Document: NRC Regulatory Guide
Document ID: 848f45be-3c4b-4f6d-a9da-73ea5383e905
Document Type: regulatory_guide
Title: Qualification of Safety-Related Battery Chargers and Inverters for Nuclear Power Plants (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2216/ML22160A570.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.210
CFR Part: 
CFR Title: 

Content:
003, “IEEE Standard for Qualifying Class 1E Electrical Equipment for Nuclear Power Generating Stations” (Ref. 20). In 2016, the IEEE issued Std. 323 jointly with the International Electrotechnical Commission (IEC) as IEC/IEEE Std. 60780-323-2016, “IEC/IEEE International Standard—Nuclear Facilities—Electrical Equipment Important to Safety—Qualification” (Ref. 21). The joint standard describes principles, methods, and procedures for qualifying, maintaining, and extending qualification, as well as updating qualification, of Class 1E equipment and interfaces, including components or equipment of any interface whose failure could adversely affect any Class 1E equipment. IEEE Std. 650-2017 provided updates to the 2006 version including the qualification of safety- related UPS systems. UPS systems are designed to provide a continuous, highly reliable source of alternating current (ac) supply automatically, without delay or transients, during any period when the normal power supply is incapable of performing acceptably. UPS systems may include inverters, battery chargers, rectifiers (ac-dc converters), static transfer switches, maintenance bypass switches, and line regulating transformers. Power supplies for low voltage critical loads such as reactor protection systems may include a standalone UPS or a UPS formed by an inverter connected to a dc source working in conjunction with an alternate ac source and a fast-acting automatic transfer switch. Components used in inverters are included in UPS systems. IEEE Std. 650-2017 also clarified the use of the standard for qualification of safety-related battery chargers, inverters, and UPS systems located in a mild environment. The definition of “mild environment”, as provided in 10 CFR 50.49(c)(3), is, “an environment that would at no time be significantly more severe than the environment that would occur during normal plant operation, including anticipated operational occurrences,” which include loss of all