Document: NUREG-0800
Document ID: 106978f1-fb10-4fa9-ad95-601f3c16bd36
Document Type: srp
Title: Revision 5 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550072.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
SAR). If a postulated common-cause failure could disable a safety function that is required to respond to the design basis event being analyzed, a diverse means of effective response (with documented basis) is necessary. The diverse means may be an automatic or manual non-safety system if the system is of sufficient quality to perform the necessary function under the associated event conditions and within the required time. BTP 7-19-5 Revision 5 - March 2007 The D3 analysis methods used in ALWR design certification and for operating plant retrofits are documented in NUREG/CR-6303. This document describes an acceptable method for performing such assessments. When the RTS or ATWS mitigation system in an operating plant is modified, the requirements of the ATWS rule, 10 CFR 50.62, must be met. 10 CFR 50.62 requires that the ATWS mitigation system be composed of equipment that is diverse from the RTS. If "sufficient" difference in manufacturer cannot be demonstrated, a case-by-case assessment of the mitigation system designs should be conducted. This analysis should include differences such as manufacturing division (within a corporate entity), software (including implementation language), equipment (including central processing unit architecture), function, people (design and verification/validation team), and initiating events. 2. Information to be Reviewed The information to be reviewed is the D3 assessment conducted by the applicant/licensee. 3. Acceptance Criteria The D3 assessment submitted by the applicant/licensee should demonstrate compliance with the four-point position described above. To reach a conclusion of acceptability, the following four conclusions should be reached and supported by summation of the results of the analyses. Since the acceptance criteria address confirmation that anticipated operational occurrences and design basis accidents are mitigated in the presence of common-cause failure, D3 analyses focus on the protection systems. Other