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:
e reviewer on the importance of redundancy in transmission grid protective schemes is provided by operating experience events (Reference 27). For those designs that utilize a backfeed path through the main generator step-up transformer, the reviewer must first ascertain if this path is required to satisfy the GDC 17 requirement for an immediate or delayed access circuit. If the circuit is for delayed access only, then the same determination (as discussed in the previous paragraph) must be made, i.e., there is sufficient time to make this circuit available (assuming the availability of the grid itself but the unavailability of the immediate access circuit and the onsite power supplies) such that the reactor remains in a safe condition. If the circuit is required for immediate access or utilizes generator circuit breakers or generator load break switches, then the reviewer should use the guidelines contained in Appendix A to this SRP section. E. Each of the circuits from the offsite system to the onsite distribution buses shall have the capacity and capability to supply the loads assigned to the bus or buses it is connected to during normal or abnormal operating conditions, accident conditions, or plant shutdown conditions. Therefore, the loads to be supplied during these conditions should be determined from information obtained in coordination with other staff. The capacity and electrical characteristics of transformers, circuit breakers, buses, transmission lines, other electrical equipment, and the preferred power source for each path should be evaluated to ensure that there is adequate capability to supply the maximum connected load during all plant conditions. The design should also be examined to ensure that during transfer from one power source to another the design limits of equipment are not exceeded. Industry standards (References 46 & 48) and, for COL applications, RG 1.206 (Section C.I.8.2.2), provide further information for the reviewer regarding power