Browse wiki
Jump to navigation
Jump to search
100 +
At 0519 CDT on June 17th, Unit 2 was closi … At 0519 CDT on June 17th, Unit 2 was closing the 2CS009B, Containment Spray Recirc Sump Isolation Valve, as part of post maintenance testing when the valve stopped stroking (i.e. mid position). The 2CS009B valve was being stroked closed for restoration from a successful timed stroke in the open direction. The 2CS009B valve was manually closed and verified closed via limit switch indication.</br>With the 2CS009B valve unable to be closed from the Main Control Room, an unanalyzed condition may have existed where, during a large break LOCA requiring cold leg recirc, the Refueling Water Storage Tank (RWST) had an additional flow path to the containment recirc sump. This potentially challenges the operators to complete the switchover prior to the RWST reaching 9%, the point at which pumps taking a suction from the RWST only are shutdown. This condition is still being evaluated.</br>The licensee notified the NRC Resident Inspector.</br> * * * RETRACTION FROM P. MOODY TO P. SNYDER AT 0404 ON 2/1/11 * * *</br>At 0509 on June 17, 2010, Unit 2 was closing the 2CS009B, Containment Spray (CS) Recirculation Sump Isolation Valve, as part of post maintenance testing when the valve stopped stroking (i.e., mid-position). The 2CS009B was being stroked closed for restoration from a successful timed stroke in the open direction. The 2CS009B was manually closed and verified closed via limit switch indication. </br>With the 2CS009B unable to close from the Main Control Room, an unanalyzed condition may have existed where, during a large break LOCA requiring cold leg recirculation, the Refueling Water Storage Tank (RWST) had an additional flow path to the recirculation sump. This potentially challenged the operators to complete the switchover prior to the RWST reaching 9%, the point at which pumps taking a suction from the RWST only are shutdown. While this condition was being evaluated, an ENS notification was made per ENS 46021 under 10CFR50.72(b)(3)(ii)(B).</br>As the evaluation approached the 60-day reporting period, LER 2010-002 was issued in accordance with 10 CFR 50.73(a)(2)(ii)(B), assuming the results would yield an unanalyzed condition.</br>Since then, an evaluation was completed. The results concluded the operators would have performed the switchover steps within the allowed time, before reaching the RWST empty alarm set point. Therefore, the Emergency Core Cooling System (ECCS) and CS system would have performed their design functions. The evaluation also determined the RWST outflows with 2CS009B in the open position during the ECCS switchover sequence did not affect the RWST vortex analysis. Based on no loss of design function, the plant was not in an unanalyzed condition and this event is not reportable per 10CFR 50.72(b)(3)(ii)(B) or 10CFR 50.73(a)(2)(ii)(B). This event was screened for additional reportability criteria contained in the Exelon Reportability Manual. Again, since there was no loss of design function there is no reportability requirement.</br>Therefore ENS notification 46021 is being retracted.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector.
10:19:00, 17 June 2010 +
46,021 +
14:15:00, 17 June 2010 +
10:19:00, 17 June 2010 +
At 0519 CDT on June 17th, Unit 2 was closi … At 0519 CDT on June 17th, Unit 2 was closing the 2CS009B, Containment Spray Recirc Sump Isolation Valve, as part of post maintenance testing when the valve stopped stroking (i.e. mid position). The 2CS009B valve was being stroked closed for restoration from a successful timed stroke in the open direction. The 2CS009B valve was manually closed and verified closed via limit switch indication.</br>With the 2CS009B valve unable to be closed from the Main Control Room, an unanalyzed condition may have existed where, during a large break LOCA requiring cold leg recirc, the Refueling Water Storage Tank (RWST) had an additional flow path to the containment recirc sump. This potentially challenges the operators to complete the switchover prior to the RWST reaching 9%, the point at which pumps taking a suction from the RWST only are shutdown. This condition is still being evaluated.</br>The licensee notified the NRC Resident Inspector.</br> * * * RETRACTION FROM P. MOODY TO P. SNYDER AT 0404 ON 2/1/11 * * *</br>At 0509 on June 17, 2010, Unit 2 was closing the 2CS009B, Containment Spray (CS) Recirculation Sump Isolation Valve, as part of post maintenance testing when the valve stopped stroking (i.e., mid-position). The 2CS009B was being stroked closed for restoration from a successful timed stroke in the open direction. The 2CS009B was manually closed and verified closed via limit switch indication. </br>With the 2CS009B unable to close from the Main Control Room, an unanalyzed condition may have existed where, during a large break LOCA requiring cold leg recirculation, the Refueling Water Storage Tank (RWST) had an additional flow path to the recirculation sump. This potentially challenged the operators to complete the switchover prior to the RWST reaching 9%, the point at which pumps taking a suction from the RWST only are shutdown. While this condition was being evaluated, an ENS notification was made per ENS 46021 under 10CFR50.72(b)(3)(ii)(B).</br>As the evaluation approached the 60-day reporting period, LER 2010-002 was issued in accordance with 10 CFR 50.73(a)(2)(ii)(B), assuming the results would yield an unanalyzed condition.</br>Since then, an evaluation was completed. The results concluded the operators would have performed the switchover steps within the allowed time, before reaching the RWST empty alarm set point. Therefore, the Emergency Core Cooling System (ECCS) and CS system would have performed their design functions. The evaluation also determined the RWST outflows with 2CS009B in the open position during the ECCS switchover sequence did not affect the RWST vortex analysis. Based on no loss of design function, the plant was not in an unanalyzed condition and this event is not reportable per 10CFR 50.72(b)(3)(ii)(B) or 10CFR 50.73(a)(2)(ii)(B). This event was screened for additional reportability criteria contained in the Exelon Reportability Manual. Again, since there was no loss of design function there is no reportability requirement.</br>Therefore ENS notification 46021 is being retracted.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector.
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>.
100 +
00:00:00, 1 February 2011 +
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>.
02:07:56, 2 March 2018 +
14:15:00, 17 June 2010 +
true +
false +
0.164 d (3.93 hours, 0.0234 weeks, 0.00538 months) +
10:19:00, 17 June 2010 +
Unanalyzed Condition Due to Containment Spray Recirc Sump Isolation Valve Failure to Stroke Closed +
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.