ENS 52201
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ENS Event | |
|---|---|
20:23 Aug 25, 2016 | |
| Title | Unanalyzed Condition Involving Potential Tornado Missile Damage |
| Event Description | On August 25, 2016, Engineering staff were reviewing a proposed modification to install additional internal flooding protection for the Intake Building staircase down to the Raw Water Pump vault. Fort Calhoun Station determined that the existing Intake Building internal flooding and tornado-borne missile analyses did not sufficiently account for the potential of tornado-borne missiles striking Fire Protection piping in the Intake Building. A tornado-borne missile strike could potentially cause a double-ended rupture of Fire Protection piping in the vicinity of the stairwell down to the Raw Water Pump vault, which could cause flooding and subsequent failure of all four Raw Water Pump motors more quickly than bounded by the Engineering Analysis. The Engineering Analysis uses a postulated crack from a Moderate Energy Line Break per USNRC Branch Technical Position MEB 3-1, vice postulating a double ended pipe rupture. The resulting flow rate from this postulated crack is less than that possible from a tornado-borne missile strike.
This condition creates a potential loss of safety function from the Fort Calhoun Station Raw Water System (ultimate heat sink). All four Raw Water Pump motors could potentially become inoperable from flooding caused by a tornado-borne missile impacting the Fire Protection System Piping near the Raw Water vault stairwell prior to operator action to secure both Fire Pumps. This condition is reportable per 10 CFR 50.72(b)(3)(ii)(B) for any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety, and per 10 CFR 50.72(b)(3)(v)(D) for any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. Interim compensatory measures are to isolate the Fire Protection piping in the vicinity of the Raw Water Pump vault stairwell when severe weather is forecast. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+0.8 h0.0333 days <br />0.00476 weeks <br />0.0011 months <br />) | |
| Opened: | Charles Smith 21:11 Aug 25, 2016 |
| NRC Officer: | Daniel Mills |
| Last Updated: | Aug 25, 2016 |
| 52201 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Fort Calhoun with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
WEEKMONTHYEARENS 522012016-08-25T20:23:00025 August 2016 20:23:00
[Table view]10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Involving Potential Tornado Missile Damage ENS 519172016-05-10T16:38:00010 May 2016 16:38:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Containment Cooling Water System Inoperable Due to Unanalyzed Condition ENS 514872015-10-21T18:50:00021 October 2015 18:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Pressurizer Heater Bank Potential Circuit Failure Vulnerability ENS 508002015-02-09T23:30:0009 February 2015 23:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Safety Injection Tank Level Results in an Unanalyzed Condition ENS 494782013-10-28T17:30:00028 October 2013 17:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Event Could Result in a Hot Short That Could Adversely Impact Safe Shutdown Equipment ENS 493782013-09-23T18:40:00023 September 2013 18:40:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Epoxy Floor Coatings Do Not Meet Design Basis Requirements in Two Rooms ENS 493242013-09-05T13:31:0005 September 2013 13:31:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Potential Low Pressure Safety Injection Pump Run Out Condition ENS 491192013-06-14T16:00:00014 June 2013 16:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Invalid Conditions Discovered Due to Exclusion of Small Bore Piping from Analysis ENS 491122013-06-13T13:05:00013 June 2013 13:05:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 490502013-05-17T05:00:00017 May 2013 05:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Embedment Depth for Seismic Anchors Inadequate ENS 488062013-03-04T20:00:0004 March 2013 20:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Mechanical Seal Material Design ENS 487872013-02-27T02:12:00027 February 2013 02:12:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Relay Backing Plate Fasteners Discovered to Be at Less than Specified Torque ENS 487812013-02-24T23:00:00024 February 2013 23:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Inverters Potentially Inoperable During Emergency Diesel Generator Operation ENS 487302013-02-07T20:30:0007 February 2013 20:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Possible Run-Out of High Pressure Safety Injection Pump ENS 480942012-07-11T21:03:00011 July 2012 21:03:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Analysis of Internal Containment Support Beam Exceeds Load Combination Limit ENS 479922012-06-04T20:14:0004 June 2012 20:14:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Reactor Coolant System in a Degraded Condition Due to an Instrument Rack Seismic Design Issue ENS 479002012-05-04T15:00:0004 May 2012 15:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Containment Equipment Not Analyzed for Environmental Conditions of Record ENS 478922012-05-02T16:55:0002 May 2012 16:55:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Potential Unanalyzed Condition with Containment Pressure Instruments ENS 478622012-04-25T14:00:00025 April 2012 14:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Conditions Resulting from a Non-Conservative Error in Calculations ENS 478842012-03-02T13:41:0002 March 2012 13:41:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Potential Degradation of Reactor Containment Electrical Penetration Seals ENS 476582012-02-10T06:00:00010 February 2012 06:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Guidance Not Adequate to Mitigate a Design Basis Flood ENS 473592011-10-20T15:50:00020 October 2011 15:50:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Flood Barrier Penetrations Not Water Tight ENS 478482011-10-06T18:44:0006 October 2011 18:44:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Waste Disposal System Class One Seismic Support Inoperable ENS 470882011-07-22T13:30:00022 July 2011 13:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Fire Supression Pumps Inoperable ENS 469652011-06-16T17:30:00016 June 2011 17:30:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Additional Penetration Identified for Mitigation During Walkdown ENS 468932011-05-26T05:15:00026 May 2011 05:15:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Potential Flooding Path Discovered ENS 467472011-04-12T14:15:00012 April 2011 14:15:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Unsealed Flood Barrier Penetration ENS 467412011-04-08T15:24:0008 April 2011 15:24:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Unsealed Flood Barrier Penetration ENS 467232011-04-04T20:00:0004 April 2011 20:00:00 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Scaffolding Affecting Safety Related Equipment ENS 467162011-04-01T02:26:0001 April 2011 02:26:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Identified Unsealed Flood Barrier Penetrations ENS 466902011-03-22T18:08:00022 March 2011 18:08:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Potential Flooding of Raw Water Pump ENS 466892011-03-22T15:58:00022 March 2011 15:58:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Containment Coolers Declared Inoperable ENS 466742011-03-15T20:56:00015 March 2011 20:56:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Flood Barrier Penetration Not Sealed ENS 465902011-01-27T22:23:00027 January 2011 22:23:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Unsealed Penetrations Discovered in the Intake Structure 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 462972010-09-30T21:16:00030 September 2010 21:16:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Potential Flooding Via Condensate Drain Lines 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 454672009-10-26T15:50:00026 October 2009 15:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Pressurizer and Feedwater Storage Tank Level Indications Do Not Meet Appendix R Requirements ENS 465942009-09-09T14:02:0009 September 2009 14:02:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Unsealed Penetrations Discovered in the Intake Structure ENS 441382008-04-14T17:45:00014 April 2008 17:45:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident High Energy Line Break Analysis Revealed Potential Accident Mitigation Deficiency ENS 429432006-10-28T22:09:00028 October 2006 22:09:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 429022006-10-12T22:30:00012 October 2006 22:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Steam Generator Instrumentation Nonconformance ENS 428962006-10-10T20:00:00010 October 2006 20:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Containment Spray Valve Mispositioned ENS 425122006-04-19T14:45:00019 April 2006 14:45:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Postulated Scenario Where Containment Spray System May Be Unable to Fulfill Design Safety Function ENS 413862005-02-08T15:20:0008 February 2005 15:20:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Steam-Driven Auxiliary Feedwater (Afw) Pump Declared Inoperable Due to Design Issue 2016-08-25T20:23:00 | |
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