ENS 47783
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ENS Event | |
|---|---|
20:00 Mar 28, 2012 | |
| Title | Degraded Condition Identified in the B Train Containment Cooler Units |
| Event Description | At 1500 on March 28, 2012, Callaway Plant personnel discovered that the installation of a modification on the two 'B' train containment cooler units had inadvertently introduced a potential failure mechanism to the 'B' train containment coolers. Specifically, with the containment cooling fans initially in fast-speed operation, combined with certain initial plant conditions, thermal overload tripping of the coolers could occur.
In such an event, during some postulated accidents, slow-speed restart of the containment coolers by the Load Shedding and Emergency Load Sequencing system could be prevented. As a result, the 'B' train containment coolers could be rendered unavailable for a portion of a postulated accident. Thus, the safety function of the 'B' train containment cooling fans cannot be assured when this degraded equipment condition is present and the containment cooling fans are run in fast-speed operation. This condition existed for the 'B' train containment cooling units since they were restored to service from maintenance at 0400 on March 15, 2012. Upon identification of this condition, the 'B' train containment cooling fans were switched from fast-speed to slow-speed operation and restored to operable status at 1515. This action precludes this degraded equipment condition from adversely affecting containment cooling fan function during an accident. Concurrent with this condition, the opposite train of containment coolers was removed from service for scheduled maintenance at 0505 on March 27, 2012. As a result, from 0505 on March 27, 2012 until 1515 on March 28, 2012, the safety function of the containment cooling system could not be assured for certain postulated accident conditions. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Callaway  Missouri (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-1.57 h-0.0654 days <br />-0.00935 weeks <br />-0.00215 months <br />) | |
| Opened: | Tim Holland 18:26 Mar 28, 2012 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Mar 28, 2012 |
| 47783 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Callaway with 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 | |
WEEKMONTHYEARENS 548062020-07-30T13:15:00030 July 2020 13:15:00
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Mitigate the Consequences of an Accident Discovery of a Condition That Could Have Prevented Fulfillment of a Safety Function ENS 532232018-02-20T18:25:00020 February 2018 18:25:00 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)(ii)(B), Unanalyzed Condition All Three Auxiliary Feedwater Pumps Inoperable Due to Helb Door Being Open ENS 529052017-08-15T16:46:00015 August 2017 16:46:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 526072017-03-13T18:58:00013 March 2017 18:58:00 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)(ii)(B), Unanalyzed Condition Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 518742016-04-20T19:05:00020 April 2016 19:05:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Essential Service Water Pressure Transient ENS 506252014-11-19T01:00:00019 November 2014 01:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - 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Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Two Out of Three Auxiliary Feedwater Pumps Out of Service ENS 424542006-03-30T22:50:00030 March 2006 22:50:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Inadequate Operator Response Time for Component Cooling Water System Realignment During a Large Break Loca ENS 422572006-01-13T14:30:00013 January 2006 14:30:00 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 Pressurizer Porv Stroke Times Exceed Analysis Assumptions ENS 422422006-01-04T19:45:0004 January 2006 19:45:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Related to Emergency Diesel Fuel Oil Tank Vortex Formation ENS 418772005-07-28T02:25:00028 July 2005 02:25:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Two Trains of Control Room Emergency Ventilation Systems (Crevs) Inoperable and Not Restored within 24 Hours ENS 413262005-01-12T19:30:00012 January 2005 19:30:00 Other Unspec Reqmnt, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 24 Hour Condition of License Report Regarding Halon System Actuator Port Connection Error ENS 403732003-12-03T18:30:0003 December 2003 18:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Emergency Procedure Deficiency Causes Unanalyzed Condition 2020-07-30T13:15:00 | |
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