ENS 55506
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ENS Event | |
|---|---|
19:33 Oct 4, 2021 | |
| Title | Degraded Condition Discovered on Reactor Vessel Head Penetration |
| Event Description | At 1433 CDT, on October 4, 2021, Arkansas Nuclear One, Unit 2 (ANO-2) completed the analysis related to an indication revealed on head penetration 46 during Reactor Vessel Closure Head inspections. It was determined the indication is not acceptable under ASME code requirements. The indication displays characteristics consistent with primary water stress corrosion cracking. No leak path signal was identified during ultrasonic testing.
The plant was in cold shutdown at 0 percent power and in Mode 6 for a refueling outage at the time of discovery. Repair actions will be completed prior to plant startup from the outage. This condition has no impact to the health and safety of the public. This report is being made in accordance with 10 CFR 50.72(b)(3)(ii)(A) for degradation of a principal safety barrier. This is the only indication that is currently present, however, if additional indications are found, they will also be repaired prior to the plant startup. The NRC Senior Resident Inspector has been notified. |
| Where | |
|---|---|
Arkansas Nuclear  Arkansas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | |
| Time - Person (Reporting Time:+0.43 h0.0179 days <br />0.00256 weeks <br />5.89014e-4 months <br />) | |
| Opened: | Derek Mosher 19:59 Oct 4, 2021 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Oct 4, 2021 |
| 55506 - NRC Website
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WEEKMONTHYEARENS 534562024-05-20T20:53:00020 May 2024 20:53:00
[Table view]10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Pressure Boundary Leakage Identified While Shutdown ENS 555062021-10-04T19:33:0004 October 2021 19:33:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Degraded Condition Discovered on Reactor Vessel Head Penetration ENS 457972010-03-27T20:31:00027 March 2010 20:31:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Potentially Degraded Pressurizer Level Tap Identified ENS 414732005-03-09T11:37:0009 March 2005 11:37:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Pressurizer Heater Sleeve Leakage ENS 407212004-04-30T19:38:00030 April 2004 19:38:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded "on 4/30/2004, During Refueling Outage 1 R18, Ultrasonic Testing of the Reactor Vessel Head Identified Two Axial Indications on Control Rod Drive Mechanism, Nozzle 61. the Indications Were Located on the Outside Diameter of the Nozzle on the Lower Hillside. One of the Flaws Was at the Toe of the Fillet Weld and Extended Below the Fillet Weld Cap. the Second Flaw Extended the Full Length of the Weld and Just Below the Toe of the Fillet Weld. ENS 402162003-10-02T22:15:0002 October 2003 22:15:00 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded Rcs Boundary Leakage Due to Small Crack on Drain Line Welded Cap 2024-05-20T20:53:00 | |
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