Document: NUREG-0800
Document ID: 0d050def-90d0-4fd6-b15c-2396827c0fb4
Document Type: srp
Title: OFFSITE POWER SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070497.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.2
CFR Part: 
CFR Title: 

Content:
imum of two separate circuits from the transmission network to the onsite distribution system is provided. In determining the adequacy of this system, the independence of the two (or more) circuits is examined to see that both electrical and physical separation exists so as to minimize the chance of simultaneous failure. This includes a review of the assignment of power sources from the grid, location of rights-of-way, transmission lines and towers, transformers, switchyard interconnections (breakers and bus arrangements), switchyard control systems and power supplies, location of switchgear (in-plant), interconnections between switchgear, cable routings, main generator disconnect, and the disconnect control system and power supply, and 5 generator circuit breakers/load break switches. 2. The independence of the preferred power system is evaluated with respect to the onsite power system and any AAC power source provided for station blackout is evaluated. 6 The scope of review extends to the safety-related distribution system buses that are capable of being powered by standby power sources. It does not include the supply breakers of the safety-related distribution system buses. This evaluation will include a review of the electrical protective relaying and breaker control circuits and power supplies to assure ensure that loss of one preferred system circuit will not cause or result 7 in loss of the redundant counterpart, nor any AAC power source or standby power 8 source. 3. Design information and analyses demonstrating the suitability of the power sources from the grid, including transmission lines, breakers, and transformers used for supplying preferred power from distant sources, are reviewed to assure ensure that each path has sufficient capacity and capability to perform its intended function. This will require examination of loads required to be powered for each plant operating conditions;9 continuous and fault ratings of breakers, transformers, and