ENS 41966
ENS Event | |
|---|---|
18:28 Aug 31, 2005 | |
| Title | Unit 3 Experienced an Automatic Reactor Trip During Routine Testing |
| Event Description | Event: At 1428 hours0.0165 days <br />0.397 hours <br />0.00236 weeks <br />5.43354e-4 months <br /> on 8/31/2005, Oconee Unit 3 tripped. A routine test of the alternate power source for the Control Rod Drive System was in progress when power to the Control Rod Drive system was interrupted, which resulted in a reactor trip. AC power transferred to the Start-up source (switchyard). Normally the Main Steam Header pressure control setpoint is automatically increased for post-trip RCS temperature control. This did not occur. As a result the RCS cooled down to approximately 536F (versus a normal post-trip temperature of approximately 555F), reducing RCS pressure to the actuation setpoint for Engineered Safeguards Channels 1 and 2. This started the High Pressure Injection pumps in ECCS mode, caused partial containment isolation and initiated start-up of both Keowee Hydro Units (emergency power). Because Start-up power was available, Keowee did not supply power but remained in stand-by. At 1133 hours0.0131 days <br />0.315 hours <br />0.00187 weeks <br />4.311065e-4 months <br /> Operators terminated ECCS injection.
Initial Safety Significance: Because RCS pressure decreased below normal post-trip levels which resulted in an ECCS actuation, this is considered an abnormal transient. Unit 3 has been stabilized and at this time the actual event is considered to have low safety significance. The exact cause of the loss of power to the Control Rod Drive system is unknown, but is under investigation. It is suspected that that loss also resulted in the failure of the Main Steam Header Pressure to shift to the post-trip Main Steam pressure control setpoint. Corrective Action(s): Operations stabilized Unit 3. A post-trip investigation is in progress, per site procedures and directives. All control rods fully inserted as a result of the reactor trip. No primary or secondary reliefs or PORVs lifted. Pressurizer level decreased off-scale low and was recovered prior to securing the High Pressure Injection pumps (the licensee estimates approximately 3000 gallons was injected). Current RCS temp is 542F (Tave) with RCS pressure in the normal post-trip band. Decay heat is being removed by the Steam Generators to Condenser through the Turbine Bypass Valves. Main Feedwater remained in service during the transient. The licensee informed the NRC Resident Inspector and does not plan a press release at this time.
During this event, the Engineering Safeguards (ES) System was manually bypassed at 14:33 on 8-31-05 to restore both High Pressure Injection (HPI) System trains to a normal lineup following an ES-initiated safety injection. Manually bypassing ES for both trains of HPI required entry into Tech Spec 3.0.3 at 15:33 on 8-31-05. Tech Spec 3.0.3 requires shutdown of Unit 3 to Mode 3 by 03:33 on 9-1-05 and to Mode 4 by 09:33 on 9-1-05. This condition was discovered to apply at 21:15 on 8-31-05. Initial Safety Significance: Units 1 and 2 remain at 100% power with no issues following the Unit 3 ES Actuation and Keowee Hydro Unit emergency start. Unit 3 remains in Mode 3. No other safety systems have actuated or exhibited abnormal behavior. Therefore, the safety significance of this condition is LOW. Corrective Action(s): Restore ES System to Automatic for the HPI System. The licensee reported this under 10 CFR 50.72(b)(2) (i), Technical Specification Shutdown. The licensee will notify the NRC Resident Inspector. R2DO (Lesser) notified. |
| Where | |
|---|---|
Oconee  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
| LER: | 05000287/LER-2005-002 |
| Time - Person (Reporting Time:+-0.83 h-0.0346 days <br />-0.00494 weeks <br />-0.00114 months <br />) | |
| Opened: | Randy Todd 17:38 Aug 31, 2005 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Aug 31, 2005 |
| 41966 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Oconee with 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 | |
WEEKMONTHYEARENS 558882022-05-07T03:10:0007 May 2022 03:10:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of Emergency Feedwater ENS 557502022-02-22T03:07:00022 February 2022 03:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 558002022-02-13T21:25:00013 February 2022 21:25:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Feedwater System Actuation 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 556122021-11-27T10:19:00027 November 2021 10:19:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of the Emergency AC Electrical Power System 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 512682015-07-27T13:56:00027 July 2015 13:56:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of Unit 2 Emergency Feedwater System During Startup 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 495272013-11-11T10:20:00011 November 2013 10:20:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Unit 1 Commenced a Technical Specification Required Shutdown Due to Rcs Leakage 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 465262011-01-08T19:00:0008 January 2011 19:00:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Partial Closure of Letdown Line Isolation Valve 1Hp-5 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 425762006-05-15T14:59:00015 May 2006 14:59:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Momentary Loss of Dhr Due to Automatic Actuation of the Keowee Emergency Power Supply 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 414022005-02-11T04:00:00011 February 2005 04:00:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Loss of Electrical Power Sources ENS 409022004-07-28T12:00:00028 July 2004 12:00:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Plant Shutdown Required by Technical Specifications 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 ENS 404332004-01-09T00:02:0009 January 2004 00:02:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Ts Required Shutdown at Oconee 1 Due to Unidentified Rcs Leakage 2022-05-07T03:10:00 | |