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:
he main control room is necessary. The RG addresses this by defining the term “primary control station,” which is used in the NFPA 805 definition of recovery action; see Regulatory Position 2.4. 4 “Previously approved” means that it has been submitted to the NRC Office of Nuclear Reactor Regulation and approved by the NRC (e.g., in a safety evaluation report or in an exemption). 5 The additional risk could be deemed acceptable unless circumstances indicate that a forward fit under MD 8.4 (as referenced in Section D below) is warranted. RG 1.205, Revision 2, Page 11 transition license amendment request. If that additional risk (block [2]) is greater than the acceptance guidelines in RG 1.174 (i.e., in Region I of either Figure 4 or Figure 5 of RG 1.174), then the NRC staff will not normally approve any net increase in risk in that fire area (block [3]) from other variances from the deterministic requirements (VFDRs). Note that the acceptance guidelines of RG 1.174 may require the total CDF or LERF (or both) to evaluate changes for which the risk impact exceeds specific guidelines. If additional VFDRs are associated with that fire area (e.g., equipment or cables that do not meet the requirements; recovery actions not previously approved by the NRC), then those VFDRs would either have to be brought into deterministic compliance, or any additional risk associated with those VFDRs would have to be offset by an equal or greater reduction in risk for that fire area. The NRC staff will not normally approve net risk increases in fire areas for which the previously approved recovery actions represent an additional risk above the acceptance guidelines in RG 1.174 (block [5]). Block [4] represents the case in which the additional risk of previously approved recovery actions, compared to the NFPA 805 deterministic criteria, is less than the acceptance guidelines in RG 1.174. In this case, the NRC will normally approve risk increases in that fire area resulting from other