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:
g and after an SBO without any support system receiving power from the preferred power supply or the blacked-out unit’s EAC power sources. The capability of the AAC to start on demand depends on the availability of the necessary support systems to fulfill their required function. These support systems may need varying combinations of dc or ac power for varying periods to maintain operational readiness. Information Notice (IN) 97-21 (Ref. 17) discusses two examples of a failure of the AAC to start on demand because of an extended loss of auxiliary electrical power sources. L. The portions of the AAC power system subjected to maintenance activities are/will be tested before returning the AAC power system to service. M. Plant-specific technical guidelines and emergency operating procedures will be implemented (or are in place, as applicable) that identify those actions necessary for placing the AAC power source in service. N. The AAC power system will be inspected, maintained, and tested periodically to demonstrate operability and reliability. The reliability of the AAC power system should meet or exceed 95 percent as determined in accordance with NSAC-108 (Ref. 37) or equivalent methodology. O. Where EDGs are identified as AAC power sources, they should meet the following criteria: 8.4-14 March 2007 i. At single unit sites, any EAC power source(s) in excess of the number required to meet the minimum redundancy criteria (i.e., single failure) for safe shutdown may be assumed to be available. These EAC power sources may be designated as AAC power sources, provided the guidelines identified in Section C.3.3.5 of RG 1.155 are met. ii. A single unit that needs one EAC source to place the plant in safe shutdown needs one redundant EAC power source. For SBO, both the EAC power source and the redundant EAC power source are unavailable. An EDG may be designated as an AAC power source only if that EDG is neither the necessary EAC power source nor the redundant EAC power