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:
system with regard to redundancy is based on conformance to the same degree of redundancy as that needed for safety-related components and systems required by these criteria. As endorsed by RG 1.153, IEEE Std. 603 provides a method acceptable to the staff to evaluate all aspects of the electrical portions of safety-related systems and the onsite power system, including criteria addressing redundancy. Compliance with IEEE Std. 603-1991 is only required for plants with construction permits issued after May 13, 1999. Operating nuclear power plants are encouraged, but not required, to comply with IEEE Std. 603 for future system- level modifications. The staff will review the descriptive informationCincluding electrical single-line diagrams, functional P&IDs, and electrical control and schematicsCto verify that the dc power system reflects this redundancy, both in power sources and in associated distribution systems. The reviewer will also coordinate with other branches to verify that (a) redundant safety-related loads are distributed between redundant distribution systems and (b) the instrumentation and control devices for the safety- related loads and power system are supplied from the related redundant distribution systems. The review verifies that reactor core cooling is maintained after the loss of any one dc power supply or bus and a single independent active failure in any other system required for shutdown 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. To ensure electrical independence, the staff will review the design criteria, analyses,