Document: NUREG-0800
Document ID: 81256f55-72dd-4777-9472-f373c71c4554
Document Type: srp
Title: AC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550065.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
ses/loads. Therefore, the staff has concluded that the design should include at least one offsite circuit supplied directly to each redundant safety division from one of the offsite power sources with no intervening non- safety buses in such a manner that the offsite source can power the safety buses in the event of failure of any non-safety bus. 8.3.1-24 Revision 3 - March 2007 In plants where there is no alternate source to supply power to balance of plant loads such as Reactor Coolant Pumps, Reactor Recirculation Pumps, Feedwater Pumps, etc.; the loss of power to these loads due to a plant trip or a 100% load rejection caused by the opening of the main generator high-side circuit breaker will result in a loss of forced circulation in the reactor coolant system and reduced feedwater flow. Therefore, the electrical drawings should also be examined to ensure that the design includes an alternate power source for non-safety loads, unless it has been demonstrated that the design margins will result in transients for loss-of non-safety-power events that are no more severe than those associated with the turbine-trip-only event in existing plant designs. As documented in SECY-91-078, evolutionary light water reactor design applications should satisfy the requirements of GDC 17 with an electrical distribution system design that includes at least one offsite circuit to each redundant safety division supplied directly from one of the offsite power sources with no intervening non-safety buses in such a manner that the offsite source can power the safety buses upon the failure of any non-safety bus. Aside from this configuration variation, the review to ascertain the independence of the onsite with respect to the offsite power systems is similar to that for existing plant designs. Passive light water reactor design applications provide passive safety systems that do not need Class 1E ac electric power, other than that provided by the Class 1E dc batteries and their inverters,