Document: NUREG-0800
Document ID: dc63e8aa-2a74-4078-9e19-9a26ed1b4d8c
Document Type: srp
Title: Revision 6 – July 2012
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1105/ML110550791.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
Use of Automation in Diverse Means If automation is used in the diverse means, then the functions should be provided by equipment that is not affected by the postulated CCF and should be sufficient to maintain plant conditions within recommended acceptance criteria for the particular AOO or postulated accident. The automated diverse means may be performed by a non-safety system, if the system is of sufficient quality to perform the necessary function(s) under the associated event conditions. The automated diverse means should be similar in quality to systems required by the ATWS rule (10 CFR 50.62), as described in the enclosure to GL 85-06, “Quality Assurance Guidance for ATWS Equipment that is Not Safety-Related.” Other systems that are credited in the analysis that are in continuous use (e.g., the normal RCS inventory control system or normal steam generator level control system) are not required to be upgraded to the augmented quality discussed above. 3.5 Use of Manual Action as a Diverse Means of Accomplishing Safety Functions If manual operator actions are used as the diverse means or as part of the diverse means to accomplish a safety function, a suitable HFE analysis should be performed by the applicant to demonstrate that plant conditions can be maintained within recommended acceptance criteria Revision 6 – July 2012 BTP 7-19-17 for the particular AOO or postulated accident. The acceptability of such actions is to be reviewed by the NRC staff in accordance with Appendix 18-A of SRP Chapter 18, "Crediting Manual Operator Actions in Diversity and Defense-in-Depth (D3) Analyses." Note: As the difference between Time Available and Time Required for operator action is a measure of the safety margin and as it decreases, uncertainty in the estimate of the difference between these times should be appropriately considered. This uncertainty could reduce the level of assurance and potentially invalidate a conclusion that operators can perform the action reliably