ENS 47223
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ENS Event | |
|---|---|
00:24 Aug 30, 2011 | |
| Title | Maintenance Inadvertently Renders Control Room Ventilation System Inoperable |
| Event Description | On August 29, 2011, at 1724 PDT, plant operators discovered that the Control Room Envelope (CRE) boundary required by Technical Specification (TS) 3.7.10, 'Control Room Ventilation System (CRVS),' lost its integrity. This was due to maintenance personnel removing a blank flange on the line to Unit 2 CRVS dampers MOD-2 and MOD-2A with the dampers inoperable.
On August 29, 2011, at approximately 1400 PDT, plant personnel completed maintenance on Unit 2 control room dampers MOD-2 and MOD-2A and planned to perform static testing of the CRE on the morning of August 30, 2011. Prior to reporting off the clearance, maintenance personnel removed a blank flange from the upstream side of the dampers. This blank flange was maintaining the integrity of the CRE boundary while dampers MOD-2 and MOD-2A were inoperable during the maintenance. Upon completion of maintenance on the dampers, the blank flange was removed with shift foreman authorization. Later, personnel recognized that the flange had been removed prematurely while dampers MOD-2 and MOD-2A were still inoperable. Personnel took required actions associated with TS 3.7.10 and re-installed the blank flange on August 30, 2011, at 0110 PDT. The loss of the CRE boundary rendered the CRVS incapable of performing its specified safety function of mitigating the exposure of control room personnel to the consequences of an accident. The cause of the event was inadequate coordination between maintenance personnel and plant operators to maintain the integrity of the CRE boundary. Plant personnel notified the NRC Resident Inspector. |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+16.67 h0.695 days <br />0.0992 weeks <br />0.0228 months <br />) | |
| Opened: | Glenn Goelzer 17:04 Aug 30, 2011 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Aug 30, 2011 |
| 47223 - NRC Website
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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 %) |
WEEKMONTHYEARENS 544172019-11-30T19:00:00030 November 2019 19:00:00
[Table view]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 Both Trains of Containment Spray Removed from Service ENS 522602016-09-21T03:47:00021 September 2016 03:47:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Steam Line Pipe Whip Restraint Coupling Sleeve Found Not Engaged ENS 503342014-08-01T00:29:0001 August 2014 00:29:00 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)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Unanalyzed Condition ENS 498792014-03-06T17:06:0006 March 2014 17:06:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Regarding Potential Tornado Missile Damage to Emergency Diesel Exhaust Plenum ENS 496632013-12-19T15:52:00019 December 2013 15:52:00 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 Two of Three Emergencey Diesel Generators Inoperable at the Same Time ENS 496342013-12-14T23:03:00014 December 2013 23:03:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Affecting Unit 1 Emergency Diesel Generator ENS 491482013-06-26T04:58:00026 June 2013 04:58:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 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, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown Plant Shutdown Required Due to Rhr System Socket Weld Leak ENS 491472013-06-24T23:15:00024 June 2013 23:15:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Emergency Diesel Generators Unavailable for Auto-Start ENS 487262013-02-06T23:24:0006 February 2013 23:24:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition for Control Room Ventilation ENS 483952012-10-04T01:15:0004 October 2012 01:15:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Fire Protection Deficiencies ENS 482462012-08-29T00:00:00029 August 2012 00:00:00 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 Mitigating Actions Implemented for Inoperable Control Room Envelope ENS 475642011-12-31T10:00:00031 December 2011 10:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Fire Barrier Rating of Vital Swtichgear Walls May Not Meet Standards ENS 474142011-11-03T22:50:0003 November 2011 22:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Control Room Ventilation Single Point Vulnerability ENS 472582011-09-13T00:45:00013 September 2011 00:45:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Control Room Envelope Declared Inoperable ENS 472232011-08-30T00:24:00030 August 2011 00:24:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Maintenance Inadvertently Renders Control Room Ventilation System Inoperable ENS 465312011-01-10T21:21:00010 January 2011 21:21:00 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 Both Trains of Auxiliary Building Ventilation Became Inoperable ENS 457542010-03-10T03:16:00010 March 2010 03:16:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Potential Loss of 1E Pumps Due to Degraded Voltage During Postulated Accidents ENS 454612009-10-23T15:00:00023 October 2009 15:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Post Loca Recirculation Valve Position Interlocks ENS 449272009-03-22T20:34:00022 March 2009 20:34:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unit 1 Steam Generator Found in an Unanalyzed Condition Related to Gaps on Seismic Washer Plates 2019-11-30T19:00:00 | |
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