2026-10978NoticeWallet

NRC Updates Emergency Generator Testing Guidelines

Published Date: 6/2/2026

Notice

Summary

The Nuclear Regulatory Commission is updating its guide on how to use and test emergency power sources like diesel and turbine generators at nuclear facilities. This affects anyone running these facilities, helping them keep power backup systems reliable and safe. Comments on the draft are open until July 2, 2026, so now’s the time to weigh in before any new rules take effect.

Analyzed Economic Effects

3 provisions identified: 3 benefits, 0 costs, 0 mixed.

Updated guidance for nuclear facilities

The NRC issued draft Regulatory Guide DG-1477, proposed Revision 5 to RG 1.9, that provides acceptable guidance for onsite emergency alternating current (AC) power sources. It applies to production and utilization facilities licensed under 10 CFR part 50 and 10 CFR part 52 and covers emergency diesel generators (EDGs), combustion turbine generators (CTGs), and other onsite emergency AC power sources.

Endorses new IEC/IEEE standards

The draft Revision 5 endorses IEC/IEEE Std 63332 387:2024 and IEEE Std 2420-2019 as acceptable standards for emergency power supplies. These standards provide design criteria and qualification and testing guidelines for EDGs and CTGs that licensees and applicants can use.

No mandatory backfitting required

The NRC states that issuing DG-1477 (Revision 5 to RG 1.9) would not constitute backfitting, forward fitting, or affect issue finality under its rules, and applicants or licensees generally would not be required to comply with the positions in DG-1477. That means licensees are not being forced to adopt the guide's positions if it is finalized.

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Key Dates

Published Date
Comments Due
6/2/2026
7/2/2026

Department and Agencies

Department
Independent Agency
Agency
Nuclear Regulatory Commission
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