Current Comparison of Advanced Nuclear Fuel Cycles Steven Piet, Trond Bjornard, Brent Dixon, Bob Hill, Gretchen Matthern, David Shropshire Idaho Academy of Sciences Meeting April 19-21, 2007
Advanced nuclear fuel cycles would reduce, reuse, recycle … • Reduce the number of geologic repositories required this century to one. • Reuse valuable parts of used nuclear fuel to maximize the energy derived from uranium ore. • Recycle used nuclear fuel to minimize waste and control weapons-usable inventories. • Reduce nuclear terrorism and proliferation risks by using nuclear material forms that are less easily made into nuclear weapons than separated plutonium.
2
1st question: recycle or once through?
3
Accumulated SNF fuel Accumulated used nuclear (thousandtonnes) tonnes) (thousand
If once through, the U.S. will need many Growing market repositories share (3.2%/yr)
700 630
MIT Study (300 GWe in 2050)
6-lab study (~700 GWe in 2050)
560
Constant market share (1.8%/yr)
490 420 350
Constant 97 GWe (0.0%/yr)
280 210
Nuclear phase out
140 70 0 2000
Secretarial recommendation on need for second repository
2020
2040
2060
2080
Legal capacity
2100
Year 4
2nd question: if recycle, what to do with it? Transuranics (TRU)
Fission products
95% contains energy
Short, intermediate, and long-lived wastes
Uranium (U)
51 MW-day/kg burnup, 5 yrs after discharge
5
3rd question: if recycle, what type of reactor?
6
Recycle options From Light water reactors Light water reactors and fast reactors Fast reactors
To Light water reactors Light water reactors and fast reactors Fast reactors Fast reactors
7
Uranium and transuranics Strontium and cesium
100000 10000 1000 100 10 1 0.1 0.01 0.001
1,000,000
100,000
10,000
Years
1,000
100
10
Technetium and iodine Other fission products
1
Heat generation rate (W per tonne of used fuel)
Recycle reduces heat, dose, mass burden on geologic repository
8
Uranium and transuranics Strontium and cesium
100000 10000 1000 100 10 1 0.1 0.01 0.001
1,000,000
100,000
10,000
l Years
1,000
100
10
Technetium and iodine Other fission products
1
Heat generation rate (W per tonne of used fuel)
Recycle reduces disposal of transuranics & separately manages strontium and cesium Î reduces heat to repository
This time period dominates repository temperature response 9
Neutron emission complicates weapon physics Î improves proliferation resistance
Neutrons/s per kg
Neutron emission
Multiple recycles increase neutron emission
1.E+10 1.E+09 1.E+08 1.E+07 1.E+06 1.E+05 1.E+04 1.E+03 1.E+02 1.E+01 1.E+00 1.E-01
Is there a threshold?
100% U235
100% Pu239
Weapons grade
Pu from used fuel
NpPuAm from used fuel
Weapons usable
TRU from used fuel
?
51 MW-day/kg burnup, 5 yrs after discharge
10
Energy from uranium ore – not a near term constraint Strategy
Improvement factor
Once through
Status quo
Recycle – light water reactors only
1.0x to 1.2x
Recycle – both light water & fast reactors
1.4x to 2.1x
Recycle – light water reactors reactors feed fast reactors Recycle – fast reactors only
for conversion ratios of 0.25 to 0.75 50x to 100x
11
Nuclear fuel cycle costs (cents/kW-hr) Strategy Once through
Range of estimates 0.53 – 0.81
Recycle – light water reactors only
0.92 – 1.80
Recycle – both light water & fast reactors
0.86 – 1.16
Recycle – light water reactors reactors feed fast reactors Recycle – fast reactors only
0.61 – 1.02 0.63 – 1.13
• Reactor costs not included. • Fuel cycle costs only ~15% of total costs • Uncertainties dominated by “hot” fuel fabrication, separation, cost of uranium • Additional uncertainties TBD: additional geologic repositories (for once through), fast vs. light water reactors 12
Conclusions • •
•
•
Once-through would require additional geologic repositories this century, does not change proliferation risk nor uranium ore usage. Initiation of recycle starts … – Accruing improvements for geologic repositories (reduces the need to search for potential second geologic repository sites) – U.S. on path to offer complete fuel services – Draw-down of weapons-usable material – Improved uranium ore usage Recycle of all transuranics (TRU) would provide …. – Higher repository benefits than current international practice (Pu) – Higher proliferation resistance than current international practice (Pu) – Challenges from neutron-emitting fuels Adding fast reactors to the system would provide … – More complete consumption of transuranics, hence better waste mgt
13
For more information Global Nuclear Energy Partnership (GNEP) www.gnep.energy.gov Comparison Reports www.ne.doe.gov/publicInformation/nePIreports.html Dr. Steven. J. Piet
[email protected], 208-526-5252 Download these slides http://djysrv.googlepages.com/idahonuclearnews
14
BACKUP SLIDES
15
Heat generation complicates weapon fabrication Î improves proliferation resistance Multiple recycles increase heat generation
Watts/kg
Heat Generation 1000 100 10 1 0.1 0.01 0.001 0.0001 0.00001 100% U235
100% Pu239
Weapons grade
Pu from used fuel
Weapons usable
NpPuAm from used fuel
TRU from used fuel
Initially weapons usable
80% Pu238
Not weapons usable
51 MW-day/kg burnup, 5 yrs after discharge
16
Gamma emission irradiates proliferators Î slightly improves proliferation resistance
Watts/kg
Gamma energy
Multiple recycles increase gamma emission
1.E+00 1.E-01 1.E-02 1.E-03 1.E-04 1.E-05 1.E-06 100% U235 100% Pu239
Pu from used fuel
NpPuAm from used fuel
TRU from used fuel
Used fuel (with fission products)
Initially Self weapons protecting usable 51 MW-day/kg burnup, 5 yrs after discharge 17
Weapons grade
Weapons usable
