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:
wn cooling. 2. Conformance with the Single-Failure Criterion. As required by GDC 17, the dc power system must be capable of performing its safety function, assuming a single failure. In evaluating the adequacy of this system to meet the single-failure criterion, the staff will review both electrical and physical separation of redundant power sources and distribution systems, including their connected loads, to assess the independence between redundant portions of the system. 8.3.2-14 Revision 3 - March 2007 To ensure electrical independence, the staff will review the design criteria, analyses, description, and implementation—as depicted on functional logic diagrams, electrical single-line diagrams, and electrical control and schematics—to determine whether the design meets the positions of Regulatory Guides 1.153, 1.53, 1.32, and 1.6. As endorsed by Regulatory Guide 1.153, IEEE Std. 603 provides a method acceptable to the staff for evaluating all aspects of the electrical portions of safety-related systems and the onsite power system. For guidance related to the application of the single-failure criterion, IEEE Std. 603 references IEEE Std. 379. In addition, as endorsed by Regulatory Guide 1.53, IEEE Std. 379 provides an acceptable methodology for satisfying the Commission’s regulations for the application of the single-failure criterion to onsite dc power systems. The following aspects of the design need special review attention to confirm that the electrical independence and physical separation have not been compromised: A. The reviewer will examine interconnections between redundant load centers through bus tie breakers and multifeeder breakers used to connect extra redundant loads to either of the redundant distribution systems to ensure that no single failure 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,