Document: NUREG-0800
Document ID: 853719df-a6ea-408b-8d43-5956155abc38
Document Type: srp
Title: and 8.3.2.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1007/ML100740246.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
open the generator output breaker after a time delay of at least 15 seconds, during which time the rotating generator will provide voltage support for the grid. When the generator output breaker trips the plant distribution system utilizes backfeed from the grid to maintain power to the RCPs. Also, the reviewer should verify that the analyses in Chapter 15 do not assume operation of the RCPs following the turbine trip if the initiating event is an electrical system failure (such as failure of the isolated phase bus or transformers). Review of the grid stability analyses should verify that the grid remains stable for a minimum of 3 seconds following a turbine trip to support the assumptions made in the safety analyses for the passive reactor designs such as the AP1000. NUREG-1793 provides additional information on grid stability analyses for the AP1000. G. During the review of the electrical schematics, it should be determined that loss of standby power will not result in loss of preferred power, loss of one preferred power circuit will not result in loss of the other circuit, loss of the main generator will not result in loss of either preferred power circuit, and loss of any combination of these power sources will not prevent the use of AAC power. H. The reviewer verifies that the preferred power system is independent of the onsite power system. The basis for acceptance is that no single event, including 8.2-19 Revision 5 - May 2010 a single protective relay, interlock, or switchgear failure, in the event of loss of all standby power sources, will prevent the separation of the preferred power system from the onsite power distribution system or prevent the preferred power system from accomplishing its intended functions. In addition, the preferred and standby power supplies should not have common failure modes. An acceptable design must be capable of restoring the preferred power supply after the loss of either circuit in a time period such that the plant can be