Document: NUREG-0800
Document ID: 9fa7092c-7628-402d-9028-6601d5f5fdfb
Document Type: srp
Title: DC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550063.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.2
CFR Part: 
CFR Title: 

Content:
erion requires that component parts of the dc power system must not be shared among units without sufficient justification, thereby ensuring that an accident in one unit of a multiunit facility can be mitigated by using an available complement of mitigative features, including required dc power, irrespective of conditions in the other units and without creating conditions that are unduly adverse to safety in another unit. This SRP section cites Regulatory Guides 1.32 and 1.81 to establish acceptable guidance related to the sharing of onsite dc power system SSCs. Regulatory Position C.1 of Regulatory Guide 1.81 recommends that dc systems in multiunit nuclear power plants should not be shared. 4. Compliance with GDC 17 requires the provision of onsite and offsite electrical power to facilitate the functioning of SSCs important to safety. Each electric power system, assuming that the other system is not functioning, must provide sufficient capacity and capability to ensure that (a) specified acceptable fuel design limits and the design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (b) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents. GDC 17 further requires that the supply of electric power from the transmission network to the onsite electric distribution system must come from two physically independent circuits that are designed and located to minimize the likelihood of their simultaneous failure under operating, postulated accident, and postulated environmental conditions. Each of these circuits must be designed to be available, following a loss of all onsite ac power supplies and the other offsite electric power circuit, in sufficient time to ensure that specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded. One of these circuits also must be designed