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:
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 testing under Regulatory Position C.2.c. .(9) Demonstrate the required reliability by means of any 69 consecutive valid tests2 (per plant) with no failures, with a minimum of 23 or 69/n tests, whichever is the larger, per diesel generator unit (where n is equal to the number of diesel generator units of the same design and size). b. Testing of redundant diesel generator units during normal plant operation should be performed independently (nonconcurrently) to minimize com- mon failure modes resulting from undetected in- terdependences among diesel generator units. However, during reliability demonstration of diesel generator units during plant preoperational testing and testing subsequent to any plant modification where diesel generator unit interdependence may have been affected or every 10 years (during a plant shutdown), whichever is the shorter, a test should be conducted in which redundant units are started simultaneously to help identify certain common failure modes undetected in single diesel generator unit tests. c. Periodic testing of diesel generator units during normal plant operation should: (1) Demonstrate proper startup and verify that the required voltage and frequency are automatically attained within acceptable limits and time. This test should also verify that the components of the diesel generator unit required for automatic startup are operable. (2) Demonstrate full-load-carrying capability (continuous rating) for an interval of not less than one hour. The test should also verify that the cooling system functions within design limits. This test could be accomplished by synchronizing the generator with the offsite power and assuming a load at the max- imum practical rate. d. After completion of the diesel generator unit reliability demonstration