nuclear power2012

7/28/2019 Nuclear Power2012

1/49

121/04/2013

NBS-M018

Low Carbon Technologies and Solutions

2012

NUCLEAR POWERhttp://www2.env.uea.ac.uk/energy/nbs-m018/nbs-m018.htm

http://www2.env.uea.ac.uk/energy/energy.htm Alternate server under development

http://www.uea.ac.uk/~e680/energy/nbs-m018/nbs-m018.htm

http://www.uea.ac.uk/~e680/energy/energy.htm

N.K. Tovey () M.A, PhD, CEng, MICE, CEnv.. .., -

Energy Science DirectorCRedProject

HSBC Director of Low Carbon Innovation
http://www2.env.uea.ac.uk/energy/nbs-m018/nbs-m018.htmhttp://www2.env.uea.ac.uk/energy/energy.htmhttp://www.uea.ac.uk/~e680/energy/nbs-m018/nbs-m018.htmhttp://www.uea.ac.uk/~e680/energy/energy.htmhttp://www.uea.ac.uk/~e680/energy/energy.htmhttp://www.uea.ac.uk/~e680/energy/nbs-m018/nbs-m018.htmhttp://www.uea.ac.uk/~e680/energy/nbs-m018/nbs-m018.htmhttp://www.uea.ac.uk/~e680/energy/nbs-m018/nbs-m018.htmhttp://www.uea.ac.uk/~e680/energy/nbs-m018/nbs-m018.htmhttp://www.uea.ac.uk/~e680/energy/nbs-m018/nbs-m018.htmhttp://www2.env.uea.ac.uk/energy/energy.htmhttp://www2.env.uea.ac.uk/energy/nbs-m018/nbs-m018.htmhttp://www2.env.uea.ac.uk/energy/nbs-m018/nbs-m018.htmhttp://www2.env.uea.ac.uk/energy/nbs-m018/nbs-m018.htmhttp://www2.env.uea.ac.uk/energy/nbs-m018/nbs-m018.htmhttp://www2.env.uea.ac.uk/energy/nbs-m018/nbs-m018.htm


2/49

221/04/2013

NUCLEAR POWER

Background Introduction

5. Nature of Radioactivity

a. Structure of the Atom

b. Radioactive Emissions

c. Half Life of Elements

d. Fission

e. Fusion

f. Chain Reactions

g. Fertile Materials

6. Fission Reactors

7. Nuclear Fuel Cycle

8. Fusion Reactors

LectureSli Lecture 2 Lecture 3


3/49

321/04/2013

0

2000

4000

6000

8000

10000

12000

14000

1955 1965 1975 1985 1995 2005 2015 2025 2035

Installe

dCapacity(MW) New Build ?

ProjectedActual New Build

Assumes 10 new

nuclear power

stations are

completed (one

each year from

2019).

NUCLEAR POWER in the UK

Generation 1: MAGNOX: (Anglo-French design) three reactors ( two stations)

still operating on extended lives of 43 and 41 years

Generation 2a: Advanced Gas Cooled reactors (unique UK design)most

efficient nuclear power stations ever built - 14 reactors operating.

Generation 2b: Pressurised Water Reactormost common reactor Worldwide.UK has just one Reactor 1188MW at Sizewell B.


4/49

0

100

200

300

400

500

600

1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030

TWh

Nuclear new nuclear coal new coal CCS

oil Other Renewables onshore wind offshore wind

UK gas Imported gas Demand

Existing Nuclear

Existing Coal

Oil

UK Gas

Imported

Gas

New Nuclear

New Co

Other

Renewables

Offshore

Wind

Onshore

Wind

1 new nuclear station completed each year after 2020.

1 new coal station fitted with CCS each year after 2020

1 million homes fitted with PV each year from 2020 -

40% of homes fitted by 2030

19 GW of onshore wind by 2030 cf 4 GW now

Data for modelling derived from DECC & Climate Change Committee (2011) - allowing for

significant deployment of electric vehicles and heat pumps by 2030.

Our looming over-dependence on gas for electricity generation

4


5/49

521/04/2013

Historic and Future Demand for Electricity

Number of households will rise by 17.5% by 2025 and consumption

per household must fall by this amount just to remain static

0

50

100

150

200

250

300

350

400

450

500

1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025

ElectricityConsumption(TWh)

Business

as usual

Energy

Efficient

Future ?


6/49

621/04/2013

Carbon Dioxide Emissions

0

50

100

150

200

250

1990 1995 2000 2005 2010 2015 2020 2025

MTonnesCO2

Actual

Business as Usual

Energy Efficiency

The Gas Scenario

Assumes all new non-renewable

generation is from gas.

Replacements for ageing plant

Additions to deal with demand changes

Assumes 10.4% renewables by 2010

25% renewables by 2025

Energy Efficiency consumption

capped at 420 TWh by 2010

But 68% growth in gas demand(compared to 2002)

Business as Usual

257% increase in gas consumption

( compared to 2002)

Electricity Options for the Future

Gas Consumption

0

10

20

30

40

50

60

70

80

90

100

1990 1995 2000 2005 2010 2015 2020 2025

billioncubicme

tres Actual

Business as UsualEnergy Efficiency


7/49721/04/2013

Energy Efficiency Scenario

Other Options

Some New Nuclear needed by 2025 if CO2

levels are to fall significantly and excessivegas demand is to be avoided

Business as Usual Scenario

New Nuclear is required even to reduceback to 1990 levels


0

50

100

150

200

250

1990 1995 2000 2005 2010 2015 2020 2025

MTonnesCO2

ActualGasNuclearCoal40:20:40 Mix


0

50

100

150

200

250

300

350

1990 1995 2000 2005 2010 2015 2020 2025

MtonnesCO2

Actual

Gas

Nuclear

Coal

40:20:40 Mix

25% Renewables by 2025

20000 MW Wind

16000 MW Other Renewables inc.

Tidal, hydro, biomass etc.

Alternative Electricity Options for the Future


8/49

To District Heat Main ~

90oC

Boiler

Heat Exchanger

Combined heat and power can also be used with NuclearPower

e.g. Switzerland, Sweden, Russia

Nuclear Power can be used solely as a source of heat

e.g. some cities in Russia - Novosibirsk


9/49921/04/2013

NUCLEAR POWER



a. Structure of the Atom

b. Radioactive Emissions

c. Half Life of Elements

d. Fission

e. Fusion

f. Chain Reactions

g. Fertile Materials

6. Fission Reactors


8. Fusion Reactors


10/491021/04/2013

NATURE OF RADIOACTIVITY (1)

Structure of Atoms.

Matter is composed of atoms which consist

primarily of a nucleus of: positively charged PROTONS

and (electrically neutral) NEUTRONS.

The nucleus is surrounded by a cloud of

negatively charged ELECTRONS whichbalance the charge from the PROTONS.

PROTONS and NEUTRONS have

approximately the same mass

ELECTRONS are about 0.0005 times themass of the PROTON.

A NUCLEON refers to either a PROTON or a

NEUTRON

+

++

3p

4n

Lithium Atom

3 Protons 4 Neutrons


11/491121/04/2013

NATURE OF RADIOACTIVITY (2)Structure of Atoms.

Elements are characterized by the number of PROTONS present

HYDROGEN nucleus has 1 PROTON HELIUM has 2 PROTONS

OXYGEN has 8 PROTONS

URANIUMhas 92 PROTONS.

Number of PROTONS is the ATOMIC NUMBER (Z)

N denotes the number of NEUTRONS.

The number of neutrons present in any element varies.

3 isotopes of hydrogen all with 1 PROTON:-

HYDROGEN itself with NO NEUTRONS

DEUTERIUM (heavy hydrogen) with 1 NEUTRON TRITIUM with 2 NEUTRONS.

only TRITIUM is radioactive.

Elements up to Z = 82 (Lead) have at least one isotope which is stable

Symbol D

Symbol T


12/491221/04/2013


Structure of Atoms.

URANIUM has two main ISOTOPES

235U which is present in concentrations of 0.7% in naturally

occurring URANIUM

238U which is 99.3% of naturally occurring URANIUM.

Some Nuclear Reactors use Uranium at the naturally occurring

concentration of 0.7%

Most require some enrichment to around 2.5% - 5%

Enrichment is energy intensive if using gas diffusion

technology, but relatively efficient with centrifuge technology.

Some demonstration reactors use enrichment at around 93%.


13/491321/04/2013

Radioactive emissions.

FOURtypes of radiation:-

1) ALPHA particles ()- large particles consisting of 2 PROTONS and 2 NEUTRONS

the nucleus of a HELIUM atom.

2) BETA particles () which are ELECTRONS

3) GAMMA - RAYS. () Arise when the kinetic energy of Alpha and Beta particles is lost

passing through the electron clouds of atoms. Some energy is used

to break chemical bonds while some is converted into GAMMA -

RAYS.

4) X - RAYS.

Alpha and Beta particles, and gamma-rays may temporarily

dislodge ELECTRONS from their normal orbits. As the electrons

jump back they emit X-Rays which are characteristic of theelement which has been excited.



14/491421/04/2013


- particles are stopped by a thin sheet of paperparticles are stopped by ~ 3mm aluminium

- rays CANNOT be stopped they can be attenuated to safelimits using thick Lead and/or concrete


15/491521/04/2013

U23592


UNSTABLE nuclei emit Alpha or Beta particles

If an ALPHA particle is emitted, the new element will have an

ATOMIC NUMBER two less than the original.

U235

92


If an ELECTRON is emitted as a result of a NEUTRON

transmuting into a PROTON, an isotope of the element ONE

HIGHER in the PERIODIC TABLE will result.

Th231

90

He4

2

Np235

93

e


16/491621/04/2013


235U consisting of 92 PROTONS and 143 NEUTRONS is one

of SIX isotopes of URANIUM

decays as follows:-


URANIUM

235

U

alpha

THORIUM

231

Th

PROTACTINIUM

231PaACTINIUM

227Ac

Thereafter the ACTINIUM - 227 decays by further alpha and

beta particle emissions to LEAD - 207 (207Pb) which is stable.

Two other naturally occurring radioactive decay series exist.

One beginning with 238U, and the other with 232Th.

Both also decay to stable (but different) isotopes of LEAD.

beta alpha


17/491721/04/2013

HALF LIFE.

Time taken for half the remaining atoms of an element to

undergo their first decay e.g:-

238U 4.5 billion years

235U 0.7 billion years

232Th 14 billion years

All of the daughter products in the respective decay series

have much shorter half - lives some as short as 10-7 seconds.

When 10 half-lives have expired,

the remaining number of atoms is less than 0.1% of theoriginal.

20 half lives

the remaining number of atoms is less than one millionth

of the original



18/491821/04/2013

HALF LIFE.

From a radiological hazard point of view

short half lives - up to say 6 months have intenseradiation, but

decay quite rapidly. Krypton-87 (half life 1.8 hours)-

emitted from some gas cooled reactors - the radioactivity

after 1 day is insignificant. For long half lives - the radiation doses are small, and also

of little consequence

For intermediate half lives - these are the problem - e.g.

Strontium -90

has a half life of about 30 years which means it has a

relatively high radiation, and does not decay that quickly.

Radiation decreases to 30% over 90 years


A O A OAC (11) i i


19/491921/04/2013

This reaction is one of several which

might take place. In some cases, 3daughter products are produced.

n

n

n

140Cs

93

Rb

235U

Some very heavy UNSTABLE elements exhibit FISSION e.g. 235U

NATURE OF RADIOACTIVITY (11): Fission



20/49

2021/04/2013

FISSION

Nucleus breaks down into two or three fragments

accompanied by a few free neutrons and the release of verylarge quantities of energy.

Free neutrons are available for further FISSION reactions

Fragments from the fission process usually have an atomic

mass number (i.e. N+Z) close to that of iron. Elements which undergo FISSION following capture of a

neutron such as URANIUM - 235 are known as FISSILE.

Diagrams of Atomic Mass Number against binding energy per

NUCLEON enable amount of energy produced in a fissionreaction to be estimated.

All Nuclear Power Plants currently exploit FISSION reactions,

FISSION of 1 kg of URANIUM produces as much energy as

burning 3000 tonnes of coal.


NATURE OF RADIOACTIVITY (13) F i


21/49

2121/04/2013

n

4He 2H

3H

Deuterium

Tritium

Deuterium Tritium fusion

(3.5 MeV)

(14.1 MeV)

In each reaction 17.6 MeV is liberated or 2.8 picoJoules (2.8 * 10-15J)

Fusion of light elements e.g. DEUTERIUM and TRITIUM produces

even greater quantities of energy per nucleon are released.

NATURE OF RADIOACTIVITY (13): Fusion

NATURE OF RADIOACTIVITY (14) Bi di E


22/49

22

1) The energy released per nucleon in fusion reaction is much greater than the

corresponding fission reaction.

2) In fission there is no single fission product but a broad range as indicated.

NATURE OF RADIOACTIVITY (14): Binding Energy

0 50 100 150 200 250

Atomic Mass Number

-2

-4

-6

-8

-10

BindingEnergypernucleon[MeV]

Iron 56

Uranium 235Range of Fission

Products

Fusion Energyrelease per

nucleon

Fission Energy

release pernucleon

1 MeV per nucleon isequivalent to 96.5 TJ per kg

Redrawn from 6th report on Environmental Pollution Cmnd. 6618 - 1976

NATURE OF RADIOACTIVITY (15) F i


23/49

2321/04/2013

Developments at the JET facility in Oxfordshire have achieved

the break even point.

Next facility (ITER) will be built in Cadarache in France.

Commercial deployment of fusion from about 2040 onwards

One or two demonstration commercial reactors in 2030s perhaps No radioactive waste from fuel

Limited radioactivity in power plant itself

8 litres of tap water sufficient for all energy needs of oneindividual for whole of life at a consumption rate comparable to

that in UK.

Sufficient resources for 1 10 million years

NATURE OF RADIOACTIVITY (15): Fusion

NATURE OF RADIOACTIVITY (16) Ch i R ti


24/49

2421/04/2013

n

n

n235U

n

n

n

235

U

Slow neutron

Slow neutron

fast neutron

fast

neutron

Fast Neutrons are

unsuitable for sustainingfurther reactions

NATURE OF RADIOACTIVITY (16): Chain Reactions



25/49

2521/04/2013

CHAIN REACTIONS

FISSION of URANIUM - 235 yields 2 - 3 free neutrons.

If exactly ONE of these triggers a further FISSION, then a

chain reaction occurs, and continuous power can be

generated.

UNLESS DESIGNED CAREFULLY, THE FREE

NEUTRONS WILL BE LOST AND THE CHAIN

REACTION WILL STOP.

IF MORE THAN ONE NEUTRON CREATES A NEW

FISSION THE REACTION WOULD BE SUPER-

CRITICAL

(or in layman's terms a bomb would have been created).




26/49

2621/04/2013

CHAIN REACTIONS IT IS VERY DIFFICULT TO SUSTAIN A CHAIN

REACTION,

Most Neutrons are moving too fast

TO CREATE A BOMB, THE URANIUM - 235 MUST BE

HIGHLY ENRICHED > 93%,

Normal Uranium is only 0.7% U235

Material must be LARGER THAN A CRITICAL SIZE and

SHAPE OTHERWISE NEUTRONS ARE LOST.

Atomic Bombs are made by using conventional explosive tobring two sub-critical masses of FISSILE material together for

sufficient time for a SUPER-CRITICAL reaction to take place.

NUCLEAR POWER PLANTS CANNOT EXPLODE LIKE AN

ATOMIC BOMB.




27/49

2721/04/2013

FERTILE MATERIALS

Some elements like URANIUM - 238 are not FISSILE, but

can transmute:-


n

238U

fast

neutron

239U

238UUranium - 238

239UUranium - 239

+n

ee

239NpNeptunium -239

239PuPlutonium -239

beta beta

239Np239Pu

PLUTONIUM - 239 is FISSILE and may be used in place ofURANIUM - 235.

Materials which can be converted into FISSILE materials are FERTILE.



28/49

2821/04/2013

FERTILE MATERIALS

URANIUM - 238 is FERTILE as is THORIUM - 232

which can be transmuted into URANIUM - 233.

Naturally occurring URANIUM consists of99.3% 238U

which is FERTILE and NOT FISSILE, and 0.7% of235U

which is FISSILE. Normal reactors primarily use the

FISSILE properties of235U.

In natural form, URANIUM CANNOT sustain a chain

reaction: free neutrons are travelling fast to successfully

cause another FISSION, or are lost to the surrounds.

MODERATORS are thus needed to slow down/and or

reflect the neutrons in a normal FISSION REACTOR.

The Resource Base of235U is only decades

But using a Breeder Reactor Plutonium can be produced

from non-fissile 238U producing 239Pu and extending the

resource base by a factor of 50+




29/49

29

n

n

n235U

n

n

n

235

U

fast

neutron

Slow neutron

fast neutron

fast

neutron

n

Fast Neutrons are

unsuitable for sustainingfurther reactions


Slow neutron

n

Insert a moderator to

slow down neutrons

Sustaining a reaction in a Nuclear Power Station

NUCLEAR POWER


30/49

30

NUCLEAR POWER



6. Fission Reactorsa) General Introduction

b) MAGNOX Reactors

c) AGR Reactors

d) CANDU Reactorse) PWRs

f) BWRs

g) RMBK/ LWGRs

h) FBRs

i) Generation 3 Reactors

j) Generation 3+ Reactors


8. Fusion Reactors

FISSION REACTORS (1):


31/49

3121/04/2013

FISSION REACTORS CONSIST OF:-

i) a FISSILE component in the fuel

ii) a MODERATOR

iii) a COOLANT to take the heat to its point of use.

The fuel elements vary between different Reactors

Some reactors use unenriched URANIUM i.e. the 235U in fuel elements is at 0.7% of fuel

e.g. MAGNOX and CANDU reactors,

ADVANCED GAS COOLED REACTOR (AGR) uses 2.5 2.8% enrichment

PRESSURISED WATER REACTOR (PWR) and BOILING WATERREACTOR (BWR) use around 3.5 4% enrichment.

RMBK (Russian Rector of Chernobyl fame) uses ~2% enrichment

Some experimental reactors - e.g. High Temperature Reactors (HTR) use

highly enriched URANIUM (>90%) i.e. weapons grade.


FISSION REACTORS (2): Fuel Elements


32/49

3221/04/2013

FISSION REACTORS (2): Fuel Elements

PWR fuel assembly:

UO2 pellets loaded into fuelpins of zirconium each ~ 3 m

long in bundles of ~200

Magnox fuel rod:

Natural Uranium metal barapprox 35mm diameter and

1m long in a fuel cladding

made of MagNox.

AGR fuel

assembly:

UO2 pellets loaded

into fuel pins of

stainless steel each~ 1 m long in

bundles of 36.

Whole assembly in

a graphite

cylinder

Burnable

poison



33/49

3321/04/2013

No need for the extensive coal handling plant.

In the UK, all the nuclear power stations are sited on the

coast so there is no need for cooling towers.

Land area required is smaller than for coal fired plant.

In most reactors there are three fluid circuits:-

1) The reactor coolant circuit

2) The steam cycle

3) The cooling water cycle.

ONLY the REACTOR COOLANT will become radioactive

The cooling water is passed through the station at a rate of

tens of millions of litres of water and hour, and the outlet

temperature is raised by around 10oC.




34/49

3421/04/2013

REACTOR TYPES summary 1

MAGNOX - Original British Design named after the magnesium

alloy used as fuel cladding. Four reactors of this type were built inFrance, One in each of Italy, Spain and Japan. 26 units were built

in UK.

They are only in use now in UK. On December 31st 2006,

Sizewell A, Dungeness A closed after 40 years of operation leavingOldbury with two reactors is now continuing beyond its original

extended 40 year life. Wylfa (also with 2 reactors) will close this

year or next. All other units are being decommissioned

AGR - ADVANCED GAS COOLED REACTOR - solelyBritish design. 14 units are in use. The original demonstration

Windscale AGR is now being decommissioned. The last two

stations Heysham II and Torness (both with two reactors), were

constructed to time and have operated to expectations.




35/49

3521/04/2013

REACTOR TYPES - summary SGHWR - STEAM GENERATING HEAVY WATER

REACTOR - originally a British Design which is a hybridbetween the CANDU and BWRreactors.

PWR - Originally an American design ofPRESSURIZED WATER REACTOR (also known as a LightWater Reactor LWR). Now most common reactor.-

BWR - BOILING WATER REACTOR - a derivativeof the PWRin which the coolant is allowed to boil in thereactor itself. Second most common reactor in use.

RMBK - LIGHT WATER GRAPHITE MODERATINGREACTOR (LWGR)- a design unique to the USSR whichfigured in the CHERNOBYL incident. 16 units still inoperation in Russian and Lithuania with 9 shut down.




36/49

3621/04/2013

REACTOR TYPES - summary

CANDU - A reactor named initially after CANadian

DeUterium moderated reactor (hence CANDU),alternatively known as PHWR(pressurized heavy waterreactor). 41 currently in use.

HTGR - HIGH TEMPERATURE GRAPHITE

REACTOR - an experimental reactor. The original HTR inthe UK started decommissioning in 1975. The new PebbleBed Modulating Reactor (PBMR) is a development of thisand promoted as a 3+ Generation Reactor by South Africa.

FBR - FAST BREEDER REACTOR - unlike allprevious reactors, this reactor 'breeds' PLUTONIUM fromFERTILE 238U to operate, and in so doing extends resourcebase of URANIUM over 50 times. Mostly experimental atmoment with FRANCE, W. GERMANY and UK, Russia

and JAPAN having experimented with them.


MAGNOX REACTORS (also known as GCR):


37/49

3721/04/2013

FUEL TYPE - unenriched URANIUMMETAL clad in Magnesium alloy

MODERATOR - GRAPHITE

COOLANT - CARBON DIOXIDE DIRECT RANKINE CYCLE

- no superheat or reheat efficiency ~20% to 28%.

ADVANTAGES:-

LOW POWER DENSITY- 1 MW/m3.Thus very slow rise in temperature infault conditions.

UNENRICHED FUEL GASEOUS COOLANT

ON LOAD REFUELLING

MINIMAL CONTAMINATIONFROM BURST FUEL CANS

VERTICAL CONTROL RODS - fallby gravity in case of emergency.

MAGNOX REACTORS (also known as GCR):

DISADVANTAGES:-

CANNOT LOAD FOLLOW[Xepoisoning]

OPERATING TEMPERATURELIMITED TO ABOUT 250oC - 360oC

limiting CARNOT EFFICIENCY to ~40 -

50%, and practical efficiency to ~ 28-30%.

LOW BURN-UP - (about 400 TJ pertonne)

EXTERNAL BOILERS ON EARLY

DESIGNS.

ADVANCED GAS COOLED REACTORS (AGR):


38/49

3821/04/2013

FUEL TYPE - enriched URANIUMOXIDE - 2.3% clad in stainless steel


COOLANT - CARBON DIOXIDE SUPERHEATED RANKINE CYCLE

(with reheat) - efficiency 39 - 41%

ADVANTAGES:- MODEST POWER DENSITY- 5 MW/m3.

slow rise in temperature in fault conditions.

GASEOUS COOLANT(40- 45 BAR cf 160

bar for PWR) ON LOAD REFUELLINGunder part load

MINIMAL CONTAMINATION FROMBURST FUEL CANS

RELATIVELY HIGHTHERMODYNAMIC EFFICIENCY 40%

VERTICAL CONTROL RODS- fall bygravity in case of emergency.

ADVANCED GAS COOLED REACTORS (AGR):

DISADVANTAGES:-

MODERATE LOAD FOLLOWING

CHARACTERISTICS SOME FUEL ENRICHMENT

NEEDED. - 2.3%

OTHER FACTORS:-

MODERATE FUEL BURN-UP - ~

1800TJ/tonne (c.f. 400TJ/tonne forMAGNOX, 2900TJ/tonne for PWR).

SINGLE PRESSURE VESSEL with

pres-stressed concrete walls 6m thick.

Pre-stressing tendons can be replaced

if necessary.

CANDU REACTOR (PHWR):


39/49

3921/04/2013

FUEL TYPE - unenriched URANIUMOXIDE clad in Zircaloy

MODERATOR - HEAVY WATERCOOLANT - HEAVY WATER

ADVANTAGES:- MODEST POWER DENSITY- 11 MW/m3.

HEAVY WATER COOLANT -lowneutron absorber hence no need for

enrichment. ON LOAD REFUELLING- and very

efficient indeed permits high load factors.

MINIMAL CONTAMINATION fromburst fuel can -defective units can beremoved without shutting down reactor.

MODULAR:- can be made to almost any size

CANDU REACTOR (PHWR):

DISADVANTAGES:-

POOR LOAD FOLLOWINGCHARACTERISTICS

CONTROL RODS AREHORIZONTAL, and therefore cannotoperate by gravity in fault conditions.

MAXIMUM EFFICIENCY about 28%

OTHER FACTORS:-


MODEST FUEL BURN-UP - about1000TJ/tonne

FACILITIES PROVIDED TO DUMP

HEAVY WATER MODERATORfromreactor in fault conditions

MULTIPLE PRESSURE TUBES

instead of one pressure vessel.

PRESSURISED WATER REACTORS PWR (WWER):


40/49

4021/04/2013

FUEL TYPE - 3 4% enrichedURANIUM OXIDE clad in Zircaloy

MODERATOR - WATER

COOLANT - WATER

ADVANTAGES:-

GOOD LOAD FOLLOWINGCHARACTERISTICS - claimed forSIZEWELL B. - most PWRs are NOToperated as such.

HIGH FUEL BURN-UP- about2900TJ/tonne

VERTICAL CONTROL RODS - drop bygravity in fault conditions.

PRESSURISED WATER REACTORS PWR (WWER):

DISADVANTAGES:-

ORDINARY WATER as COOLANT -

pressure to prevent boiling (160 bar). If

break occurs then water will flash to

steam and cooling will be less effective.

ON LOAD REFUELLING NOTPOSSIBLE - reactor must be shut down.

SIGNIFICANT CONTAMINATION OF

COOLANT CAN ARISE FROM BURST

FUEL CANS - as defective units cannot be

removed without shutting down reactor.

FUEL ENRICHMENT NEEDED. - 3-4%.

MAXIMUM EFFICIENCY ~ 31 - 32%

latest designs ~ 34%

OTHER FACTORS:-

LOSS OF COOLANT also means LOSS

OF MODERATOR so reaction ceases - but

residual decay heat can be large.

HIGH POWER DENSITY - 100 MW/m3,

and compact. Temperature can rise

rapidly in fault conditions. NEEDS active

ECCS.

SINGLE STEEL PRESSURE VESSEL 200mm thick.

BOILING WATER REACTORS BWR:


41/49

4121/04/2013

FUEL TYPE - 3% enriched URANIUMOXIDE clad in Zircaloy

MODERATOR - WATER

COOLANT - WATER

ADVANTAGES:-

HIGH FUEL BURN-UP- about2600TJ/tonne

STEAM PASSED DIRECTLY TOTURBINEtherefore no heat exchangersneeded. BUT SEE DISADVANTAGES..

BOILING WATER REACTORS BWR:

DISADVANTAGES:-

ORDINARY WATER as COOLANTbut

designed to boil: pressure ~ 75 bar.

CONTROL RODS MUST BE DRIVEN

UPWARDS - SO NEED POWER IN FAULT

CONDITIONS. Provision made to dump water(moderator in such circumstances).

ON LOAD REFUELLING NOT

POSSIBLE - reactor must be shut down.

SIGNIFICANT CONTAMINATION OF

COOLANT CAN ARISE FROM BURST

FUEL CANS - as defective units cannot beremoved without shutting down reactor.ALSO IN SUCH CIRCUMSTANCES

RADIOACTIVE STEAM WILL PASS

DIRECTLY TO TURBINES.

FUEL ENRICHMENT NEEDED. - 3%.

MAXIMUM EFFICIENCY ~ 34-35%

OTHER FACTORS:-

LOSS OF COOLANT also means LOSS

OF MODERATOR so reaction ceases - but

residual decay heat can be large. HIGH POWER DENSITY - 100 MW/m3,

and compact. Temperature can rise

rapidly in fault conditions. NEEDS active

ECCS.

SINGLE STEEL PRESSURE VESSEL 200

mm thick.

RMBK (LWGR): (involved in Chernobyl incident)


42/49

4221/04/2013

FUEL TYPE - 2% enriched URANIUMOXIDE clad in Zircaloy


COOLANT - WATER

ADVANTAGES:-

ON LOAD REFUELLING

VERTICAL CONTROL RODSwhich

can drop by GRAVITY in faultconditions.

NO THEY CANNOT!!!!

RMBK (LWGR): (involved in Chernobyl incident)

DISADVANTAGES:-

ORDINARY WATER as COOLANT -

flashes to steam in fault conditions

hindering cooling.

POSITIVE VOID COEFFICIENT !!! -

positive feed back possible in some fault

conditions -other reactors have negative

voids coefficient in all conditions.

IF COOLANT IS LOST moderator will

keep reaction going.

FUEL ENRICHMENT NEEDED. - 2%

PRIMARY COOLANT passed directly to

turbines. This coolant can be slightly

radioactive.

MAXIMUM EFFICIENCY ~30% ??

OTHER FACTORS:-


MODEST FUEL BURN-UP - about1800TJ/tonne

LOAD FOLLOWINGCHARACTERISTICS UNKNOWN

POWER DENSITY probablyMODERATE?

MULTIPLE PRESSURE TUBES

FAST BREEDER REACTORS (FBR or LMFBR)


43/49

4321/04/2013

FUEL TYPE - depleted Uranium or UO2surround PU in centre of core. Allelements clad in stainless steel.

MODERATOR - NONE

COOLANT - LIQUID METAL

ADVANTAGES:-

LIQUID METAL COOLANT- atATMOSPHERIC PRESSURE. Willeven cool by natural convection in eventof pump failure.

BREEDS FISSILE MATERIALfromnon-fissile 238U increases resource base50+ times.

HIGH EFFICIENCY(~ 40%)

VERTICAL CONTROL RODS drop byGRAVITY in fault conditions.

FAST BREEDER REACTORS (FBR or LMFBR)

DISADVANTAGES:-

DEPLETED URANIUM FUEL

ELEMENTS MUST BE REPROCESSED

to recover PLUTONIUM and sustain the

breeding of more plutonium for future use. CURRENT DESIGNS have SECONDARY

SODIUM CIRCUIT

WATER/SODIM HEAT EXCHANGER.

If water and sodium mix a significant

CHEMICAL explosion may occur which

might cause damage to reactor itself.

OTHER FACTORS:- VERY HIGH POWER DENSITY - 600

MW/m3 but rise in temperature in fault

conditions limited by natural circulation of

GENERATION 3 REACTORS: the EPR1300


44/49

4421/04/2013

Schematic of Reactor is very similar to later PWRs (SIZEWELL) with 4Steam Generator Loops.

Main differences? from earlier designs.

Output power ~1600 MW from a single turbine(cf 2 turbines for 1188 MW at Sizewell).

Each of the safety chains is housed in a separate building.

GENERATION 3 REACTORS: the EPR1300

Construction is under way at

Olkiluoto, Finland.

Second reactor under

construction in

Flammanville, France

Possible contender for new

UK generation

Efficiency claimed at 37%

But no actual experience

and likely to be less

GENERATION 3 REACTORS: the AP1000


45/49

4521/04/2013

GENERATION 3 REACTORS: the AP1000

A development from SIZEWELL

Power Rating comparable with SIZEWELL

Will two turbines be used ?? Passive Cooling water tank

on top water falls by gravity

Two loops (cf 4 for EPR)

Significant reduction in

components e.g. pumps etc.

Possible Contender for new

UK reactors

GENERATION 3 REACTORS: the ACR1000


46/49

4621/04/2013

GENERATION 3 REACTORS: the ACR1000

A development from CANDU with added safety features less Deuterium

needed

Passive emergency cooling as with AP1000

See Video Clip of on-line refuelling

ESBWR: Economically Simple BWR


47/49

4721/04/2013

S W : co o c y S p e W

A derivative of Boiling Water Reactor for which it is claimed has

several safety features but which inherently has two disadvantages of

basic design

Vertical control rods which must be driven upwards

Steam in turbines can become radioactive


48/49


49/49

Kung Hei Fat Choi !

Gong Xi Fa Cai !

http://www2.env.uea.ac.uk/energy/env-2A82\env-2A82.htm

http://www2.env.uea.ac.uk/energy/energy.htm
http://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/gmmc/env/energy.htmhttp://www2.env.uea.ac.uk/gmmc/env/energy.htmhttp://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/energy/env-2A82/env-2A82.htmhttp://www2.env.uea.ac.uk/gmmc/energy/env-2e04/env-2e04.htmhttp://www2.env.uea.ac.uk/gmmc/energy/env-2e04/env-2e04.htmhttp://www2.env.uea.ac.uk/gmmc/energy/env-2e04/env-2e04.htmhttp://www2.env.uea.ac.uk/gmmc/energy/env-2e04/env-2e04.htm

nuclear power2012

Documents