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:
G, 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 document. Where the deterministic requirements in Chapter 4 of NFPA 805 are not met for the protection of required circuits, circuit analysis assumptions about the number of spurious actuations, the manner in which they occur (e.g., sequentially or simultaneously), and the time between spurious actuations should be supported by engineering analysis or test results (or both) that are accepted by the NRC. Aspects of circuit protection that do not conform to the deterministic requirements in Chapter 4 of NFPA 805 and were not previously approved by the NRC in accordance with Regulatory Position 2.3.2 may be evaluated using the fire risk evaluation (transition) or the plant change evaluation (post-transition) in NFPA 805. The NRC developed NUREG/CR-7150, “Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE),” Volumes 1, 2, and 3 (Refs. 21, 22, and 23) as a consensus report on technical issues related to multiple spurious operations (MSOs) by technical experts based on the current best available evidence and represents the current state of the art. Based on NUREG/CR-7150, and industry guidance document NEI 00-01, the following should be considered when performing a circuit analysis: (1) The spurious operation of a three-phase alternating current (AC) motor due to proper polarity hot shorts on three-phase power cabling, and the spurious operation of a direct current (DC) compound-wound motor due to proper polarity hot shorts in the motive/power cabling, are considered “incredible.” Therefore, these failure modes no longer need to be evaluated for any safe-shutdown components, including high-/low-pressure interface components. (2) Based in part on current transformer (CT) testing performed at Brookhaven National Laboratory (Ref. 24),