Document: NUREG-0800
Document ID: 3e629b04-65dd-490a-8062-4b8bc7cfc1ae
Document Type: srp
Title: B-5
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159A226.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.1
CFR Part: 
CFR Title: 

Content:
all protective functions; a manual initiation capability is also a requirement (see Clause 4.17 of IEEE Std 279-1971 and RG 1.62, “Manual Initiation of Protection Actions”). The evaluation of the precision of the protection system is addressed to the extent that setpoints, margins, errors, and response times are factored into the analysis. The topic of reliability is addressed in the following paragraphs. Staff acceptance of system reliability is based on the deterministic criteria described in IEEE Std 279-1971 rather than on quantitative reliability goals. The NRC staff does not endorse the concept of quantitative reliability goals as a sole means of meeting the requirements for reliability of protection systems. Quantitative reliability determination, using a combination of analysis, testing, and operating experience can provide an added level of confidence in the reliable performance of the I&C system. The applicant/licensee should justify that the degree of redundancy, diversity, testability, and quality provided in the protection system design is adequate to achieve functional reliability commensurate with the safety functions to be performed. 4.2. Single-Failure Criterion (IEEE Std 279-1971, Clause 4.2) Clause 4.2 of IEEE Std 279-1971 requires in part that any single failure within the protection system shall not prevent proper protective action at the system level when required. The applicant’s or licensee’s analysis should confirm that the requirements of the single-failure criterion are satisfied. Guidance in the application of the single-failure criterion is provided in