ENS 56856
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ENS Event | |
|---|---|
07:27 Nov 16, 2023 | |
| Title | Automatic Reactor Trip |
| Event Description | The following information was provided by the licensee via email:
At 0227 EST on 11/16/23, Calvert Cliffs Unit 2 experienced an automatic trip from the reactor protection system (RPS) based on reactor trip bus undervoltage (UV). At that time, a loss of U-4000-22 (13 kV to 4 kV transformer) caused a loss of 22, 23, and 24 4 kV busses. This resulted in a loss of both motor generator (MG) sets causing the reactor trip bus UV. The loss of 22 and 23 4 kV non-safety related busses resulted in a loss of main feedwater. Auxiliary feedwater (AFW) was manually initiated and is feeding both steam generators. The 2B diesel generator (DG) started and restored the 24 4 kV safety related bus. Heat removal is via the normal turbine bypass valves to the main condenser. RPS actuation is reportable under 10 CFR 50.72(b)(2)(iv)(B) - 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> report ESFAS (engineering safety features actuation system) actuation (2B DG start on UV) is reportable under 10 CFR 50.72(b)(3)(iv)(A) - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> report AFW operation is reportable under 10 CFR 50.73(a)(2)(iv)(A) - 60 day report The NRC Senior Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: All rods fully inserted. There was no impact on Unit 1 operations. Unit 2 is stable in mode 3.
ESFAS actuation (AFW manual initiation) is reportable under 10CFR50.72(b)(3)(iv)(A) - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> report Notified R1DO (Defrancisco). |
| Where | |
|---|---|
Calvert Cliffs  Maryland (NRC Region 1) | |
| 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:+-2.2 h-0.0917 days <br />-0.0131 weeks <br />-0.00301 months <br />) | |
| Opened: | Corey Donahoo 05:15 Nov 16, 2023 |
| NRC Officer: | Adam Koziol |
| Last Updated: | Nov 16, 2023 |
| 56856 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
Calvert Cliffs with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 569972024-02-28T18:50:00028 February 2024 18:50:00
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Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Dual Unit Automatic Reactor Trips Due to a Voltage Transient Resulting in Generator Trips ENS 500782014-05-01T14:16:0001 May 2014 14:16:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 497542014-01-22T02:25:00022 January 2014 02:25:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Dual Unit Trip on the Loss of the "21" 13Kv Bus ENS 490542013-05-21T09:33:00021 May 2013 09:33:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip After a Feed Pump Trip ENS 490122013-05-09T01:47:0009 May 2013 01:47:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip ENS 472082011-08-28T03:02:00028 August 2011 03:02:00 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 - Transformer Explosion Near Turbine Building ENS 459202010-05-12T17:51:00012 May 2010 17:51:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Actuation - Load Reject ENS 457092010-02-18T13:24:00018 February 2010 13:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Dual Unit Automatic Reactor Trips Due to Partial Loss of Offsite Power ENS 430462006-12-12T14:07:00012 December 2006 14:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip During Turbine Control System Maintenance ENS 429952006-11-16T05:18:00016 November 2006 05:18:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Turbine Trip and Discovery of After-The-Fact Emergency Condition of an Unsual Event ENS 414522005-03-01T05:43:0001 March 2005 05:43:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Scram from 15% Power Due to High Turbine Vibration ENS 406012004-03-20T18:40:00020 March 2004 18:40:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip at Calvert Cliffs Unit 1 Due to a Loss of Feedwater ENS 404722004-01-23T20:29:00023 January 2004 20:29:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip with Safety Injection Actuation Signals 2024-02-28T18:50:00 | |
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