ENS 47848
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ENS Event | |
|---|---|
18:44 Oct 6, 2011 | |
| Title | Waste Disposal System Class One Seismic Support Inoperable |
| Event Description | The Waste Disposal System [WDS] Class 1 piping requires operable seismic supports downstream of the isolation valve class break. Currently, eight (8) INC [International Nuclear Safety, Corp.] snubbers have been degraded to [Non Nuclear System] NNS Class 4 ridged struts. The snubbers original design function was to allow thermal motion but restrain seismic motion.
The snubbers have been identified as potential to create an unanalyzed condition that over stresses the safety class 1 drain pipe upstream of the isolation valve if the snubbers on the drain pipe downstream of the isolation valve were in a locked condition (acting as a strut). Per NRC bulletin 81-01, these snubbers are assumed to be frozen and do not allow movement of the pipe; thus, they have been degraded to rigid struts as they are not in the snubber program and are not tested. They still provide a seismic safety function for [class] II/I issues and act as a strut to provide horizontal restraint to the WDS piping. The snubbers were removed from the piping system and tested to determine their performance and if they would have moved to allow thermal growth. Six snubbers failed the test and were either in a locked condition or their movement was dimensionally small relative to the required movement. The [Reactor Coolant System] RCS is within acceptable stress values with the snubbers removed. The 8-hour regulatory reporting time has been exceeded. An initial Reportability Evaluation was completed on March 26, 2012 and had determined the supports were operable. A second Reportability Evaluation later determined the supports have been inoperable since October 6, 2011. The WDS is used to drain the RCS. The licensee will notify the NRC Resident Inspector.
Additional review and testing demonstrated that [there was] no degradation of the RCS from thermal fatigue. The analysis demonstrates adequate past performance of the snubbers with regard to thermal fatigue. The impact of the snubber has been analyzed and determined to have not resulted in an unanalyzed condition that significantly degraded plant safety. Therefore, this event is being retracted. The failure to retract this notification in a timely fashion has been entered into the corrective action system. The licensee will notify the NRC Resident Inspector. Notified R4DO (Werner). |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+4680.15 h195.006 days <br />27.858 weeks <br />6.411 months <br />) | |
| Opened: | Amy Burkhart 18:53 Apr 18, 2012 |
| NRC Officer: | John Shoemaker |
| Last Updated: | Sep 26, 2012 |
| 47848 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
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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