Document: NUREG-0800
Document ID: b351c30f-74b4-4d36-833e-939d23abae4e
Document Type: srp
Title: D-C POWER-SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350494.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.2
CFR Part: 
CFR Title: 

Content:
verified that the tabulation of all safety-related loads to be connected to each d-c supply is consistent with the Information obtained incoordination 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 run out condition, or estimated load under expected flow and pressure) are utilized to verify the calculations establishing the combined load demand to be connected to each d-c 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 is guided by Regulatory Guide 1.106. Where the proposed design provides for the sharing of d-c supplies between units at the same site, and connection and disconnection of nonsafety- related loads to and from the safety-related distribution buses, particular attention is given in the review to assure that the implementation of such design provisions does not compromise the capacity, capability, or reliability of these supplies. In the absence of specific criteria in IEEE Std 308 governing the connection and disconnection of nonsafety-related loads to and from the safety-related distribution buses, the review of the interconnections will consider isolation devices as defined in Regulatory Guide 1.75 and engineering 3udgement to determine the adequacy of the design. In assuring that the interconnections between nonsafety-related loads and safety-related buses will not result in the degradation of the safety-related system, the isolation device through which d-c power is supplied to the nonsafety- related load, including control circuits and connections to the safety- related bus, must be designed to meet safety Class IE requirements. Should the d-c power supplies not have