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:
the system. 2. Conformance with the Single Failure Criterion In determining the adequacy of this system to meet the single failure criterion, the electrical and physical separation of redundant power sources and associated distribution systems are examined to assess the independence between redundant portions of the system. This will include a review of the interconnections between redundant buses, buses and loads, and buses and power supplies; proposed sharing of the dc power system between units at the same site; the design criteria and bases governing the installation of electrical cable for redundant portions of the systems; and physical arrangement of redundant switchgear and power supplies. 3. Power Supplies Design information and analyses demonstrating the suitability of batteries and battery chargers as dc power supplies and inverters that convert dc to ac for instrumentation and control power are reviewed to assureensure that they have sufficient capacity and 6 capability to perform their intended functions, including the ability to cope with a station blackout event. This will require an examination of the characteristics and design 7 requirements of each load, the length of time each load is required, the combined load demand connected to each battery or battery charger during the "worst" operating condition, the voltage recovering characteristics of the battery and battery chargers, and the continuous and short-term ratings for the battery and battery chargers. In addition, Where the proposed design provides for the connection of nonsafety-related loads to the 8 dc power system and sharing of batteries and battery chargers between units at the same site, particular review emphasis is given to assuring ensure against marginal capacity and degradation of reliability that may result from implementing such design provisions. In addition, where the proposed design provides for portions of the onsite dc system to cope with a station blackout event, the