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
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should confirm that the protection system has been qualified to demonstrate that the performance requirements are met. The evaluation should confirm that the general functional requirements have been appropriately allocated to the various system components. Automatic initiation is required for all protective functions; a manual initiation capability is also a requirement (see Section 4.17 and Reg. Guide 1.62, "Manual Initiation of Protection Action"). 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 ANSI/IEEE Std 279 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 safety 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 safety system design is adequate to achieve functional reliability commensurate with the safety functions to be performed. 3. Section 4.2 — Single-Failure Criterion This section 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/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 Reg. Guide 1.53, "Application of the Single-Failure Criterion to Nuclear Power Plant Protection Systems," which endorses ANSI/IEEE Std 379, "Standard