ENS 55679
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ENS Event | |
|---|---|
20:52 Dec 29, 2021 | |
| Title | Manual Reactor Trip and Automatic Actuation of Containment Isolation Valves |
| Event Description | This following information was conveyed by the licensee via phone and email:
At 1552 EST on 12/29/21, with Unit 1 in Mode 1 at 90 percent power, the reactor was manually tripped due to reactor pressure perturbations. The cause of the reactor pressure perturbations is under investigation. Additionally, closure of [containment isolation valves] CIVs in multiple systems occurred during the trip as a result of reaching the actuation setpoint on reactor water level. The trip was not complex, with all systems responding normally post-trip. Operations responded and stabilized the plant. Reactor water level is being maintained via condensate / feedwater. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Unit 2 is not affected. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). It is also reportable under 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of CIVs. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Hatch  Georgia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-1.6 h-0.0667 days <br />-0.00952 weeks <br />-0.00219 months <br />) | |
| Opened: | Ron Wheeler 19:16 Dec 29, 2021 |
| NRC Officer: | Karen Cotton-Gross |
| Last Updated: | Dec 29, 2021 |
| 55679 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | Yes, Manual Scram |
| Before | Power Operation (90 %) |
| After | Hot Standby (0 %) |
Hatch with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 579282025-09-13T21:04:00013 September 2025 21:04:00
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ECCS Discharge Manual Reactor Scram After Feed Pump Trip ENS 443372008-07-04T12:39:0004 July 2008 12:39:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Scram on Turbine Trip ENS 440462008-03-07T19:46:0007 March 2008 19:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Automatic Reactor Scram with Hpci/Rcic Actuation Due to Loss of Condensate Feedwater ENS 435522007-08-07T19:06:0007 August 2007 19:06:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Scram on Low Reactor Water Level Following Partial Loss of Condensate Feedwater Flow ENS 424712006-04-05T04:16:0005 April 2006 04:16:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Reactor Scram Following Main Turbine Control Valve Fast Closure ENS 420962005-10-29T17:25:00029 October 2005 17:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event - Main Transformer Fire ENS 417252005-05-23T21:47:00023 May 2005 21:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Scram Due to Condenser Hotwell Chemistry ENS 410702004-09-25T05:06:00025 September 2004 05:06:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Group 2 Containment Isolation Actuation ENS 405652004-03-03T18:45:0003 March 2004 18:45:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Swing Diesel Generator Auto Started from a Bus Undervoltage Valid Signal 2025-09-13T21:04:00 | |
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