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:
mode failures as described in item 6 above are considered by the staff to comply with the fundamental reliability requirements of GDC 21, IEEE Std 279, and IEEE Std 603. The assessment of reliability should consider the effect of possible hardware and software failures and the design features provided to prevent or limit the effects of these failures. Hardware failure conditions considered should include failures of portions of the computer itself and failures of portions of communication systems. Both hard failures and transient failures should be considered. Both sustained and partial failures should be considered. Software failure conditions considered should include, as appropriate, software common-mode failure, cascading failures, and undetected failures. Reg. Guide 1.152 indicates that the concept of quantitative reliability goals is not sufficient as a sole means of meeting the NRC's regulations for the reliability of digital computers used in safety systems. This is discussed in more detail as part of item 4 above. 21. Section 6 — Sense and Command Features — Functional and Design Requirements This section provides requirements for sensors and command features. Section 7, Executive Features — Functional and Design Requirements, provides requirements for actuators and other execute features. The review guidance for items in these sections are discussed together. 22. Sections 6.1 and 7.1 — Automatic Control The safety system should, with precision and reliability, automatically initiate and execute protective action for the range of conditions and performance except as justified in Section 4.5. The applicant/licensee's analysis should confirm that the safety system has been qualified to demonstrate that the performance requirements are met. The evaluation of the precision of the protection system should be addressed to the Rev. 4 — June 1997 SRP 7.1-C-12 extent that setpoints, margins, errors, and response times are factored into the analysis. BTP