Topical Report on Actinide-Only Burnup Credit for PWR Spent Nuclear Fuel Packages. Revision 2
The objective of this topical report is to present to the NRC for review and acceptance a methodology for using burnup credit in the design of criticality control systems for PWR spent fuel transportation packages, while maintaining the criticality safety margins and related requirements of 10 CFR Part 71 and 72. The proposed methodology consists of five major steps as summarized below: (1) Validate a computer code system to calculate isotopic concentrations in SNF created during burnup in the reactor core and subsequent decay. (2) Validate a computer code system to predict the subcritical multiplication factor, keff, of a spent nuclear fuel package. (3) Establish bounding conditions for the isotopic concentration and criticality calculations. (4) Use the validated codes and bounding conditions to generate package loading criteria (burnup credit loading curves). and (5) Verify that SNF assemblies meet the package loading criteria and confirm proper fuel assembly selection prior to loading. (This step is required but the details are outside the scope of this topical report.) When reviewed and accepted by the NRC, this topical report will serve as a criterion document for criticality control analysts and will provide steps for the use of actinide-only burnup credit in the design of criticality control systems. The NRC-accepted burnup credit methodology will be used by commercial SNF storage and transportation package designers. Design-specific burnup credit criticality analyses will be defined, developed, and documented in the Safety Analysis Report (SAR) for each specific storage or transportation package that uses burnup credit. These SARs will then be submitted to the NRC for review and approval. This topical report is expected to be referenced in a number of storage and transportation cask applications to be submitted by commercial cask and canister designers to the NRC. Therefore, NRC acceptance of this topical report will result in increased efficiency of the review process for these SNF storage and transportation cask applications. The DOE will also reference NRC-accepted topical reports in its license application for a geologic repository. DOE is requesting NRC acceptance for two general aspects of the actinide-only burnup credit methodology. First, data is sufficient to validate the burnup credit criticality analysis methodology presented in this topical report. This includes the chemical assay data used to validate the spent fuel isotopic concentration calculations and critical experiments used to validate the burnup credit criticality calculations. Second, the conservative methodology in utilizing this data for burnup credit is acceptable. A detailed breakdown of what the DOE is specifically seeking NRC acceptance of is presented in Section 1.6.
- Research Organization:
- Yucca Mountain Project, Las Vegas, Nevada (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC08-91RW00134
- OSTI ID:
- 762177
- Report Number(s):
- DOE/RW-0472(Rev.2); TRN: US0108844
- Country of Publication:
- United States
- Language:
- English
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