Document: NUREG-0800
Document ID: 949ca18d-b0e4-4b54-9ca9-fdb657988111
Document Type: srp
Title: Revision 5 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070660170.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
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Content:
ignment during plant operation. The review should confirm that the I&C systems provide the functions, performance, and reliability necessary to initiate and control the cooling water systems such that the functions important to safety described in GDC 44 are achieved. This review is coordinated with the organization responsible for the review of containment systems. 3. Staff Requirements Memoranda Note: This section quotes positions that are extracted from SRM and the associated SECY papers. Specific positions are not necessarily separated from explanatory material in these documents. The quotes given here do not include the explanatory material provided in the SECY or SRM. The quotes may also combine material from the SRM and SECY to fully represent the NRC position. (a) Item II.Q, “Defense Against Common-Mode Failures in Digital Instrumentation and Control Systems” of Staff Requirements Memorandum on SECY-93-087, “Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light-Water Reactor (ALWR) Designs,” dated July 21, 1993. Appendix 7.1-A-24 Revision 5 - March 2007 (1) The applicant should assess the diversity and defense-in-depth of the proposed I&C system to demonstrate that vulnerabilities to common-cause failures have adequately been addressed. (2) In performing the assessment, the vendor or applicant should analyze each postulated common-cause failure for each event that is evaluated in the accident analysis section of the SAR using best-estimate methods. The vendor or applicant should demonstrate adequate diversity within the design for each of these events. (3) If a postulated common-cause 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-cause failure, should be provided 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