ENS 45709
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ENS Event | |
|---|---|
13:24 Feb 18, 2010 | |
| Title | Dual Unit Automatic Reactor Trips Due to Partial Loss of Offsite Power |
| Event Description | Both U-1 and U-2 automatically tripped due to valid actuation of the Reactor Protection Systems (RPS). U-1 due to loss of 12B Reactor Coolant Pump (RCP) which resulted in a RCS Low Flow RPS Trip. Cause for loss of 12B RCP is currently not known but is suspected to be related to the electrical transient that occurred on U-2. U-2 tripped due to Loss of Load RPS Trip when the main turbine tripped due to an electrical malfunction and partial loss of offsite power. The electrical malfunction resulted in loss of power to all 4 Kv buses on U-2 with the exception of 21 4Kv bus (ZA train power) (Lost 22-26 4Kv buses) and the loss of 14 Kv bus (ZB train power) on U-1. All the buses lost are powered from the same in house service transformer, P-13000-2, which was lost due to the electrical transient. Cause of the electrical transient is being pursued but is unknown at this time. Loss of the 14 4Kv bus on U-1 and the 24 4Kv bus on U-2 resulted in an Engineered Safeguards Actuation System (ESFAS) valid actuations on both units due to Under Voltage (UV) conditions on those buses. The 1B [Diesel Generator] DG started automatically due to the 14 bus UV and is carrying that bus. The 2B DG received an automatic start signal due to the 24 bus UV but failed to start as expected. No other system actuations occurred. Both units are currently stable in Mode 3 at normal operating temperature (532 degrees) and pressure (2250 PSIA) with no other significant equipment malfunctions. Due to the loss of P-13000-2 [transformer], U-2 sustained a loss of normal heat removal due to loss of the main condenser cooling and the loss of secondary pumps. U-2 is removing heat with auxiliary feedwater pumps and [Steam Generator] SG atmospheric dump valves without issues. Current plans are to cool U-2 down to 445 degrees to maintain RCP seals cool until RCP's can be restarted. A decision on U-1 cool down has not yet been made.
There is no primary to secondary leakage. U-2 is currently in a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> LCO due to the partial loss of offsite power and 2B DG failing to start. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Calvert Cliffs  Maryland (NRC Region 1) | |
| Reporting | |
| Emergency class: | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000317/LER-2010-001 05000318/LER-2010-001 |
| Time - Person (Reporting Time:+-1.62 h-0.0675 days <br />-0.00964 weeks <br />-0.00222 months <br />) | |
| Opened: | Kent Mills 11:47 Feb 18, 2010 |
| Last Updated: | Feb 18, 2010 |
| 45709 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (93 %) |
| 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)(iv)(A), System Actuation | |
WEEKMONTHYEARENS 569972024-02-28T18:50:00028 February 2024 18:50:00
[Table view]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 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 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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