can thermal reactor recycle eliminate the need for multiple repositories?

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


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


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


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


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


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


Production (Recycle) Rates of Key Radionuclides with 30-year Decay Cycles

10


Comparison of 5- and 30-Year-Decay Production (Recycle) Rates

11


Comparison of 5- and 30-Year-Decay Production (Recycle) Rates with Time

12


Limited Facilities Are Required for a Store and LWR-Irradiate P/T Strategy

Existing LWRs→

Reprocessing-fabrication plant→

←SNF dry storage

13


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

can thermal reactor recycle eliminate the need for multiple repositories?

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