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:
on buses, the review gives particular attention to ensuring that the implementation of such design provisions does not compromise the capacity, capability, or reliability of these supplies. Regulatory Position C.1 of Regulatory Guide 1.81 recommends that dc systems in multiunit nuclear power plants should not be shared. Because sharing of dc power systems and their interactions between units could compromise safe shutdown, Regulatory Guide 1.32 does not endorse the IEEE Std. 308-2001 criteria for sharing safety-related dc power systems in multiunit nuclear power plants. 8.3.2-16 Revision 3 - March 2007 If the proposed design provides for the connection and disconnection of nonsafety-related loads to and from the safety-related distribution buses, the review of the interconnections will consider isolation devices, as defined in Regulatory Guide 1.75, and engineering judgment to determine the adequacy of the design. To ensure that the interconnections between nonsafety-related loads and safety-related buses will not result in the degradation of the safety-related system, the isolation device through which dc power is supplied to the nonsafety-related load, including control circuits and connections to the safety-related bus, must be designed to meet safety Class 1E requirements. If the dc power supplies have not been sized to accommodate the added nonsafety-related loads during emergency conditions, the design must provide for the automatic disconnection of those nonsafety-related loads upon detection of the emergency condition. This action must be accomplished regardless of whether the load was already connected to the power supply. For new applications licensed under 10 CFR Part 52, the review should ensure that dc power systems are not shared between units. 4. Identification of Cables, Raceways, and Terminal Equipment. The staff will review the identification scheme used for safety-related cables, raceways, and terminal equipment in the plant and internal wiring in