ENS 42921
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ENS Event | |
|---|---|
22:56 Oct 19, 2006 | |
| Title | Automatic Scram Following Spontaneous Feedwater Valve Closure |
| Event Description | At 1756 CDT with the plant operating at 100% power, a reactor scram occurred in response to a reactor water level 3 signal from an apparent loss of feedwater. Both feedwater injection lines isolated when isolation valves were inadvertently closed, The cause of the isolation valve closure is under investigation.
When reactor water level lowered to level 2, high pressure core spray (HPCS) initiated automatically and recovered water level. The reactor core isolation cooling system (RCIC) was tagged out for maintenance at the time of the event. Following the scram, main steam isolation valves isolated on low main steam header pressure. As a result, reactor pressure control was being controlled with the safety relief valves. SRV pressure control in turn led to EOP entry conditions on containment pressure and suppression pool level. Both feedwater lines were opened, and normal reactor level control was restored. The MSIV's were opened and pressure control was returned to the turbine bypass valves and the main condenser. Initial indications are that all plant equipment functioned as designed with the exception of the 'B' feed pump which experienced an apparent seal failure. The plant is stable in Mode 3. All plant conditions are understood. This event is being reported in accordance with 10CRF50.72(b)(2) as an RPS actuation and an injection of HPCS into the reactor vessel, and in accordance with 10CRF50.72(b)(3) as a loss of safety function of HPCS, as it was manually disabled during recovery from the event. The HPCS Injection valve was manually overridden closed for 76 minutes. In addition,' containment isolation valves in multiple systems actuated in response to the RPV level 2 signal. Reactor vessel water level lowered to below level 2. Decay heat is being removed by normal feedwater to the reactor vessel steaming to the main condenser. Offsite power is available and stable. Emergency Diesel Generators are available. The licensee notified the NRC Resident Inspector.
The closure signal to the main feedwater header isolation valves occurred when part of a chart recorder above the isolation valve control switches was dropped by an operator. The operator was attempting to adjust the paper drive mechanism in the recorder, and accidentally dropped the paper cartridge, which struck the 'CLOSE' pushbuttons on the isolation valve control switches. Following the scram, there was a delay in placing the reactor mode switch in the 'SHUTDOWN' position, which is an immediate action required by procedure. Placing the mode switch to 'SHUTDOWN' bypasses the reactor low steam pressure MSIV Isolation. Reactor steam pressure began dropping after the scram, until it reached the MSIV automatic closure setpoint, and the MSIVs isolated, In addition the licensee corrected one of the 10 CFR Section entries from "50.72(b)(3)(v)(A) POT UNABLE TO SAFE SD" to "50.72(b)(3)(v)(D) ACCIDENT MITIGATION." The licensee notified the NRC Resident Inspector. Notified R4 DO (D. Powers) and NRR EO (N. Chokshi) |
| Where | |
|---|---|
River Bend  Louisiana (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-0.35 h-0.0146 days <br />-0.00208 weeks <br />-4.7943e-4 months <br />) | |
| Opened: | Dan Williamson 22:35 Oct 19, 2006 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Oct 20, 2006 |
| 42921 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Shutdown (0 %) |
River Bend with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 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)(2)(iv)(A), System Actuation - ECCS Discharge | |
WEEKMONTHYEARENS 568872023-12-13T07:02:00013 December 2023 07:02:00
[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 568632023-11-18T05:55:00018 November 2023 05:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram ENS 561162022-09-19T06:32:00019 September 2022 06:32:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Safety System Inoperability ENS 551692021-04-02T15:17:0002 April 2021 15:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram Due to Turbine Trip ENS 551542021-03-25T14:18:00025 March 2021 14:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Lowering Condenser Vacuum ENS 548802020-09-04T01:48:0004 September 2020 01:48:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray Inoperable ENS 548492020-08-21T14:18:00021 August 2020 14:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram ENS 543482019-10-24T15:35:00024 October 2019 15:35:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Automatic Depressurization System Inoperable ENS 543382019-10-18T07:07:00018 October 2019 07:07:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident En Revision Imported Date 11/20/2019 ENS 540962019-06-01T04:45:0001 June 2019 04:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram Due to Low Reactor Water Level ENS 537322018-11-10T05:00:00010 November 2018 05:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram on High Reactor Pressure ENS 536222018-09-25T05:00:00025 September 2018 05:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Control Building Chillers in Unanalyzed Condition ENS 533822018-05-04T16:29:0004 May 2018 16:29:00 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)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Associated with Damaging Effects of Tornados ENS 533652018-04-26T20:31:00026 April 2018 20:31:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Inadvertent Injection of High Pressure Core Spray ENS 533242018-04-11T06:50:00011 April 2018 06:50:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Condition That Could Impair Function of Control Building Ac System ENS 531922018-02-01T16:57:0001 February 2018 16:57:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram ENS 529952017-09-27T15:00:00027 September 2017 15:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Accident Mitigation - Loss of Secondary Containment ENS 529152017-08-19T01:55:00019 August 2017 01:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Scram While at 100 Percent Power ENS 528252017-06-24T01:18:00024 June 2017 01:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram on Main Generator Trip ENS 526312017-03-23T07:56:00023 March 2017 07:56:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray Declared Inoperable ENS 526022017-03-10T13:14:00010 March 2017 13:14:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram Due to Closure of the Main Turbine Control Valves ENS 518992016-05-03T03:29:0003 May 2016 03:29:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray System Inoperable Due to a Control Room Chiller Trip ENS 517012016-01-29T21:18:00029 January 2016 21:18:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation After Loss of One Offsite Power Source ENS 516442016-01-09T08:37:0009 January 2016 08:37:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram on Main Steam Isolation Due to Electrical Fault ENS 516002015-12-11T10:16:00011 December 2015 10:16:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray Declared Inoperable ENS 515682015-11-27T10:31:00027 November 2015 10:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Following Partial Loss of Offsite Power ENS 515522015-11-19T13:24:00019 November 2015 13:24:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray Declared Inoperable ENS 515452015-11-18T05:55:00018 November 2015 05:55:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray Declared Inoperable ENS 511122015-06-02T02:11:0002 June 2015 02:11:00 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 Low Reactor Water Level ENS 510282015-05-01T04:44:0001 May 2015 04:44:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray System Inoperable ENS 508722015-03-08T03:40:0008 March 2015 03:40:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation Due to Loss of One Reserve Station Service Offsite Power Source ENS 507042014-12-25T14:37:00025 December 2014 14:37:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram ENS 505462014-10-17T08:03:00017 October 2014 08:03:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram on High Average Power Range Monitor Flux ENS 503372014-08-02T02:42:0002 August 2014 02:42:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray Declared Inoperable Due to Test Return Valve Leakage ENS 493622013-09-19T19:37:00019 September 2013 19:37:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Secondary Containment Inoperable Due to an Unattended Open Door ENS 479602012-05-24T18:48:00024 May 2012 18:48:00 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)(3)(xiii), Loss of Emergency Preparedness Manual Reactor Scram Due to a Loss of Feed as Result of a Loss of Switchgear ENS 479402012-05-21T19:52:00021 May 2012 19:52:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram Resulting from a Low Condenser Vacuum-Turbine Trip ENS 475492011-12-23T12:10:00023 December 2011 12:10:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram Due to a Turbine Trip ENS 463992010-11-07T15:23:0007 November 2010 15:23:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Pressure Core Spray Pump Oil Leak ENS 460482010-06-26T01:24:00026 June 2010 01:24:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Hpcs Inoperable ENS 453882009-09-29T16:27:00029 September 2009 16:27:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Water from Upper Refuel Pool ENS 453692009-09-20T22:47:00020 September 2009 22:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Scram Due to Reactor Recirc Pump Trip ENS 451192009-06-09T23:52:0009 June 2009 23:52:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Door for Secondary Containment Boundary Left Open ENS 440342008-03-05T20:43:0005 March 2008 20:43:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Scram Due to Apparent Malfunction in Turbine Control System ENS 437732007-11-07T09:06:0007 November 2007 09:06:00 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)(iv)(A), System Actuation - ECCS Discharge Reactor Scram as a Result of Loss of Normal Power 13.8 Kv Bus ENS 436682007-09-27T03:44:00027 September 2007 03:44:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram During the Performance of Aprm Surveillance Testing ENS 433452007-05-04T17:56:0004 May 2007 17:56:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram Due to Loss of Cooling to Number 2 Main Transformer ENS 429212006-10-19T22:56:00019 October 2006 22:56:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 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)(2)(iv)(A), System Actuation - ECCS Discharge Automatic Scram Following Spontaneous Feedwater Valve Closure ENS 425052006-04-15T21:15:00015 April 2006 21:15:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Scram from 100% Power ENS 422852006-01-25T01:32:00025 January 2006 01:32:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Invalid High Pressure Core Spray (Hpcs) Initiation Signal During Surveillance Testing ENS 413392005-01-15T08:12:00015 January 2005 08:12:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram Due to Receiving a Main Generator Alarm ENS 412522004-12-10T19:17:00010 December 2004 19:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Scram Due to Loss of Vital Instrument Bus ENS 411652004-11-01T22:44:0001 November 2004 22:44:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Automatic Start ENS 411642004-11-01T03:56:0001 November 2004 03:56:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Plant Had Auto Start of the Division 1 Emergency Diesel Generator ENS 410822004-10-01T12:30:0001 October 2004 12:30:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Reactor Trip Due to Main Generator Load Rejection ENS 409572004-08-15T09:05:00015 August 2004 09:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Following Partial Loss of Offsite Power ENS 401912003-09-23T03:43:00023 September 2003 03:43:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Scram Received During Main Turbine Control Valve Testing 2023-12-13T07:02:00 | |
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