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:
nuclear unit. Plant TS limiting condition for operations (LCOs) require the offsite power system to be operable. However, since the capability of the offsite power system cannot be tested except when challenged during an actual event, the design bases for the offsite power system can only be assured through analysis of the grid and plant conditions. Plant operators should therefore be aware of: (1) the capability of the offsite power system to supply power, as required by TS, during operation and (2) situations that can result in a LOOP following a trip of the plant. Plant operators are expected to declare the offsite power system inoperable in the event of degraded grid conditions that can not support adequate post-trip voltages. Additional information on the adequacy of grid voltage, grid stability and grid reliability challenges due to deregulation of the utility industry, and the effect of grid events on NPP performance are provided in References 21, 24, 25, 29, 30, and 43. GDC 17 also requires that the onsite power supplies and the onsite electrical distribution system have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure. Therefore, no single failure will prevent the onsite 8.2-12 Revision 5 - May 2010 power system from supplying electric power, thereby permitting safety functions and other vital functions requiring electric power to be performed in the event of any single failure in the power system. As documented in SECY 94-084, the preferred electrical distribution system for evolutionary light water reactor design plants should include: 1) an alternate offsite power source available for non-safety-related loads, unless the design margins for loss of non-safety-related loads are no more severe than turbine-trip-only events in current plants, and 2) at least one offsite circuit to each redundant safety division supplied directly from offsite power sources, with no intervening non-safety-related