Document: NUREG-0800
Document ID: a2680f96-0e15-402d-89ab-688ff09806a8
Document Type: srp
Title: with respect to the specified station blackout event/duration.13
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070497.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.2
CFR Part: 
CFR Title: 

Content:
ire and Catawba, References 1, 2, and 3, an expert consultant was retained to evaluate the generator circuit breaker verification testing program and its results. These guidelines are formalization of the results of that extensive work. Also guidelines for the load break switches are incorporated, as these devices have some common functional requirements as generator breakers as described above. The staff has made a determination that only devices which have the capability of interrupting the system maximum available fault current, i.e., circuit breakers will be approved as a means of isolating the unit generators from the offsite power system in order to provide immediate access in accordance with GDC 17. This is necessary because a non fault current interrupting device, i.e., load break switch, must delay its trip for electrical faults until the switchyard circuit breakers have interrupted the current. Following opening of the load break switch, the switchyard circuit breakers must then be reclosed to establish offsite power to the unit. A generator circuit breaker, however, could interrupt the fault current and isolate the unit generator at the same time, maintaining continuous power to the onsite ac power system. B. Specific Guidelines 1. Only devices which have maximum fault current interrupting capability i.e., circuit breakers, can be used to isolate the unit generator from the offsite and onsite ac power systems in order to provide immediate access for the onsite ac power system to the offsite source. Generator load break switches can only be used for isolating the unit generator for the purpose of providing a delayed access offsite source. 2. Generator circuit breakers should be designed to perform their intended function during steady-state operation, power system transients and major faults; tests 8.2-19 DRAFT Rev. 4 - April 1996 should be performed on the circuit breaker to verify these capabilities. As a minimum, the following performance tests and