ENS 41837
ENS Event | |
|---|---|
13:17 Jul 13, 2005 | |
| Title | Turbine Trip/Reactor Trip |
| Event Description | On July 13, 2005, at approximately 0917 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.489185e-4 months <br />, Unit 1 received a Reactor Protection System (RPS) trip and a Main Turbine trip. All control rods fully inserted into the core. Plant response to the reactor shutdown resulted in a reactor coolant level transient that caused a Low Level 2 signal and subsequent High Pressure Coolant Injection (HPCI) system initiation. The HPCI system started but did not inject into the vessel because reactor coolant level was already recovered by the Reactor Feedwater system. Proper operation of the RCIC system has not been conclusively determined. Both Reactor Recirculation pumps tripped, as expected, from the low reactor coolant level and high pressure transient.
Additionally, primary containment isolation system actuation signals for valve groups 2, 3, 6, and 8 were received and the valves, that were open, closed as required. The Reactor Building Ventilation System isolated and both trains of the Standby Gas Treatment (SBGT) System automatically started and operated successfully. The RPS trip was reset and the HPCI turbine secured. Both trains of the SBGT system were secured. At 1119 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.257795e-4 months <br />, the plant exited the scram recovery procedure and entered General Plant Operating procedure 0GP-05, "Unit Shutdown." Investigation into the cause of the RPS and Main Turbine trip is still in progress. The plant is currently in Mode 3 (i.e., Hot Shutdown) and activities are in progress to transition to Mode 4 (i.e., Cold Shutdown). The resident inspector has been notified. INITIAL SAFETY SIGNIFICANCE EVALUATION The initial safety significance of this condition is considered to be minimal. The plant responded as designed to the transient, with the exception of the verification of RCIC system performance, and the plant was safely shut down. CORRECTIVE ACTIONS An event investigation team has been assembled to determine the cause of the event. Plant response to the event is being evaluated and identified issues will be addressed prior to plant restart. During the transient, four safety relief valves lifted and reset. The plant is currently in a normal shutdown electrical lineup. Reactor vessel level is being maintained using normal feedwater. The bypass valves are available for cooldown. There was no effect on unit-2.
On July 13, 2005, at approximately 0917 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.489185e-4 months <br />, Unit 1 received a Reactor Protection System (RPS) trip and a Main Turbine trip. All control rods fully inserted into the core and the plant safely shut down. A non-emergency notification (Event Number 41837) was made to the NRC Operations Center at 1303 hours0.0151 days <br />0.362 hours <br />0.00215 weeks <br />4.957915e-4 months <br />. This follow-up notification discusses plant recovery from the Unit 1 event. After investigation team review of plant data, it was determined that the RCIC system performed appropriately (i.e., was not required to start) in response to the reactor coolant level transient. Reactor coolant level decreased to near, but did not exceed, the RCIC System actuation instrumentation setpoint. The investigation team determined that the direct cause of the RPS/Main Turbine trip is the shorting to ground of one phase of the Unit 1 Main Generator No-Load Disconnect Switch, which electrically connects the generator to the Main Transformer. The switch grounding caused a generator ground fault that resulted in a backup generator lockout and fast closure of the turbine control valves. Fast closure of the turbine control valves provided the trip input to the RPS. Unit 1 is now making preparations to go to mode 4, cold shutdown. Unit 1 and Unit 2 are currently in Technical Specification (TS) Limiting Condition for Operation (LCO) 3.8.1 'AC Sources - Operating,' for one of two required Unit 1 offsite AC circuits inoperable. The resident inspector has been notified. CORRECTIVE ACTIONS Further testing of RCIC System Low Reactor Level actuation instrumentation will be performed to further verify satisfactory RCIC System performance during the event. Activities are in progress to address the damaged No-Load Disconnect Switch and to determine the cause of the switch failure. Notified the R2DO (Fredrickson). |
| Where | |
|---|---|
Brunswick  North Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000325/LER-2005-005 |
| Time - Person (Reporting Time:+-0.23 h-0.00958 days <br />-0.00137 weeks <br />-3.15054e-4 months <br />) | |
| Opened: | Ken Chism 13:03 Jul 13, 2005 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Jul 14, 2005 |
| 41837 - NRC Website
Loading map... {"minzoom":false,"maxzoom":false,"mappingservice":"leaflet","width":"350px","height":"250px","centre":false,"title":"","label":"","icon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"zoom":6,"defzoom":14,"layers":["OpenStreetMap"],"image layers":[],"overlays":[],"resizable":false,"fullscreen":false,"scrollwheelzoom":true,"cluster":false,"clustermaxzoom":20,"clusterzoomonclick":true,"clustermaxradius":80,"clusterspiderfy":true,"geojson":"","clicktarget":"","imageLayers":[],"locations":[{"text":"\u003Cb\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003E\u003Ca class=\"mw-selflink selflink\"\u003EENS 41837\u003C/a\u003E - \u003Ca href=\"/Brunswick\" title=\"Brunswick\"\u003EBrunswick\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003ETurbine Trip/Reactor Trip\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 41837 - Brunswick\n","link":"","lat":33.95840833333333,"lon":-78.00979722222222,"icon":"/w/images/7/75/Duke_Energy_icon.png"}],"imageoverlays":null} | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Shutdown (0 %) |
Brunswick with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 569772024-02-19T04:25:00019 February 2024 04:25:00
[Table view]10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of Emergency Diesel Generator ENS 564782023-04-20T05:48:00020 April 2023 05:48:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to a Turbine Trip ENS 556272021-12-06T16:25:0006 December 2021 16:25:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Safety System Actuation ENS 545972020-03-22T16:55:00022 March 2020 16:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram ENS 540162019-04-22T03:07:00022 April 2019 03:07:00 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 Automatic Reactor Trip and Specified System Actuation ENS 539662019-03-30T21:47:00030 March 2019 21:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Scram and Specified System Actuation ENS 539622019-03-28T20:54:00028 March 2019 20:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of the Primary Containment Isolation System and the Reactor Protecton System ENS 539552019-03-25T08:02:00025 March 2019 08:02:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Start of Four Emergency Diesel Generators ENS 539112019-03-05T10:35:0005 March 2019 10:35:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of the Primary Containment Isolation System ENS 533192018-04-07T12:36:0007 April 2018 12:36:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip and Pcis Actuation During Stator Cooling System Testing ENS 529742017-09-17T13:38:00017 September 2017 13:38:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator and Primary Containment Isolation System Actuations ENS 526832017-04-17T04:04:00017 April 2017 04:04:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Actuation of Emergency Diesel Generators ENS 517152016-02-07T18:26:0007 February 2016 18:26:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Scram and Alert Declaration Due to Electrical Fault Resulting in Fire/Explosion ENS 478172012-04-09T09:29:0009 April 2012 09:29:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Emergency Diesel Generator Actuation ENS 476972012-02-24T05:37:00024 February 2012 05:37:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Reactor Protection System Actuation During Neutron Instrument Testing ENS 476902012-02-23T04:19:00023 February 2012 04:19:00 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 High Delta-P Across Circulating Water Pump Traveling Screens ENS 474442011-11-16T08:01:00016 November 2011 08:01:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Due to Drywell Leakage Greater than 10 Gpm ENS 459022010-05-05T15:44:0005 May 2010 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 Due to Reactor Feed Pump Trip ENS 457322010-02-27T06:58:00027 February 2010 06:58:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Core Isolation Cooling (Rcic) System Manually Started to Maintain Reactor Pressure Vessel Level Following a Pre-Planned Reactor Scram ENS 453752009-09-21T18:46:00021 September 2009 18:46:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Protection System and Primary Containment Isolation System Actuation After Placing Hpci System Inservice ENS 451902009-07-08T14:13:0008 July 2009 14:13:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Emergency Diesel Generator Actuation ENS 446852008-11-26T17:00:00026 November 2008 17:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram Due to Ehc Malfunction ENS 446472008-11-09T16:08:0009 November 2008 16:08:00 Other Unspec Reqmnt, 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 Spurious Srv Opening ENS 444532008-08-30T19:03:00030 August 2008 19:03:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Electro-Hydraulic Control Malfunction Leads to Reactor Scram ENS 430622006-12-25T10:39:00025 December 2006 10:39:00 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 Due to Trip from Neutron Monitoring System ENS 429862006-11-11T17:43:00011 November 2006 17:43:00 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 Conductivity Excursion ENS 429552006-11-01T23:37:0001 November 2006 23:37:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Unit 2 Declared an Unusual Event Due to Loss of Offsite Power to the 4Kv Emergency Buses ENS 418372005-07-13T13:17:00013 July 2005 13:17:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Turbine Trip/Reactor Trip ENS 415822005-04-09T05:50:0009 April 2005 05:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scrammed from 61% Power Due to Low Reactor Water Level ENS 409542004-08-14T16:59:00014 August 2004 16:59:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Rps Actuation Due to Loss of Offsite Power ENS 402972003-11-04T22:32:0004 November 2003 22:32:00 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 Brunswick Unit 2 Scram Due to Generator/Turbine Trip 2024-02-19T04:25:00 | |