05000280/LER-2004-001
| Document Number | |
| Event date: | 0-4-2004 |
|---|---|
| Report date: | 02-02-2005 |
| 2802004001R00 - NRC Website | |
FACILITY NAME (1) DOCKET� LER NUMBER r) PAGE (3) 1.0 DESCRIPTION OF THE EVENT Circulating water (CW) pumps [EIIS: KE, P] draw water from the James River into an elevated intake canal. The canal supplies circulating water by gravity feed for the condensers as well as service water for normal and emergency cooling. Should the CW pumps not be available, three manually started diesel-driven emergency service water (ESW) pumps [EIIS: BI, P] can be utilized to supply make-up water to the intake canal for cooling water needs during accident conditions.
On December 4, 2004, Surry Power Station Unit 1 was at 40% reactor power after returning to service from the fall refueling outage. Unit 2 was operating at 100% reactor power. At 0952 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.62236e-4 months <br />, ESW pump 1C failed to start during its monthly inservice test.
The pump was declared inoperable and a 7-day Technical Specification (TS) action statement was entered.
Troubleshooting determined that the diesel's starter motor [EIIS: BI, MSTR] pinion gear was damaged, and the solenoid that engages the pinion gear with the engine flywheel had failed. Further evaluation determined that damage to these parts occurred during a return-to-service run on November 24, 2004, when the solenoid was energized after the start sequence was completed and therefore, engaged the starter motor pinion gear with the flywheel while the diesel was running.
The cause for the starter solenoid being energized was the failure to remove unused wiring during the implementation of a design change on the ESW pump 10 diesel engine.
Following the start failure, the unused wiring was removed and the starter solenoid and starter motor were replaced. ESW pump 1C was successfully tested and returned to service on December 7, 2004. The starting circuitry of the other two diesel driven ESW pumps 1A and 1B had not been modified and remained fully operable.
ESW pump 1C was determined to be inoperable following the November 24, 2004 post modification test until repairs were completed on December 7, 2004. When the pump became inoperable, Unit 1 was at cold shutdown (CSD) and its heat load and the spent fuel pit heat load was less than 25 million BTU/hour. In this condition, only two ESW pumps were required to be operable in accordance with TS 3.14.B. On December 1, 2004, Unit 1 reactor coolant system (RCS) exceeded 350 degrees F and 450 psig in preparation for unit startup with only two ESW pumps operable. In this condition, a 7-day limiting condition for operation allows two ESWPs to be operable in accordance with TS 3.14.B. Since TS has no specific section 3.0 limitation on entry into a Mode when a limiting condition for operation is not met, a voluntary LER is being submitted.
FACILITY NAME (1) DOCKET LER NUMBER 6) PAGE (3) 2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS Each ESW pump has a design capacity of 15,000 gallons per minute (gpm). The long term service water requirements for a loss-of-coolant accident in one unit with the simultaneous loss-of-station power and for the second unit to be brought to hot shutdown is greater than 15,000 gpm. Additional service water is required to bring the non-accident unit to cold shutdown. TSs require three ESW pumps to be operable, taking into consideration a single active failure of one pump, to ensure sufficient cooling water is available in the event of an accident. TSs permit one ESW pump to be inoperable for up to a 7-day period to provide operational flexibility for testing or maintenance without requiring unit outages. When one unit is in CSD and its heat load and spent fuel heat loads are less than 25 million BTU/HR, TSs permit two ESW pumps to be inoperable for up to a 7-day period.
During this event, the appropriate number of the ESW pumps were either operable in accordance with the TS requirements, or complied with the ESW pump TS action statements that permitted pumps to be out of service for testing or maintenance. On November 24, 2004, ESW pump 1C was declared operable without the knowledge that the starter motor was damaged. With Unit 1 at CSD and heat loads at 25 million BTU/hr or less, only two ESW pumps were required to be operable to be in full compliance with TS 3.14.B. ESW pumps 1A and 1B were fully operable. On November 28, 2004, with Unit 1 still at CSD, ESW pump 1B was removed from service due to a suspected head gasket leak. After an evaluation found no head gasket issues, ESW pump 1B was returned to service on November 29, 2004. Considering that ESW pump 1C was out of service due to its starter and ESW 1B out of service to investigate a head gasket issue, the station continued to comply with TS 3.14.B, limiting operation with one operable ESW pump to less than the 7-day action statement.
On December 1, 2004, Unit 1 RCS exceeded 350 degrees F and 450 psig. On December 4, 2004, ESW pump 1C was discovered to be inoperable. When Unit 1 exceeded 350 degrees F and 450 psig on December 1, 2004, TS 3.14.A required three ESW pumps to be operable. TS 3.14.B, however, permits modification of TS 3.14.A to allow one ESW pump to be inoperable for a period not to exceed 7-days. Repairs were made to the ESW pump 1C starter and the pump was successfully tested and returned to service within the 7-day action statement on December 7, 2004. Since TSs do not limit mode changes while in an action statement, a voluntary report is being submitted.
The unavailability of an ESW pump increases the Core Damage Frequency by less than 1.0E-8 per year and the Large Early Release Frequency by less than 1.0E-9 per year. Since the ESW pump 1C was unavailable for approximately 14 days, the Core Damage Probability is less than 1.0E-9 and the Large Early Release Probability is less than 1.0E-10. These probabilities are low and would be classified as an issue of very low safety significance.
FACILITY NAME (1) DOCKET LER NUMBER 6) PAGE (3) Therefore, this event resulted in no safety consequences or significant implications and the health and safety of the public were not affected.
3.0 CAUSE The cause of ESW pump 10 failure to start was the incomplete implementation of the ESW pump pre-lubrication system. Specifically, the portion of the design change package for the pre-lubrication system was to be completed in two parts; the first to install and connect the new equipment, and the second to remove circuit components that were no longer needed. During the implementation phase of the design change, the installation of the new pre-lubrication equipment was to be completed during the fall refueling outage while the demolition of the unused circuit components was to follow at a later time. The design change package did not identify the need to implement these two parts of the design change together. The result was unused wiring that should have been removed, tied into the new circuitry and energized the starter solenoid. After the start sequence was completed, the starter motor pinion gear continued to engage the flywheel with the diesel running and subsequently failed.
The post modification test plan did not identify this condition. In addition, the planning and preparation to implement the ESW design change work package was not adequate.
4.0 IMMEDIATE CORRECTIVE ACTION(S) At 0952 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.62236e-4 months <br /> on December 4, 2004, the ESW pump 1C was declared inoperable and Unit 1 and Unit 2 entered a 7-day TS action statement to return the ESWP to operable status. The ESW pump 10 was quarantined, and ESW pump 1A and 1B were designated as protected equipment.
5.0 ADDITIONAL CORRECTIVE ACTIONS The unused wiring was removed from the ESW pump 10 diesel's starting circuit. A detailed circuitry evaluation was performed to verify proper configuration. The starter solenoid and starter motor were replaced. ESW pump 10 was successfully tested and returned to service at 2031 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.727955e-4 months <br /> on December 7, 2004.
6.0 ACTIONS TO PREVENT RECURRENCE The design change for ESW pumps 1A and 1B will be revised to require the unused circuit components to be removed with implementation of the new pre-lubrication system.
A detailed circuitry evaluation will be performed following implementation.
FACILITY NAME (1)� DOCKET LER NUMBER 6) PAGE (3) �REVISIONSURRY POWER STATION NUMBER I NUMBER Engineering Training will emphasize the appropriate identification of work prerequisites, required sequences, and assumptions in design change packages.
Programmatic tools used by Maintenance to implement design changes will be reviewed and strengthened to ensure design change packages are effectively implemented.
7.0 SIMILAR EVENTS None 8.0 MANUFACTURER/MODEL NUMBER Detroit Diesel Part # 0461128P starter motor 9.0 ADDITIONAL INFORMATION None