ENS 52967
ENS Event | |
|---|---|
04:47 Sep 13, 2017 | |
| Title | Unusual Event Due to Letdown Relief Valve Discharge to the Pressurizer Relief Tank |
| Event Description | At 0047 EDT, the licensee declared a notification of unusual event under emergency action level (EAL) S8 due to actuation of the letdown relief valve which resulted in reactor coolant system leakage to the pressurizer relief tank exceeding 10 gpm.
The plant was in mode 3 at the time making preparations to proceed to cold shutdown to support their refueling outage. Operators were in the process of reducing reactor coolant system letdown from 120 gpm to 45 gpm when the letdown system relief valve lifted. The relief discharged to the pressurizer relief tank at approximately 12 gpm. Operators isolated the letdown line which reduced the leakage to approximately 1 gpm. Plant staff is in the process of determining where the 1 gpm leakage is from and evaluating the basis for terminating the unusual event. Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA National Watch Center (email) and Nuclear SSA (email).
At 0800 EDT, the licensee terminated the notification of unusual event. The basis for termination was that the letdown line was isolated which reduced leakage to less than the EAL threshold of 10 gpm. The cause of the letdown relief lifting is still under investigation. The licensee has notified the NRC Resident Inspector and will be notifying the state of Michigan and Berrien County. The licensee has issued a press release to the media concerning this event. Notified R3DO (Riemer), IRD MOC (Stapleton), NRR (Miller), DHS SWO, DHS NICC, FEMA Ops Center, FEMA National Watch Center (email) and Nuclear SSA (email).
The condition reported in Event Notification #52967 pursuant to 10 CFR 50.72(a)(1)(i) has been evaluated, and determined not to have met the threshold for classification as an Unusual Event under Emergency Action Level (EAL) S-8 and is being retracted. During the events of 9/13/17, Control Room staff calculated Reactor Coolant System (RCS) leakage to the Pressurizer Relief Tank (PRT) through the Letdown Relief Valve to be greater than the EAL S-8 threshold of 10 gallons per minute. Subsequent review of trends associated with PRT level increase during the event determined that the RCS leakage to the PRT was less than 10 gallons per minute and therefore did not represent an Unusual Event under EAL S-8. The NRC Resident Inspector was notified of this retraction. Notified R3DO (Riemer). |
| Where | |
|---|---|
Cook  Michigan (NRC Region 3) | |
| 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:+-3.65 h-0.152 days <br />-0.0217 weeks <br />-0.005 months <br />) | |
| Opened: | Ronnie Simmons 01:08 Sep 13, 2017 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Sep 15, 2017 |
| 52967 - 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 52967\u003C/a\u003E - \u003Ca href=\"/Cook\" title=\"Cook\"\u003ECook\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003EUnusual Event Due to Letdown Relief Valve Discharge to the Pressurizer Relief Tank\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 52967 - Cook\n","link":"","lat":41.97790555555556,"lon":-86.56431666666667,"icon":"/w/images/3/39/American_Electric_Power_icon.png"}],"imageoverlays":null} | |
Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
Cook 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 556912022-01-06T15:44:0006 January 2022 15:44:00
[Table view]10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to a Fire in the Aux Cable Vault ENS 547292020-05-27T13:12:00027 May 2020 13:12:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Inadvertent Actuation of Sirens ENS 540362019-04-30T00:29:00030 April 2019 00:29:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to a Spurious Actuation of an Emergency Siren ENS 529672017-09-13T04:47:00013 September 2017 04:47:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Due to Letdown Relief Valve Discharge to the Pressurizer Relief Tank ENS 526492017-03-30T07:10:00030 March 2017 07:10:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Loss of All Control Room Annunciators ENS 525852017-03-01T18:03:0001 March 2017 18:03:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Notification of Offsite Agencies Due to Sulfuric Acid Leak within the D.C. Cook Protected Area ENS 520652016-07-06T04:38:0006 July 2016 04:38:00 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 Manual Reactor Trip and Unusual Event Declaration Due to Steam Leak in Turbine Building ENS 518592016-04-08T22:20:0008 April 2016 22:20:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Oil Leak in a Switchyard Transformer Oil System ENS 508222015-02-13T18:15:00013 February 2015 18:15:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification to Michigan Osha ENS 506972014-12-20T17:12:00020 December 2014 17:12:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Oil Leak from Main Turbine Lube Oil System ENS 504982014-09-28T12:30:00028 September 2014 12:30:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Inadvertent Activation of an Emergency Siren ENS 504622014-09-16T19:19:00016 September 2014 19:19:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notifications and Press Release Regarding Onsite Fatality ENS 503862014-08-21T06:10:00021 August 2014 06:10:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Suspected Fuel Oil Leak to the Environment ENS 501882014-06-11T03:27:00011 June 2014 03:27:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to an Inadvertent Activation of an Emergency Siren ENS 493642013-09-20T02:30:00020 September 2013 02:30:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to an Inadvertent Activation of an Emergency Siren ENS 489452013-04-19T03:12:00019 April 2013 03:12:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Inadvertent Activation of an Emergency Siren ENS 487472013-02-12T20:30:00012 February 2013 20:30:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Notification of Offsite Agencies Due to Discovery of Potential Human Remains ENS 487312013-02-07T22:35:0007 February 2013 22:35:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Related to Death of Contractor Onsite ENS 478642012-04-26T02:46:00026 April 2012 02:46:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Notification to Offsite Agencies Due to Oil Spill ENS 471942011-08-23T18:24:00023 August 2011 18:24:00 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 an Unusual Event Due to a Seismic Event ENS 462342010-09-08T11:47:0008 September 2010 11:47:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release Offsite Notification Due to Body Discovered in the Owner Controlled Area ENS 460372010-06-23T18:28:00023 June 2010 18:28:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Declaration of Unusual Event Due to Seismic Event ENS 445072008-09-21T00:18:00021 September 2008 00:18:00 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 Unit 1 Manual Reactor Trip from 100% Power Due to a Fire in the Main Turbine ENS 441472008-04-18T10:02:00018 April 2008 10:02:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Seismic Activity ENS 404022003-12-19T23:44:00019 December 2003 23:44:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event 2022-01-06T15:44:00 | |