ENS 44851
ENS Event | |
|---|---|
21:26 Feb 13, 2009 | |
| Title | Unusual Event - Engineering Analysis Requires Technical Specification Shutdown |
| Event Description | On February 13, 2009 at 1526 CST, Fort Calhoun Station declared a Notification of Unusual Event [NOUE] based upon EAL 4.2 - Both Diesel Generators NOT Operable. The station has entered Technical Specification 2.0.1(1) requiring the Unit to be placed in at least HOT SHUTDOWN within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
The cause of the NOUE is a potential common mode failure of the diesel generators. Design Engineering has identified an unanalyzed condition in which a High Energy Line Break in Room 81, Main Steam Lines Containment Penetration Room, or an auxiliary steam leak in Room 82, Turbine Building Ventilation Room, can potentially result in water entering both diesel generator rooms through the floor of Room 82 located directly above the diesel rooms, Rooms 63 and 64. This condition presents a potential common mode failure of the diesel generators due to loss of diesel generator auxiliaries from a single failure. The possibility of water leaking into Rooms 63, 64 and the Switchgear rooms prompted this declaration. Compensatory measures to exit the NOUE will be to remove auxiliary steam from room 82 and blockading shut the door between rooms 81 and 82. These actions are expected to be completed within one to three hours. The licensee notified the NRC Resident Inspector.
At 1828 CST, Fort Calhoun Station exited the Notification of Unusual Event. Both Diesel Generators were declared operable based upon establishing compensatory measures. Diesel 2 was confirmed operable by running in accordance with approved procedures. Diesel 1 was successfully run on February 11, 2009 per a monthly surveillance tests. No additional water intrusion had occurred into the diesel 1 room since completion of the surveillance test. Compensatory measures to prevent water intrusion into Room 82 include isolating auxiliary steam to room 82 to eliminate a source of water to room 82, installing a temporary barrier at the door between rooms 81 and 82 to prevent water from flowing from room 81 to room 82, should an HELB occur in room 81, and to open the door between room 81 and the turbine building to allow water to flow out of room 81 so as not to flow into room 82. Technical Specification 2.0.1 has been exited as of time 1828 CST. The licensee will notify the NRC Resident Inspector. Notified the R4DO (Miller), IRD (McDermott, McMurtray), DHS (Doyle), and FEMA (Via).
This is a retraction [of the report made under 10 CFR 50.72(b)(3)(ii)(B) - Unanalyzed Condition] Fort Calhoun has performed a detailed evaluation of water intrusion through cracks in the floor of room 82 above the emergency diesel generators, as identified in part in the notification of 2/13/2009. This evaluation determined that no common mode failure mechanism existed and that the diesel generators were capable of performing their design safety functions. The licensee informed the Resident Inspector. Notified R4DO (Rick Deese). |
| Where | |
|---|---|
Ft Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
| Time - Person (Reporting Time:+-4.43 h-0.185 days <br />-0.0264 weeks <br />-0.00607 months <br />) | |
| Opened: | Shannon Shea 17:00 Feb 13, 2009 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Apr 1, 2009 |
| 44851 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Fort Calhoun with 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
WEEKMONTHYEARENS 514392015-10-02T14:05:0002 October 2015 14:05:00
[Table view]10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event ENS 502142014-06-20T05:01:00020 June 2014 05:01:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown ENS 500382014-04-15T20:15:00015 April 2014 20:15:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Failure of Control Room Air Conditioning ENS 497042014-01-09T11:18:0009 January 2014 11:18:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Tech Spec Required Shutdown Due to Inoperable Raw Water Pumps. ENS 492412013-08-06T12:22:0006 August 2013 12:22:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to High Winds ENS 470512011-07-15T00:13:00015 July 2011 00:13:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared Due to Suspected Introduction of Contraband Into the Protected Area ENS 469322011-06-07T14:40:0007 June 2011 14:40:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Fire in the West Switchgear Room ENS 469292011-06-06T13:00:0006 June 2011 13:00:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Unusual Event Declared Due to River Level ENS 464902010-12-19T06:08:00019 December 2010 06:08:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness Quickly Concluded Notice of Unusual Event Due to a Loss of Communications ENS 463682010-10-27T17:22:00027 October 2010 17:22:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Unit Commenced Shutdown After Declaring Containment Spray Inoperable ENS 458282010-04-08T21:22:0008 April 2010 21:22:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Inoperable Steam Generator Inlet Isolation Valve ENS 448512009-02-13T21:26:00013 February 2009 21:26:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Unusual Event - Engineering Analysis Requires Technical Specification Shutdown ENS 436362007-09-13T10:01:00013 September 2007 10:01:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event for a Hydrazine Spill in the Turbine Building ENS 424862006-04-10T15:55:00010 April 2006 15:55:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Personnel Air Lock Door Equalizing Valve Leaking by ENS 401942003-09-23T18:20:00023 September 2003 18:20:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event ENS 401652003-09-17T13:43:00017 September 2003 13:43:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Post Alert Emergency Declaration Based on Calculated Rcs Inventory Loss 2015-10-02T14:05:00 | |