Produc've  Use  of  Nuclear  Spent  Fuel  

Outline  of  Presenta'on  

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²  Data Sources ²  CANDU and PWR Fuel Cycles ²  Useable Components of Used Fuel ²  Thermal versus Fast Neutron Reactors ²  Uranium versus Thorium Fast Neutron Reactors ²  Reducing Lifetime and Radio-toxicity of Used Fuel ²  Advantages of Reprocessing Used Fuel for Energy ²  Challenges to Developing Fast Reactors ²  Q&A period.

Produc've  Use  of  Nuclear  Spent  Fuel  

Data  Sources  for  Today’s  Presenta'on    

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²  “Plentiful Energy – The Story of the Integral Fast Reactor”, Charles E. Till and Yoon Il Chang, available from www.amazon.ca

²  “Thorium – Energy Cheaper than Coal”, Robert Hargrave, available from www.amazon.ca

²  “Why Throw It Away? Productive Use of Nuclear Spent Fuel”, Peter Ottensmeyer, PEO-OSPE Joint Technical Forum, April 2013.

²  “CANDU Spent Fuel: A Waste or a Resource?”, D. Rozon, NWMO Advisory Council Discussion Paper, Jan 2005.

²  “Reprocessing Versus Direct Disposal of Spent CANDU Nuclear Fuel: A Possible Application of Fluoride Volatility”, D. Rozon and D. Lister, Jan 2008.

²  If you are interested in the other energy related information or downloading this presentation, please visit OSPE’s website at:

http://www.ospe.on.ca/?page=adv_issue_energy

Produc've  Use  of  Nuclear  Spent  Fuel  

CANDU  and  PWR  Fuel  Cycles  

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²  A chain reaction only occurs with fissile isotopes. For thermal neutrons.

²  U235 is the only fissile isotope found in nature. ²  Fast neutrons can fission most transuranic (actinide) elements

(Np, Pu, Am, Cm, etc.) ²  Nuclear reactor fuel can come in two forms. Fissile isotopes

and fertile isotopes. ²  We can make more fissile isotopes inside a reactor by adding

neutrons to a fertile isotope. ²  Ontario’s CANDU reactors use natural uranium fuel with 0.72%

U235 and 99.28% U238 and a heavy water moderator. ²  PWR reactors use enriched uranium fuel at typically 3.2% U235

(enriched) and 96.8% U238 and ordinary (light) water moderator.

 

Produc've  Use  of  Nuclear  Spent  Fuel  

CANDU  and  PWR  Fuel  Cycles  

 

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²  To make enriched fuel we also create a depleted uranium stockpile as part of the fuel cycle.

²  Depleted uranium is primarily U238 which has low levels of radioactivity because it does not go through the reactor. It is stored in drums.

²  CANDU reactors utilize Uranium about 30% more efficiently than PWR reactors due to a more neutron efficient heavy water moderator.

²  CANDU reactors produce more high level used fuel waste by weight per kWh compared to PWR’s because all the original mined Uranium goes through the reactor.

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Useable  Components  of  Used  Fuel  

 Isotope                            CANDU        PWR  U238:                                                            98.58  %    93.79  %  U235:                  0.23  %        0.91  %  U236:          0.07  %        0.40  %  Pu239:              0.25  %        0.59  %  Pu240:              0.10  %        0.23  %  Pu241:              0.02  %        0.08  %  Pu242:              0.01  %        0.05  %  Waste  +  Minor  Ac,nides:          0.67  %        3.21  %  

   Total                100.00  %                                    100.00  %  

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Thermal  versus  Fast  Neutrons  

²  Thermal Neutrons (found in CANDU, PWR, BWR)

²  Typically 0.025 eV (move at about 2.2 km/sec).

²  Do not fission actinides very well (only 1% of Pu240 and Pu242).

²  Are absorbed readily by Xe135 which interferes with reactor operation and can poison out a reactor after a power reduction.

²  Thermal reactors cannot load cycle easily.

²  Thermal reactors consume only about 1% of fuel.

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Thermal  versus  Fast  Neutrons  

²  Fast Neutrons (found in LFTR, IFR, FBR)

²  Typically 2 MeV (move at 20,000 km/sec). ²  Efficiently fission actinides (about 55% of Pu240 & Pu

242). ²  Are NOT absorbed readily by Xe135. ²  Fast reactors can load cycle easily. ²  Fast reactors with fuel recycling consume nearly 100%

of fuel. ²  Fast reactors with no recycling consume about 20% of

fuel.

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Uranium  versus  Thorium  Fast  Neutron  Reactors  

²  Uranium Fast Reactor (Integral Fast Reactor - IFR)

²  U235 or Pu239 as startup fuel – both are fissile.

²  U238 is used to breed more Pu239.

²  Pu239 fission produces excess neutrons that can be used to breed more fuel than the reactor consumes.

²  Breeding time can be adjusted by design but typically takes about 9 years to double the fuel supply.

²  Breeding capability can expand the supply of fissile isotopes for thousands of years as energy requirements grow.

²  Passively safe - shuts down on loss of power or coolant flow. Operates at low pressure – simplifies containment.

²  Design close to a commercial scale demonstration (about 10 years away).

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Uranium  versus  Thorium  Fast  Neutron  Reactors  

²  Thorium Fast Reactors (Liquid Fluoride Thorium Reactor – LFTR) ²  Typically uses U235 or Pu239 as startup fuel – both are

fissile. ²  Th232 is used to breed U233 which is a fissile isotope. ²  Cannot breed more fuel than consumed due to fewer

available neutrons in the Th232/U233 fission process. ²  Passively safe - shuts down on loss of power or coolant

flow. ²  Not yet ready for commercial scale demonstration

(likely 20+ years away). ²  Thorium is about 3 to 4 times more abundant and more

evenly distributed around the world than uranium.  

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Reducing  Life'me  and  Radio-­‐toxicity  of  Used  Fuel  

²  Intensity of radioactivity & lifetime are both important measures of radio-toxicity or biological damage potential.

²  There are 3 major components in thermal reactor used fuel: ²  U238/U235

²  Actinides (Np, Pu, Am, Cm, etc.)

²  Fission products

²  U238/U235 are essentially natural uranium – long lived but not very radioactive.

²  Actinides are isotopes made in the reactor via neutron absorption. Actinides are highly radioactive with a long life.

²  Fission products are the isotopes created from splitting the uranium or actinides. Both short and long lived products are produced. Highly radioactive until the isotopes have decayed.

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Reducing  Life'me  and  Radio-­‐toxicity  of  Used  Fuel  

Years  AOer  U238/      IFR  (U)                  IFR  &  LFTR          LFTR  (Th)  Irradia,on  U235  Ac,nides          Fission  Products          Ac,nides    

10        1  1000                            1000              700  100        1  1000                                100              500  400        1  1000    1              500  1,000        1  1000                                          0.01              100  10,000      1      800    0.01                30  100,000      1          30                                          0.007                    2  1,000,000      1              0.3    0.002                    0.6      

Note:  Radiological  toxicity  “rela,ve”    to  natural  uranium  is  shown.    The  values  have  been  rounded  for  readability.  

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Advantages  of  Recycling  Used  Fuel  for  Energy  

²  Recycling allows us to separate the waste into two piles.

²  One pile contains the fission products that will be directed to a storage facility that would be designed for 400 years of storage.

²  Storage can be on the surface, in an above ground mine or in a deep geological repository (DGR) depending on public acceptance.

²  Theoretically after the fission products have decayed sufficiently we could retrieve and extract the rare earth isotopes for industrial use.

²  The other pile contains the U238/U235 and actinides. These can be sent back into the reactor to be consumed to produce either thermal (steam) or electrical energy.

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Challenges  to  Developing  Fast  Reactors  

²  While the advantages appear substantial we also have a number of challenges to overcome:

²  Some technical uncertainties still need to be resolved as we scale up the facilities to commercial size.

²  Fuel reprocessing needs to be improved to extract at least 99.9% of the actinides.

²  Chemical recycling is expensive. Electrolysis promises to be more cost effective but not yet proven at commercial scale.

²  Governments are reluctant to step up and put billions of dollars on the table for a new reactor type.

²  There is no consensus yet of whether the new reactors should be large (>1000 MW) or small factory fabricated units (20 to 100 MW).

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EBR-­‐II  (beginning  of  the  IFR  concept)  

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MSRE (beginning of the LFTR concept)

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Summary

²  IFR and LFTR technology promise a 100 fold increase in energy output and a 1000 fold reduction in radioactive waste lifetime.

²  Breeding capability of an IFR can supply enough fissile materials for full utilization of Thorium reserves in an LFTR.

²  Technical and cost challenges need to be overcome.

²  Fuel reprocessing and proliferation is a public concern.

²  Nuclear technology and radioactive wastes is a public concern.

Produc've  Use  of  Nuclear  Spent  Fuel  

Questions ?

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