Document: NUREG-0800
Document ID: 9cfc38bf-7808-446e-a43d-4ca9ff55df2a
Document Type: srp
Title: AC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1007/ML100740289.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
e relaying schemes and their coordination, relay settings, and assigned control power supplies are reviewed. The reviewer should ensure that, in the event of an electrical fault, between the preferred power transformer supply breakers and the safety buses, no single failure will result in reducing the number of preferred power circuits to less than the minimum necessary for safety or prevent the separation of the affected circuit from the respective redundant portion of the onsite power system. In addition, it is verified that no single protective relay or interlock failure will prevent separation of the necessary redundant portions of the onsite power system from the preferred power system upon loss of the latter. Industry standards (References 47, 48, and 56) and, for COL applications that are not based on certified ALWR designs, RG 1.206, Section C.I.8.3.1.2, provide further information for the reviewer regarding power system analysis studies - including load flow with voltage regulation, short circuit analysis, equipment sizing studies, protective relay setting and coordination, motor starting, grounding system design and insulation coordination - to verify the capability of the onsite ac power system and the interface with the offsite power system. RG 1.206, Section C.III.1, Chapter 8, provides similar guidance for COL applications that are based on certified ALWR designs. The analysis of the onsite ac power system should consider the effects of the offsite power system, particularly the grid voltage, on the capability of the onsite system and the 8.3.1-26 Revision 4 - May 2010 response of the undervoltage relaying. The review should ensure that the grid stability analysis considers the effect of grid events on the adequacy of offsite grid voltage available at the plant switchyard. Operating experience has shown that a variety of factors, such as power flow through the transmission grid, reactive power capacity, the plant voltage and frequency protective