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
CFR Part: 
CFR Title: 

Content:
nsequences of the residual CCF remain acceptable The reviewer should consider whether the applicant’s assessment has properly identified and addressed CCFs and whether the applicant has incorporated appropriate means to limit, 6 The review acceptance criteria in this BTP are structured as guidance to the NRC staff, so that the staff may make findings upon determining certain specified facts. The facts specified in the review acceptance criteria are not requirements, and an applicant need not establish them but may employ different facts to support the application. BTP 7-19-10 Revision 8 – January 2021 mitigate, or withstand or cope with (i.e., accept the consequences of) possible CCFs and sources of CCF vulnerability that can result in spurious operations. 1.1 Four-Point Common-Cause Failure Position and Discussion The foundation of BTP 7-19 is the NRC position on D3 from SRM-SECY-93-087, which consists of the four points quoted below: 1. The applicant shall assess the defense-in-depth and diversity of the proposed instrumentation and control system to demonstrate that vulnerabilities to common-mode failures have adequately been addressed. 2. In performing the assessment, the vendor or applicant shall analyze each postulated common-mode failure for each event that is evaluated in the accident analysis section of the safety analysis report (SAR) using best-estimate methods. The vendor or applicant shall demonstrate adequate diversity within the design for each of these events. [Emphasis in original.] 3. If a postulated common-mode failure could disable a safety function, then a diverse means, with a documented basis that the diverse means is unlikely to be subject to the same common-mode failure, shall be required to perform either the same function or a different function. The diverse or different function may be performed by a non-safety system if the system is of sufficient quality to perform the necessary function under the associated event conditions.