ENS 50961
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ENS Event | |
|---|---|
16:45 Apr 7, 2015 | |
| Title | Dual Unit Automatic Reactor Trips Due to a Voltage Transient Resulting in Generator Trips |
| Event Description | A loss of Main Generator Load which caused a Reactor Trip on Units 1 & 2. A switchyard voltage transient from a highline occurred, which caused an undervoltage condition on both units' safety related 4KV buses.
Unit 1 is on normal heat removal to the condenser. Unit 2 is on auxiliary feedwater and normal condenser bypass valves for temperature control. An Auxiliary Feedwater Actuation System (AFAS) actuation occurred on Unit 2. The [Unit 2] 2B emergency diesel generator did not start and load on its respective 24-4 KV bus. The 24-4KV Bus was repowered from the alternate feeder breaker. Cause of the emergency diesel failure to start is under investigation. All safety functions are met for both units. All control rods fully inserted. The site is in a normal shutdown electrical configuration powered from offsite. The site plans to stay in Mode 3 pending restart. The licensee notified the NRC Resident Inspector, State and local authorities. A press release is planned.
During post trip review, it was determined that the 21 saltwater pump had to be manually started. With the failure of 2B emergency diesel generator, there were no saltwater pumps running for approximately 12 minutes. Additional troubleshooting determined the 2A emergency diesel generator sequencer did not automatically start 21 saltwater pump. The 2B emergency diesel generator was returned to service on 4/8/2015 at 1730 [EDT]. The loss of saltwater [pump] and emergency diesel generator is reportable as an event that could have prevented fulfillment of a safety function and is also an unanalyzed condition. The licensee has notified the NRC Resident Inspector. Notified R1DO (Ferdas), IRD MOC (Grant), NRR EO (Morris). |
| 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 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| LER: | 05000317/LER-2015-002 |
| Time - Person (Reporting Time:+-1 h-0.0417 days <br />-0.00595 weeks <br />-0.00137 months <br />) | |
| Opened: | Dan Geneva 15:45 Apr 7, 2015 |
| NRC Officer: | Vince Klco |
| Last Updated: | Apr 9, 2015 |
| 50961 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
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)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 573722024-10-10T09:57:00010 October 2024 09:57:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Turbine Generator Loss of Field ENS 572332024-07-18T19:24:00018 July 2024 19:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip ENS 569972024-02-28T18:50:00028 February 2024 18:50:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Specified System Actuation - Automatic Start of Emergency Diesel Generators ENS 569912024-02-24T20:46:00024 February 2024 20:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Steam Generator 22 Feed Pump Trip ENS 568562023-11-16T07:27:00016 November 2023 07:27:00 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 568412023-11-08T11:45:0008 November 2023 11:45:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Actuation of Auxiliary Feedwater System (AFW) ENS 568392023-11-07T21:17:0007 November 2023 21:17:00 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 NON-SAFETY Related Bus Under Voltage ENS 561082022-09-14T17:48:00014 September 2022 17:48:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Safety Injection Actuation Signal While Shutdown ENS 556842022-01-03T17:23:0003 January 2022 17:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Loss of Electrical Load ENS 555972021-11-21T15:46:00021 November 2021 15:46:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip and Automatic Auxiliary Feedwater Actuation ENS 551472021-03-22T02:16:00022 March 2021 02:16:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip Due to Lowering Steam Generator Level ENS 550202020-12-03T14:23:0003 December 2020 14:23:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Actuation of an Emergency Diesel Generator ENS 536632018-10-11T04:00:00011 October 2018 04:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Air Start Solenoid Closure Failure ENS 534012018-05-14T17:05:00014 May 2018 17:05:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Saltwater System Non-Conforming with Licensing Basis for Tornado Generated Missiles ENS 524062016-12-04T03:24:0004 December 2016 03:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Caused by Main Turbine Trip ENS 519672016-05-31T20:26:00031 May 2016 20:26:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Calvert Cliffs Loss of Load Turbine/Reactor Trip from 100 Percent Power ENS 516832016-01-25T08:15:00025 January 2016 08:15:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Elevated Condenser Sodium Levels ENS 515772015-12-01T23:20:0001 December 2015 23:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip After Steam Generator Feed Pump Trip ENS 509612015-04-07T16:45:0007 April 2015 16:45:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - 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 507522015-01-22T22:45:00022 January 2015 22:45:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Heat Exchanger Lineup Could Exceed Design Basis Temperatures 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 498892014-03-10T20:53:00010 March 2014 20:53:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment 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 494492013-10-18T12:30:00018 October 2013 12:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Postulated Hot Short Fire Event That Could Adversely Impact Safe Shutdown Equipment 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 483672012-10-03T04:10:0003 October 2012 04:10:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to High Energy Line Break Barrier Being Partially Open ENS 476192012-01-23T18:00:00023 January 2012 18:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Breach in High Energy Line Break Barrier ENS 475122011-12-08T22:55:0008 December 2011 22:55:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Potentially Could Affect the Common Control Room ENS 474132011-11-03T22:00:0003 November 2011 22:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Diesel Generator Starting Air Not Compliant with Appendix R Requirements 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 438302007-12-08T05:50:0008 December 2007 05:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Reactor Power Inadvertently Increased Above Accident Analysis Limit 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 2024-07-18T19:24:00 | |
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