ENS 42914
ENS Event | |
|---|---|
15:21 Oct 17, 2006 | |
| Title | Accident Mitigation - Hpci System Inoperable |
| Event Description | Unit HPCI system declared inoperable. During performance of the quarterly surveillance, HPCI pump operability, the HPCI system was secured when the "HPCI Turbine Oil Pressure Low" alarm was received and confirmed. Turbine governor end bearing oil pressure was 2 PSIG. The alarm setpoint is 6 PSIG and procedure limit is 10-12 PSIG. Pressure adjust valve was throttled open to raise pressure to 11 PSIG. The HPCI system was not immediately declared inoperable since an evaluation was being performed to determine if 2 PSIG turbine bearing oil pressure was adequate. Evaluation by the vendor will not be complete until 10/18/06. At 1655 hours0.0192 days <br />0.46 hours <br />0.00274 weeks <br />6.297275e-4 months <br />, HPCI declared operable after a successful run with adequate oil pressure. HPCI is a single train system.
The licensee notified the NRC Resident Inspector.
Original report was entered in error on 10/17/06 with Unit 2 versus Unit 1. Changed EN #42914 to accurately reflect the affected unit (Unit 1).
EN #42914 was submitted by Southern Nuclear Operating Company based upon a conservative decision to declare the HPCI system inoperable pending further evaluation to support its operability. Southern Nuclear Operating Company retracts EN #42914 based on the following discussion. During a subsequent review of the parameters by the HPCI Turbine Vendor, Dresser-Rand, and site engineering it was concluded that the HPCI system would have been capable of performing its intended safety function with the lower turbine governor end bearing oil pressure. During the operation of the system, the visual local indication was approximately 2.5 PSIG oil pressure at the governor end bearing. A review of the data showed that with a governor end oil pressure of the procedural minimal of 10 PSIG, the predicted oil flow rate would be 1.08 gpm with a minimum film thickness of 0.48 mils and a maximum bearing temperature of 228 deg F. With a degraded oil pressure of 2.5 PSIG, the predicted oil flow rate would be 0.54 gpm with a minimum film thickness of 0.46 mils and a maximum bearing temperature of 233 deg F. Based on the calculated data, the turbine governor end bearing would have performed satisfactorily for at least 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> at an oil pressure of 2.5 PSIG. Using the design basis success criteria, HPCI operation is successful if the system can inject water through the core Feedwater line for a total of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> over a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period. The 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> mission time for HPCI is based on the design basis - if HPCI fails, it is backed up by the Automatic Depressurization System (ADS) in combination with Core Spray and Low Pressure Coolant Injection. The HPCI system is not credited for long term injection or late injection. Although the oil flow rate was reduced by 50% and the minimum film thickness reduced by 4%, the bearing temperatures were predicted to only increase a maximum of 5 deg F. Supporting this conclusion is the fact that the bearing was not damaged during the operation with low oil pressure when the turbine was run for 9 minutes at 2.5 PSIG governor end bearing oil pressure. The licensee will notify the NRC Resident Inspector. |
| Where | |
|---|---|
Hatch  Georgia (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:+1.68 h0.07 days <br />0.01 weeks <br />0.0023 months <br />) | |
| Opened: | Barry D. Coleman 17:02 Oct 17, 2006 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Nov 17, 2006 |
| 42914 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Hatch with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 568962023-12-18T07:23:00018 December 2023 07:23:00
[Table view]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 554482021-09-08T05:59:0008 September 2021 05:59:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Unit 1 High Pressure Coolant Injection (HPCI) System Inoperable ENS 546772020-04-22T14:15:00022 April 2020 14:15:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection System (Hpci) Inoperable ENS 542372019-08-23T02:34:00023 August 2019 02:34:00 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 ENS 539442019-03-19T05:40:00019 March 2019 05:40:00 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 525432017-02-08T16:51:0008 February 2017 16:51:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection System Inoperable Due to Degraded Dc to Ac Inverter ENS 500802014-05-02T00:45:0002 May 2014 00:45:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Loss of Hpci Operability Due to Water Accumulation in the Hpci Turbine ENS 488272013-03-18T13:10:00018 March 2013 13:10:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection Inoperable Following Refueling Outage ENS 455412009-12-05T15:59:0005 December 2009 15:59:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Out of Service Due to the Loss of the Suction Auto-Swap Function ENS 448492009-02-12T17:30:00012 February 2009 17:30:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection Suction Source Instrument Malfunction ENS 438842008-01-06T16:00:0006 January 2008 16:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Declared Inoperable Due to Failed Surveillance Test ENS 433742007-05-18T21:45:00018 May 2007 21:45:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Inoperable Hpci Pump ENS 432422007-03-15T19:32:00015 March 2007 19:32:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Declared Inoperable During Startup Testing ENS 432212007-03-08T01:50:0008 March 2007 01:50:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Declared Inoperable Following Surveillance Testing ENS 431532007-02-08T09:32:0008 February 2007 09:32:00 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 ENS 431522007-02-07T21:40:0007 February 2007 21:40:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolent Injection (Hpci) Declared Inoperable ENS 429142006-10-17T15:21:00017 October 2006 15:21:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Accident Mitigation - Hpci System Inoperable ENS 426572006-06-21T04:15:00021 June 2006 04:15:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) Declared Inoperable Due Excessvie Aux Oil Pump Motor Current ENS 425782006-05-16T13:38:00016 May 2006 13:38:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci Inoperable Due to Hpci Discharge Check Valve Body Leak ENS 422622006-01-16T23:31:00016 January 2006 23:31:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpci System Isolated Due to Atts Card Failure ENS 408242004-06-17T09:21:00017 June 2004 09:21:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Coolant Injection (Hpci) Declared Inoperable 2023-12-18T07:23:00 | |