ENS 49754: Difference between revisions

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| event date = 01/21/2014 21:25 EST
| event date = 01/21/2014 21:25 EST
| last update date = 01/22/2014
| last update date = 01/22/2014
| title = Dual Unit Trip On The Loss Of The "21" 13Kv Bus
| title = Dual Unit Trip on the Loss of the "21" 13Kv Bus
| event text = Dual Unit Trip due to loss of '21' 13 KV bus . All safety functions are met for both units. Unit 1 remained with normal heat removal. Unit 2 lost power to its normal heat sink and is stable on  Auxiliary Feed water and Atmospheric Dump Valves for temperature control. Both trips were automatic trips. Due to loss of power a Under Voltage actuation occurred on both units ('14' and '24' 4Kv bus). Due to loss of main feed on Unit 2 a Auxiliary Feed water Actuation System [AFW] actuation occurred on Unit 2. Cause is under investigation.
| event text = Dual Unit Trip due to loss of '21' 13 KV bus . All safety functions are met for both units. Unit 1 remained with normal heat removal. Unit 2 lost power to its normal heat sink and is stable on  Auxiliary Feed water and Atmospheric Dump Valves for temperature control. Both trips were automatic trips. Due to loss of power a Under Voltage actuation occurred on both units ('14' and '24' 4Kv bus). Due to loss of main feed on Unit 2 a Auxiliary Feed water Actuation System [AFW] actuation occurred on Unit 2. Cause is under investigation.
All control rods fully inserted on the loss of power to the Control Rod Drive Mechanisms [CRDMs].  Both Units Reactor Coolant Pumps [RCPs] remained running during the transient. The normal Unit 2 heat sink was unavailable due to the loss of the operating circulating water pumps resulting in a loss of condenser vacuum.  The Unit 2 AFW actuation included one of two steam-driven pumps and the motor-driven pump.  Both Units Emergency Diesel Generators started and loaded and have since been secured. Both Units are stable and will remain in mode 3 (Hot Standby) pending the results of the investigation.   
All control rods fully inserted on the loss of power to the Control Rod Drive Mechanisms [CRDMs].  Both Units Reactor Coolant Pumps [RCPs] remained running during the transient. The normal Unit 2 heat sink was unavailable due to the loss of the operating circulating water pumps resulting in a loss of condenser vacuum.  The Unit 2 AFW actuation included one of two steam-driven pumps and the motor-driven pump.  Both Units Emergency Diesel Generators started and loaded and have since been secured. Both Units are stable and will remain in mode 3 (Hot Standby) pending the results of the investigation.   

Latest revision as of 20:51, 1 March 2018

ENS 49754 +/-
Where
Calvert Cliffs Constellation icon.png
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
LER: 05000317/LER-2014-001
05000318/LER-2014-001
Time - Person (Reporting Time:+-1.87 h-0.0779 days <br />-0.0111 weeks <br />-0.00256 months <br />)
Opened: Kent Mills
00:33 Jan 22, 2014
NRC Officer: Steve Sandin
Last Updated: Jan 22, 2014
49754 - NRC Website
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