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ENS 46708
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Category
ENS Notification  and Power Reactor
CFR
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#b3v +  and 10 CFR 50.72#b3ii +
Current power
0  +  and 100  +
Current reactor mode
Power Operation +  and Refueling +
Description
The design of the Auxiliary Feedwater (AF) … The design of the Auxiliary Feedwater (AF) system is for the AF pumps to normally take suction from the condensate storage tank. If the condensate storage tank is not available, the essential service water system provides the alternate supply. Due to the AF system suction piping and valve configuration, a voided section of pipe could exist in the portion that isolates the condensate storage tank supply from the essential service water supply. A preliminary vendor analysis has determined that the void fraction to reach the pump in a dynamic scenario exceeds the acceptance criteria for AF pump operability. Based on past operation in this configuration, the event is being reported as a unanalyzed condition that significantly degrades plant safety and a condition that could have prevented the fulfillment of a safety function (i.e., remove residual heat) under 10CFR50.72(b)(3)(ii) and 10CFR50.72(b)(3)(v). Further review of the void model and pump performance characteristics are planned.</br>In 2011, prior to the completion of this analysis. The void was refilled and verified full for both trains at Byron U1 and U2.</br>Unit 1 is defueled. This condition affects both 'A' and 'B' trains of auxiliary feedwater for both Unit 1 and Unit 2.</br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified.  +
Discovered date
01:00:00, 30 March 2011  +
Emergency class
Non Emergency +
Entered date
01:39:00, 30 March 2011  +
Event date
01:00:00, 30 March 2011  +
Event description
The design of the Auxiliary Feedwater (AF) … The design of the Auxiliary Feedwater (AF) system is for the AF pumps to normally take suction from the condensate storage tank. If the condensate storage tank is not available, the essential service water system provides the alternate supply. Due to the AF system suction piping and valve configuration, a voided section of pipe could exist in the portion that isolates the condensate storage tank supply from the essential service water supply. A preliminary vendor analysis has determined that the void fraction to reach the pump in a dynamic scenario exceeds the acceptance criteria for AF pump operability. Based on past operation in this configuration, the event is being reported as a unanalyzed condition that significantly degrades plant safety and a condition that could have prevented the fulfillment of a safety function (i.e., remove residual heat) under 10CFR50.72(b)(3)(ii) and 10CFR50.72(b)(3)(v). Further review of the void model and pump performance characteristics are planned.</br>In 2011, prior to the completion of this analysis. The void was refilled and verified full for both trains at Byron U1 and U2.</br>Unit 1 is defueled. This condition affects both 'A' and 'B' trains of auxiliary feedwater for both Unit 1 and Unit 2.</br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified.  +
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ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +, ENS 46708 +  and ENS 46708 +
Initial power
0  +  and 100  +
Initial reactor mode
Power Operation +  and Refueling +
Last update date
00:00:00, 30 March 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>.
02:07:33, 2 March 2018  +
NRC officer
Joe O'Hara +
Notification date
01:39:00, 30 March 2011  +
Originated by
Alan Gustafson +
Reactor critical
false  +  and true  +
Reactor scram
false  +
Reactor type
Westinghouse PWR 4-Loop +
Region
NRC Region 3 +
Reporting criterion
10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat +  and 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition +
Reporting time
0.0271 d (0.65 hours, 0.00387 weeks, 8.9037e-4 months)  +
Site
Byron +
Start date
01:00:00, 30 March 2011  +
State
Illinois +
System
Service water +  and Auxiliary Feedwater +
Title
Potential Voiding in Auxiliary Feedwater Alternate Suction Line  +
Topic
Unanalyzed Condition +
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/2011/20110331en.html#en46708  +
Unit
1  +  and 2  +
 
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