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:
. 6.1.7 Station Battery Rooms Battery rooms important to safety should be protected against fires and explosions. Battery rooms should be separated from each other and from other areas of the plant by barriers having a minimum fire rating of 3 hours inclusive of all penetrations and openings. These battery rooms should not house DC switchgear and inverters. Automatic fire detection should alarm and annunciate in the control room and alarm locally. Battery room ventilation systems should be capable of maintaining the hydrogen concentration well below 2 percent. Loss of ventilation should be alarmed in the control room. Standpipes, hose stations, and portable extinguishers should be readily available outside the room. 6.1.8 Diesel Generator Rooms Diesel generators important to safety should be separated from each other and from other areas of the plant by fire barriers that have a fire-resistance rating of at least 3 hours. Diesel generators that are not important to safety should be separated from plant areas containing equipment and circuits important to safety by fire barriers that have a fire-resistance rating of at least 3 hours. Automatic fire suppression should be installed to suppress or control any diesel generator or lubricating oil fires. Such systems should be designed to operate without affecting the diesel when it is running. Automatic fire detection should alarm and annunciate in the control room and alarm locally. Hose stations and portable extinguishers should be readily available outside the area. Drainage for firefighting water should be provided, and a means for local manual venting of smoke should be considered. Day tanks with a total capacity of up to 4,164 L (1,100 gal) may be located in rooms with diesel generators important to safety under the following conditions: a. The day tank is located in a separate enclosure with a fire-resistance rating of at least 3 hours, including doors or penetrations. These enclosures should be capable of