Document: NRC Regulatory Guide
Document ID: 28bfa464-f1cc-4f82-9b3c-4cfbe773e040
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:
with 10 CFR 50.68(b) is when a licensee has been granted an exemption to 10 CFR 70.24. This only applies if the licensee maintains the conditions upon which the exemption was based. If the conditions deviate from the conditions for which the exemption was justified, then the licensee or applicant may need to justify why the exemption is still valid or perform an evaluation. d. Section 3.1.3 discusses the treatment of nuclides credited in the depletion and criticality analysis; however, it doesn’t provide any guidance on the treatment of lumped fission products which may be used in certain depletion codes. The NRC has previously accepted approaches in which the lumped fission products are included in the depletion calculations but removed from the isotopic compositions before use in the criticality analysis. If licensees or applicants use lumped fission products in their estimation of keff of the spent fuel pool, then they should justify their treatment of lumped fission products separately from the treatment of individual actinides and fission products. e. Section 4.2.3 states that the depletion bias and uncertainty described in this section account for all uncertainties associated with depletion. If licensees are following the guidance in Section 4.3.1 about treatment of the depletion parameters, the staff would find this approach acceptable. Licensees or applicants that do not follow the guidance in Section 4.2.3 should justify that they are adequately accounting for the depletion uncertainties. f. Section 4.3.1 discusses the lattice-specific parameters that should be accounted for when considering which types of lattices to evaluate. Section 4.3.1 should not be considered to provide a complete list of parameters. Each unique axial plane in the bundle designs should be evaluated. For example, some bundle designs may use different fuel rod pitches at different axial planes. Licensees or applicants should justify their selection of lattice parameters for