Emergency Feedwater Actuation System (EFAS) is for Emergency Feedwater System.
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| | Site | Start date | Title | Description |
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| ENS 48687 | Waterford | 21 January 2013 21:51:00 | Automatic Reactor Trip Due to Low Steam Generator Level | At 15:51 CST, Waterford 3 experienced an uncomplicated automatic reactor trip from 84.5% reactor power. The actuations of the Reactor Protection System (RPS) and the Emergency Feedwater Actuation System (EFAS) resulted from Steam Generator #1 Low Level, which is at a nominal 27.4% narrow range setpoint. Safety systems responded as expected.
All three (3) Emergency Feedwater Pumps started and injected into Steam Generator #1. Auxiliary Feedwater pump has been started, feeding both Steam Generators (#1 and #2) at levels above the EFAS low level setpoint. All control rods inserted by the automatic RPS actuation. Electrical power is being supplied from normal off-site power and condenser vacuum is available for Steam Generator heat removal via the Steam Dump Bypass Control system. There are no safety systems out of service or inoperable, nor any safety system TS (Technical Specification) LCO (Limiting Condition for Operation) actions entered.
The cause of the Steam Generator #1 Low Level condition, and associated Reactor Trip, is under investigation. This event occurred during the initial power escalation from refuel outage RF18, after attempting to place C Heater Drain Pump (HDP), the first of three, into service. After starting, C HDP tripped for a reason not yet verified. Subsequently, based on initial Control Room operator observations, the Steam Generator #1 Main Feedwater control valve position was observed to be at 10-20% open, but with an open position demand signal of 100%. Main Feedwater response to the reactor trip (Reactor Trip Override) was as expected.
The NRC Resident Inspector has been informed.
* * * UPDATE FROM WILLIAM HARDIN TO PETE SNYDER AT 1645 EST ON 3/7/13 * * *
The original reactor power level stated in the report should be 91% in lieu of 84.5%. This information has been changed in the event heading.
The licensee notified the NRC Resident Inspector. Notified R4DO (Werner). | | ENS 48169 | Arkansas Nuclear | 8 August 2012 13:23:00 | Automatic Reactor Trip Due to High Reactor Coolant System Pressurizer Pressure | At 0823 hours on August 8, 2012, Arkansas Nuclear One, Unit 2 (ANO-2) experienced an automatic reactor trip. The reactor automatically tripped due to High Reactor Coolant System Pressurizer Pressure that was caused by a Main Turbine trip due to high condenser back pressure from a degraded vacuum condition. The Reactor Protection System (RPS) performed as designed in response to the High Reactor Coolant System Pressurizer Pressure condition resulting in automatic shutdown of the reactor from approximately 100 percent power. All Control Element Assemblies (CEAs) fully inserted on the trip. The Emergency Feedwater Actuation System (EFAS) actuated for the 'A' Steam Generator only due to level trending slightly below the setpoint. The plant has transitioned to supplying the steam generators using the Auxiliary Feedwater (AFW) system.
The unit is currently in Mode 3 and implementing the transient response process. The investigation into the cause of the trip is ongoing and the local NRC Resident Inspectors have been notified.
The unit is in a normal electrical lineup, and the decay heat is being removed by the main condenser via the turbine bypass valves.
The State Department of Health was notified and ANO-2 will be issuing a press release. | | ENS 44906 | Arkansas Nuclear | 14 March 2009 02:51:00 | Feedwater Regulating Valve Failure Leads to Manual Reactor Trip | At 2151 CDT on 3/13/2009 with plant power at 84% following securing of the 2P-1A Main Feedwater Pump at 1934 due to bearing degradation, Unit 2 experienced a failure of the 'B' Main Feedwater Regulating Valve 2CV-0740 which caused 2E-24B Steam Generator level to lower. At 2151, with 2E-24B Steam Generator level at approximately 25% control room staff manually tripped the reactor anticipating an automatic trip at 22% steam generator level. Emergency Feedwater Actuation System automatically actuated at 22% steam generator level and responded to restore level to the normal post-trip levels. All Control Element Assemblies (rods) Inserted on the reactor trip.
No safeties or relief valves opened after the trip. The plant is in its normal shutdown electrical line-up. Steam generator level is being maintained with emergency feedwater and decay heat is being dumped to the main condenser.
The licensee notified the State of Arkansas and the NRC Resident Inspector. | | 3F0185-08, Application for Amend to License DPR-72,changing Tech Specs to Provide Operability & Surveillance Requirements for Emergency Feedwater Sys Automatic & Manual Initiation Channels.Fee Paid | Crystal River | 23 January 1985 | Application for Amend to License DPR-72,changing Tech Specs to Provide Operability & Surveillance Requirements for Emergency Feedwater Sys Automatic & Manual Initiation Channels.Fee Paid | |
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