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:
that do not exceed 163 degrees C (325 degrees F) cold-side temperature and pass the hose stream test provide reasonable assurance that the shutdown capability is protected without further analyses. If the temperature criterion is exceeded, sufficient additional information is needed to permit an engineering evaluation to demonstrate that the shutdown capability is protected. The temperature condition of 163 degrees C (325 degrees F) was established by allowing the temperature of the unexposed side of the fire barrier rise to 139 degrees C (250 degrees F) above the assumed ambient air temperature of 24 degrees C (75 degrees F), as measured by the thermocouples within the test specimen at the onset of the fire exposure during the fire test. Appendix B to this guide provides detailed guidance for the testing and qualification of electrical raceway fire barrier systems. DG-1359, Page 74 5. Safe-Shutdown Capability When considering the consequences of a fire in a given fire area during the evaluation of the safe-shutdown capabilities of the plant, licensees should demonstrate that one success path of SSCs that can be used to bring the reactor to hot-shutdown or hot-standby conditions remains free of fire damage. Some plant designs (those that use low-pressure systems for their success path) pass through hot shutdown in a short time and then proceed directly to cold shutdown. For the purpose of this guide, the term “safe shutdown” indicates bringing a plant to safe-shutdown condition, either hot shutdown or cold shutdown (when low-pressure systems are used as the success path), as applicable to each reactor design and as defined by the plant technical specifications. The analysis should also demonstrate that fire damage to one success path of SSCs needed for achieving cold shutdown will be limited so that a success path will be returned to an operating condition within 72 hours, or for areas requiring alternative or dedicated shutdown, the licensee should demonstrate