Evaluation of Fission Product Worth Margins in PWR Spent Nuclear Fuel Burnup Credit Calculations
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Alternative Energies and Atomic Energy Commission (CEA), Cadarache (France)
Current criticality safety calculations for the transportation of irradiated LWR fuel make the very conservative assumption that the fuel is fresh. This results in a very substantial overprediction of the actual keff of the transportation casks; in certain cases, this decreases the amount of spent fuel which can be loaded in a cask, and increases the cost of transporting the spent fuel to the repository. Accounting for the change of reactivity due to fuel depletion is usually referred to as ''burnup credit.'' The US DOE is currently funding a program aimed at establishing an actinide only burnup credit methodology (in this case, the calculated reactivity takes into account the buildup or depletion of a limited number of actinides). This work is undergoing NRC review. While this methodology is being validated on a significant experimental basis, it implicitly relies on additional margins: in particular, the absorption of neutrons by certain actinides and by all fission products is not taken into account. This provides an important additional margin and helps guarantee that the methodology is conservative provided these neglected absorption are known with reasonable accuracy. This report establishes the accuracy of fission product absorption rate calculations: (1) the analysis of European fission product worth experiments demonstrates that fission product cross-sections available in the US provide very good predictions of fission product worth; (2) this is confirmed by a direct comparison of European and US cross section evaluations; (3) accuracy of Spent Nuclear Fuel (SNF) fission product content predictions is established in a recent ORNL report where several SNF isotopic assays are analyzed; and (4) these data are then combined to establish in a conservative manner the fraction of the predicted total fission product absorption which can be guaranteed based on available experimental data.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); USDOE Office of Civilian Radioactive Waste Management (RW)
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 12014
- Report Number(s):
- ANL-FRA-1998-1; TRN: US0102327
- Resource Relation:
- Other Information: PBD: 17 Feb 1999
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
42 ENGINEERING
PWR TYPE REACTORS
BURNUP
CRITICALITY
CROSS SECTIONS
FISSION PRODUCTS
SPENT FUELS
SAFETY ANALYSIS
SPENT FUEL CASKS
TRANSPORT
REACTIVITY WORTHS
Nuclear Criticality Safety Program (NCSP)
Fuel Isotopics
CERES Experiment
DRAGON
Predictions
Absorption