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:
other systems. ii. An acceptable design should not have the AAC power source normally directly connected to the preferred power system or to the blacked-out unit’s onsite EAC power system. No single point of vulnerability should exist whereby a single active failure or weather-related event could simultaneously fail the AAC and preferred power sources or the AAC and onsite sources. The power sources should have minimum potential for common failure modes. iii. The AAC components should be physically separated and electrically isolated from safety-related components or equipment, as specified in the separation and isolation criteria applicable to the unit’s licensing basis and the guidelines in Appendix A to RG 1.155. Based upon compliance with all relevant independence criteria and guidelines, it should be demonstrated that provisions for the AAC source will not, at any time, adversely affect the functioning of offsite and/or Class 1E onsite power systems. Also, failure of the AAC power components should not adversely affect the Class 1E ac power systems. iv. Careful examination should be made of the physical arrangement of circuits and incoming source breakers (to the affected Class 1E bus or buses), separation and isolation provisions (control and main power), permissive and interlock schemes proposed for source breakers, source initiation/transfer logic, Class 1E load shedding and sequencing schemes that could affect AAC source ability to power safe-shutdown loads, source lockout schemes, and bus lockout schemes. C. The AAC power source(s) is not automatically loaded for SBO but should have provisions to be manually connected to one or all of the redundant safety buses as necessary. D. Plant staff in the control room monitor the performance of the AAC power source. As a minimum, monitoring should include the voltage, current, frequency, and circuit breaker position. 8.4-13 March 2007 E. The AAC source components are enclosed within structures that conform to