ENS 55565
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ENS Event | |
|---|---|
15:00 Nov 6, 2021 | |
| Title | Steam Supply Check Failure to Turbine Driven Auxillary Feedwater |
| Event Description | During a Unit 2 refueling outage valve overhaul activity on the steam supply check valve from the number 2 steam generator to the turbine driven auxiliary feedwater pump, 2-MS-4B, the check valve was found with its disc separated from the disc arm. This failure would have resulted in the blowdown of both steam generators during a main steam line break in the steam generator number 2 main steam line upstream of the main steam isolation valves until the operators could isolate the faulted steam generator. On November 6, at approximately 1100 EDT evaluation determined that this condition constituted an unanalyzed condition that could impact containment pressure.
There has been no radioactive release to the environment. The valve has been repaired. The check valve in the steam supply from the number 1 steam generator to the turbine driven auxiliary feedwater pump was inspected and found to be satisfactory. There has been no impact to Unit 3 which remains at 100% power. The Senior Resident has been notified. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-1.95 h-0.0813 days <br />-0.0116 weeks <br />-0.00267 months <br />) | |
| Opened: | Joseph Browning 13:03 Nov 6, 2021 |
| NRC Officer: | Kerby Scales |
| Last Updated: | Nov 6, 2021 |
| 55565 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 566102023-07-06T16:32:0006 July 2023 16:32:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 555762021-11-14T16:50:00014 November 2021 16:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition NON-FUNCTIONAL Steam Supply Check Valve to Turbine Driven Auxiliary Feedwater Pump ENS 555652021-11-06T15:00:0006 November 2021 15:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Steam Supply Check Failure to Turbine Driven Auxillary Feedwater ENS 499022014-03-12T18:00:00012 March 2014 18:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to a Postulated Hot Short That Could Affect Safe Shutdown Equipment ENS 499032014-03-12T18:00:00012 March 2014 18:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to a Postulated Hot Short That Could Affect Safe Shutdown Equipment ENS 494872013-10-30T19:25:00030 October 2013 19:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversly Impact Safe Shutdown Equipment ENS 490472013-05-17T08:39:00017 May 2013 08:39:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition for Reactor Coolant System Temperature Below Required Value ENS 444502008-08-29T14:07:00029 August 2008 14:07:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Related to Certain Fire Conditions ENS 437192007-10-12T17:30:00012 October 2007 17:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Affecting Fire Safe Shutdown ENS 436752007-09-28T21:00:00028 September 2007 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Reactor Vessel Head Vent May Not Be Isolable During a Fire 2023-07-06T16:32:00 | |
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