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:
gns 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 evaluation. DG-1373, Page 8 g. Section 5.1.6 discusses a conservative approach to modeling integral burnable absorbers using nominal dimensions combined with a minimum absorber loading. To meet the 95-percent probability, 95-percent confidence requirement of 10 CFR 50.68(b), licensees or applicants should ensure that the minimum absorber loading is based on the lower 95/95 threshold of the manufacturing tolerance range, or the manufacturing tolerances should be evaluated and treated as an uncertainty. h. Section 5.2.2 states that credit can be taken for radial leakage near the walls of the spent fuel pool for allowing lower burnup fuel requirements on the periphery of the spent fuel pool. Licensees or applicants that adopt this approach should include the spent fuel pool wall in their nuclear criticality safety analyses to account for the weak neutron reflection capability of the concrete wall, unless the distance between fuel and the spent fuel pool wall is sufficiently large to assure that the influence of the wall on criticality is not significant. i. Section 5.2.2.4 provides recommendations on the treatment of eccentric positioning for fuel assemblies within spent fuel pool cells. These recommendations are acceptable as general guidelines; however, the NRC does not endorse a generic justification for not analyzing specific configuration based on a qualitative assessment of probability. Licensees or applicants should consider any unique aspects of the configuration being analyzed that may lead to a more limiting eccentric positioning. j. Section 6.3 includes the following statement: For pressurized-water reactor (PWR) spent fuel pools that credit soluble boron, the limiting misload will be the accident which requires the highest soluble boron to ensure that the