Document: NUREG-0800
Document ID: e47fd320-f3af-41cd-883e-a51e0949005d
Document Type: srp
Title: to verify that the AAC source (or sources) will not adversely affect the
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1007/ML100740424.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.2
CFR Part: 
CFR Title: 

Content:
preferred power system or its specified functions, and will not adversely affect the onsite power system or its specified safety functions. The review should determine that sufficient information has been provided to demonstrate adequate AAC source independence as follows: 8.4-14 Revision 1- May 2010 i. With respect to independence between the AAC power source used for SBO and the preferred and onsite power systems, electrical ties between these systems and the physical arrangement of the interface equipment should minimize the potential for the loss of any system (i.e., preferred, onsite, or AAC) preventing access to any other system and the potential for such a loss to cause further failures in 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