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Can Thermal Reactor Recycle Eliminate the Need for Multiple Repositories?. C. W. Forsberg, E. D. Collins, C. W. Alexander, and J. Renier. - PowerPoint PPT Presentation
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Can Thermal Reactor Recycle Eliminate the Need for Multiple
Repositories?
C. W. Forsberg, E. D. Collins,
C. W. Alexander, and J. Renier
Actinide and Fission Product Partitioning and Transmutation: 8th Information Exchange Meeting
OECD Nuclear Energy AgencyLas Vegas, Nevada; Nov. 9-11, 2004
The submitted manuscript has been authored by a contractor of the U.S. Government under contract DE-AC05-00OR22725. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the
published form of this contribution, or allow others to do so, for U.S. Government purposes. File name: SNF Processing: P-T.Nevada.Nov04
2
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
The Existing Reactor Fleet is Made of LWRs: It Is the Only Near-Term Option for Waste Partitioning and Transmutation (P/T)
Economics currently favor LWRs Fast-reactor capital costs
are greater than LWRs Uranium prices have
remained low because of advances in uranium mining technologies
Introduction date for fast reactors is uncertain
LWRs imply lower P/T deployment costs, if the technology is viable
3
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
There are Multiple LWR Transmutation Strategies
Thermal-neutron reactor transmutation strategies Low-enriched LWR fuels High-enriched uranium driver fuel
(demonstrated at SRS and HFIR with the production of Californium)
Transmutation with time (irradiation and storage) One such option described herein
Basis For ORNL Decay and LWR-Irradiate P/T Strategy
Large U. S. inventory of old SNF
Simpler processing of old SNF
Decay of shorter-lived actinides
5
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
The U.S Has A Massive Existing Inventory of SNF
Current inventory ~45,000 MTIHM
SNF generation rate is ~2000 MTIHM/year
If one large reprocessing plant (2000 tons/year) is constructed and the oldest fuel is processed first, the plant will receive 40 to 50 year old SNF on a steady-state basis
6
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Processing Costs and Risks are Reduced with Old Spent Nuclear Fuel
Decreased heat and radioactivity
Requirements for separation are greatly reduced or eliminated for some mobile radionuclides Krypton Tritium Cesium Strontium
0
2
4
6
8
10
12
1 2 5 10010Time (years)
Decay Heat
Radioactivity
0
0.5
1.0
1.5
2.0
2.5
Dec
ay H
eat
(kW
/MT
IHM
)
Rad
ioac
tivity
(10
6 cu
ries/
MT
IHM
)
7
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Storage (Time) is a Potentially Usable Transmutation Strategy
Long (> 30-year) Decay Period Alters Transmutation Path
• Building of heavier isotopes is suppressed and regeneration of fissile isotopes occurs (Reduces LWR thermal P/T penalty)
241Am 242Am
242Pu
242Cm 238Pu 239Pu
17%
83%
241Pu 70 % fission
244Cm244mAm243Am242Pu241Pu
Short-cooled SNF transmutation
Storage transmutation
T1/2 = 18.1 y
T1/2 = 14.36 y
8
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
A Store and LWR-Irradiate P-T Scenario Was Evaluated
Only fission products go into the repository
Stored Pu in spent fuel (~ 98% of inventory) is protected by high radiation (“Spent Fuel Standard”)
Both Pu-Np and Am-Cm inventories reach near equilibrium ─“no net production”
Amounts of curium are minimized
Separate Am/Cm targets to minimize fabrication difficulties
2000 MT/ySeparations
U-Pu-NpMOX Fuel
Fab
U-Am-CmMOX Targets
LWRIrradiation
4.5- 6 y
LWRIrradiation
4.5- 6 y
LWRIrradiation
4.5- 6 y
LWR UO2
Spent Fuel30-40 y cooled
FP Wastes toRepository
U to Re-enrichment
Separations – Fuel Fab – Irradiation Period
LWR MOX Spent Fuel Storage (30- 40 y)
LWR Irradiated MA Target Storage (30 - 40 y)
6 months 5-6 y
9
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Production (Recycle) Rates of Key Radionuclides with 30-year Decay Cycles
10
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Comparison of 5- and 30-Year-Decay Production (Recycle) Rates
11
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Comparison of 5- and 30-Year-Decay Production (Recycle) Rates with Time
12
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Limited Facilities Are Required for a Store and LWR-Irradiate P/T Strategy
Existing LWRs→
Reprocessing-fabrication plant→
←SNF dry storage
13
OAK RIDGE NATIONAL LABORATORYU. S. DEPARTMENT OF ENERGY
Conclusions LWRs exist
Supports examination of thermal reactor P/T strategies
Several options available
Store and LWR-burn P/T option has several attractive features Stops growth in the actinide
inventory One repository required for
steady-state operation Minimum investment relative to
most other scenarios Only fission products go into
the repository Actinide inventory in hot SNF
Store and burn P/T option has several constraints Significant inventory of SNF Requires dry storage capacity Exit strategy is complex if no
fast reactor