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:
operation of the component is desired, the motion of the hand switch removes the short before energizing the coil to actuate the component. Any circuit using a shorting switch should have this feature of removing the short provided by the shorting switch before energizing the coil (i.e., break before make). The JACQUE-FIRE Phenomena Identification and Ranking Table (PIRT) Panel reviewed the proposed design and provided supplemental technical information to form a comprehensive set of design considerations and recommendations for the reliable use and application of shorting switches in NUREG/CR-7150. Appendix I to NEI 00-01, which outlines these design considerations and recommendations, provides one acceptable methodology for shorting switch applications. Guidance for circuit failure mode likelihood and hot short duration for use in Fire PRAs is included in NUREG/CR-7150, Volume 2. NEI 04-02, Section B.2.1, provides one acceptable approach for identifying and screening MSOs when analyzing the postfire safe-shutdown circuits. Licensees should use the fire risk evaluation or plant change evaluation (as applicable) described in Regulatory Positions 2.2.4 and 3.2.2, respectively, for unscreened spurious actuations. The nuclear safety capability circuit analysis should address both the possible equipment damage caused by spurious actuation and the inability to restore equipment operability, including the types of failures described in the NRC’s Information Notice (IN) 92-18, “Potential for Loss of Remote Shutdown Capability During a Control Room Fire,” dated February 28, 1992 (Ref. 27). In addressing the types of failures described in IN 92-18, some licensees have credited thermal overload protection installed in the electrical circuits for the associated motor-operated valves. Licensees that use thermal overload protection to prevent damage to motor-operated valves should use the guidance in RG 1.106. The types of failures described in IN 92-18 are an example of a