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:
lting in a short-to-ground, or conductor-to-conductor hot short, where residual resistance in the faulted connection maintains the fault current level below the long-term setpoint of the component’s circuit breaker. hot short: Individual conductors of the same or different cables that come in contact with each other and that may result in an impressed voltage or current on the circuit being analyzed. hot work: Activities that involve the use of heat, sparks, or open flames, such as cutting, welding, and grinding. impairment: The degradation of a fire protection system or feature that adversely affects the ability of the system or feature to perform its intended function. important to safety: Nuclear power plant SSCs “important to safety” are those required to provide reasonable assurance that the facility can be operated without undue risk to the health and safety of the public. In Appendix R to 10 CFR Part 50, “important to safety” and “safety related” apply to all safety functions. interrupting device: A breaker, fuse, or similar device installed in an electrical circuit to isolate the circuit (or a portion of the circuit) from the remainder of the system in the event of an overcurrent or fault downstream of the interrupting device. in situ combustibles: Combustible materials that constitute part of the construction, fabrication, or installation of plant SSCs and, as such, are fixed in place. isolation device: A device in a circuit that prevents malfunctions in one section of a circuit from causing unacceptable influences in other sections of the circuit or other circuits. listed: Equipment or materials included on a list published by a recognized testing laboratory, inspection agency, or other organization concerned with product evaluation that periodically inspects the production of listed equipment or materials and states that certain specific equipment or materials meet nationally recognized standards and have been tested and found suitable for