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:
reviewer should consider whether the D3 assessment addresses spurious operation resulting from CCF along with loss of function resulting from CCF. One important distinction between these two events is that, unlike loss of function, spurious operation is considered an initiating event only, that is, without a concurrent DBE for purposes of this assessment. 3.1. Means to Eliminate the Potential for Common-Cause Failure from Further Consideration Many system design and testing attributes, procedures, measures, and practices can significantly reduce the likelihood of a CCF. In a D3 assessment, the following methods can be used to eliminate a potential CCF from further consideration: (1) demonstration of adequate diversity within the DI&C system or component, (2) testing, and (3) other NRC-approved alternative methods within the application. In addition, for SSCs with low safety significance, a qualitative assessment and failure analysis showing that the likelihood of failure is sufficiently low can be used to eliminate a CCF from further consideration. The reviewer should determine whether the application demonstrates that the use of these methods, alone or in any combination, meets the criteria in this BTP to eliminate the potential CCF from further consideration. Even if the applicant does not eliminate all CCF vulnerabilities from further consideration using these methods, the reviewer should consider whether there is any portion of the SSC for which the applicant has sufficiently reduced the likelihood of a CCF such that further evaluation is unnecessary for that portion of the SSC. The following sections discuss each method. 3.1.1 Use of Diversity within the Digital Instrumentation and Control System or Component to Eliminate a Potential Common-Cause Failure from Further Consideration Diversity within an I&C system or component constitutes the use of different techniques, schemes, features, or additions to eliminate a CCF from further consideration. If diversity is