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:
lectrical independence, the design criteria, analyses, description, and implementation as depicted on functional logic diagrams, electrical single-line diagrams, and electrical schematics are reviewed to determine that the design meets the requirements set forth in IEEE Std 308 and satisfies the positions of Regulatory Guide 1.6. 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 basic criteria for addressing single failures. Additional 87 guidance in evaluating this aspect of the design is derived fromdescribed in IEEE Std 88 379, "Guide for the Application of the Single Failure Criterion to Nuclear Power Generating Station Protection Systems," as augmented by Regulatory Guide 1.53. Other aspects of the design where special review attention is given to ascertain that the electrical independence and physical separation has not been compromised are as follows: a. The interconnections between redundant load centers through bus tie breakers and multi-feeder breakers used to connect extra redundant loads to either of the DRAFT Rev. 3 - April 1996 8.3.2-14 redundant distribution systems are examined to assureensure that no single failure in the interconnections or inadvertent closure of interconnecting devices will compromise division independence in a manner that will cause the paralleling of 89 the dc power supplies. To assureensure this, the control circuits of the bus tie breakers or multi-feeder breakers must preclude automatic transferring of load centers or loads from the designated supply to the redundant counterpart upon loss of the designated supply (Position 4 of Regulatory Guide 1.6). Regarding the interconnections through bus tie breakers, an acceptable design will provide for two tie breakers connected in series and physically separated from each other in accordance with the acceptance criteria for separation of