Document: NRC Regulatory Guide
Document ID: 7fa0e9f9-cb40-463b-adc5-53fe2057e43f
Document Type: regulatory_guide
Title: Fresh and Spent Fuel Pool Criticality Analysis + HISTORY - HISTORY 08/2020 – DG-1373 , Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2018/ML20182A788.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.240
CFR Part: 
CFR Title: 

Content:
est. m. Section A.2.2 states that startup critical data from boiling-water reactors (BWRs) can be used to benchmark depletion codes and compute a bias and bias uncertainty. NEI 12-16, Revision 4, does DG-1373, Page 9 not provide clear guidance on how to accomplish this assessment, and it is not a commonly accepted practice. Therefore, licensees or applicants that use such an approach would need to provide technical justification to the NRC for review and approval, including why the critical data are applicable to the compositions and to which geometries the benchmarking is intended be applicable. n. Section A.4 discusses use of a secondary code as an intermediate means to validate the primary code used for the nuclear criticality safety analyses. This is not an approach that the NRC has recently received for review and approval, and there is no justification for this approach in NEI 12-16, Revision 4. Therefore, the NRC does not endorse this approach as a generally acceptable means of validating a code intended specifically for use in the nuclear criticality safety analyses (as opposed to use in the generation of spent fuel isotopic compositions or screening of fuel lattices for evaluation). o. NEI 12-16, Revision 4, provides many recommendations that are based on analyses performed using typical geometries and compositions associated with spent fuel pools and bundle designs that are currently in widespread use in the United States (e.g., cylindrical uranium dioxide fuel pellets enclosed in zirconium alloy tubes). Novel configurations and concepts, such as accident-tolerant fuel designs, may require justification for continued use of the assumptions. For example, dispositions of specific uncertainties as not significant may no longer be valid, simplifying assumptions may become nonconservative, and additional uncertainties may need to be considered. Licensees or applicants are responsible for justifying use of the guidance in NEI 12-16, Revision 4, in any such