ENS 48525
From kanterella
Jump to navigation
Jump to search
ENS Event | |
|---|---|
11:45 Nov 20, 2012 | |
| Title | Condition That Could Have Prevented Automatic Isolation of Reactor Water Cleanup System |
| Event Description | Susquehanna Unit 2 discovered a condition that could have prevented the primary containment isolation valves for the reactor water cleanup (RWCU) system from automatically isolating on a high differential flow instrumentation signal.
The RWCU system high differential flow signal was found to be indicating downscale due to an instrument failure. Both divisions of the RWCU high differential flow isolation logic utilize the same differential flow instrument loop. Thus, this single instrument failure would have prevented automatic isolation of the RWCU inboard and outboard primary containment isolation valves on a high differential flow signal. The other RWCU primary containment isolation instrumentation functions remained operable and the associated RWCU system primary containment isolation valves were capable of being remotely closed by the control room operators. At the time of discovery, Unit 2 was in Mode 2 due to an unplanned shutdown and all control rods had already been fully inserted as part of a soft shutdown sequence. The licensee has notified the NRC Resident Inspector.
Following the ENS report (EN 48525), Susquehanna determined that although the RWCU high differential flow isolation instrumentation would have prevented automatic isolation of the RWCU inboard and outboard primary containment isolation valves on a high differential flow signal, the RWCU high flow isolation instrumentation would detect a high flow condition and generate an isolation signal that would close the isolation valves. The RWCU high differential flow instrumentation is downstream of the RWCU pumps and it calculates the difference (delta) in flow between the inlet and the outlet of the RWCU heat exchangers. The SSES [Susquehanna Steam Electric Station] Technical Specification (TS) Bases Section 3.3.6.1 states that the RWCU Differential Flow signal is to detect a break in the RWCU system (pipe severance and separation). Engineering analysis determined that the RWCU pumps would run-out if a break occurs downstream of the pumps and the RWCU system flow rate would be approximately 1000 gpm, with one RWCU pump in operation. The flow rate would be higher for two RWCU pumps in operation. Therefore, RWCU isolation would occur from the RWCU Flow - High isolation signal due to a flow rate that is greater than 472 gpm (TS Table 3.3.6.1-1). This high flow isolation does not rely on the RWCU high differential flow instrumentation. The above analysis is consistent with the FSAR discussion in section 7.3.1.1a.2.4.1.9.3. Based on the above, Susquehanna has determined that the RWCU isolation function would still be completed if a pipe break occurred downstream of the RWCU heat exchangers and the RWCU high differential flow instrumentation is inoperable. Since there was no loss of safety function of structures or systems that are needed to control the release of radioactive material, this ENS report is retracted. The licensee will notify the NRC Resident Inspector. |
| Where | |
|---|---|
Susquehanna  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+0.75 h0.0313 days <br />0.00446 weeks <br />0.00103 months <br />) | |
| Opened: | Todd Creasy 12:30 Nov 20, 2012 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jan 11, 2013 |
| 48525 - 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 48525\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\u003ECondition That Could Have Prevented Automatic Isolation of Reactor Water Cleanup System\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 48525 - Susquehanna\n","link":"","lat":41.09256666666667,"lon":-76.14176944444445,"icon":"/w/images/c/c7/Talen_Energy_icon.png"}],"imageoverlays":null} | |
Susquehanna with 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
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 533102018-04-03T04:19:0003 April 2018 04:19:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Following Surveillance Testing ENS 532022018-02-12T03:03:00012 February 2018 03:03:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Differential Pressure Out of Specification ENS 530982017-11-30T15:26:00030 November 2017 15:26:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Differential Pressure Briefly Indicated Outside of Tech Spec Limit ENS 529732017-09-16T17:30:00016 September 2017 17:30:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Differential Pressure ENS 528922017-08-09T00:44:0009 August 2017 00:44:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Differential Pressure ENS 528442017-07-10T06:50:00010 July 2017 06:50:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Due to Failure of Non-Safety Related Discharge Damper ENS 528262017-06-24T14:28:00024 June 2017 14:28:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment ENS 527972017-06-09T09:09:0009 June 2017 09:09:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Exhaust Fan Breaker Failure Causing Low Secondary Containment Differential Pressure ENS 525992017-03-08T07:39:0008 March 2017 07:39:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Due to Containment Fan Trip ENS 525522017-02-15T18:37:00015 February 2017 18:37:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Differential Pressure ENS 523692016-11-16T15:45:00016 November 2016 15:45:00 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)(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 Failure of Unit 2 B Engineered Safeguards System Bus Sync Selector Switch ENS 522662016-09-27T20:44:00027 September 2016 20:44:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Leakage Exceeding Requirements ENS 522552016-09-22T07:20:00022 September 2016 07:20:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Differential Pressure ENS 519252016-05-13T05:10:00013 May 2016 05:10:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Manual Reactor Scram Due After Loss of an Essential Motor Control Center ENS 518722016-04-20T01:59:00020 April 2016 01:59:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Inoperable Secondary Containment ENS 518512016-04-06T17:37:0006 April 2016 17:37:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Reactor Building Airlock Doors Opened Simultaneously ENS 518302016-03-30T02:56:00030 March 2016 02:56:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Differential Pressure ENS 517772016-03-08T07:32:0008 March 2016 07:32:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Differential Pressure Outside Specification ENS 517642016-03-02T18:30:0002 March 2016 18:30:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Inoperable ENS 517502016-02-22T18:45:00022 February 2016 18:45:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Unit 1 Secondary Containment Inoperable When Personnel Opened Both Access Doors Simultaneously ENS 515882015-12-06T10:46:0006 December 2015 10:46:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Differential Pressure Due to Exhaust Fan Trip ENS 515872015-12-06T08:50:0006 December 2015 08:50:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Differential Pressure Due to Icing of Intake Supply Plenum Screens ENS 515762015-12-01T17:45:0001 December 2015 17:45:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Inoperable Due to Reactor Building Airlock Doors Being Opened Simultaneously ENS 515332015-11-12T16:32:00012 November 2015 16:32:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Inoperable ENS 514322015-09-29T14:30:00029 September 2015 14:30:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Both Trains of the Standby Gas Treatment System Declared Inoperable ENS 513552015-08-27T17:47:00027 August 2015 17:47:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Brief Loss of Secondary Containment Due to Both Airlock Doors Open Simultaneously ENS 512692015-07-27T15:18:00027 July 2015 15:18:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Due to Opening Single Door Without Proper Authorization ENS 510402015-05-04T18:39:0004 May 2015 18:39:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Low Differential Pressure Resulting in Loss of Secondary Containment ENS 510172015-04-27T12:50:00027 April 2015 12:50:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Boundary Door Found Ajar ENS 510012015-04-22T02:58:00022 April 2015 02:58:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Inoperable Secondary Containment ENS 509742015-04-11T04:51:00011 April 2015 04:51:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Inoperable Due to Failure of Running Fans ENS 508852015-03-13T13:19:00013 March 2015 13:19:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment Due to Ventilation Plenum Door Open ENS 505952014-11-05T16:15:0005 November 2014 16:15:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Zones 2 and 3 Unintentionally Crosstied ENS 500552014-04-24T06:30:00024 April 2014 06:30:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment During Routine Swap of a Power Supplies ENS 500402014-04-17T07:35:00017 April 2014 07:35:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Loss of Secondary Containment During Preparation for Loca/Loop Testing ENS 498842014-03-08T08:25:0008 March 2014 08:25:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Unit 2 Loss of Secondary Containment Due to Discharge Damper Failure ENS 498672014-03-04T05:25:0004 March 2014 05:25:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Declared Inoperable During Surveillance Testing ENS 498212014-02-12T12:11:00012 February 2014 12:11:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Boundry Door Found Ajar ENS 496142013-12-07T14:50:0007 December 2013 14:50:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Fails Retest of Drawdown Surveillance Test ENS 495882013-11-27T15:01:00027 November 2013 15:01:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Unit 1 Reactor Building Secondary Containment Differential Pressure Out of Specification ENS 495652013-11-21T03:40:00021 November 2013 03:40:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Fails Drawdown Surveillance Testing ENS 495312013-11-13T07:26:00013 November 2013 07:26:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Zone II Differential Pressure Lost During Recovery from Ventilation Drawdown Test ENS 494922013-11-01T07:09:0001 November 2013 07:09:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Differential Pressure Not within Limits Following Trip of Exhaust Fan ENS 494892013-10-31T06:51:00031 October 2013 06:51:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Differential Pressure Not within Limits Following Trip of Exhaust Fan ENS 494652013-10-23T10:20:00023 October 2013 10:20:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Reactor Building Differential Pressure Less than Required by Technical Specifications ENS 494322013-10-13T08:20:00013 October 2013 08:20:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Secondary Containment Differential Pressure at Zero Inches Water Gauge ENS 485252012-11-20T11:45:00020 November 2012 11:45:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Condition That Could Have Prevented Automatic Isolation of Reactor Water Cleanup System ENS 478442012-04-17T19:40:00017 April 2012 19:40:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Unit 2 Secondary Containment Affected by Violation of Unit 1 Secondary Containment Integrity During Outage ENS 439632008-02-05T23:45:0005 February 2008 23:45:00 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 Irradiated Fuel Movement Performed with a Required Accident Mitigation/Radiation Release System Bypassed ENS 435632007-08-13T18:20:00013 August 2007 18:20:00 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 Inoperable Radiation Monitors Due to Setpoint Calculation Errors ENS 412152004-11-22T20:10:00022 November 2004 20:10:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Portion of Primary Instrument Lines Not Aligned to Secondary Containment ENS 409702004-08-20T16:15:00020 August 2004 16:15:00 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Railroad Access Process Radiation Monitors Actuation Capability Was Inadvertently Defeated ENS 406462004-04-05T15:40:0005 April 2004 15:40:00 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)(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 Loss of Safety Function for Emergency Diesel Generators During Surveillance Testing 2019-05-22T06:56:00 | |
Retrieved from "https://kanterella.com/w/index.php?title=ENS_48525&oldid=423365"