ENS 42093
ENS Event | |
|---|---|
03:32 Oct 29, 2005 | |
| Title | Technical Specification Required Shutdown Due to Inoperable Control Rods |
| Event Description | On 10/28/2005, Susquehanna Unit 1 operators began the process of shutting down the unit for a maintenance outage to address control cell friction. It was expected that during this evolution, "slow to settle" control rods would be encountered, and rather than delay the continuance of the shutdown to perform operability testing, it was determined that these control rods would conservatively be declared inoperable. Based on previous testing data and trending analysis of operability testing performed during the cycle, PPL [Pennsylvania Power and Light] believes that the subject control rods would have passed operability tests.
Accordingly, at 2332 EDT, Technical Specification 3.1.3.f was entered which requires the unit to be taken to Mode 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when nine or more control rods are inoperable. Entry into this specification was also required per 3.1.3.e when it was determined that four inoperable rods resided within one Banked Position Withdrawal Sequence (BPWS) group. The inoperable control rods are fully inserted and disarmed, shutdown margin requirements are met, and the control rod system was always fully capable of performing its safety function. At the time when the ninth control rod was declared inoperable, Unit One was operating at 18% power. Unit Two is continuing operation at 100% power. PPL is reporting this event as a Technical Specification required shutdown per 10CFR 50.72(b)(2)(i). The NRC Resident Inspector was notified by the licensee. Unit 2 is not affected by this problem and will continue to operate at 100% power.
At 0744 the plant reached All Rods In and at 0805 entered Mode 3 in accordance with plant procedures to fulfill the requirement of Technical Specification 3.1.3. As stated in the original EN# 42093, it was expected that during this evolution, "slow to settle"' control rods would be encountered, and rather than delay the continuance of the shutdown to perform operability testing, it was determined that these control rods would conservatively be declared inoperable. This action was taken on a total of 41 control rods that failed to settle at position 00 during the shutdown. There are 4 additional control rods that were declared inoperable previously during the cycle and subsequently settled to 00. Of the 41 control rods that failed to settle at the time of the shutdown, 6 have settled to 00 at the time of this update. Based on previous testing data and trending analysis of operability testing performed during the cycle, PPL continues to believe that the subject control rods would have passed operability tests. The inoperable control rods are fully inserted, shutdown margin requirements are met, and the control rod system was always fully capable of performing its safety function. There were no ECCS initiations and no challenges to containment. The licensee notified the NRC Resident Inspector. R1DO (Silk) notified. |
| Where | |
|---|---|
Susquehanna  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
| Time - Person (Reporting Time:+-1.8 h-0.075 days <br />-0.0107 weeks <br />-0.00247 months <br />) | |
| Opened: | Rich Klinefelter 01:44 Oct 29, 2005 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Oct 29, 2005 |
| 42093 - 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 42093\u003C/a\u003E - \u003Ca href=\"/Susquehanna\" title=\"Susquehanna\"\u003ESusquehanna\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003ETechnical Specification Required Shutdown Due to Inoperable Control Rods\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 42093 - Susquehanna\n","link":"","lat":41.09256666666667,"lon":-76.14176944444445,"icon":"/w/images/c/c7/Talen_Energy_icon.png"}],"imageoverlays":null} | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (18 %) |
| After | Power Operation (18 %) |
WEEKMONTHYEARENS 540782019-05-22T06:56:00022 May 2019 06:56:00
[Table view]10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Technical Specification Required Shutdown ENS 519832016-06-06T09:56:0006 June 2016 09:56:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Isolable Leakage Identified from Seal Water Line Weld Inside Rcs Pressure Boundary ENS 485952012-12-14T18:50:00014 December 2012 18:50:00 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 Technical Specification Required Shutdown - Control Structure Chillers Inoperable ENS 480362012-06-19T21:20:00019 June 2012 21:20:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Mode Change Required by Technical Specifications ENS 466542011-03-04T03:59:0004 March 2011 03:59:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Techncial Specification Required Shutdown Due to Inoperable Hpci ENS 437222007-10-13T06:20:00013 October 2007 06:20:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Inoperable Control Rods ENS 423852006-03-04T10:17:0004 March 2006 10:17:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Control Rods Declared Inoperable During Shutdown ENS 420932005-10-29T03:32:00029 October 2005 03:32:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Inoperable Control Rods ENS 415852005-04-10T15:50:00010 April 2005 15:50:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Technical Specification Required Shutdown Due to Failed 125V Dc Battery Charger 2019-05-22T06:56:00 | |