ENS 46708
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ENS Event | |
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01:00 Mar 30, 2011 | |
Title | Potential Voiding in Auxiliary Feedwater Alternate Suction Line |
Event Description | 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.
In 2011, prior to the completion of this analysis. The void was refilled and verified full for both trains at Byron U1 and U2. Unit 1 is defueled. This condition affects both 'A' and 'B' trains of auxiliary feedwater for both Unit 1 and Unit 2. The NRC Resident Inspector has been notified. |
Where | |
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Byron Illinois (NRC Region 3) | |
Reporting | |
10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
Time - Person (Reporting Time:+0.65 h0.0271 days <br />0.00387 weeks <br />8.9037e-4 months <br />) | |
Opened: | Alan Gustafson 01:39 Mar 30, 2011 |
NRC Officer: | Joe O'Hara |
Last Updated: | Mar 30, 2011 |
46708 - NRC Website
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Unit 2 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
Byron with 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 | |
WEEKMONTHYEARENS 519582016-05-25T18:00:00025 May 2016 18:00:00
[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 Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 517722016-03-07T10:00:0007 March 2016 10:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Involving Diesel Driven Auxiliary Feedwater Pump Air Intakes ENS 513352015-08-20T22:55:00020 August 2015 22:55:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Condition That Could Prevent Pressurizer Porv Block Valves from Operating ENS 467082011-03-30T01:00:00030 March 2011 01:00:00 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 Potential Voiding in Auxiliary Feedwater Alternate Suction Line ENS 464162010-11-12T19:00:00012 November 2010 19:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Inaccurate Information Provided in License Amendment Request 2016-05-25T18:00:00 | |
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