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:
P&IDs, expected system performance as established in the accident and/or other relevant analyses (e.g., for SBO), modes of system operation and interactions during normal and accident conditions, and interactions among systems. Subsequently, the reviewer will verify that the tabulation of all safety-related loads to be connected to each dc supply is consistent with the information obtained in coordination with other branches. The characteristics of each load (such as motor horsepower and volt-amp ratings, inrush current, starting volt-amps, and torque), the length of time each load is required, and the basis used to establish the power required for each safety-related load (such as motor name plate rating, pump runout condition, or estimated load under expected flow and pressure) are used to verify the calculations establishing the combined load demand to be connected to each dc supply during the worst operating conditions. In reviewing the design of the thermal overload protection for motors of motor-operated safety-related valves, the reviewer uses RG 1.106. If the proposed design provides for the sharing of dc supplies between units at the same site and for connection and disconnection of nonsafety-related loads to and from the safety-related distribution buses, the review gives particular attention to ensuring that the implementation of such design provisions does not compromise the capacity, capability, or reliability of these supplies. Regulatory Position C.1 of RG 1.81 recommends that dc systems in multiunit nuclear power plants should not be shared. Because sharing of dc power systems and their interactions between units could compromise safe shutdown, RG 1.32 does not endorse the IEEE Std. 308-2001 criteria for sharing safety-related dc power systems 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