ENS 52260
ENS Event | |
|---|---|
03:47 Sep 21, 2016 | |
| Title | |
| Event Description | On 9/20/2016, a coupling sleeve on a pipe whip restraint located on the 119 foot elevation of the turbine building associated with Unit 2 main steam line 4 was found to be not engaged. As a result of the detached coupling, the restraint was not capable of performing its restraint function for a postulated pipe whip event on the main steam line. The coupling was reconnected on 9/20/2016, restoring its functionality. An extent of condition walkdown was subsequently performed for the other Unit 1 and Unit 2 steam line restraints and no similar issues were identified.
This concern did not result in any adverse effect on the radiological health and safety of the public. The purpose of this whip restraint is to restrain the steam line for a postulated loss at the G-line anchor (east side of Turbine Building above the 104 foot elevation). The restraint protects the floor slab at the 104 foot elevation, which extends over the Unit 2 component cooling water heat exchangers. With the detached coupling, equipment in the area may have been vulnerable to damage if a pipe whip event occurred. Further analysis is needed to conclude whether the heat exchangers and other equipment would have remained protected in such an event and whether this would have significantly affected the designed plant response to a pipe event. Based on the need for further analysis, this event is being reported as an unanalyzed condition that may have significantly degraded plant safety in accordance with 10 CFR 50.72(b)(3)(ii)(B). The NRC Senior Resident Inspector was notified.
The purpose of this notification is to retract a previous report made on EN #52260, reported 9/23/2016. NRC notification was initially made as a result of a condition that required further analysis to determine whether the condition would have significantly degraded plant safety in accordance with 10 CFR 50.72(b)(3)(ii)(B). Further analysis of the condition concluded that PG&E Design Class I equipment located inside the Turbine Building would have remained undamaged and capable of performing their safety functions. The Turbine Building would not have experienced failure of major structural elements or adverse impact to the overall building stability. Therefore, the coupling sleeve on a pipe whip restraint located on the 119 foot elevation of the Turbine Building associated with Unit 2 main steam line 4 that was found to be not engaged did not constitute an unanalyzed condition that may have significantly degraded plant safety in accordance with 10 CFR 50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified. Notified R4DO (Azua) |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+64.38 h2.683 days <br />0.383 weeks <br />0.0882 months <br />) | |
| Opened: | Bryan Galvan 20:10 Sep 23, 2016 |
| NRC Officer: | Dong Park |
| Last Updated: | Nov 18, 2016 |
| 52260 - NRC Website
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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 | |