Document: NRC Regulatory Guide
Document ID: 08964ae0-0fa8-4e51-af44-0c6a1ee6e94c
Document Type: regulatory_guide
Title: Periodic Testing of Diesel Generator Units Used as Onsite Electric Power Systems at Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1221/ML12216A011.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.108
CFR Part: 
CFR Title: 

Content:
erator units during the plant preoperational test program and at least once every 18 months should: (1) Demonstrate proper startup operation by simulating loss of all a.c. voltage and demonstrate that the diesel generator unit can start automatically and attain the required voltage and frequency within acceptable limits and time. (2) Demonstrate proper operation for design- accident-loading-sequence to design-load require- ments and verify that voltage and frequency are maintained within required limits. (3) Demonstrate full-load-carrying capability for an interval of not less than 24 hours, of which 22 hours should be at a load equivalent to the con- tinuous rating of the diesel generator and 2 hours at a load equivalent to the 2-hour rating of the diesel generator. Verify that voltage and frequency require- ments are maintained. The test should also verify that the cooling system functions within design limits. (4) Demonstrate proper operation during diesel generator load shedding, including a test of the loss of the largest single load and of complete loss of load, and verify that the voltage requirements are met and that the overspeed limits are not exceeded. (5) Demonstrate functional capability at full- load temperature conditions by rerunning the test phase outlined in Regulatory Positions C.2.a.(l) and (2) above immediately following (3) above. I 1.108-2 (6) Demonstrate the ability to (a) synchronize the diesel generator unit with offsite power while the unit is connected to the emergency load, (b) transfer this load to the offsite power, (c) isolate the diesel generator unit, and (d) restore it to standby status. (7) Demonstrate that the engine will perform properly if switching from one fuel oil supply system to another is a part of the normal operating procedure to satisfy the 7-day storage requirement. (8) Demonstrate that the capability of the diesel generator unit to supply emergency power within the required time is not impaired during periodic