflected light of individualplanets from the much brighter lightof their parent stars “turns out to bea tall order”, writes Kasting. As aplanetary scientist at PennsylvaniaState University in the US, Kastingwas involved in a design study for aspace-based telescope that wouldhave examined light reflected fromthe surfaces of extrasolar planets forclues about their composition.Unfortunately, the mission wascancelled while it was still in thedesign phase, and NASA has not yetrevived it. How to Find a HabitablePlanet offers an eloquentexplanation of why such a missionwould still be desirable.● 2010 Princeton University Press£20.95/$29.95hb 360pp

Weird scienceTired of biscuits that crumble into asoggy mess at the bottom of yourteacup? Uncertain of the besttechnique for skimming stonesacross water? If you need answers tothese pressing problems – plus adviceon how to win at Trivial Pursuit and arather invasive way to cure hiccups –then Dunk Your Biscuit Horizontally isthe place to look. This light-heartedbook of bite-sized strange sciencewas compiled by the Dutchjournalists Rik Kuiper and TonieMudde, and would make a great giftfor anyone whose sense of humourencompasses both the scientific andthe scatological. It is probably notone for younger children, though:the best cure for intractable hiccupsturns out to be either good sex or“digital rectal massage”.● 2010 Summersdale Books £7.99pb128pp

Between the lines

Shock and ore

The story of theimpact of uranium on humankind.

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physicswor ld.com

Physics Wor ld Oc tober 2010 59

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Careers

After a period of decline, there is now a realsense of excitement in the UK’s nuclear in-dustry. The previous UK government’scommitment to allow new reactors to bebuilt on 10 sites has proved invigorating forthe entire sector. Even firms that had tradi-tionally focused on keeping the currentpower stations operational are now making“new build” a growing part of their business.

My own employer, AMEC, is one suchfirm. As contractors, we do work that othercompanies cannot do, either because they donot have enough people or because they lackthe right skills. Following the company’sacquisition of the nuclear consulting firmNNC in 2005, the nuclear part of AMEC’sUK business has expanded considerably.There are now offices around the country,including one in London near the head-quarters of EDF Energy (one of the maincompanies planning to build new reactors inthe UK), which lends project-managementsupport and other expertise.

I joined AMEC two years ago after com-pleting an MSci in maths and physics atDurham University. I had planned to con-tinue my studies with a PhD, but after doinga final-year project in theoretical physics, I decided that this was enough theory for me. At a careers fair, I came across AMEC,which was looking for physicists to work inits nuclear sector. I applied, was acceptedonto its graduate scheme and I now work as an analyst at AMEC’s Booths Park site in Cheshire.

AMEC is split into three divisions:Natural Resources, which deals with the oil and gas industries; Power and Process,which works in the nuclear sector; andEarth and Environmental, which provides

geoscience services. The Booths Park site is part of the Power and Process division,and has been home to nuclear scientistssince the 1950s. Back then, the offices werein a mansion house, and the workers werehelping to design the Magnox reactors – the UK’s first commercial nuclear plants.Today, the offices are more modern, but thesame view of a small local lake, BoothsMere, is available – along with cows makingthe daily parade for milking! There is also anice link to the original work, as AMEC hasrecently been involved in decommissioningthe Magnox reactors.

Safety firstIn my team of about 30 analysts, projectmanagers and planners, most of our con-sulting work comes from British Energy,although we also work with Rolls Royce andBAE Systems. British Energy (now part ofEDF Energy) owns the majority of the UK’scommercial reactors, which are mainly ad-vanced gas-cooled reactors (AGRs). Someof these reactors were constructed 30 yearsago and they are now coming to the end oftheir lives. But with power stations able togenerate £1m worth of electricity a day,keeping them online for even a few extrayears is big business. A lot of AMEC’s worktherefore deals with life extension – deter-mining whether or not the reactors are safeto operate for a little longer.

Deciding when a reactor needs to be de-commissioned can be a challenge. Every-thing gets weaker as it ages – even in coalpower stations, parts must be replaced con-tinuously. But once you throw irradiation

into the mix, dealing with ageing powerplants gets more complicated. For example,in an AGR, the reactor core is constructedfrom graphite blocks that fit together to formwhat is known as the diagrid. Over time, thegraphite is irradiated, and also gets oxidizedby any small quantities of air present, makingit weaker and lighter. Eventually, such “coreageing” processes will render the reactorunsafe for continued operation.

Safety is paramount in this industry, so ifthe Nuclear Installations Inspectorate – theregulatory body that issues licences for run-ning a reactor in the UK – is not happy, thena reactor will simply be shut down. Gettingthe evidence we need to prove that a reactoris still safe has required some novel ap-proaches to testing. One of these is AMEC’s“test rig”, which is essentially a steel cagewith a quarter of the footprint of a real reac-tor core, containing quarter-size “graphite”blocks (actually made from aluminium) invarious states of wear and tear. Tilting thisrig allows cameras to see whether the ageingblocks would cause problems during normaloperation, or in more extreme conditions,such as a major earthquake.

Measuring the damageOne of the main projects I have been in-volved in is proving that it is safe to connectinspection equipment to empty reactorchannels, to allow video equipment to be slidinto the channels and video footage to beobtained from inside the core. The idea is to see how many cracks are present: eventhough it will not be possible to fix any thatare found, given the extreme environment,

Playing itsafe with reactorsWith new nuclear reactors on thehorizon, Mike Yule explains whyhelping to keep the UK’s existingplants running safely is a greatjob for a physicist

Putting safety to the test Graduate analyst Mike Yule finds lots to challenge him at consultancy firm AMEC.

AMEC

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it is still useful to know how much the corehas degraded.

Within this project, my specific job is toevaluate the consequences of what areknown as “dropped fuel faults”. In a reactor,the uranium fuel is contained in bullet-likepellets within stainless-steel tubes, calledfuel rods or pins. An arrangement of 36 fuelpins in three concentric rings, held inside a graphite “sleeve” using steel braces, isknown as a fuel element. These fuel ele-ments are lifted into and out of the reactorand various other components during re-fuelling or discharging operations. If a ele-ment drops at any point, then its potentialenergy goes into processes such as crumblingthe sleeves and buckling the pins.

Thanks to specially conducted drop testsof fuel elements, we have a good idea of howthey can be damaged, and how much energycan be absorbed in the various processes. Byincorporating energy-absorption mechan-isms into spreadsheets, we can calculate how

much damage would occur in a particular sit-uation, and can show how damage dependson drop height, channel diameter, ductilityand many other factors.

Another problem is that because the pinscontain fuel, they generate heat even whenthe reactor is shut down (so-called decayheat). If the pins buckle due to mechanicalloading in a dropped fuel fault, the fuel be-comes more concentrated and less easy tocool. We need to model this too, so some ofthe work I do uses software (written in goodold Fortran) to predict how faults will affect

fuel temperatures, which have to stay withinlimits to ensure safety.

I have found this work interesting becauseit has built on knowledge gained over thecourse of my degree, particularly that ofspreadsheets and programming languages.My degree has also helped by giving me abetter understanding of physical situations,such as where heat is being transported byflows and radiation.

The AMEC graduate scheme is a greatintroduction to the nuclear industry, and agood way of meeting the other graduateswho joined the firm at around the same time.I have greatly benefited from the supervisionof specialists, who are always ready to sharetheir expertise. I enjoy the work I do and ithas given me confidence in the safety of ourreactors. In a growing industry, that is nobad thing.

Mike Yule is an analyst in AMEC’s Power and Processdivision, e-mail mike.yule@amec.com

The AMEC graduatescheme is a greatintroduction to thenuclear industry

John Hemming is theMember of Parliament forBirmingham Yardley, UK

What sparked your interest in physics?I have always been interested understanding howthings work. I prefer maths and physics asacademic subjects because they have more of anobjective truth or falsity about them, whereas thehumanities are more about agreeing with aconsensus. Philosophically, I prefer the idea thatthere is such a thing as objective reality that weattempt to measure, and it is not something thatvaries depending on the opinion of senior membersof society.

Did you enjoy studying it at university?Yes, although admittedly there was one term I wentto more PPE (politics, philosophy and economics)lectures than physics lectures. I was also someonewho did not do enough practical work during theterm and I therefore had to do a practical examboth in my first year and in my final year. This did,however, make physics more time-efficient as asubject, allowing me more time to do other things.Luckily, in the early 1980s one could get anhonours degree in physics without doing lots ofpracticals – unlike chemistry, which required morepractical work. I am someone who is happy doingpractical things, but I tended to spend more timerepairing bicycles, playing croquet and puntingthan doing physics practicals.

Why did you go into the software business?After I left Oxford University in 1981, finding workwas a challenge. My first job was to clear up therubbish at Edgbaston Cricket Ground. That did notreally have attractive career possibilities. I triedvarious things, including offering to teach physicsand introduce croquet at a school in the Black Country, but I was told they wanted apostgraduate teaching certificate first. Then Imanaged to get employed as a computerprogrammer by offering to learn from the manuals.After a few changes of employer, I started my ownbusiness in late 1983 – the same year I fought myfirst general election, standing as the Liberal Partycandidate in Birmingham Hall Green.

How did you become interested in politics?I joined the Liberal Party in 1976 at the age of 16because I wanted to see a fairer world where properattention is given to environmental issues andpeople are treated justly as individuals. I was alsointerested in constitutional improvements,including electoral reform. Initially, I was agent forvarious elections, but I felt unhappy at the calibre ofone early candidate and after that I concluded Ishould offer to be the candidate myself. I foughtevery general election between 1983 and 2001,and also served on Birmingham City Council beforewinning the Yardley parliamentary seat in 2005,and retaining it in 2010.

The Liberal Democrat Party is opposed tonuclear power. As someone with a physicsbackground, what is your view on this?The view of the [Conservative–Liberal Democrat]coalition government is that fission should not be

subsidized. We do have fission-based electricitygeneration in the UK, but there is a medium-termissue with the availability of easily refined uranium-235. Hence, in the long term fission canonly really be relied upon if a breeder technologycan be made to work. However, I take the view thatwe should be aiming for sustainable energysources. I am quite happy to rely on nuclear fusionas long as the power plant is kept on average some93 million miles away. I do not have a problem withresearch on operating fusion at a closer distance;however, that project has generally been one that isconstantly 40 years away from completion. If youwere to forecast the true completion date bycalculating the velocity at which it tends towardsthe value of “now”, you would conclude that thefusion project will never be completed.

What do you think is the greatest challenge that the UK faces in terms ofscience policy?A culture based on subjectivity and the celebrationof celebrity.

Do you have any advice for the physicsstudents of today?Remember that it is normally a cock-up rather thana conspiracy, and yes, people really don’tunderstand. Don’t be surprised.

To make the most of your physics degree, visitwww.brightrecruits.com

Once a physicist: John Hemming

physicsworld.com Careers

61Physics World October 2010

PWOct10careers 17/9/10 09:59 Page 61

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Top maths prize for former physicistElon Lindenstrauss, who gainedundergraduate degrees in physics andmathematics before turning to puremathematics, is among four winners of the2010 Fields Medal. A researcher at theHebrew University of Jerusalem’s EinsteinInstitute of Mathematics, Lindenstrauss isrecognized for work that focuses on theapplications of ergodic theory – a branch ofmathematics that grew out of statisticalphysics in the early 20th century – tonumber theory. The Fields Medal isawarded every four years to scholars up tothe age of 40 and is viewed as theequivalent of a Nobel prize formathematics. Also honoured in 2010 wereNgô Bào Châu of Paris-Sud 11 Universityand the Institute for Advanced Study inPrinceton, US; Stanislav Smirnov of theUniversity of Geneva, Switzerland; andCédric Villani of the Ecole NormaleSupérieure de Lyon, France.

Physics trio wins research awardsThree physicists are among 12 scholars to receive the Royal Society’s Wolfson Research Merit Award in 2010.

David Manolopoulos of the University ofOxford, Mervyn Miles of the University ofBristol and Sheila Rowan of the Universityof Glasgow will each receive grants of up to£30 000 per year over five years for researchprojects on atomic physics, nanophysicsand astronomy, respectively. The awards, which are jointly funded by the Wolfson Foundation and the UKDepartment for Business, Innovation andSkills, are designed to support scientists inany discipline who wish to do research atUK universities.

Biophysics acknowledges key playersSix researchers working in a broad range of fields have been named as Fellows of the Biophysical Society for 2011.Bioengineer Valerie Daggett of theUniversity of Washington; biophysicists Donald Engelman and Lynne Regan ofYale University; cell biologist Jennifer Lippincott-Schwartz andcomputational biologist Ruth Nussinov ofthe US National Institutes of Health; andbiochemist Anthony Watts of theUniversity of Oxford were honoured for“expanding the field of biophysics”.

Movers and shakersThe Materials Research Society has givenits David Turnbull Award to spintronicspioneer David Awshalom of the Universityof California, Santa Barbara.

Pallava Bagla and Roberta Kwokhave won the American GeophysicalUnion’s 2010 awards for excellence inscience journalism.

Two Durham University researchershave won the Society of Rheology’s topannual prizes. Suzanne Fielding receivedthe Metzner Award for early-careerresearchers, while Tom McLeish won the Bingham Medal for contributions tothe science of the deformation and flow of matter.

Fusion scientist Martin Peng of the Oak Ridge National Laboratory in the UShas received the 2010 Fusion PowerAssociates Leadership Award for showing “outstanding leadership qualities inaccelerating the development of fusion”.

Theoretical physicist Michelle Povinelliof the University of South Carolina is oneof 35 people named in Technology Reviewmagazine’s annual list of top scientists andtechnologists under the age of 35.

Careers and people

physicsworld.com

Next month in Physics WorldMultiverse pioneer

US quantum physicist Hugh Everett III was the inspirationfor the idea of multiple universes, but he led a troubled lifethat led to an untimely death at aged just 51

Living with a star

How a series of space missions dedicated to observing the Sun are enriching our knowledge of space weather andstar behaviour

Microscopy frontiers

Scanning probe microscopy has transformed our ability tounderstand matter at the nanoscale, but what exactly does it mean to “see” atoms?

Plus News & Analysis, Forum, Critical Point, Feedback, Reviews, Careers and much more

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physicsworld.com Careers

63Physics World October 2010

PWOct10careers 20/9/10 14:12 Page 63

Quantitative Understanding of BiosystemsAn Introduction to BiophysicsThomas M. NordlundUniversity of Alabama at Birmingham, USA

Catalog no. 89772, December 2010, c. 864 pp., ISBN: 978-1-4200-8972-1, $79.95 / £49.99

Computational Methods in Plasma PhysicsStephen JardinPrinceton Plasma Physics Laboratory, New Jersey, USA

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Thin-Film Optical FiltersFourth EditionH. Angus MacleodThin Film Center Inc., Tucson, Arizona, USA

Catalog no. C7302, March 2010, 800 pp., ISBN: 978-1-4200-7302-7, $139.95 / £89.00

Light SourcesTechnologies and ApplicationsSpyridon KitsinelisAthens, Greece

Catalog no. K11102, November 2010, c. 216 pp., ISBN: 978-1-4398-2079-7, $129.95 / £82.00

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66 Physics World October 2010

EMBL International PhDProgramme 2011Biology, Chemistry, Physics, Mathematics, Computer Science, Engineering, Molecular Medicineat our sites in Heidelberg, Grenoble, EBI Hinxton, Hamburg and Monterotondo

All applications have to be made online at www.embl.org/phdprogramme

For further information, see our web page or contact: Dean of Graduate Studies, Dr. Helke Hillebrand, predocs@embl.de

Deadline for registration is 1 December 2010

Deadline for completion of the online application is 13 December 2010

Would you like to contribute your creativity to an international team of scientists from all disciplines focusing on basic research in the molecular sciences?

European Molecular Biology Laboratory (EMBL) invites you to apply for PhD positions in Heidelberg, Grenoble,Hamburg, Hinxton (near Cambridge) and Monterotondo (near Rome).

EMBL opens the door to your scientific career – our students have an outstanding publication record, are a vital part of our global collaborations and receive their degrees jointly with our network of excellent partner universities in 20 countries.

Our PhD positions come along with generous fellowships including broad health care benefits.

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Physics World October 2010 67

Announcement of Lindhard Scholarships in Physics and Astronomy

The Department of Physics and Astronomy at Aarhus University invites applications for 10-15 Scholarships, each covering a 3 or 6 months preparation period for enrolment in the PhD programme. The aim of this honours scholarship programme is to increase international recruitment of top-level students in Physics and Astronomy. The successful applicants are expected to follow courses taught in English and engage in research activities that may lead to formulation of a PhD project.

The Department has a large range of internationally competitive activities, so the PhD-education takes place in a scientifically inspiring environment.

Information about the research activities and the PhD-programme can be found on the Department homepage www.phys.au.dk.

The Scholarship covers travelling expenses and local expenses including housing with 8.000 DKK (roughly equivalent to 1075 Euro) for each month of stay in Aarhus. This amount is sufficient for accommodation and living expenses for one person. Adequate accommodation will be available for the successful applicants.

The Scholarships start on January 15, 2011, one week before the beginning of the official teaching period in the winter of 2011, and they terminate after evaluation of courses and projects, either April 14 or July 14, 2011.

The minimum background education required is a top 5 % Bachelor of Science degree in Physics, Astronomy, or a closely related subject, and students may apply for a Lindhard Scholarship up to two years after obtaining this degree. An alternative, relevant especially for students with considerable experience after the Bachelor degree, is a 2-week visit to the Department to find a thesis adviser and discuss the formulation of a PhD project. The application procedure and the deadlines are the same for such visits as for the Lindhard Scholarships.

At the end of the Scholarship period the student may in competition with other Danish and international applicants apply for enrolment in a 3 or 4 year PhD-programme. For top level students, chances are excellent to obtain a fully financed fellowship for the whole period (about 300.000 DKK per year).

The application must be submitted online and should include a curriculum vitae, specifics about the background education including a list of grades covering all courses, preferences of fields in theoretical or experimental Physics or in Astronomy, the preferred length of the visit (between 3 and 3 months or 2 weeks), motivation for the application (max one page) and recommendation letters (max three). Applicants are expected if asked to be available for a Skype interview and successful applicants will be required to submit authenticated copies of certificates.

For more information see www.phys.au.dk/Lindhard.Scholar or contact the Chairman of the PhD-committee, Aksel S. Jensen, Tel: +45 8942 3655, email: asj@phys.au.dk.

Please apply online here: http://phys.au.dk/nyhed/article/announcement-of-lindhard-scholarships-in-physics-and-astronomy-1/

Lindhard_17x2.indd 1 17/09/2010 09:25

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The Department of Applied Physics and Applied Mathematics (APAM) at Columbia University in the City of New York welcomes excellent and motivated international applicants for its PhD programs in Materials Science and Engineering; Condensed Matter and Optical Physics; Plasma Physics; Atmospheric, Oceanic, and Earth Physics; and Applied Mathematics. All applicants accepted into the PhD program will receive a full financial aid package including tuition and a generous stipend for the full term of study. Columbia is one of the top-ranked Universities in the world, situated on a beautiful campus in the heart of New York City. APAM offers excellent research opportunities from distinguished faculty with an excellent record of attracting federal and industrial research funding. For more information about the faculty and research in the department, and instructions about applying, please see the department website: http://www.apam.columbia.edu.

The application deadline for fall 2011 admission is December 1st 2010.

PhD opportunities in Materials Science, Applied Physics and Applied Mathematics

at Columbia University

8.5x2.indd 1 20/09/2010 13:22

68 Physics World October 2010

Do you want to study for a doctorate whilst gaining invaluable commercial experience?

The EngD is a 4-year fully funded PhD-level doctorate with an emphasis on research and development in a commercial environment.

Research projects are offered in three themes: Optics and Photonics

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Successful candidates will normally work closely with their chosen sponsoring company, with support from an Academic and Industrial Supervisor. Funds are also available to support company employees who wish to study for an EngD whilst remaining in employment.

Funding

Fees plus a stipend of at least £20,090 (2010/11) are provided for eligible students.

Entry Qualifi cationsMinimum entrance requirement is a 2i Bachelors or Masters degree in a relevant physical science or engineering topic.

Further DetailsFor more details including a list of current projects and eligibility criteria visit www.engd.hw.ac.uk or contactProf Andy Harvey(e: engd@hw.ac.uk;t: 0131 451 3356)

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Project Engineers We have an exciting opportunity for Physics/Astronomy graduates to become part of a pioneering team working as Project Engineers on e2v’s groundbreaking projects. If you have recently graduated and are looking for a unique opportunity to work on world leading technology in Science & Space exploration this could be your ideal career start.

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Physics World October 2010 69

UNIVERSITY OF THE WITWATERSRAND, JOHANNESBURG – FACULTY OF SCIENCE

CHAIR/ASSOCIATE CHAIR IN THEORETICAL PARTICLE COSMOLOGY

SCHOOL OF PHYSICSWe invite applications for a research Chair in Theoretical Particle Cosmology, which was awarded to the School of Physics, University of the Witwatersrand. This Chair can be taken at the Associate Professor level or at a full Professor level, depending on qualifications, experience and research record of the candidate.

Very generous research funds, including running expenses and studentships, are associated with this Chair.

Research fields in the School include theoretical high energy physics, including string theory, theoretical particle phenomenology and experimental particle physics. The School hosts the DST/NRF Chair of Fundamental Physics and String Theory and the Gauteng node of the National Institute for Theoretical Physics. It is also involved in a number of initiatives aimed at increasing the scope of its activities in Astrophysics, particularly in view of the expected commissioning of the MeerKAT radio telescope and possible award of the SKA to South Africa.

QualificationsWe are looking for candidates who will complement the current research interests in the School and lead a vibrant high quality research program in Particle Cosmology.

A PhD and an excellent publication record with evidence of independent research are essential. Experience in post-graduate supervision will be an advantage, as post-graduate supervision is one of the key expectations of the Chair incumbent. Applicants whose research interests include analysis of observational data will also be considered.

The rank of the appointment and final selection will be made on the basis of scholarship and potential to contribute to the work and reputation of the School.

EnquiriesFor further information contact the Head of School, Professor J.A.P. Rodrigues, Fax: +21-11-717-6879 or Email: Joao.Rodrigues@wits.ac.za

Applications: Submit a detailed CV including relevant qualifications and experience, research publications and a statement of research interests, together with names and addresses/email details of 3 referees to:Prof. J.A.P. Rodrigues, Head, School of Physics, University of the Witwatersrand, Johannesburg, Private Bag 3, WITS, 2050, South Africa.

Email: Joao.Rodrigues@wits.ac.zafax: 27 11 717-6879.Closing date: 22 October 2010

The University reserves the right not to make an appointment and continue searching after the closing date and only short-listed candidates will be contacted.

Committed to excellence and equity

UnivWitwatersrand.indd 1 14/09/2010 13:46

PhD studentshipsFusion Energy Science and Technology

World-leading facilities in the UK, including JET, MAST and the Central Laser Facility, offer opportunities for scientists and engineers, while for the future, construction of ITER has begun and NIF should demonstrate ignition next year.

The Universities of Durham, Liverpool, Manchester and York, with Culham Centre for Fusion Energy, the Central Laser Facility and AWE have formed the Fusion Doctoral Training Network with EPSRC support, offering science and engineering graduates:

-up to eight PhD studentships (some with enhanced stipend)-a six-month training course in fusion science and technology-exciting science and technology research projects, linked to world-leading fusion facilities-internationally renowned research groups

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70 Physics World October 2010

* Terms & conditions apply. See website for details.All information correct at time of press.

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Web-based MSc Courses in

Plasma Physics and Vacuum TechnologyThe School of Mathematics and Physics at Queen’s University Belfast offers a range of web-based, taught modules in Plasma Physics and Vacuum Technology. The modules can be taken individually and followed entirely online (on a free-lance basis, e.g., as PhD foundation courses) or can be combined to form the basis of a • Master of Science (MSc) in Plasma Physics

or a • Master of Science (MSc) in Plasma and Vacuum Technology. The former course requires a presence at Queen’s University only for a short period in the second semester and possibly for the summer research project. The latter course is part-time, specifically designed for those in full time employment and does not require attendance at Queen’s University. For research students or employees who need to quickly acquire a basic knowledge of plasma physics, there is a 4 week “Introduction to Plasma Physics”. Other modules are taught over 8 or 12 weeks. Full information on module content and course and application details can be downloaded at http://www.qub.ac.uk/mp/cpp/MScCourses/.

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Are you looking to deepen yourknowledge of physics? Comeand see the range of Masterscourses in physics taught in theDepartment of Physics, ImperialCollege, London, one of the world’s leading scientific universities in the heart of London.

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Physics World October 2010 71

Start something BIGwith an IOM3 accredited Masters orfunded PhD at Cranfield.Cranfield University is ranked third in the UK for the impact of ourmechanical, aeronautical and manufacturing research*, and graduatesthe highest number of engineering and technology postgraduates in theUK. Our specialist Master’s programmes include:

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PhD Studentships in Advanced Light Alloys and Materials Performance

Applications are invited for studentships in Advanced Alloy Research at The University of Manchester. The Manchester light alloys group has gained an international reputation in light alloys research, and these opportunities have arisen as a result of the group’s successful bid for a £5.7mn EPSRC Programme Grant LATEST2 “Light Alloys Towards Environmentally Sustainable Transport - 2nd Generation”. The Programme aims to support dramatic reductions in the environmental impact of transport, by facilitating a step change in high-performance light alloy design solutions in the transport sector. This research Programme involves collaborations with AIRBUS UK, Alcoa Europe, Bridgnorth Aluminium Ltd, CSIRO, GKSS Research Centre, Innoval Technology Ltd, Jaguar LandRover, Keronite Ltd, Magnesium Elektron Ltd, Meridian Business Development UK, NAMTEC, Norton Aluminium, Novelis Global Technology Centre, Rio Tinto Alcan, Rolls-Royce Plc, TWI.

Applications are also invited for studentships in the Materials Performance Centre working in the areas of graphite, corrosion, residual stress measurement and damage characterisation, fracture mechanics, creep continuum modelling and Computational Fluid Dynamics. All the Centre’s research areas is undertaken for a wide range of organisations within the UK, Europe and overseas including British Energy, EDF, the Engineering and Physical Sciences Research Council (EPSRC), Health and Safety Executive/Nuclear Installations Inspectorate (HSE/NII), Ministry of Defence (MoD), Rolls-Royce, Serco Assurance, TWI, Corus, INSS (Japan) and Westinghouse.

Who should apply?Applications are welcomed from graduates with a relevant honours degree (at least UK 2.1 hons or equivalent grade) in science or engineering as well as knowledge of one or more of the above research themes. In addition to having an excellent aptitude for research, applicants should also exhibit a wide range of personal skills.

Full scholarships, covering living expenses and fees, are available to eligible students.

How to apply?http://bit.ly/9Z6oAF

For informal enquiries, please contact Sandra.kershaw@manchester.ac.uk

Manchester_13x4.indd 1 20/09/2010 15:44

Physics World October 201072

RecruitmentThe place for physicists and engineers to find jobs, studentships, courses, calls for proposals and announcements

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The Department of Physics and the Enrico Fermi Institute at the University of Chicago invite applications for two tenure-track positions: one in experimental elementary particle physics with an emphasis on neutrino and non-accelerator physics, and one in experimental particle astrophysics and cosmology. The appointments will start in the Fall of 2011.

Successful candidates must have a doctoral degree in physics or a related field, a record of excellence in research, and are expected to contribute effectively to the Department’s undergraduate and graduate teaching programs while engaging in forefront research. The appointments are expected to be at the level of Assistant Professor; however, an Associate or Full Professor appointment is possible for exceptionally well qualified candidates.

Applicants must apply online at The University of Chicago academic jobs website, http://tinyurl.com/2011EFI-search and upload a cover letter, curriculum vitae with a list of publications, and a brief research statement. The cover letter should be addressed to either Professor Ed Blucher, Chair, Experimental Elementary Particle Physics Search Committee, or to Professor Bruce Winstein, Chair, Experimental Particle Astrophysics Search Committee, depending on the discipline of interest. In addition, three reference letters will be required. (Referral letter submission information will be provided during the application process.)

Review of applications will start in the fall of 2010 and will continue until the positions are filled. To ensure full consideration, applications and recommendation letters should be received no later than November 1, 2010.

The University of Chicago is an Affirmative Action / Equal Opportunity Employer.

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Associate Director for Experimental Nuclear PhysicsThe Associate Director for Experimental Nuclear Physics is responsible for the execution of the experimental nuclear physics program. Responsibilities include the management of the Experimental Physics Division of approximately 140 staff, including 85 scientists and engineers. The division is responsible for the experimental nuclear physics program including the management of the experimental operations schedule for the program

in conjunction with the accelerator division and matched to the available resources.

The Associate Director participates in strategic planning, policy formation, budgeting, and science initiatives. The Associate Director represents the laboratory with government agencies, the international physics community, other laboratories, universities, as well as stakeholders.

The successful candidate will be a distinguished scientist with a proven record of physics research leadership and publication in nuclear physics or a related field. The candidate will have demonstrated leadership, communication skills, ability to manage resources, personnel, and technical knowledge relevant to accelerator-based experimental nuclear physics. A Ph.D. and substantial history of relevant experience in Nuclear Physics or related field, including increasing responsibility in nuclear physics research projects are required. The candidate will also have proven negotiation and interpersonal skills to develop and maintain excellent relations with internal and external stakeholders.

Deputy Associate Director Experimental Nuclear PhysicsThe Deputy Associate Director participates in all aspects of the management of the Experimental Nuclear Physics Division and reports to the Associate Director. The Physics Division has primary responsibility for the operation and continuous upgrading of the Jefferson Lab nuclear physics experimental

Thomas Jefferson National Acceleratoris a U.S. Department of Energy, Office of Science laboratory that has a central and unique role in the field of nuclear physics, both in the U.S. and worldwide. Jefferson Lab’s present and future program is as a world leader in hadronic physics and superconducting accelerator technologies. The primary nuclear physics facility is the Continuous Electron Beam Accelerator Facility currently operating at 6 GeV and being upgraded to 12 GeV. The laboratory has an international user community numbering approximately 1,300 physicists. Jefferson Lab is currently seeking outstanding individuals to fill three senior leadership positions.

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EUROMAGNET CALL FOR PROPOSALSFOR MAGNET TIME

The next deadline for applications for magnet time atthe LABORATOIRE NATIONAL DES CHAMPS MAGNETIQUES INTENSES

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and the HOCHFELD LABOR DRESDEN (www.fzd.de/hld)is November 15th, 2010.

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Scientists of EU countries and Associates States* are entitled to apply under FP7 for financial support according to the rules defined by the EC.*listed on ftp://ftp.cordis.europa.eu/pub/fp7/docs/third_country_agreements_en.pdf

For further information concerning feasibility and planning, please contact the facility of your choice.

A POSTDOCTORAL OPPORTUNITY

http://www.uark.edu/misc/aaron5/index.html

for a computational condensed matter scientist in the area of multiferroics and ferroelectrics

(in their bulk and nanostructure forms)is available at the

University of Arkansas.

For more information, see

PWOct10_Arkansas_5.5x2.indd 1 20/09/2010 13:45

Physics World October 2010 73

The Paul Scherrer Institute is with 1300 employees the largest research centre for the natural and engineering sciences in Switzerland and a worldwide leading user laboratory. Its research activities are concentrated on the three main topics structure of matter, energy and environmental research as well as human health.

The activities of the PSI Laboratory for Particle Physics focus on projects in theoretical physics, in high energy physics within the CMS experiment at the LHC, and in low energy precision physics at PSI’s own world-leading facilities for pions, muons and ultracold neutrons, see ltp.web.psi.ch.

We invite applications for the newly established

Postdoctoral Fellowshipfor Excellence in Particle Physics

The named postdoc position is accompanied by a competitive salary and open to both experimental and theoretical physicists. Candidates are se-lected based on the strengths of their academic and research accomplish-ments and plans. Research activities proposed by the candidates should be in line with the program of the Laboratory for Particle Physics. Appli-cants must hold a doctoral or PhD degree in physics. You are welcome to contact the group leaders of the research groups to discuss your ideas prior to application. The successful candidate will join one of the laboratory’s groups. In the future, this prestigious position will be adver-tised and filled every two years

For further information please contact: Prof Dr Klaus Kirch, phone +41 56 310 23 78, klaus.kirch@psi.chPlease submit your application at the latest until October 30th, 2010 (including CV, list of publications, statement of research interests and addresses of at least three referees) quoting the ref. code by e-mail to thomas.erb@psi.ch or to Paul Scherrer Institut, Human Resources, ref. code 3200, Thomas Erb, 5232 Villigen PSI, Switzerland.www.psi.ch

Untitled-1 1 26/07/2010 15:21

facilities installed in Halls A, B, C, and D. The Deputy also serves as the Division Safety Offi cer and manages to oversee the Physics Division EH&S program.

The Deputy Associate Director provides support for the infrastructure necessary for assuring a user-friendly atmosphere, serves as a member of the Technical Advisory and Scheduling Committees, and advises the Associate Director on short-range experimental priorities. In particular, the Deputy has primary responsibility for overseeing/managing the details of the beam time schedule consistent with the broad directions defi ned by the Scheduling Committees.

The successful candidate will be an internationally recognized scientist in nuclear physics or a related fi eld. The position requires a Ph.D. and signifi cant relevant experience in Nuclear Physics or related fi eld, and a demonstrated track record of resource and technical management or signifi cant projects in design, construction, commissioning and/ or operation.

Hall A Group Leader The Hall A Group Leader provides overall management of the physics research group for the hall. This includes leading the development of the research program through collaboration with users, staff, and advisory committee. The Hall leader oversees the staging and execution of the

scientifi c experiments. Additionally, the Hall Leader is responsible for the provision of appropriate experimental equipment for the balance of operations at 6 GeV and with special emphasis on the 12 GeV era, which will begin in 2013. The responsibilities also include management of all Hall scientifi c, post doc, engineering and technical staff, budgeting, planning and resource allocation.

The successful candidate will be an internationally recognized expert in the forefront of nuclear/ particle physics. A record of scientifi c excellence as demonstrated by extensive publication in nuclear/ particle physics is required. A Ph.D. in Experimental Nuclear or Particle Physics or the equivalent combination of education, experience, and specifi c training is required.

Interested candidates should submit a CV, publication list and letters of reference.More information or to apply: http://www.jlab-jobs.com/

TJNAF is an Equal Opportunity/ Affi rmative Action Employer.

CCSepClassified38-42.indd 39 10/08/2010 14:27

The European Commission’s Joint Research Centre (JRC) is a reference centre of science and technology for the European Union. Operating in Belgium, Germany, Italy, Spain and the Netherlands, with a headcount of over 2,700, the JRC is currently seeking researchers with the right blend of competence, experience and language skills to work at the cutting edge of scientifi c and technological developments supporting EU policies.

If you have a sound track record of research in Chemistry, Biology and Health Sciences, Physics, Structural Mechanics, Quantitative Policy Analysis, Spatial Sciences, Environmental Sciences, Energy Sciences or Communication/Information Technology, you can make all the diff erence within the JRC’s

stimulating multicultural environment. In return, you can expect a lifetime of diff erent opportunities, a competitive remuneration package, fl exible working arrangements and the chance to become involved in some of the most exciting research initiatives in Europe today.

To learn more, visit www.jrc.ec.europa.eu/competitions and as soon as you are ready to apply, fi ll in your on-line application at www.eu-careers.eu

Registration closes on 4th November 2010.

References: COM/AD/01/10 – COM/AD/16/10

The JRC promotes equal opportunities and non-discriminatory practices in the workplace.

Post-doctoral Position“Quantum Dot-Microcavity Interactions”Semiconductor Photonics Group and CRANN Research Institute, Trinity College DublinThe research project deals with CdTe based quantum dots and their interactions with microcavity structures to control the emission from coupled microcavity structures in the regime of single photon emission. The laboratory is world-class with fluorescence lifetime, confocal and scanning near-field microscopes, an optical trap and a fs-laser system. Candidates must have a PhD in Physics with direct experience in microcavity research.

The closing date is Oct. 29th 2010. Please send a CV to Professor John Donegan, e-mail jdonegan@tcd.ie with subject Postdoctoral Researcher Microcavity.

TRINITY TEST.indd 1 20/09/2010 13:33

Physics World October 201074

The Faculty of Engineering at McMaster University invites applications for a tenure-track faculty position in Engineering Physics. The appointment is intended to be at the Assistant or Associate Professor level.

The applicant should have expertise and interest in photonic, optoelectronic, or photovoltaic device engineering. The department has many active research projects spanning such topics as biophotonics, electro-optic systems, nanostructured and nonlinear optical materials, nano- and micro-devices, silicon photonics, solar photovoltaics, and III-V materials and devices. There will be opportunities to capitalize on existing infrastructure at the university including the facilities of the Centre for Emerging Device Technologies (CEDT), the Brockhouse Institute for Materials Research (BIMR), and the Canadian Centre for Electron Microscopy (CCEM). In addition, within the past year, faculty members in our department have been successful recently with major initiatives in photovoltaics, nuclear materials, and positron physics, funded through the Canada Foundation for Innovation and the Ontario Research Fund, adding very significantly to McMaster University’s infrastructure supporting R&D in advanced materials.

Applicants must have earned a Ph.D. in Engineering Physics, Physics, Applied Physics or a closely related discipline. The successful applicant will be expected to develop an effective, externally funded research program and demonstrate a strong commitment to teaching and curriculum development at both the undergraduate and graduate levels. The Faculty expects the successful candidate to become registered as a Professional Engineer in the Province of Ontario.

Interested applicants should send a letter of application, curriculum vitae, statements of teaching and research interests, a selection of four research publications, and the names and addresses of at least three references to:

Department ChairDepartment of Engineering Physics, McMaster University1280 Main St. WestHamilton, Ontario, Canada, L8S 4L7This position is available as of January 1, 2011 and will remain open until the position is filled. Applications by e-mail will not be accepted.

Note: All qualified candidates are encouraged to apply. However, Canadian citizens and permanent residents will be considered first for these positions. McMaster University is strongly committed to employment equity within its community, and to recruiting a diverse faculty and staff. The University encourages applications from all qualified candidates, including women, members of visible minorities, Aboriginal peoples, members of sexual minorities and persons with disabilities.

This advertisement is repeated with a new final paragraph, omitted in a previous version.

Department of Engineering PhysicsTenure-track Faculty Position,Assistant or Associate Professor LevelPhotonic, Optoelectronic, or Photovoltaic Device Engineering

AMENDED ADVERTISEMENT

Shaped by the past, creating the future

DE PA R T M E N T O F PH YS I C S

LECTURER IN EXPERIMENTAL CONDENSEDMATTER PHYSICS£36,715 to £43,840 per annum

Applications are invited for two lectureships in experimental condensedmatter physics. Applicants should have excellent research records in areas thataugment or bridge across existing strengths which include biophysics; light-emitting diodes; photovoltaics; nanophysics; superconductivity; x-rayscattering and magnetism (http://www.dur.ac.uk/physics/research/cmp),and take advantage of the access to world-class equipment available either in-house or using international facilities. Applicants will be expected to make asubstantial contribution to the research activities of the group and toundertake teaching and administrative duties.

Closing date: 30 November 2010 Ref: 0460

Further details of the post and an application form are availableon our website (http://www.dur.ac.uk/jobs/) or telephone 0191 334 6499; fax 0191 334 6504

The Department of Physics and the Enrico Fermi Institute at the University of Chicago invite applications for two tenure-track positions: one in experimental elementary particle physics with an emphasis on neutrino and non-accelerator physics, and one in experimental particle astrophysics and cosmology. The appointments will start in the Fall of 2011.

Successful candidates must have a doctoral degree in physics or a related field, a record of excellence in research, and are expected to contribute effectively to the Department’s undergraduate and graduate teaching programs while engaging in forefront research. The appointments are expected to be at the level of Assistant Professor; however, an Associate or Full Professor appointment is possible for exceptionally well qualified candidates.

Applicants must apply online at The University of Chicago academic jobs website, http://tinyurl.com/2011EFI-search and upload a cover letter, curriculum vitae with a list of publications, and a brief research statement. The cover letter should be addressed to either Professor Ed Blucher, Chair, Experimental Elementary Particle Physics Search Committee, or to Professor Bruce Winstein, Chair, Experimental Particle Astrophysics Search Committee, depending on the discipline of interest. In addition, three reference letters will be required. (Referral letter submission information will be provided during the application process.)

Review of applications will start in the fall of 2010 and will continue until the positions are filled. To ensure full consideration, applications and recommendation letters should be received no later than November 1, 2010.

The University of Chicago is an Affirmative Action / Equal Opportunity Employer.

CCSep10ClChicago16x2.indd 1 20/09/2010 13:57

Fresh jobs straight to your in-box

brightrecruits.com

Sign up to the jobs by e-mail alert from brightrecruits.

PWOctClFillerFreshJobs_8.5x2.indd 1 20/09/2010 14:28

Don’t miss physicsworld.com’s latest multimedia offerings.

Hamish Johnston, editor of physicsworld.com,

talks exclusively to…

Reinventing DESY: from particle physics to photon science

V I D E O S E R I E S

l Helmut Dosch, director of DESY in Hamburg, for a progress report on the laboratory’s move away from particle physics to become a world-leading centre for photon science

l Edgar Weckert, director for photon science at DESY, about the FLASH X-ray free-electron laser (XFEL) and how that facility is informing plans for the 1.2 bn European XFEL project

Thursday 14 October 4.00 p.m. BST

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JOIN US FOR THIS FREE ONLINE LECTURE

Lecturer: Peter Byrne

Many worlds: how Hugh Everett III changed quantum mechanics

ONL INE LECTURE SER IES

In 1957 Hugh Everett III believed he had solved the infamous measurement problem in quantum mechanics by explaining probability as an illusion in an evolving, deterministic universe of universes. In this lecture, Everett’s biographer Peter Byrne traces how this “many worlds” interpretation of quantum mechanics evolved over the course of Everett’s often troubled life.

Register now at physicsworld.com/cws/go/webinar15

physicsworld.com/cws/channel/multimedia

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M PW AD 0910 Webinar_Full_02.indd 1 20/09/2010 11:26

The phrase “too cheap to meter” has haunted the nuclear-power industry almost since its inception. It was coined in1954 by Lewis Strauss, the chairman of the US AtomicEnergy Commission, just three years after the world’s firstelectricity-generating nuclear power plant announced itsarrival in a blaze – or, more precisely, a glow – of four 200Wlight bulbs. Designing and building the plant, known asExperimental Breeder Reactor-1 (EBR-1), cost $5.2m.You have to admire Strauss’s optimism.

To be fair, EBR-1’s main job was to produce pluto-nium, not electricity. It fulfilled this mission quite hand-somely, by “breeding” plutonium from non-fissionableuranium-238. The plant also improved a bit in the elec-tricity stakes over the years, eventually producing enoughto power its own building. Still, as energy breakthroughsgo, EBR-1 was never going to set the world alight – al-though it gave it a good shot in December 1955, when itsuffered a partial meltdown.

Yet the faltering progress of early atom-tamers waslargely absent from contemporary rhetoric. Strauss’s “toocheap to meter” comment may be the most notorious, buthe was hardly alone. Newspaper reports at the time pro-mised a future of nuclear-powered trains, ships and aero-planes. A1956 educational film, A Is For Atom, spoke intypically admiring tones of “a giant of limitless power atthe command of man”. The film featured animations ofdancing uranium atoms, fizzing with useful energy. Withthe benefit of hindsight, it all seems rather cute.

There was, of course, a darker side to the naivety of the early nuclear age, and the nuclear-power industry haslong struggled to emerge from its shadow. Many earlyreactors were dual-purpose machines that generatedweapons-grade plutonium alongside electricity. And onthe weapons side, ignorance could kill. Consider SurvivalUnder Atomic Attack, a pamphlet produced in 1951 by theUS Federal Civil Defense Administration. Its contents areinstructive, although not necessarily in the way intended.After a reasonably accurate discussion of the three haz-ards of atomic bombs – blast, burns and radioactivity – the actual advice offered to would-be survivors is under-whelming. Much of it is either common sense (“try to getshielded”) or weirdly preoccupied with housekeeping (“besure to keep wastepaper baskets empty”). Venetian blindsalso feature prominently; indeed, future anthropologistswill almost certainly conclude that 1950s America re-garded them as a sovereign remedy against blast damage,such is the emphasis on keeping them closed.

Yet the pamphlet’s artlessness regarding blast and burnhazards pales in comparison to its attitude towards radio-activity. Fallout features prominently in the pamphlet’smiddle section, which lists “Six Survival Secrets for AtomicAttack”. The list is full of blackly comic gems, but the worstis number four: “Don’t rush outside right after a bomb-ing. After an air burst, wait a few minutes then go to helpfight fires. After other kinds of bursts, wait at least 1 hourto give lingering radiation some chance to die down.”

Even in the 1950s, “some chance” was probably a sooth-ing euphemism for “no chance”. Certainly, the true pur-pose of such pamphlets was often psychological ratherthan practical. But it is also true that as time went on, theadvice got more realistic. A 1964 series of UK films, forexample, eschews the earlier “hiding under desks” strata-

gem in favour of measures such as sandbagging staircasesand bricking up windows. Although one film does have atouching faith in the fallout-repelling properties of wel-lington boots, Venetian blinds are not mentioned.

Later films continued this trend towards greater real-ism. The UK’s “Protect and Survive” series of the early1980s infamously described what to do with a dead body ina fallout shelter, while the 1982 US television film The DayAfter presented viewers with horrific images of radioactiveKansans. By spurring a political backlash, the semi-real-istic depictions of nuclear warfare in these films did moreto save lives than their predecessors’ “survival secrets”ever could have. The Day After even reportedly helpedconvince US President Ronald Reagan to sign the 1987US–Soviet Intermediate-Range Nuclear Forces Treaty.Like his Soviet counterparts, Reagan eventually acknow-ledged reality: a nuclear war would not be winnable, oreven survivable.

The nuclear-power industry has faced several realitychecks over the years, too. In particular, it has made greatstrides in tackling the safety problems that devastatedreactors from EBR-1 to Chernobyl. It has also moderatedits rhetoric. As this special issue of Physics World explains,the big promise these days is green(er) “baseline” powerto supplement variable sources of renewable energy. Newplant designs are in the works, but their developers areclear-headed about their drawbacks, and they talk aboutcarbon taxes, not unlimited energy.

The only scientists who might conceivably mention un-limited energy today are those who work on nuclear fusion.And they may be right: fusion is far cleaner and the fuel forit far more abundant than fission ever was or will be. Un-fortunately, we have known this for a long time: it was, infact, fusion not fission that Strauss had in mind with his“too cheap to meter” remarks. But give it another 50years.Some day, Strauss may yet be remembered as a visionary.

Margaret Harris is Reviews and Careers Editor of Physics World, and anon-radioactive native Kansan, e-mail margaret.harris @iop.org

The rise and fall of nuclear naivety

Don’t rushoutside right after abombing – waitat least 1 hourto give lingeringradiation somechance to die down

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76 Physics World October 2010

PWOct10lateral 14/9/10 17:38 Page 76

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