ENS 40389
ENS Event | |
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16:19 Dec 12, 2003 | |
Title | Both Trains of Auxiliary Feewater Were Declared Inoperable for One Hour and 22 Minutes. |
Event Description | Surry Power Station has determined that an unanalyzed condition related to Auxiliary Feedwater (AFW) isolation during a steam generator tube rupture (SGTR) event exists. The existing accident analysis for a SGTR requires that AFW to the ruptured steam generator (SG) be isolated prior to the water level in that SG rising into the main steam pipe. Failing to take these actions could result in a radioactive release or failure of equipment important to safety, which has not been previously analyzed.
The current configuration of the AFW system has six motor operated valves (MOVs), two for each SG, which are used to control flow from one of two AFW headers. Three MOVs are powered from "H" emergency bus and three MOVs are powered from "J" emergency bus. The MOVs are maintained normally open. With a loss of emergency power to either train of AFW MOVs, the control room operators are not able to close the three MOVs from the de-energized emergency bus without manual action inside containment. A review of the plant safety analysis design basis indicates that with this AFW configuration, isolation of AFW to a ruptured SG would not be possible within the time frame specified in the analysis. Unit One and Unit Two entered a TS 3.0.1 clock at 1119 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.257795e-4 months <br /> on December 12, 2003 due to the AFW systems being declared inoperable. The station took immediate actions to address the configuration control issue in order to meet the assumptions made in the SGTR accident analysis and both Unit One and Unit Two exited the TS 3.0.1 clock at 13:41 hours on December 12, 2003. The NRC Resident Inspector was notified of this event by the licensee. |
Where | |
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Surry Virginia (NRC Region 2) | |
Reporting | |
10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
Time - Person (Reporting Time:+-1.77 h-0.0738 days <br />-0.0105 weeks <br />-0.00242 months <br />) | |
Opened: | Larry Wheeler 14:33 Dec 12, 2003 |
NRC Officer: | John Mackinnon |
Last Updated: | Dec 12, 2003 |
40389 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
Unit 2 | |
---|---|
Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
WEEKMONTHYEARENS 554592021-09-13T22:22:00013 September 2021 22:22:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition of Fire Safe Shutdown Equipment ENS 544372019-12-11T18:56:00011 December 2019 18:56:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Potential Tornado Missile Vulnerabilities ENS 407702004-05-22T01:46:00022 May 2004 01:46:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Auxiliary Feedwater Not Being in Compliance with Justification for Continued Operation (Jco). ENS 403892003-12-12T16:19:00012 December 2003 16:19:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Both Trains of Auxiliary Feewater Were Declared Inoperable for One Hour and 22 Minutes. ENS 402922003-11-03T22:20:0003 November 2003 22:20:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Non-Conservatism in Design Methodology for Loss of Rcp (Reactor Coolant Pump) Seal Cooling 2021-09-13T22:22:00 | |