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:
idence 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 consequence of hardware failures are caused by design errors and, therefore, do not follow the random failure behavior used for hardware reliability analysis. Consequently, different methodologies may need to be used to assess the unreliability introduced by hardware and by software. For example, reliability of hardware components might be demonstrated by an evaluation of system redundancy and quantitative reliability modeling. Reliability of software might be demonstrated by evaluation of the development process combined with testing under a wide range of input conditions. Rev. 4 — June 1997 SRP 7.1-C-5 5. Section 5 — Safety System Criteria This section requires that the safety systems shall, with precision and reliability, maintain plant parameters within acceptable limits established by design basis events. The applicant/licensee's analysis 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. The HICB review in this regard should confirm that the system design fulfills the system design basis requirements established. Confirming the adequacy of system design basis requirements and verifying that the system meets these requirements will normally be a substantial portion of the HICB review. The subsections of Section 5, and Sections 6, 7, and 8 (discussed below) deal with specific guidance that safety systems should meet as part of fulfilling the design basis requirements. Most of these items identify deterministic criteria that, if met, will normally provide the level of reliability needed for safety systems. These criteria may be relevant for both individual