Document: NUREG-0800
Document ID: 4b0fa4a0-ce32-4f59-9360-9426826a668c
Document Type: srp
Title: Rev. 4 — June 1997
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500496.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
ion of the single-failure criterion is provided in Reg. Guide 1.53, "Application of the Single-Failure Criterion to Nuclear Power Plant Protection Systems," which endorses ANSI/IEEE Std 379, "Standard Application of the Single-Failure Criterion to Nuclear Power Generating Station Safety Systems." Where it is determined that the spatial dependence of a parameter requires several sensor channels to ensure plant protection, the redundancy requirements are determined for the individual case. In certain designs, for example, adequate monitoring of core power requires a minimum number of sensors arranged in a given configuration to provide adequate protection. This aspect of redundancy is dealt with in coordination with the Reactor Systems Branch (SRXB) to establish redundancy requirements. Components and systems not qualified for seismic events or accident environments and non-safety-grade components and systems are assumed to fail to function if failure adversely affects protection system Rev. 4 — June 1997 SRP 7.1-B-5 performance. Conversely, these components and systems are assumed to function if functioning adversely affects protection system performance. All failures in the protection system that can be predicted as a result of an event for which the protection system is designed to provide a protective function are assumed to occur if the failure adversely affects the protection system performance. In general, the lack of equipment qualification may serve as a basis for the assumption of certain failures. After assuming the failures of non-safety-grade, non-qualified equipment and those failures caused by a specific event, a random single failure is arbitrarily assumed. With these failures assumed, the protection system must be capable of performing the protective functions required to mitigate the consequences of the specific event. 4. Section 4.3 — Quality of Components and Modules The applicant/licensee should confirm that quality assurance provisions of