ENS 51536
ENS Event | |
|---|---|
12:39 Nov 13, 2015 | |
| Title | Notification of Unusual Event Due to Unidentified Rcs Leakage Greater than 10 Gpm |
| Event Description | While in Mode 3, South Texas Project Unit 1 declared an Unusual Event at 0639 CST on 11/13/15, due to SU7 of EAL1- Unidentified RCS or Pressure Boundary leakage greater than 10 gpm.
The excessive leakage to the WHT (waste holding tank) occurred when a letdown system demineralizer was placed in service. Operators bypassed the demineralizer and the RCS leakage was stopped. The excess leakage lasted for approximately 8 minutes and the maximum leakage was estimated to be 12-15 gpm. There was no impact on South Texas Unit 2 which continues to operate at 100% power. South Texas Project Unit 1 exited the Unusual Event at 0802 CST on 11/13/15, after verifying Unidentified RCS leakage less than 1 gpm. The demineralizer drain valve was partially open and was the cause of the excess leakage. The drain valve has been closed. The licensee has notified the NRC Resident Inspectors. Notified DHS SWO, FEMA Ops Center, FEMA NWC, NICC Watch Officer, and NuclearSSA via email
Due to entering the STP [South Texas Project] Emergency Plan (Unusual Event), STP has officially determined to make a planned press release. Per 10 CFR 50.72(b)(2)(xi), STP is making a notification to the NRC via the emergency notification system (ENS). The NRC Resident Inspector has been notified of the press release. The planned press release shares the following information: On November 13, 2015, STP Nuclear Operating Station, Unit 1, declared an Unusual Event at 0639 CST. Plant operators identified increasing reactor coolant system leakage in Unit 1. Plant Operators took immediate actions to verify the source and safely isolate and stop the leakage. Upon identifying the source of the leakage, the Unusual Event was exited at 0802 CST on November 13, 2015. The leakage was captured and maintained within an on-site storage tank and there was no radioactive release to the environment. STP Unit 1 is preparing for restart following a scheduled refueling and maintenance outage. Notified the R4DO (Gaddy).
The purpose of this report is to retract the ENS report made in accordance with 10 CFR 50.72 (a)(1)(i) on November 13, 2015, at 08:21 EST (ENS # 51536). STP Nuclear Operating Company declared an Unusual Event at 0639 CDT on November 13, 2015, based on Initiating Condition for Reactor Coolant System (RCS) Leakage Emergency Action Level (EAL) SU7. The event was reported to the NRC under EN # 51536 and the event was subsequently terminated on November 13, 2015 at 0802 CST. After further review, the emergency declaration is being retracted because the source of the leakage was from the Chemical and Volume Control System (CVCS) and not from the RCS. The NRC Resident Inspector will be notified. Notified the R4DO (Hagar). |
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | |
| Time - Person (Reporting Time:+-4.3 h-0.179 days <br />-0.0256 weeks <br />-0.00589 months <br />) | |
| Opened: | Jeffrey Hestand 08:21 Nov 13, 2015 |
| NRC Officer: | John Shoemaker |
| Last Updated: | Dec 8, 2015 |
| 51536 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
South Texas with 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | |
WEEKMONTHYEARENS 572372024-07-24T12:02:00024 July 2024 12:02:00
[Table view]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 Due to Loss of Offsite Power ENS 572012024-06-30T17:22:00030 June 2024 17:22:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification ENS 564392023-03-30T06:03:00030 March 2023 06:03:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to ON-SITE Fatality ENS 559182022-05-25T18:54:00025 May 2022 18:54:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification for Inadvertent Discharge of Halon ENS 550532020-12-30T21:50:00030 December 2020 21:50:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Inadvertent Emergency Siren Activation ENS 547142020-05-14T21:10:00014 May 2020 21:10:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification for Hydraulic Oil Release ENS 545872020-03-17T20:58:00017 March 2020 20:58:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Notification to Other Government Agency ENS 545612020-03-04T13:18:0004 March 2020 13:18:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release ENS 545292020-02-17T23:17:00017 February 2020 23:17:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Notification to Other Government Agency ENS 541452019-07-03T15:26:0003 July 2019 15:26:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Offsite Notification Due to Radio Transmitter Out of Service ENS 540972019-06-01T21:18:0001 June 2019 21:18:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Gasoline Leakage to Site Drainage System ENS 534052018-05-17T03:02:00017 May 2018 03:02:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification of Fires in the Owner Controlled Area ENS 531412018-01-01T16:15:0001 January 2018 16:15:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification - Emergency Notification Siren Inadvertent Actuation ENS 531162017-12-12T21:19:00012 December 2017 21:19:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Inadvertent Actuation of Emergency Notification Siren ENS 529112017-08-17T19:42:00017 August 2017 19:42:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Non Work Related Onsite Fatality ENS 527332017-05-05T02:03:0005 May 2017 02:03:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Miscommunication During On-The-Job Training ENS 527162017-04-29T21:23:00029 April 2017 21:23:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Small Grass Fire in Owner Controlled Area ENS 521422016-08-01T20:18:0001 August 2016 20:18:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Unintentional Release of Halon ENS 521062016-07-13T16:00:00013 July 2016 16:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Exercise Press Releases Aired on Radio as an Actual Event ENS 519642016-05-28T01:46:00028 May 2016 01:46:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to an Inadvertent Actuation of One Emergency Siren ENS 517872016-03-14T07:47:00014 March 2016 07:47:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Inadvertent Actuation of Offsite Emergency Notification Siren ENS 515362015-11-13T12:39:00013 November 2015 12:39:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Due to Unidentified Rcs Leakage Greater than 10 Gpm ENS 513392015-08-23T18:00:00023 August 2015 18:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Grass Fire in Owner Controlled Area ENS 510732015-05-15T22:53:00015 May 2015 22:53:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Inadvertent Siren Actuation ENS 507162015-01-05T23:45:0005 January 2015 23:45:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Death of Employee ENS 497402014-01-18T10:01:00018 January 2014 10:01:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Due to Fire in the Protected Area ENS 486592013-01-08T22:40:0008 January 2013 22:40:00 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 Unusual Event Declared Due to Main Transformer Fire ENS 473622011-10-20T21:50:00020 October 2011 21:50:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to the Offsite Fatality of an Employee ENS 463872010-11-03T15:21:0003 November 2010 15:21:00 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 an Explosion in the Protected Area Which Affects Normal Operations ENS 452622009-08-13T20:41:00013 August 2009 20:41:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to a Grass Fire in the Owner Controlled Area ENS 436122007-09-01T21:58:0001 September 2007 21:58:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Related to Fatality ENS 427572006-08-08T20:43:0008 August 2006 20:43:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Inadvertent Emergency Notification Siren Activation ENS 423222006-02-08T22:30:0008 February 2006 22:30:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification ENS 415052005-03-19T14:27:00019 March 2005 14:27:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Injured Contract Employee ENS 413942005-02-10T02:20:00010 February 2005 02:20:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Press Release for Plant Shutdown ENS 406572004-04-08T14:44:0008 April 2004 14:44:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification of a Fatality 2024-07-24T12:02:00 | |