05000338/LER-2008-001
| Document Number04 17 2008 2008 -- 001 -- 00 06 13 2008 05000 | |
| Event date: | 04-17-2008 |
|---|---|
| Report date: | 06-13-2008 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3382008001R00 - NRC Website | |
1.0 DESCRIPTION OF THE EVENT On March 24, 2008, with Units 1 and 2 in Mode 1 at 100% power, planned preventive maintenance (PM) commenced on the Unit 2 "H" (2H) Emergency Diesel Generator (EDG) (EIIS System EK, Component DG). Maintenance included, but was not limited to normal preventive maintenance, inspections of the diesel engine and electrical generator, scheduled radiator replacement, voltage regulator PMs and corrective maintenance associated with the rebuild of the standby lube oil circulating pump, 2-EG-P-4H (EllS System LA, Component P). All maintenance was completed and an associated post maintenance run was completed on March 29, 2008. The 2H EDG was returned to operable status.
On April 1, 2008, at 0248, the Service Water (SW) (EIIS System BI) return header was placed on full spray to verify SW throttled conditions in preparation for the Unit 1 "B" SW pump, 1-SW-P-1B, being tagged out for maintenance. On April 1, 2008, at 0300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br />, the Unit 1 "B" SW pump was removed from service for maintenance. The non-limiting action of Technical Specification (TS) 3.7.8 was entered.
On April 5, 2008, it was identified that there was excessive oil leakage coming from the exhaust system associated with the 2H EDG. Inspection identified that the excessive leakage was due to standby lube oil circulating pump, 2-EG-P-4H, pushing oil to the engine upper crank line and overfilling the engine upper pistons. It was determined that during planned maintenance activities completed on March 29, 2008, the incorrect gear set was installed in 2-EG-P-4H. On April 5, 2008, at 1314 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />4.99977e-4 months <br />, Operations personnel declared 2H EDG inoperable and entered the appropriate required action of Technical Specification (TS) 3.8.1.E. At 1714 hours0.0198 days <br />0.476 hours <br />0.00283 weeks <br />6.52177e-4 months <br />, Operations personnel entered the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limiting action of TS 3.7.8.B and 3.7.8.0 due to having two inoperable SW pumps. Operations personnel verified SW was throttled within one hour. These actions were entered four hours after 2H EDG was declared inoperable because 1-SW-P-1B is inoperable, therefore as required by TS 3.8.1.E, 2-SW-P-1A became inoperable.
On April 6, 2008, 1-SW-P-1B was returned to operable status. On April 9, 2008, the 2H EDG was returned to operable status.
On April 17, 2008, Engineering completed an evaluation of previous operability and determined that due to the fact that the standby lube oil circulating pump, 2-EG-P-4H, had been in service since completion of the maintenance run on March 29, 2008 with the incorrect pump internals, there was the potential for hydraulic lock of the 2H EDG beginning on March 29, 2008 following the maintenance run. Thus, the 2H EDG was conservatively considered inoperable since March 29, 2008.
� With I-SW-FYI B inoperable from April 1, 2008 through April 6, 2008 and 2-SW-P-1A inoperable from April 1, 2008 through April 6, 2008 coincident with its required redundant feature (1-SW-P-1B) inoperable, two SW pumps were inoperable for a duration longer than the TS allowed completion time. Therefore, this event is reportable pursuant to 10 CFR 50.73(a)(2)(i)(B) as an operation or condition prohibited by Technical Specifications. The condition was not determined to be a reportable condition until April 17, 2008 when the Engineering evaluation on previous operability of the 2H EDG was completed.
In addition, while the 2H EDG was inoperable, the Unit 1 "H" (1H) EDG was inoperable from 1409 hours0.0163 days <br />0.391 hours <br />0.00233 weeks <br />5.361245e-4 months <br /> to 1426 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.42593e-4 months <br /> on March 31, 2008 for performance of Solid State Protection System (EIIS System JE) testing. The 1H EDG was returned to operable within the 2-hour completion time of TS 3.8.1.1.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS A probabilistic risk assessment (PRA) was performed of shared equipment that may have been affected during the timeframe the 2H EDG was inoperable. The PRA analysis determined the sum totaled risk calculation for the components that were out of service during the period that the 2H EDG was unavailable. During the time period that the 2H EDG was inoperable, the 1H EDG was out of service and 1-SW-P-1B was out of service.
The PRA analysis concludes the Core Damage Probability from the unavailability of the 2H EDG, concurrent with the unavailability of the 1H EDG and the 1-SW-P-1B was calculated to be 2.06 X 10-7 which is well below 10-6 CDP. The health and safety of the public were not affected at any time during the event.
3.0 CAUSE The cause for having two SW pumps inoperable greater than the allowed TS completion time was not knowing that the 2H EDG was inoperable because of the installation of the incorrect gear set on standby lube oil circulating pump 2-EG-P-4H during the March 24 29, 2008 maintenance outage. The inoperability of the 2H EDG was not discovered until April 5, 2008 when excessive oil leakage was identified. Maintenance on SW pump 1-SW- P-1B had already commenced on April 1, 2008 when it was determined that the 2H EDG and associated SW pump 2-SW-P-1A had been inoperable.
4.0 IMMEDIATE CORRECTIVE ACTION(S) Operations personnel entered the appropriate TS required actions for the 2H EDG and SW pumps.
1NRC FORM 366A (9-2007) PRINTED ON RECYCLED PAPER 5.0 ADDITIONAL CORRECTIVE ACTIONS Maintenance activities were completed on the Unit 1 "B" SW pump and 2H EDG and the equipment was returned to operable status.
6.0 ACTIONS TO PREVENT RECURRENCE Corrective actions associated with the incorrect gear set being installed in the standby lube oil circulating pump are being tracked with in the Corrective Action Program.
7.0 SIMILAR EVENTS 'pumps were inoperable for a timeframe greater than the Technical Specification completion time due to inoperability of both Unit 1 EDGs.
8.0 ADDITIONAL INFORMATION Description: Emergency Diesel Generators Manufacturer: Fairbanks Morse Model No.: 38TD8.125 �