ENS 48334
From kanterella
Jump to navigation
Jump to search
ENS Event | |
|---|---|
20:00 Sep 21, 2012 | |
| Title | Isolation Valves Could Fail to Fully Close |
| Event Description | A review of load sequencing during a design basis loss of coolant accident (LOCA) with offsite power available has identified an issue with 24 motor operated valves (MOVs - 12 per unit). These valves all use limit switch 8 (LS-8) as an isolation permissive and may indicate closed if they are in a dead band zone when stroking closed from a containment isolation signal at the time of the load shed. The valves will then not resume movement to full isolation when power is restored potentially impacting containment leakage. This condition could occur during specific LOCA conditions, dependent on several variables.
The systems affected by this issue are: - RWCU - DWCW - PCIG - CAC - Suppression Pool Cleanup Actions are in progress to resolve the LS-8 issue with a modification to remove this vulnerability. Appropriate testing will be done to prove that all valves perform their required safety function after the modifications are complete for each valve. All affected valves are either closed and de-energized, or have been modified at this time. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Limerick  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| LER: | 05000352/LER-2012-007 |
| Time - Person (Reporting Time:+1.48 h0.0617 days <br />0.00881 weeks <br />0.00203 months <br />) | |
| Opened: | Dan Williamson 21:29 Sep 21, 2012 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Sep 21, 2012 |
| 48334 - 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 48334\u003C/a\u003E - \u003Ca href=\"/Limerick\" title=\"Limerick\"\u003ELimerick\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003EIsolation Valves Could Fail to Fully Close\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 48334 - Limerick\n","link":"","lat":40.22646666666667,"lon":-75.58323333333334,"icon":"/w/images/b/be/Constellation_icon.png"}],"imageoverlays":null} | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Limerick with 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
WEEKMONTHYEARENS 527382017-05-08T13:25:0008 May 2017 13:25:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Through-Wall Leakage Identified on Reactor Coolant System Pressure Boundary During Testing ENS 518092016-03-21T01:54:00021 March 2016 01:54:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Technical Specification (Ts) Required Shutdown Due to Pressure Boundary Leakage ENS 506702014-12-11T14:45:00011 December 2014 14:45:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Both Secondary Containment Airlock Doors Opened Simultaneously ENS 497062014-01-09T16:35:0009 January 2014 16:35:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Entry Into & Exit from Technical Specification 3.6.5.1.1 Due to Open Air Lock Doors ENS 496592013-12-18T19:09:00018 December 2013 19:09:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Unit 2 Secondary Containment Integrity ENS 496512013-12-18T14:39:00018 December 2013 14:39:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Unit 1 Secondary Containment Integrity ENS 495262013-11-10T18:51:00010 November 2013 18:51:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Integrity Momentarily Declared Inoperable ENS 493182013-09-03T10:46:0003 September 2013 10:46:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Access Air Lock Doors Opened Simultaneously Resulting in Momentary Degradation ENS 483722012-10-03T20:00:0003 October 2012 20:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Fire Safe Shutdown Analysis Failed to Identify Unprotected Cable ENS 483342012-09-21T20:00:00021 September 2012 20:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Isolation Valves Could Fail to Fully Close ENS 453072009-08-28T03:10:00028 August 2009 03:10:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Non-Conservative Technical Specification Setpoints Discovered 2017-05-08T13:25:00 | |
Retrieved from "https://kanterella.com/w/index.php?title=ENS_48334&oldid=423606"