Document: NRC Regulatory Guide
Document ID: 1731a882-b0c5-418d-b65e-55646c26be5c
Document Type: regulatory_guide
Title: 03/2007
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0703/ML070380553.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.9
CFR Part: 
CFR Title: 

Content:
boundaries and may also be used as guidance; however, generator breakers should be considered as part of the diesel generator boundary. The following definitions apply to the regulatory positions that address testing, recordkeeping, and reporting of emergency diesel generator performance: Start demands: All valid and inadvertent start demands, including all start-only demands and all start demands that are followed by load-run demands, whether by automatic or manual initiation, are start demands. In a start-only demand, the emergency diesel generator is started, but no attempt is made to load the emergency diesel generator (see the exceptions below). Start failures: Any failure within the emergency diesel generator system that prevents the generator from achieving a specified frequency (or speed) and voltage within specified time allowance is classified as a valid start failure. (For monthly surveillance tests, the emergency diesel generator can be brought to rated speed and voltage in the time recommended by the manufacturer to minimize stress and wear.) Any condition identified during maintenance inspections (with the emergency diesel generator in the standby mode) that would definitely have resulted in a start failure if a demand had occurred should count as a valid start demand and failure. Load-run demands: To be valid, the load-run attempt should follow a successful start and meet one of the following criteria (see the exceptions below): • a load-run of any duration that results from a real (i.e., not a test) automatic or manual signal • a load-run test to satisfy the plant’s load and duration test specifications • other operations (e.g., special tests) in which the emergency diesel generator is planned to run for at least 1 hour with at least 50 percent of design load Load-run failures: A load-run failure should be counted when the emergency diesel generator starts but does not pick up the load and run successfully. Any failure during a valid load-run