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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sed (1) in requests for license amendments as modifications to licensed NPPs, or (2) in applications for CPs, OLs, COLs, DCs, SDAs, and MLs. This BTP does not apply to proposed modifications performed under the change process in 10 CFR 50.59, “Changes, tests and experiments.” This BTP does not cover review criteria for single random failures and cascading failures from shared resources (i.e., not due to latent design defects in DI&C SSCs). The reviewer can find guidance for addressing single failures in systems credited to perform safety functions in RG 1.53, “Application of the Single-Failure Criterion to Safety Systems.” SRP Section 7.7, “Control Systems,” provides guidance for analyzing postulated failures in NSR systems. 4. Purpose This BTP provides the NRC staff with guidance for evaluating an applicant’s assessment of the adequacy of D3 for a proposed DI&C system. The applicant performs this D3 assessment to identify and address potential CCFs in a proposed DI&C system and to evaluate the effects of any unprevented CCFs on plant safety. This BTP also provides guidance for review of the following: • the appropriateness of an applicant’s chosen methods for performing a D3 assessment, including any categorization of proposed DI&C SSCs based on the safety significance of the functions they perform • proposed design attributes—such as the use of diverse equipment, testing, or NRC-approved alternative methods, including defensive measures, in the design of a system or component—that may eliminate a potential CCF from further consideration5 • an applicant’s use of diverse external equipment, including manual controls and displays, to mitigate a potential CCF, as well as other measures to ensure conformance 5 Section B.3.1 of this BTP describes how a potential CCF can be eliminated from further consideration. BTP 7-19-9 Revision 8 – January 2021 with the NRC’s position on addressing CCFs in DI&C systems as specified in SRM-SECY-93-087