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:
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 does not compromise the capacity or capability of the standby power supplies. Pursuant to GDC 5, diesel generators may not be shared unless it can be shown that the diesel generators are capable of performing all necessary safety functions in the event of an accident in one unit and an orderly shutdown and cooldown of the remaining units. In ensuring that the proposed design for sharing diesel generators between units meets the requirements of GDCs 5 and 17 as supplemented by GDCs 34, 35, 38, 41, and 44 and satisfies the positions of RG 1.9, the reviewer is guided by RG 1.81. This guide sets forth two principal positions. Position C.3 applies to those CP applications docketed after June 1, 1973, and does not recommend the sharing of onsite power systems between units. Conformance of the design with Position C.3 is verified by reviewing the descriptive information, including electrical drawings, to ensure that the onsite power system of each unit is electrically independent with respect to the onsite power system of other units. Position C.2 of RG 1.81 establishes acceptable bases under which sharing of onsite power systems between units is permitted. Conformance with Position C.2 with regard to the adequacy of diesel generator capacity and capability under the sharing mode of operation is verified by following the procedure discussed above for tabulating and summing all loads. In particular, the load tabulation and calculations establishing the diesel generator capacity are examined to ensure that the selected capacity is sufficient to power the minimum engineered safety feature (ESF) loads in any unit and safely shut down the remaining units in the event of an accident in one unit and a single failure or spurious or false accident signal from another unit and loss of