ENS 55457
ENS Event | |
|---|---|
21:28 Sep 12, 2021 | |
| Title | Degraded Condition Identified While Unit Shutdown |
| Event Description | On September 12, 2021, at 1728 EDT, with Unit 1 in Mode 5 (Cold Shutdown) while performing inspections of the North Anna Power Station Unit 1 reactor vessel head flange area, a weld leak was identified on the reactor vessel flange leak-off line that connects to the flange between the inner and outer head o-rings. Entered TRM 3.4.6 Condition B for ASME Code Class 1,2, and 3 components. With known leakage past the inner head o-ring, this condition is reported since the fault in the tubing is considered pressure boundary [Reactor Coolant System] leakage.
This event is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(A) for any event or condition that results in the condition of the nuclear power plant, including its principle safety barriers, being seriously degraded. The NRC Resident has been notified.
The condition identified in EN 55457, pursuant to 10 CFR 50.72 (b)(3)(ii)(A) has been evaluated, and has been determined not to be Reactor Coolant System (RCS) pressure boundary leakage. As such, the 8-hour report is being retracted, as it is not an event or condition that results in, 'the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded.' The leakage was subsequently determined to be in a tubing connection downstream of the reactor vessel inner O-ring. Leakage past a seal or gasket is not considered to be pressure boundary leakage, as defined by Technical Specifications. The NRC Resident Inspector has been notified. Notified R2DO (Miller) |
| Where | |
|---|---|
North Anna  Virginia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| Time - Person (Reporting Time:+1.22 h0.0508 days <br />0.00726 weeks <br />0.00167 months <br />) | |
| Opened: | David Mcgowan 22:41 Sep 12, 2021 |
| NRC Officer: | Thomas Kendzia |
| Last Updated: | Oct 21, 2021 |
| 55457 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 567742023-10-03T15:54:0003 October 2023 15:54:00
[Table view]10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition ENS 554572021-09-12T21:28:00012 September 2021 21:28:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Identified While Unit Shutdown ENS 521372016-07-30T15:52:00030 July 2016 15:52:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Technical Specification Required Shutdown Due to Unisolable Reactor Coolant System Boundary Leakage ENS 507002014-12-23T03:30:00023 December 2014 03:30:00 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Unit 1 Technical Specification Shutdown Due to Rcs Pressure Boundary Leakage ENS 504572014-09-15T13:00:00015 September 2014 13:00:00 10 CFR 20.2201(a)(1)(ii), 10 CFR 74.11(a), 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Failed Fuel Assembly Identified During Core Off-Load ENS 489402013-04-17T20:00:00017 April 2013 20:00:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Due to Suspected Valve Body Leakage ENS 477672012-03-24T22:55:00024 March 2012 22:55:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degradation of Steam Generator Nozzle Weld Areas 2023-10-03T15:54:00 | |