Produc've Use of Nuclear Spent Fuel Outline of Presenta'on ²  Data Sources
²  CANDU and PWR Fuel Cycles
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Useable Components of Used Fuel
Thermal versus Fast Neutron Reactors
Uranium versus Thorium Fast Neutron Reactors
Reducing Lifetime and Radio-toxicity of Used Fuel
Advantages of Reprocessing Used Fuel for Energy
Challenges to Developing Fast Reactors
Q&A period.
2 Produc've Use of Nuclear Spent Fuel Data Sources for Today’s Presenta'on 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
3 Produc've Use of Nuclear Spent Fuel CANDU and PWR Fuel Cycles
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.
4 Produc've Use of Nuclear Spent Fuel CANDU and PWR Fuel Cycles
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.
5 Produc've Use of Nuclear Spent Fuel Useable Components of Used Fuel Isotope CANDU
U238: 98.58 %
U235: 0.23 %
U236:
0.07 %
Pu239: 0.25 %
Pu240: 0.10 %
Pu241: 0.02 %
Pu242: 0.01 %
Waste + Minor Ac,nides: 0.67 %
Total 100.00 %
PWR 93.79 % 0.91 % 0.40 % 0.59 % 0.23 % 0.08 % 0.05 % 3.21 % 100.00 % 6 Produc've Use of Nuclear Spent Fuel 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.
7 Produc've Use of Nuclear Spent Fuel 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.
8 9 Produc've Use of Nuclear Spent Fuel 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).
10 Produc've Use of Nuclear Spent Fuel 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. Produc've Use of Nuclear Spent Fuel 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.
11 12 Produc've Use of Nuclear Spent Fuel Reducing Life'me and Radio-­‐toxicity of Used Fuel
Years AOer
Irradia,on
U238/
U235
IFR (U) IFR & LFTR
Ac,nides Fission Products
LFTR (Th) Ac,nides 1
1
1
1
1
1
1
1000
1000
1000
1000
800
30
0.3
700 500 500 100 30 2 0.6 10 100 400 1,000 10,000
100,000
1,000,000
1000
100
1
0.01
0.01
0.007
0.002
Note: Radiological toxicity “rela,ve” to natural uranium is shown. The values have been rounded for readability. 13 Produc've Use of Nuclear Spent Fuel 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.
14 Produc've Use of Nuclear Spent Fuel 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).
Produc've Use of Nuclear Spent Fuel EBR-­‐II (beginning of the IFR concept) 15 Produc've Use of Nuclear Spent Fuel MSRE (beginning of the LFTR concept)
16 Produc've Use of Nuclear Spent Fuel 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.
17 Produc've Use of Nuclear Spent Fuel Questions ?
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