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:
or sustain the combustion process when ignited or otherwise exposed to fire conditions. common enclosure: An enclosure (e.g., cable tray, conduit, junction box) that contains circuits required for the operation of safe-shutdown components and circuits for nonsafe-shutdown components. common power supply: A power supply that feeds safe-shutdown circuits and nonsafe-shutdown circuits. control room complex: The area served by the control room emergency ventilation system. dedicated shutdown: The capability to shut down the reactor and maintain shutdown conditions by adding to an existing plant new SSCs that are dedicated to performing post-fire safe-shutdown functions. Like alternative shutdown, plant operators use dedicated shutdown when it is not feasible to provide the required protection for redundant safe-shutdown trains in one or more fire areas (see also alternative shutdown and success path). electrical raceway fire-barrier system: A nonload-bearing partition-type envelope system installed around the electrical components and cabling that are rated by test laboratories in hours of fire resistance and are used to maintain safe-shutdown functions free of fire damage. emergency control station: A location outside the main control room where actions are taken by operations personnel to manipulate plant systems and controls to achieve the safe shutdown of the reactor. DG-1359, Page 107 exposure fire: A fire in a given area that involves either in situ or transient combustibles and is external to any SSCs important to safety located in or adjacent to that same area. The effects of such a fire (e.g., smoke, heat, ignition) can adversely affect those SSCs important to safety. Thus, a fire involving one success path of safe-shutdown SSCs may constitute an exposure fire for the redundant success path located in the same area, and a fire involving combustibles other than those in either redundant success path may constitute an exposure fire to multiple redundant success