Document: NUREG-0800
Document ID: f03d2c71-27a1-41fd-9362-1e62c6142e13
Document Type: srp
Title: Containment Systems and Severe Accidents (Tier 1)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070653.pdf
Revision Date: 2023-06
Chapter: 14
Section ID: 14.3.11
CFR Part: 
CFR Title: 

Content:
he electrical equipment that is part of the Class 1E system but is included to improve the reliability of the individual Class 1E divisions (for example equipment protective trips), additional factors need to be considered. For example, if a failure or false actuation of a feature such as a protective device could prevent the safety function, and operating experience has shown problems related to this feature; then treatment in Tier 1 should probably be included. In addition, some fire protection analyses are based on the ability of breakers to clear fire caused faults. With respect to the non-Class 1E portions of the electrical system (powering the BOP loads), a brief certified design description may be included. The DD for this portion should focus on the aspects, if any, needed to support the Class 1E portion. Therefore, based on the above, the following equipment should be treated in the DD: 1. Overall Class 1E electric distribution system - this would include any high level treatment for cables, buses, breakers, disconnect switches, switchgear, motor control centers, motor starters, relays, protective devices, distribution transformers, and connections/terminations 2. Power sources including: - Offsite, including feeds from the main generator (a generator breaker to allow backfeed should be addressed), main power transformers, UATs, RATS, etc. - DC system - battery/battery chargers - Emergency diesel generator, including load sequencing (EDG support systems need to be covered also - Plant Systems Branch has lead responsibility) - Class 1E vital AC inverters, regulating transformers, transfer devices - Alternate AC (AAC) power sources for Station Blackout (SBO) 3. Other Electrical Features including: - Containment electrical penetrations 14.3-53 DRAFT Rev. 0 - April 1996 - Lighting - emergency control room, remote shutdown panel NOTE:It may be difficult to rationalize its inclusion based on "accomplishing a direct safety function." The basis has to be more