05000443/LER-2002-002
| Seabrook Station | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i)(b) |
| 4432002002R00 - NRC Website | |
I. Description of Event
On July 24, 2002, with the plant operating at 100 % power, a surveillance test was performed on emergency diesel generator [EK] DG-1B (DG-1B). After approximately three hours of fully loaded operation of DG-1B, plant operators noted that the kilovolt amperage reactive (kVAR) indication was fluctuating at a magnitude of approximately 1200 to 1500 kVAR (peak-to-peak). As a result of the subject fluctuations, plant operators decreased DG-1B load and the kVAR indication stabilized. Generator load was then increased and the fluctuations reoccurred at approximately the same load values.
Plant operators then shutdown the engine and DG-1B was declared inoperable at 2302 on July 24, 2002. DG-1B remained inoperable until 0735 on July 27, 2002.
Technical Specification (TS) 3.8.1.1 Action b. requires that when one diesel generator is inoperable, the remaining diesel must be demonstrated operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. TS 3.8.1.1 Action b. also identifies that the operability of the remaining diesel generator need not be verified if it has been successfully operated within the last 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or if currently operating, or if the diesel generator became inoperable due to 1.) Preplanned preventive maintenance or testing; 2.) An inoperable support system with no potential common mode failure for the remaining diesel generator; or 3.) An independently testable component with no potential common mode failure for the remaining diesel generator. A decision was made by the plant operators not to perform a test of the remaining engine (DG-1A) due to the lack of evidence of a potential common mode failure for DG-1A. Subsequent analysis of the event determined that the decision not to test DG-1A within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> was not consistent with guidance provided in TS Bases section 3/4.8.1.
Contrary to the requirements of TS 3.8.1.1 Action b., the remaining engine (DG-1A) was not run nor were the exceptions to the subject action statement met within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The failure to meet the requirements of TS 3.8.1.1 action b. is a condition prohibited by the Technical Specifications and is reportable pursuant to the requirements of 10 CFR 50.73(a)(2)(i)(b). Subsequent testing of DG-1A was satisfactorily completed at 0247on July 31, 2002. This condition was initially identified by the Nuclear Regulatory Commission (NRC) and documented in NRC Special Inspection Report Number 50-443/02-010 dated September 13, 2002 as a green finding. There was no safety system functional failure as a result of this condition.
II. Cause of Event
The cause of this event was the lack of formal training given to the plant operators regarding the requirements of TS 3.8.1.1 Action b. Although the requirements of TS 3.8.1.1 Action b. have not changed since 1993, when Amendment 30 to the Technical Specifications was issued, plant operators were not fully aware of recent changes made of the Technical Specification Bases section 3/4.8.1 (Amendment 80). Amendment 80 incorporated improvements to the Bases section regarding the interpretation of the TS 3.8.1.1 Action b, which if utilized would have clarified the intent of the subject action statement. A review of the Technical Specifications determined that exceptions to TS 3.8.1.1 Actions b. and c. are unique and do not apply to other Technical Specification requirements.
III. Analysis of Event
There were no adverse safety consequences as a result of this event. This event is significant because plant operators did not correctly perform the actions required by TS 3.8.1.1 Action b. In the event of a loss of offsite power, the standby power supply for the two safety related busses is provided by two redundant diesel generators of identical design and characteristics, which supply onsite power of sufficient capacity and capability to reliably shut down the reactor. Through out the period that DG-1B was inoperable, DG-1A remained operable and was capable of performing its safety function.
DG-1A was tested satisfactorily on July 31, 2002.
IV. Corrective Actions
1. DG-1A was tested satisfactorily on July 31, 2002.
2. The details of this event have been reviewed by the licensed plant operators to ensure that they are aware of the requirement to prove that no common mode failure exists prior to determining that the remaining diesel generator does not have to be run in accordance with TS 3.8.1.1 Action b.
3. A review of the Seabrook Station Technical Specifications was performed to determine if there were other requirements similar to TS 3.8.1.1 Actions b and c. This review indicated that the requirements of TS 3.8.1.1 Actions b. and c. are unique and do not apply to other Technical Specification requirements.
4. Plant operators will receive formal training on the requirements of TS 3.8.1.1 to ensure that the changes and associated bases are clearly understood.
V. Additional Information
None Similar Events There have been no similar events reported by Seabrook Station.
Manufacturer Data Not Applicable.