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ENS 47783
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Category
ENS Notification  and Power Reactor
CFR
10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident +  and 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition +
Current power
100  +
Current reactor mode
Power Operation +
Description
At 1500 on March 28, 2012, Callaway Plant … 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.</br>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.</br>This condition existed for the 'B' train containment cooling units since they were restored to service from maintenance at 0400 on March 15, 2012.</br>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.</br>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.</br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified.  +
Discovered date
20:00:00, 28 March 2012  +
ENS id number
47,783  +
Emergency class
Non Emergency +
Entered date
18:26:00, 28 March 2012  +
Event date
20:00:00, 28 March 2012  +
Event description
At 1500 on March 28, 2012, Callaway Plant … 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.</br>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.</br>This condition existed for the 'B' train containment cooling units since they were restored to service from maintenance at 0400 on March 15, 2012.</br>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.</br>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.</br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified.  +
Has query"Has query" is a predefined property that represents meta information (in form of a <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Subobject">subobject</a>) about individual queries and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +, ENS 47783 +  and ENS 47783 +
Initial power
100  +
Initial reactor mode
Power Operation +
Last update date
00:00:00, 28 March 2012  +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
02:04:33, 2 March 2018  +
NRC officer
Bill Huffman +
Notification date
18:26:00, 28 March 2012  +
Originated by
Tim Holland +
Reactor critical
true  +
Reactor scram
false  +
Reactor type
Westinghouse PWR 4-Loop +
Region
NRC Region 4 +
Reporting criterion
10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident +  and 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition +
Reporting time
-0.0654 d (-1.57 hours, -0.00935 weeks, -0.00215 months)  +
Site
Callaway +
Start date
20:00:00, 28 March 2012  +
State
Missouri +
Title
Degraded Condition Identified in the B Train Containment Cooler Units  +
URL"URL" is a <a href="/Special:Types/URL" title="Special:Types/URL">type</a> and predefined property provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a> to represent URI/URL values.
http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2012/20120329en.html#en47783  +
Unit
1  +
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