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:
d assigned control power supplies for each load and each diesel generator. In reviewing the criteria governing the design of the thermal overload protection for motors of motor-operated safety-related valves, the reviewer is guided by RG 1.106. Motor starting studies, load flow studies, demand load (bus loading) studies, and short circuit studies should be reviewed in accordance with the guidance provided in 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. RG 1.206, Section C.III.1, Chapter 8, provides similar guidance for COL applications that are based on certified ALWR designs. Regarding the review of the electrical protective trip circuits of the diesel generator sets, Positions C.1.7 and C.1.8 of RG 1.9 are used as an evaluation guide. The capability of the automatic sequential loading circuits to reset during a sustained low-voltage condition on the diesel generators is reviewed to ensure that upon restoration of normal voltage, the safety-related loads can be connected in the prescribed sequence. Otherwise, the reconnection of all the loads at the same time could result in an overload condition causing the trip of the respective diesel generator. In ensuring that those safety-related loads being powered through latched-type breakers are capable of being reconnected to their respective buses after restoration of power, the design should provide for resetting the breaker anticycle feature when there is an undervoltage 8.3.1-29 Revision 4 - May 2010 condition. The normal function of this feature is to prevent immediate reclosure of a breaker following a trip. Where the proposed design provides for the sharing of diesel generators between units at the same site, and connection and disconnection of non-Class 1E loads to and from the Class 1E distribution buses, particular attention is given in the review to ensure that the implementation of such design provisions