ENS 50781
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ENS Event | |
|---|---|
19:31 Jan 31, 2015 | |
| Title | Manual Rps Actuation Due To Oscillations In The Feedwater System |
| Event Description | At 1431 EST on 1/31/15, Oconee Unit 3 was manually tripped due to oscillations in the feedwater system in anticipation of an automatic trip. At 1427 EST, Unit 3 began experiencing small feedwater oscillations. Specifically, 3FDW-32, the 3A main feedwater control valve, appeared to be oscillating with corresponding feedwater flow oscillation. Feedwater oscillations continued to grow in magnitude and at 1431 EST a manual trip was directed by the Unit 3 control room supervisor. The shutdown was orderly and the unit is currently stable and in Mode 3 (Hot Standby). Units 1 and 2 were unaffected by the trip and are currently 100% power (Mode 1).
Due to the RPS actuation while critical, this event is being reported as a 4-hour non-emergency per 10CFR50.72(b)(2)(iv)(B). Following the reactor trip, a main steam relief valve (MSRV) failed to reseat as expected. Emergency Operating procedure guidance was utilized to reduce main steam system pressure by approximately 80 psig to reseat the valve (valve reseated at 1506 EST). All of the main steam relief valves are now seated. In addition, the 3B condensate booster pump experienced a mechanical seal leak (approximately 4-5 gpm). The pump was subsequently secured at 1447 EST. All other post trip conditions were normal and all other systems performed as expected. Unit 3 is currently in Mode 3 and stable. All rods fully inserted. Main Feedwater is feeding the steam generators and decay heat is being removed to the Main Condenser. The cause of the trip is under investigation. There is no known primary to secondary leakage. The NRC Resident Inspector has been informed. |
| Where | |
|---|---|
Oconee  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation | |
| LER: | 05000287/LER-2015-001 05000287/LER-2015-001 Manual Reactor Trip Due to Unacceptable Main Feedwater Flow Control Valve Oscillations |
| Time - Person (Reporting Time:+-1.52 h-0.0633 days <br />-0.00905 weeks <br />-0.00208 months <br />) | |
| Opened: | Daniel D Wilson 18:00 Jan 31, 2015 |
| NRC Officer: | Charles Teal |
| Last Updated: | Jan 31, 2015 |
| 50781 - NRC Website
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Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | Yes, Manual Scram |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 557502022-02-22T03:07:00022 February 2022 03:07:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 557332022-02-05T08:57:0005 February 2022 08:57:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Visual Observation of Smoke and Multiple Fire Alarms in the West Penetration Room ENS 556382021-12-10T05:49:00010 December 2021 05:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip ENS 546612020-04-11T01:25:00011 April 2020 01:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip ENS 536772018-10-19T04:00:00019 October 2018 04:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Steam Seal Header Pressure Malfunction ENS 533292018-04-13T06:27:00013 April 2018 06:27:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Following Main Feedwater Control Problem ENS 528702017-07-24T20:38:00024 July 2017 20:38:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Load Rejection ENS 517702016-03-06T20:20:0006 March 2016 20:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Emergency Declaration Due to Fire/Explosion in the Main Transformer ENS 507812015-01-31T19:31:00031 January 2015 19:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Rps Actuation Due to Oscillations in the Feedwater System ENS 494712013-10-24T09:53:00024 October 2013 09:53:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip from Full Power Due to Feedwater System Oscillations ENS 461592010-08-07T18:51:0007 August 2010 18:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip After Reactor Coolant Pumps High Vibration ENS 450882009-05-22T00:15:00022 May 2009 00:15:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Rps Actuation (Reactor Trip) Due to Generator Phase Differential Lockout ENS 446382008-11-07T13:34:0007 November 2008 13:34:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 441092008-03-31T17:52:00031 March 2008 17:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip on Turbine Trip During Maintenance Activities ENS 431692007-02-15T21:54:00015 February 2007 21:54:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 1 and Unit 2 Reactor Trip ENS 424932006-04-12T17:35:00012 April 2006 17:35:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 2 Experienced an Automatic Reactor Trip Following the Loss of the "2B2" Reactor Coolant Pump ENS 419662005-08-31T18:28:00031 August 2005 18:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Unit 3 Experienced an Automatic Reactor Trip During Routine Testing ENS 405482004-02-26T16:51:00026 February 2004 16:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Rps Actuation While Critical 2022-02-05T08:57:00 | |
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