Document: NUREG-0800
Document ID: ac4cde5a-7464-48b8-9067-860c672cbb68
Document Type: srp
Title: STATION BLACKOUT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550061.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.4
CFR Part: 
CFR Title: 

Content:
n presented in the safety analysis report (SAR) should be sufficient to support the conclusion that the plant is capable of withstanding and recovering from a complete loss of ac electric power to the essential and nonessential switchgear buses for a specified period of 8.4-2 March 2007 time. The staff will perform the review to ensure conformance with the requirements of 10 CFR 50.63, 10 CFR 50.65, and General Design Criteria (GDC) 17 and 18 in Appendix A to 10 CFR Part 50 by verifying that the licensee is implementing the relevant guidance of RG 1.155, as supplemented by the guidance and criteria herein. The analyses performed to demonstrate compliance with 10 CFR 50.63 should remain valid for the life of the NPP. Therefore, if the underlying assumptions change during the life of the NPP, licensees are expected to reevaluate the specified coping duration for their NPPs and the accompanying coping analyses using RG 1.155 or NUMARC-8700, Revision 0, as endorsed by RG 1.155. The specific areas of review are as follows: 1. SBO Coping Duration. The SBO coping duration is defined as the time from the onset of an SBO to the time when either offsite (preferred) or onsite (EDGs) ac power is restored to at least one of the safe shutdown buses. The SBO rule requires each plant to specify an SBO coping duration that is justified by an analysis of site- and plant- specific factors that contribute to the likelihood and duration of an SBO. Because passive plants will not have emergency AC (EAC) power sources, applicants for such plants need not evaluate SBO coping duration as long as they are able to demonstrate that the design selected is capable of performing safety-related functions for 72 hours. The 72 hour approach is consistent with the duration approved by the NRC staff for the AP 1000 design. The review should determine that the selected minimum coping duration conforms to the guidance provided in Section C.3.1 of RG 1.155. 2. SBO Coping Capability. The review should