Document: NRC Regulatory Guide
Document ID: 666e1303-0170-4974-a7d6-af27eb586524
Document Type: regulatory_guide
Title: Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2104/ML21048A448.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.205
CFR Part: 
CFR Title: 

Content:
ain the documentation in accordance with the requirements of NFPA 805, Section 2.7. 3.2.5 Combined Changes and Cumulative Risk of Changes Section 2.4.4.1 of NFPA 805 requires licensees to evaluate the cumulative effect of plant changes (including all previous changes that have increased risk) on overall risk. Licensees should evaluate the cumulative risk in accordance with Section 6.3.2 of RG 1.174. After the transition to NFPA 805, the cumulative risk of subsequent FPP changes is the change in risk compared to the post-transition baseline risk (see Regulatory Position 2.2.4). Also, after the transition to NFPA 805, licensees should only include changes associated with the FPP in cumulative RG 1.205, Revision 2, Page 22 risk evaluations. In the example license condition in Regulatory Position 3.1, the NRC chose risk acceptance criteria low enough to provide reasonable assurance that the effect of self-approved changes on cumulative risk would be acceptable. However, when licensees request FPP changes that they may not self-approve after the transition to NFPA 805, their license amendment requests should address the cumulative impact of all previous FPP changes since adopting NFPA 805. Section 2.4.4.1 of NFPA 805 further states that, if more than one plant change is combined into a group for the purpose of evaluating acceptable risk, each individual change shall be evaluated, along with the evaluation of the combined change. Any risk increases may be combined with risk decreases when estimating the total risk change. Licensees should address combined changes in accordance with the guidance in Regulatory Positions 1.1 and 1.2 of RG 1.174. 3.3 Circuit Analysis Chapter 3 of industry guidance document NEI 00-01, Revision 4, when used in conjunction with NFPA 805 and this RG, provides one acceptable approach to circuit analysis for a plant implementing an FPP under 10 CFR 50.48(c). All references to NEI 00-01 in these regulatory positions refer to Revision 4 of that NEI