Document: NRC Regulatory Guide
Document ID: 8e45dce1-e1e7-4415-b1dd-7e2a610e545b
Document Type: regulatory_guide
Title: Fire Protection for Nuclear Power Plants (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2023/ML20231A835.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.189
CFR Part: 
CFR Title: 

Content:
mits specified in the design criteria. This testing may be performed as a series of overlapping tests. c. Molded case circuit breakers should periodically be manually exercised and inspected to ensure ease of operation. On a rotating refueling outage basis, a sample of these breakers should be tested to determine that breaker drift is within that allowed by the design criteria. Breakers should be tested in accordance with an accepted QC testing methodology. d. Fuses, when used as interrupting devices, do not require periodic testing because of their stability, lack of drift, and high reliability. Administrative controls should ensure that replacement fuses with ratings other than those selected for proper coordinating are not accidentally used. 5.4.4.2 Spurious Actuation Circuits Spurious actuation is considered to be mitigated if one of the following criteria is met (the fire-induced spurious actuations of components included in the safe-shutdown success path should be prevented using the methods described in Regulatory Position 5.3.1): a. Provide a means to isolate the equipment and components from the fire area before the fire (i.e., remove power, open circuit breakers). b. Provide electrical isolation that prevents spurious actuation. Potential isolation devices include breakers, fuses, amplifiers, control switches, CTs, fiber optic couplers, relays, and transducers. c. Provide a means to detect spurious actuations and develop procedures to mitigate the maloperation of equipment (e.g., closure of the block valve if a power-operated relief valve spuriously operates, opening the breakers to remove the spurious actuation of safety injection). 5.4.4.3 Common Enclosures To ensure that the coordination criteria are met, one of the following the following should be provided: a. Provide appropriate measures to prevent propagation of the fire. b. Provide electrical protection (e.g., breakers, fuses, or similar devices). 5.4.5 Control Room Fires The control room fire area