ENS 46763
ENS Event | |
|---|---|
02:52 Apr 17, 2011 | |
| Title | Hpci Inoperable Due to Lube Oil Pressure Low Out of Band |
| Event Description | Event Description: On 4/16/2011 at 2252 [EDT], the Unit 2 High Pressure Coolant Injection (HPCI) System was declared inoperable due to the determination that its Lube Oil System was not providing adequate lube oil pressure and flow to the HPCI Turbine/Pump bearings. This was determined following the high steam pressure operability run (i.e., within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of achieving adequate test pressure following a scheduled refueling/maintenance outage) as required by Technical Specification Surveillance Requirement 3.5.1.7. The HPCI system is inoperable in accordance with Technical Specification 3.5.1.
This report is being made in accordance with 10 CFR 50.72(b)(3){v)(D), as a condition that at the time of discovery could have prevented the fulfillment of the safety function of systems that are needed to mitigate the consequences of an accident. Initial Safety Significance Evaluation: The safety significance of this event is considered minimal. The Reactor Core Isolation Cooling (RCIC) system, Automatic Depressurization System (ADS). and Low Pressure Emergency Core Cooling systems (ECCS) remain operable at this time. Actions have been taken to protect redundant safety systems. Corrective Actions: The HPCI system remains inoperable pending further troubleshooting of the low lube oil pressure condition. The NRC Resident Inspector has been notified.
Upon further review, it has been determined that the HPCI system was not rendered inoperable as a result of the condition identified on April 16, 2011. During performance of 0PT-09.2, the Control Room received a HPCI turbine bearing oil pressure low alarm. Following 0PT-09.2, preventive maintenance procedure 0PM-TRB507, 'High Pressure Coolant Injection (HPCI) Operational Inspection', was performed. During performance of 0PM-TRB507, the turbine governor end oil pressure was found indicating 8.5 psig. The procedure specifies a normal value of 10-12 psig. Due to the above condition, HPCI was conservatively declared inoperable at 2252 [EDT] on April 16, 2011. Subsequent Engineering evaluation has determined that HPCI could have run long enough to complete its intended safety function [24 hrs.]. Pressure outside of the normal band specified in 0PM-TRB507 is a condition that requires correction, but is not detrimental to the bearing itself. The critical characteristic of proper bearing lubrication is to assure a film of oil between the tilting pads and the rotating shaft of the HPCI turbine. Bearing outlet temperatures are recorded during each performance of 0PT-092 for trending and no abnormal temperatures were noted during the last performance of 0PT-09.2 on April 16, 2011. This indicates there was a film of lubrication between the rotating shaft and the tilting pads of the journal bearing. The two hour turbine operation of the most recent 0PT-09.2 performance resulted in higher oil temperature, which can result in lower oil pressure. Adjustments can be made to the ball valve of the HPCI governor end bearing to attain the specified supply pressure to each bearing. These adjustments are not unexpected, as discussed in the Electric Power Research Institute (EPRI) maintenance guide for HPCI turbines. A slight adjustment was made to the HPCI governor end bearing on April 17, 2011 to establish pressure at 11.5 psig. At 1009 hrs. on April 17, 2011, 0PT-09.2 was performed satisfactorily, with the HPCI governor end oil bearing supply pressure verified to be within the 10-12 psig range at 2100 rpm and 4100 rpm. Oil flow to and from the bearing is required only for lubrication and cooling and does not provide any lift or other force to assist the bearing in performing its function. The oil flow during this event was still adequate to provide sufficient lubrication and cooling of the bearings. Therefore, the slight decrease in oil pressure to the HPCI governor end bearing did not indicate degradation in performance. On this basis, the HPCI system was capable of performing its safety function to mitigate the consequences of an accident and this issue is not reportable under 10 CFR 50.72(b)(3)(v)(D). Investigation of this condition is documented in the corrective action program in Nuclear Condition Report (NCR) 460134. The NRC Resident Inspector was notified of this retraction. Notified R2DO (O'Donohue). |
| 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:+1.48 h0.0617 days <br />0.00881 weeks <br />0.00203 months <br />) | |
| Opened: | Mike O'Dell 04:21 Apr 17, 2011 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Apr 17, 2011 |
| 46763 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (50 %) |
| After | Power Operation (50 %) |
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 | |