ENS 51560
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ENS Event | |
|---|---|
16:40 Nov 23, 2015 | |
| Title | Reactor Scram Due to a Reactor Recirculation Pump Lockout |
| Event Description | At 1040 CST, with the plant at 100% power, a lockout of the 11 recirculation pump occurred. Following the 11 recirculation pump lockout, at 1041 CST, a reactor scram and a Group 1 isolation occurred. All Main Steam Isolation Valves closed as a result of the Group 1 isolation signal. HPCI [High Pressure Core Injection] has been placed in service to control RPV [Reactor Pressure Vessel] pressure. HPCI did not inject into the RPV and was not needed to control RPV level.
At 1104 CST, a Group 2 containment isolation signal was received due to RPV level less than +9 inches. The Group 2 isolation signal has been reset. The cause(s) of the 11 recirculation pump lockout, the reactor scram, and the Group 1 isolation are currently not known and are under investigation. This event is being reported under 50.72(b)(2)(iv)(B) due to the actuation of the Reactor Protection System when the reactor is critical. For the following reasons, this event is also being reported under 50.72(b)(3)(iv)(A): 1) This event resulted in a valid Group 2 containment isolation signal, 2) Since the cause of the Reactor Protection System actuation is not known, the event is being reported as a valid actuation of the Reactor Protection System, and 3) Since the cause of the Group 1 isolation is not known, the event is being reported as a valid primary containment isolation signal affecting multiple Main Steam Isolation Valves. All systems have responded as expected, all control rods fully inserted following the Reactor Protection System actuation. The plant is currently shutdown in mode 3, RPV pressure and RPV level are stable. This event did not result in any radiological release from the plant. This event did not challenge the health and safety of the public. The NRC Resident Inspector has been notified. The plant is in its normal shutdown electrical lineup. HPCI is in pressure suppression mode with RHR cooling the suppression pool. |
| Where | |
|---|---|
Monticello  Minnesota (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-1.62 h-0.0675 days <br />-0.00964 weeks <br />-0.00222 months <br />) | |
| Opened: | Matthew Quick 15:03 Nov 23, 2015 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Nov 23, 2015 |
| 51560 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Shutdown (0 %) |
Monticello with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 569952024-02-28T14:39:00028 February 2024 14:39:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram ENS 567592023-09-27T15:41:00027 September 2023 15:41:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Actuation of Reactor Protection and Containment Isolation Systems ENS 526822017-04-15T09:41:00015 April 2017 09:41:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Reactor Protection System and Partial Primary Containment Isolation System Actuations on Low Water Level ENS 515602015-11-23T16:40:00023 November 2015 16:40:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram Due to a Reactor Recirculation Pump Lockout ENS 491132013-06-13T19:30:00013 June 2013 19:30:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Emergency Diesel Generators Start ENS 490662013-05-24T08:34:00024 May 2013 08:34:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of Emergency Diesel Generator Due to Bus Undervoltage ENS 485032012-11-12T21:51:00012 November 2012 21:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Building Isolation with Standby Gas Treatment System Actuation During Radioactive Material Move ENS 483412012-09-25T15:44:00025 September 2012 15:44:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram During Maintenance on 4160V Bus 12 Ammeter ENS 474602011-11-20T05:12:00020 November 2011 05:12:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram While Performing Turbine Bypass Valve Testing ENS 473642011-10-21T17:50:00021 October 2011 17:50:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Lockout of Auxiliary Power Transformer ENS 464962010-12-20T09:57:00020 December 2010 09:57:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Fuel Pool/Reactor Building Exhaust Plenum Primary Power Supply Failed ENS 445082008-09-21T02:35:00021 September 2008 02:35:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Loss of Shutdown Cooling Due to Containment Isolation ENS 444982008-09-17T15:17:00017 September 2008 15:17:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Due to Loss of Shutdown Cooling ENS 444842008-09-12T03:47:00012 September 2008 03:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 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 Reactor Scram and Isolation Due to Transformer Lockout ENS 432462007-03-18T04:46:00018 March 2007 04:46:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Trip Signal and Containment Isolations Received During Maintenance ENS 430882007-01-10T21:28:00010 January 2007 21:28:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram with Stuck Open Main Turbine Control Valves ENS 414412005-02-25T03:11:00025 February 2005 03:11:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Esf Actuation Following Trip of Reactor Protection Motor-Generator Set ENS 414362005-02-23T18:00:00023 February 2005 18:00:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Potential Vulnerability with Alternate Shutdown System (Asds) Isolation Design. 2024-02-28T14:39:00 | |
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