ENS 50800
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ENS Event | |
|---|---|
23:30 Feb 9, 2015 | |
| Title | Safety Injection Tank Level Results in an Unanalyzed Condition |
| Event Description | On October 14, 2013 a calculation for the containment internal structural analysis was revised and accepted by the station. This calculation limited the Safety injection tank level to 74%. On October 16, 2013 Safety injection tank level was raised to 100% for approximately 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> in preparations for plant start-up. While the plant was safely in a cold shutdown condition, this represents a reportable unanalyzed condition. This issue is of a historical nature and does not question the current operability of any plant systems or structures. This was self identified during a Fort Calhoun calculation review.
The licensee notified the NRC Resident Inspector.
Following review of the reported event, attendant calculations and associated documentation, engineering personnel determined that the condition described in event notification EN50800 did not place the plant in an unanalyzed condition. Revision 1 of a calculation for the containment internal structural analysis demonstrated that when the safety injection tanks 'B' and 'D' are 100% filled in an outage condition, approximately a 10% safety margin is maintained. This revision was the calculation of record at the time the safety injection tank levels were raised above 74%, in October, 2013. Revision 2 of the calculation was completed to remove excess conservatism and to provide a closer representation of available margin. In addition, margin was also improved by limiting tank level to 74%. However, improving margin by limiting tank level to 74% does not result in an unanalyzed condition when tank level is 100%, as adequate margin remains. Therefore this event is being retracted. The licensee will notify the NRC Resident Inspector. Notified the R4DO (Okeefe). |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+1.92 h0.08 days <br />0.0114 weeks <br />0.00263 months <br />) | |
| Opened: | Scott Moeck 01:25 Feb 10, 2015 |
| NRC Officer: | Vince Klco |
| Last Updated: | Mar 12, 2015 |
| 50800 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 522012016-08-25T20:23:00025 August 2016 20:23:00
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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 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 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 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 2016-08-25T20:23:00 | |
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