Document: NUREG-0800
Document ID: eb1d19c1-686c-42f5-ba0a-c417c7b12b8e
Document Type: srp
Title: DC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070499.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.2
CFR Part: 
CFR Title: 

Content:
y function can be accomplished assuming a single failure. The acceptability of the onsite dc power system with regard to redundancy is based on conformance to the same degree of redundancy required of safety-related components and systems required by these GDC criteria. IEEE Std 603, as endorsed by Regulatory Guide 1.153, provides criteria used to evaluate all aspects of the electrical portions of safety-related systems and the onsite power system, including criteria addressing redundancy. The descriptive 84 information, including electrical single-line diagrams (CP and OL stages), functional P&IDs (CP and OL stages), and electrical schematics (OL stage) , is reviewed to verify 85 that this redundancy is reflected in the dc power system with regard to both power sources and associated distribution systems. Also, it is verified in coordination with other branches that redundant safety-related loads are distributed between redundant distribution systems and that 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.86 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, both electrical and physical separation of redundant power sources and distribution systems, including their connected loads, are reviewed to assess the independence between redundant portions of the system. To assureensure electrical independence, the design criteria, analyses, description, and implementation as depicted on functional logic diagrams, electrical single-line diagrams, and electrical schematics are reviewed