ENS 43197
ENS Event | |
|---|---|
03:26 Feb 28, 2007 | |
| Title | High Pressure Coolant Injection (Hpci) Inoperability |
| Event Description | On February 27, 2007, at approximately 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br />, testing of the Unit 2 High Pressure Coolant Injection (HPCI) system was in progress in accordance with 0PT-09.2, HPCI System Operability Test following system maintenance. Soon after the HPCI turbine was started a high level alarm condition in the HPCI barometric condenser was experienced. Evidence suggests the most probable cause was due to failure of the 2-E41-F048, Condensate Pump Discharge Check Valve, to open. The adverse consequence of this check valve failing to open is inadequate cooling flow to the HPCI lube oil cooler. The HPCI turbine was removed from service per applicable plant procedures.
At the time of discovery, the HPCI system was inoperable for scheduled maintenance. However, this equipment failure would have prevented the HPCI system from fulfilling its safety function. Limiting Condition for Operation (LCO) per Technical Specifications (TS) 3.5.1. 'ECCS - Operating' Condition D had been previously entered on 2/25/07 at 1500, which required maintaining the Reactor Core Isolation Cooling (RCIC) system operable and restoration of HPCI operability in 14 days. All other ECCS systems are operable including RCIC. The LCO allowed outage time is due to expire on 3/11/07 at approximately 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />. The licensee notified the NRC Resident Inspector.
On February 28, 2007, at 0540 hours0.00625 days <br />0.15 hours <br />8.928571e-4 weeks <br />2.0547e-4 months <br />, the Control Room Supervisor made a notification (Event Number 43197) to the NRC Operations Center in accordance with 10 CFR 50.72(b)(3)(v)(D) (i.e., any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident). The notification was made as a result of an unexpected high level alarm condition for the High Pressure Coolant Injection (HPCI) system barometric condenser, which was received during the post-maintenance operability testing of the HPCI system. At the time of discovery, the HPCI system was inoperable; having been properly removed from service for planned maintenance. It was believed that check valve 2-E41-F048, which is in the discharge piping of the HPCI barometric condenser condensate pump, downstream of a connection from the HPCI lube oil cooler cooling water discharge line, did not open, as required, during the HPCI post maintenance operability run. With valve 2-E41-F048 closed, there is a potential for inadequate cooling flow for the HPCI lube oil and, as such, a potential that the HPCI system could be inoperable as a result. Basis for Retraction Upon further review, it has been determined that the 2-E41-F048 functioned properly during the post-maintenance HPCI system operability testing. The valve was disassembled and inspected during the recent Unit 2 refueling outage and confirmed to be operating properly. As such, adequate HPCI lube oil cooling existed and HPCI could have fulfilled its intended safety function. Physical inspection of the HPCI lube oil cooler piping, during the Unit 2 refueling outage, revealed that the lube oil cooler outlet orifice was missing. The missing orifice can result in higher than design flows through the lube oil cooler and higher backpressure at the barometric condenser condensate pump discharge. The higher backpressure can affect the ability to pump down the barometric condenser vacuum tank. Additionally, during troubleshooting activities performed prior to the refueling outage, valve 2-E41-F058, which is in the discharge piping of the HPCl barometric condenser condensate pump, upstream of the connection from the HPCI lube oil cooler cooling water discharge line, showed evidence of sticking. Either of these conditions could have caused the barometric condenser high level alarm without affecting HPCI lube oil cooling. If the barometric condenser becomes completely full, a relief valve on the tank will lift and relieve water to the HPCI room sump. The room sump pump has adequate capacity to keep up with the maximum expected flow. Operability of the HPCI system will not be affected by this condition. The higher than design cooling water flow rate does not adversely affect the capability of the lube oil cooler to remove heat from HPCI system lube oil and, as such, does not affect HPCI operability. Additionally, physical inspection of the cooler during the refueling outage found no damage or erosion of the cooler internals, and the cooler was successfully pressure tested. The barometric condenser condensate pump, barometric condenser vacuum pump, and barometric condenser water level instrumentation are not required to support operability of the HPCI system. Investigation of this condition is documented in the corrective action program in Nuclear Condition Report (NCR) 223820. On this basis, the HPCI system was capable of performing its function to mitigate the consequences of an accident and the issue is not reportable under 10 CFR 50.72(b)(3)(v)(D). The NRC resident was notified of this retraction." Notified R2DO(Payne).
On February 28, 2007, at 0540 hours0.00625 days <br />0.15 hours <br />8.928571e-4 weeks <br />2.0547e-4 months <br />, the Control Room Supervisor made a notification (EN 43197) to the NRC Operations Center in accordance with 10 CFR 50.72(b)(3)(v)(D), 'any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident'. The notification was made as a result of an unexpected high level alarm condition for the High Pressure Coolant Injection (HPCI) system barometric condenser, which was received during the post-maintenance operability testing of the HPCI system. Revised Basis for Retraction On April 26, 2007, EN 43197 was retracted. The basis for the retraction stated that the 2-E41-F048 functioned properly and adequate HPCI lube oil cooling existed. It also attributed the high level in the HPCI barometric condenser to either a missing lube oil cooler outlet orifice or potential sticking of valve 2-E41-F058 versus the originally believed malfunction of the 2-E41-F048 valve. In either case, the retraction stated that if the barometric condenser becomes completely full, a relief valve (2-E41-F018) on the tank will lift and relieve water to the HPCI room sump. The room sump pump has adequate capacity to keep up with the maximum expected flow. As such, operability of the HPCI system would not be affected by either a missing lube oil cooler outlet orifice or potential sticking of valve 2 -E41-F058. During the Unit 2 refueling outage, which began on February 28, 2009, it was discovered that the HPCI barometric condenser relief valve (2-E41-F018) had been assembled incorrectly and would not have functioned as described in the April 26, 2007 retraction of EN 43197. However, EN 43197 can be retracted without relying on proper operation of the relief valve. At the time of the event, the HPCI barometric condenser condensate pump, the HPCI barometric condenser vacuum pump, and the HPCI barometric condenser water level instrumentation were functioning properly and would have prevented condensate from reaching the HPCI turbine casing. On this basis, the HPCI system was capable of performing its function to mitigate the consequences of an accident and the issue is not reportable under 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector was notified of this revised retraction. Notified R2DO (Mark Lesser) |
| Where | |
|---|---|
Brunswick  North Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+2.23 h0.0929 days <br />0.0133 weeks <br />0.00305 months <br />) | |
| Opened: | Dave Jester 05:40 Feb 28, 2007 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Jun 4, 2009 |
| 43197 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Brunswick with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 559972022-07-16T00:20:00016 July 2022 00:20:00
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Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) System Inoperable Due to Seal Leak ENS 437112007-10-11T02:45:00011 October 2007 02:45:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Unit 2 Hpci Pump Seal Failure ENS 431972007-02-28T03:26:00028 February 2007 03:26:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) Inoperability ENS 429062006-10-13T17:57:00013 October 2006 17:57:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) System Declared Inoperable Due to Potential Turbine Exhaust Diaphragm Failure ENS 424882006-04-10T20:30:00010 April 2006 20:30:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Control Room Emergency Ventilation System Declared Inoperable Due to Design Deficiency ENS 423052006-02-03T04:36:0003 February 2006 04:36:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) System Inoperable Due to One Hpci Turbine Exhaust Vacuum Breaker Isolation Valve Failure ENS 422542006-01-12T14:20:00012 January 2006 14:20:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Control Room Air Conditioning and Control Room Emergency Ventilation Systems Inoperable ENS 418952005-08-05T22:40:0005 August 2005 22:40:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Inoperability of All Emergency Diesel Generators ENS 416922005-05-12T08:11:00012 May 2005 08:11:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.73(a)(1), Submit an LER Technical Specification Required Shutdown Due to Loss of Emergency Bus E1 ENS 408332004-06-22T13:00:00022 June 2004 13:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Presure Coolant Injection System Inoperable Due to Maintenance ENS 407142004-04-29T02:30:00029 April 2004 02:30:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci System Inoperable Following Planned Maintenance ENS 406362004-04-03T08:00:0003 April 2004 08:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection System Inoperable ENS 403182003-11-13T03:22:00013 November 2003 03:22:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection System Isolation During Testing 2022-07-16T00:20:00 | |