Document: NUREG-0800
Document ID: 1f39c574-c7ef-40fa-80ba-d9a8d86263f0
Document Type: srp
Title: 8.4
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070496.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.2
CFR Part: 
CFR Title: 

Content:
ite electric distribution system shall be supplied by two physically independent circuits (not necessarily on separate rights of way) designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. A switchyard common to both circuits is acceptable. c. The offsite system shall be comprised of two physically independent circuits connecting the transmission network (grid) to the onsite distribution system (safety busses). [Separate transmission line towers are required but common switchyard structures are acceptable. No requirement for meeting single failure, and in the absolute sense single failure cannot be met because there is only one power source, the grid.] GDC 17 Staff Interpretation 8.1-11 DRAFT Rev. 3 - April 1996 Each of these circuits shall be designed to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuit, to assure that specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded. d. Each of the two required offsite power circuits shall be designed to be available in sufficient time to affect safe shutdown in event of loss of all onsite power and the loss of the other offsite circuit. [the second circuit has been designated by the staff as the “delayed access circuit.” The offsite power system, i.e., the two circuits considered together, must meet the single failure criterion, but only with respect to the delayed access circuit function.] One of these circuits shall be designed to be available within a few seconds following a loss-of-coolant accident to assure that core cooling, containment integrity, and other vital safety functions are maintained. e. One of these circuits shall be designed to be available within a few seconds following a loss-of-coolant accident. [The staff has designated