ENS 41607
ENS Event | |
|---|---|
12:42 Apr 17, 2005 | |
| Title | Alert Declared Due to Unit 3 Main Steam Relief Valves Not Reseating After Actuation |
| Event Description | At 09:23 the licensee indicated that several Main Steam Relief Valves lifted and stayed open. A high pressure flow signal from the secondary Steam Generator caused initiation of Unit 3 Safety Injection, which in turn caused the Reactor to trip. All rods fully inserted as required. Activation of the Safety Injection subsequently caused the Pressurizer level to go solid. About 30 minutes into the event the primary Reactor Coolant and Main Steam Systems stabilized, including the Pressurizer level and pressure. During the initial briefing, about 09:35, the licensee reported that all secondary Safety Relief Valves have reseated. Decay heat is being directed to the Atmospheric Dumps due to the Main Condenser not being available. The licensee is attempting to establish ERDS.
Initial assessment of this incident is believed not to be security related, however, follow-up is being conducted to verify same. At 09:48, NRC management made a decision to enter into Monitoring Mode. At about 11:15 the licensee indicated that a valve in the Charging System indicated some leakage, therefore it was isolated. Licensee stated that no radiological releases and no S/G tube leakage was indicated. Licensee notified State and local emergency response agencies. They will notify the NRC Resident Inspector. Notified DHS (Doyle), FEMA (Biscue), DOE (Smith), USDA (Magners), and HHS (Hogan).
At approximately 0830 on April 17, 2005 Millstone Unit 3 experienced an automatic reactor trip from full power. The Reactor is in a stable shutdown condition and is proceeding to Mode 5 cold shutdown. No release of radioactivity other than those minor releases associated with normal plant operation has occurred. There were no personnel injuries associated with the event. In addition to the Reactor Trip, half-train Safety Injection (SI) and half-train Main Steam Isolation (MSI) actuations occurred. Control room personnel were successful at manually initiating full SI and MSI. SI has since been terminated and RCS pressure control has been restored. Multiple steam line safety valves (MSSV) lifted with at least one MSSV indicating a failure to reclose. As a result, an ALERT was declared at approximately 0853 due to the failure of at least one MSSV failing to reclose. All MSSVs are currently closed. Auxiliary Feedwater (AFW) actuated automatically as expected, however, the turbine driven auxiliary feedwater pump (TDAFWP) tripped on start-up and was subsequently reset locally. Both motor driven auxiliary feedwater pumps (MDAFWPs) operated as expected to maintain steam generator water levels. Due to the additional inventory injected to the Reactor Coolant System (RCS) as a result of the SI actuation, the pressurizer filled and a primary system safety valve (PSSV) actuated at a lower than expected pressure. All PSSVs are currently closed, however, there is indication of leakage past either a PSSV or Pilot Operated Relief Valve (PORV). Upon alignment of the Charging system to Refueling Water Storage Tank recirculation flow path, 2 valves had indication of packing leakage. Those packing leaks have been terminated. The cause of the event is under investigation. The licensee has issued a press release. The licensee will notify the NRC Resident Inspector. Notified R1 DO (J. White) and IRD Manager (T. McGinty)
The previously reported time of the Alert declaration should be corrected to read 08:42. Millstone Unit 3 entered Mode 4 [Hot Shutdown] at approximately 19:03 on April 17, 2005. The event at Millstone Unit 3 was terminated at 19:05. The cause of the event is under investigation. A recovery plan is being formulated. Internal NRC notifications, DHS (Frost), NRC/EPA (Threatt), FEMA (Erwin), DOE (Morone), USDA (Smeltzer), HHS (Desi) The licensee will notify the NRC Resident Inspector. At 23:45 the Agency exited Monitoring Mode and entered into Normal Mode. |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| Emergency class: | Alert |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 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 | |
| Time - Person (Reporting Time:+-3.32 h-0.138 days <br />-0.0198 weeks <br />-0.00455 months <br />) | |
| Opened: | Michael Gobeli 09:23 Apr 17, 2005 |
| NRC Officer: | John Knoke |
| Last Updated: | Apr 17, 2005 |
| 41607 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Millstone with 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 | |
WEEKMONTHYEARENS 565442023-05-30T08:46:00030 May 2023 08:46:00
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20:15:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip After Turbine Trip Due to Loss of Condenser Vacuum ENS 459452010-05-22T20:45:00022 May 2010 20:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Loss of Steam Generator Water Level Control ENS 459312010-05-17T14:17:00017 May 2010 14:17:00 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 Low Steam Generator Water Level ENS 457292010-02-26T16:25:00026 February 2010 16:25:00 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 Loss of Two Circulating Water Pumps ENS 455832009-12-20T03:53:00020 December 2009 03:53:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Caused by a 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Lightning Strike ENS 441212008-04-06T17:17:0006 April 2008 17:17:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event from Reactor Coolant System Leakage ENS 433182007-04-25T15:01:00025 April 2007 15:01:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Loss of Offsite Power While Defueled ENS 427252006-07-25T13:45:00025 July 2006 13:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Reactor Trip Breakers Opened During Maintenance on Steam Generator Wide Level Channels ENS 423672006-02-23T15:22:00023 February 2006 15:22:00 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 Loss of Main Feedwater ENS 421802005-12-01T19:45:0001 December 2005 19:45:00 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 Low Steam Generator Level ENS 420242005-09-29T17:10:00029 September 2005 17:10:00 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 Loss of Circulating Water Pumps ENS 416072005-04-17T12:42:00017 April 2005 12:42:00 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 Alert Declared Due to Unit 3 Main Steam Relief Valves Not Reseating After Actuation ENS 413332005-01-14T14:55:00014 January 2005 14:55:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Licensee Reported a Fire in the Turbine Building ENS 405912004-03-16T01:20:00016 March 2004 01:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip at Millstone 2 Due to Spurious Loss of One Main Feed Pump ENS 405702004-03-06T05:50:0006 March 2004 05:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip at Millstone 2 Due to Spurious Trip of the "B" Feed Pump ENS 403612003-11-29T03:05:00029 November 2003 03:05:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip from 11% Power Due to Turbine Vibration ENS 403582003-11-27T11:29:00027 November 2003 11:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Plant Had a Manual Reactor Trip from 23% Power Due to Turbine Vibration ENS 402452003-10-14T08:04:00014 October 2003 08:04:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared - Loss of Shutdown Cooling 2023-05-30T08:46:00 | |