05000324/LER-2004-001
| Docket Number Mo Day Year Year I Sequential Ir Rev Mo Day Year | |
| Event date: | 06-22-2004 |
|---|---|
| Report date: | 08-19-2004 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
| Initial Reporting | |
| ENS 40833 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
| 3242004001R00 - NRC Website | |
On June 21, 2004, Unit 2 was operating at 96 percent of rated thermal power with all Emergency Core Cooling Systems (ECCS) and Reactor Core Isolation Cooling (RCIC) [BN] System operable. The High Pressure Coolant Injection System (HPCI) [BJ] surveillance test 2MST-HPCI28R, "HPCI Reactor High Water Level Channel Calibration and Functional Test," was being performed as a planned surveillance.
During performance of the test, the channel reset for level transmitter [LT] 2-B21-LT-N017B-2 trip reset was found to be outside of normal calibration specifications, but within the analytical limits and was still capable of performing its safety function. The decision was made to perform troubleshooting and repair activities on the level instrument channel. Taking this channel out of service disabled the HPCI High Vessel Water Level automatic trip function. Therefore, Technical Specification (TS) 3.3.5.1 Required Action C.2 was entered, which required the instrument channel to be restored to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
During the maintenance activity to restore the instrument channel, the High Vessel Water Level automatic trip function was disabled for 29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> and 55 minutes, resulting in HPCI being declared inoperable in accordance with TS Required Action G.1, when the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> completion time of Required Action C.2 was exceeded.
On June 22, 2004 at 1525 hours0.0177 days <br />0.424 hours <br />0.00252 weeks <br />5.802625e-4 months <br />, notification was made to the NRC (i.e., Event Number 40833) in accordance with 10 CFR 50.72(b)(3)(v)(D).
This event is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of a safety function that is needed to mitigate the consequences of an accident.
EVENT DESCRIPTION
On June 21, 2004, at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, the Unit 2 surveillance test 2MST-HPCI28R, "HPCI Reactor High Water Level Channel Calibration and Functional Test," was being performed as a planned surveillance. During performance cf the test, the channel reset for level transmitter 2-B21-LT-N017B-2 trip reset was found to be outside of normal calibration specifications, but within the analytical limits and was still capable of performing its safety function.
Although the instrument channel was not failed, it did require a recalibration to restore full functionality.
Therefore, the decision was made to perform troubleshooting and repair activities on the level instrument channel. Taking this channel out of service disabled the HPCI High Vessel Water Level automatic trip function and required entry into TS LCO 3.3.5.1, which required the level transmitter channel to be restored to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. On June 22, 2004, at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, when the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> expired, the level transmitter channel had not been restored to operable status, so the operators declared the HPCI system inoperable and verified the RCIC system was operable as required by the TS 3.5.1, "ECCS-Operating" Required Action D.1. Maintenance activities and post maintenance testing were completed at 1455 hours0.0168 days <br />0.404 hours <br />0.00241 weeks <br />5.536275e-4 months <br /> on June 22, 2004, allowing the HPCI system to be restored to operable status.
EVENT CAUSE
Plant personnel failed to establish an effective maintenance plan for restoring the HPCI instrument channel to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, thus requiring the HPCI system to be declared inoperable. The cause of the event was personnel error due to ineffective supervision and oversight of the maintenance activities. A contributing cause was the mindset that existed relative to previous failures of trip units and transmitters that biased the troubleshooting, contingency planning, and repair.
CORRECTIVE ACTIONS
1. Maintenance activities and post maintenance testing were completed at 1455 hours0.0168 days <br />0.404 hours <br />0.00241 weeks <br />5.536275e-4 months <br /> on June 22, 2004, allowing the HPCI system to be restored to operable status.
2. To prevent recurrence, the Maintenance Supervisor Conduct of Maintenance, procedure 0J0-02, will be revised to include a detailed action plan, including contingency planning, and resource allocation.
3. Maintenance supervisors have received training on this event with respect to management expectations that will be reinforced in the revision to procedure 0J0-02.
PREVIOUS SIMILAR EVENTS
A review of reportable events for the past three years did not identify previous similar events. On occasions in the past, level transmitter trip units similar to the one in this event have experienced random failures or have been found to be out of calibration; however, the maintenance activities to restore function did not exceed TS completion times.
SAFETY ASSESSMENT
The safety significance of this condition is considered to be minimal because HPCI was available for injection with operator action, and adequate core cooling was ensured by the operability of the redundant and diverse low pressure ECCS injection/spray subsystems in conjunction with the Automatic Depressurization System. Also, the RCIC system would automatically provide makeup water at high reactor operating pressures.
COMMITMENTS
Those actions committed to by Progress Energy Carolinas, Inc. (PEC) in this document are identified below.
Any other actions discussed in this submittal represent intended or planned actions by PEC. They are described for the NRC's information and are not regulatory commitments. Please notify the Manager - Support Services at BSEP of any questions regarding this document or any associated regulatory commitments.
The Maintenance Supervisor Conduct of Maintenance procedure 0J0-02 will be revised to include a detailed action plan, including contingency planning, and resource allocation. This will be complete by February 15, 2005.