ENS 40119
ENS Event | |
|---|---|
19:28 Aug 29, 2003 | |
| Title | Automatic Reactor Trip on High Rcs Pressure |
| Event Description | Unit 1 experienced an automatic reactor trip at approximately 14:28 CDT as a result of a turbine trip. Initial indications are that the trip was associated with a lightning strike on site. Plant is stable in Mode 3. All control rods fully inserted and there are no offsite radiation releases. Anomalies noted are 'C' Main Phase Transformer Sudden Pressure Trip Alarm, Main Generator Output Breakers failed to automatically open and were subsequently manually opened, and 'B' Once Through Steam Generator (OTSG) main feedwater block valve failed to indicate closed which resulted in a low level condition on 'B' OTSG and subsequent automatic actuation of Emergency Feedwater (EFW). EFW is controlling both OTSG levels at low level limits.
A normal fast transfer to the Startup Transformer occurred following the trip and offsite power remains available. All EDGs are in standby, if needed. There is no safety related equipment out of service at this time. Decay heat is currently being removed via the steam dumps to the main condenser. The licensee will conduct an investigation into the equipment failures and determine if any plant equipment was damaged by the lightning strike. The licensee informed the NRC Resident Inspector.
This message is intended to provide clarifying information for Event Notification #40119. Unit 1 experienced an automatic reactor trip at approximately 14:28 CDT as a result of a turbine trip. Initial indications are that the trip was associated with a lightning strike on site. Plant is stable in Mode 3. All control rods fully inserted and there are no offsite radiation releases. The following anomalies were noted in conjunction with plant trip. A 'C' Main Phase Transformer Sudden Pressure Trip Alarm occurred as a result of an indication problem only. The Main Generator Output Breakers failed to automatically open and were subsequently manually opened. The 'B' Once Through Steam Generator (OTSG) main feedwater (MFW) block valve failed to fully close. Complications associated with manual control of feedwater flow when the MFW block valve failed to fully close resulted in a momentary low level in the 'B' OTSG and Emergency Feedwater (EFW) automatic actuation. EFW flow quickly restored the 'B' OTSG level to normal. Both MFW pumps remained operating throughout the transient, and MFW flow was never lost. The EFW System was allowed to recirc for approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. After the MFW block valve was manually closed, the auxiliary feedwater pump was placed in service and EFW and the MFW pumps were secured. The licensee will be notifying the NRC Resident Inspector.
The following information was provided as an update: This message is intended to update the information provided in previous notifications concerning Event Notification #40119. Based on subsequent investigation the automatic reactor trip which occurred at approximately 14:28 CDT on August 29, 2003, was a result of high reactor coolant system (RCS) pressure. The high RCS pressure resulted from the inadvertent closure of the main turbine governor valves. Although not conclusively determined, the closure of these valves is most likely due to a lightning strike on site. This automatic reactor trip also resulted in a main turbine trip. Anomalies associated with this event remain as previously reported. The primary PORV (2450 psia) and Safeties (2500 psia) did not lift during the pressure excursion. The High RCS Pressure setpoint for RPS actuation is 2355 psia. The licensee informed the NRC Resident Inspector. Notified R4DO(Runyan). |
| Where | |
|---|---|
Arkansas Nuclear  Arkansas (NRC Region 4) | |
| 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:+2.52 h0.105 days <br />0.015 weeks <br />0.00345 months <br />) | |
| Opened: | John Hathcote 21:59 Aug 29, 2003 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Aug 30, 2003 |
| 40119 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Arkansas Nuclear with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 563512023-02-14T17:03:00014 February 2023 17:03:00
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50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to an Auxiliary Trip on Core Protection Calculator ENS 499952014-04-03T18:01:0003 April 2014 18:01:00 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 496182013-12-09T14:00:0009 December 2013 14:00:00 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(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Unit 2 Auxiliary Transformer Explosion ENS 488692013-03-31T15:33:00031 March 2013 15:33:00 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(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Notification of Unusual Event Declared Due to a Breaker Explosion in the Protected Area ENS 481692012-08-08T13:23:0008 August 2012 13:23:00 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 High Reactor Coolant System Pressurizer Pressure ENS 458722010-04-26T05:00:00026 April 2010 05:00:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 1 Experienced an Automatic Reactor Trip During an Ni Calibration ENS 458542010-04-18T18:57:00018 April 2010 18:57:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip During Reactor Startup ENS 455492009-12-08T14:42:0008 December 2009 14:42:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Low Steam Generator Level Caused by Loss of Main Feed Water Pump ENS 453672009-09-20T10:11:00020 September 2009 10:11:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Emergency Diesel Auto Start During Surveillance Testing ENS 449062009-03-14T02:51:00014 March 2009 02:51:00 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 Feedwater Regulating Valve Failure Leads to Manual Reactor Trip ENS 448372009-02-07T16:59:0007 February 2009 16:59:00 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 a Fire Onsite ENS 448312009-02-05T21:24:0005 February 2009 21:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 1 Manually Tripped Due to Control Rod Drive Motor High Temperatures ENS 447362008-12-20T18:12:00020 December 2008 18:12:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip When Control Rod Bank Inserted Without Operator Action ENS 447162008-12-12T14:55:00012 December 2008 14:55:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unit 1 Was Manually Tripped from 32% Power Due to an Abnormal Rod Pattern ENS 441252008-04-07T18:45:0007 April 2008 18:45:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Core Element Assembly Calculators Declared Inoperable ENS 422292005-12-26T16:47:00026 December 2005 16:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Following Turbine Trip ENS 401192003-08-29T19:28:00029 August 2003 19:28:00 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 High Rcs Pressure 2023-02-14T17:03:00 | |