Document: NUREG-0800
Document ID: 96afb1d6-6ce9-41e4-b4ec-1fc7747bc0b2
Document Type: srp
Title: Revision 8 – January 2021
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML2033/ML20339A647.pdf
Revision Date: 2023-05
Chapter: 7
Section ID: 7
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ether the proposed system is of low safety significance. Section 4 of the attachment to RIS 2002-22, Supplement 1, provides guidance on factors to consider for review of failure analyses of DI&C SSCs. Acceptance Criteria If the application meets the acceptance criteria identified below, the reviewer should conclude that a D3 assessment is not necessary because a failure analysis demonstrates that failure of the specified SSC cannot adversely affect a safety function or place the plant in a condition that cannot reasonably be mitigated. The acceptance criteria are as follows: • The SSC has the characteristics listed in item (c) of Section B.2.1 above, or documented risk insights demonstrate that its level of safety significance is similar to that of SSCs with those characteristics. BTP 7-19-16 Revision 8 – January 2021 • The SSC is not integrated or interconnected with a more safety-significant SSC. • The application includes an analysis of a postulated failure of the SSC to perform its design functions and evaluates the effects of that failure, including potential spurious operations. • The failure does not adversely affect a safety function or place the plant in a condition that cannot reasonably be mitigated. 3. Diversity and Defense-in-Depth Assessment A D3 assessment is a systematic approach used to analyze a proposed DI&C system for CCFs that can occur concurrently within a redundant design, for example, within two or more independent divisions. These CCFs could cause the DI&C system to fail to perform its intended safety function or could lead to spurious operations. Reviewers should determine whether the applicant’s D3 assessment is adequate to protect against CCFs that are either (1) identified through design analysis or (2) postulated as design defects that are not identifiable through design analysis. The reviewer should also consider whether the D3 assessment includes an analysis of the effects of CCFs to verify that these effects are bounded