Document: NUREG-0800
Document ID: f9d2d9cb-1d13-407e-ad7a-523fff64de06
Document Type: srp
Title: DC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1007/ML100740391.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.2
CFR Part: 
CFR Title: 

Content:
in multiunit nuclear power plants. 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 RG 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 8.3.2-16 Revision 4 - May 2010 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 the control boards to confirm that it is consistent with IEEE Std. 384, as augmented by RG 1.75. This includes the criteria for differentiating among (a) safety-related cables, raceways, and terminal equipment of different channels or divisions, (b) nonsafety-related cable that is run in safety raceways, (c) nonsafety- related cable that is not associated physically with any safety division, and (d) safety- related cables, raceways, and terminal equipment of one unit with respect to the other units at a multiunit site. 5. Vital Supporting Systems.