Document: NUREG-0800
Document ID: 97120913-d26f-4324-ab62-22f3f5b73925
Document Type: srp
Title: and 8.3.2.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0636/ML063600410.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
s, surge and lightning protection features for outdoor equipment and circuits, and the measures for isolation of instrumentation grounding systems. Regulatory Guide 1.204 and IEEE Stds 665, 666, 1050, and C62.23, provide acceptable guidelines for the design, installation, and performance of station grounding systems and surge and lightning protection systems. J. The reviewer should verify that provisions are included in the design to minimize the probability of losing electric power from any of the remaining supplies as a result of, or coincident with, the loss of power generated by the nuclear power unit, the loss of power from the transmission network, or the loss of power from the onsite electric power supplies. The trip of the nuclear power unit is an anticipated operational occurrence that can result in reduced switchyard voltage, potentially actuating the plant’s degraded voltage protection and separating the plant’s safety buses from offsite power. It can also result in grid instability, potential grid collapse, inadequate switchyard voltages, and a subsequent LOOP due to loss of the real and/or reactive power support supplied to the grid from the nuclear unit. Plant technical specifications (TS) 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 post-trip voltages. Further, the reviewer should verify that communications (both voice and data) between the NPP and