Document: NUREG-0800
Document ID: f4b8f0c1-9a14-46be-88c9-a6cb74d64dff
Document Type: srp
Title: Rev. 4 — June 1997
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500499.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
part the identification of the analytical limit associated with each variable. Review considerations in confirming that an adequate margin exists between analytical limits and setpoints are discussed in item 30 below. Section 4.7 requires in part that the range of transient and steady-state conditions be identified for both the energy supply and the environment during normal, abnormal, and accident conditions under which the system must perform. This information is used in subsequent evaluations. Section 4.8 requires in part the identification of conditions having the potential for causing functional degradation of safety system performance, and for which provisions must be incorporated to retain necessary protective action. This information is used in subsequent evaluations, with special attention given to Section 5.4 of the standard, "Equipment Qualification." Section 4.9 requires the identification of the methods used to determine that the reliability of the safety system design is appropriate for each such design, and the identification of the methods used to verify that any qualitative or quantitative reliability goals imposed on the system design have been met. Staff acceptance of system reliability is based on deterministic criteria described in IEEE Std 603 and IEEE Std 7-4.3.2, rather than on quantitative reliability goals. Therefore, the system design basis should discuss the methods to be used to confirm that these deterministic criteria have been met. The NRC staff does not endorse the concept of quantitative reliability goals as a sole means of meeting the NRC's regulations 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. For safety systems that include digital computers, both hardware and software reliability should be considered. Software failures that are not the