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:
re in the interconnections or inadvertent closure of interconnecting devices will compromise division independence in a manner that will cause the paralleling of the dc power supplies. To ensure this, the control circuits of the bus tie breakers or multifeeder breakers must preclude automatic transferring of load centers or loads from the designated supply to the redundant counterpart upon loss of the designated supply (Regulatory Position 4 of Regulatory Guide 1.6). Regarding the interconnections through bus tie breakers, an acceptable design will provide for two tie breakers connected in series and physically separated from each other in accordance with the acceptance criteria for separation of safety-related systems, as discussed below. Furthermore, the interconnection of redundant load centers must be accomplished only manually. B. To ensure physical independence, the staff will review the criteria governing the physical separation of redundant equipment, including cables and cable trays and their implementation as depicted on preliminary or final physical arrangement drawings, to confirm that the design arrangement satisfies the requirements of IEEE Std. 384 and the positions of Regulatory Guide 1.75. These guides and standards set acceptance criteria for the separation of circuits and electrical equipment contained in, or associated with, the safety-related dc power system. To determine whether the independence of the redundant cable installation is consistent with the requirements in IEEE Std. 384 and the positions in Regulatory Guide 1.75, the staff will review the proposed design criteria governing the separation of safety-related cables and raceways, including criteria such as those for cable derating; raceway filling; cable routing in containment penetration areas, cable spreading rooms, control rooms, and other congested areas; sharing raceways with nonsafety-related cables or with cables of the same system or other systems; prohibiting cable splices in