United States Nuclear Regulatory Commission - Protecting People and the Environment
Home > NRC Library > Document Collections > Reports Associated with Events > Event Notification Reports > 2006 > April 17

Event Notification Report for April 17, 2006

U.S. Nuclear Regulatory Commission
Operations Center

Event Reports For
04/14/2006 - 04/17/2006

** EVENT NUMBERS **


42504 42505 42506

To top of page
Power Reactor Event Number: 42504
Facility: PRAIRIE ISLAND
Region: 3 State: MN
Unit: [1] [ ] [ ]
RX Type: [1] W-2-LP,[2] W-2-LP
NRC Notified By: DOUG SMITH
HQ OPS Officer: BILL GOTT
Notification Date: 04/14/2006
Notification Time: 16:07 [ET]
Event Date: 04/14/2006
Event Time: 14:25 [CDT]
Last Update Date: 04/14/2006
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
THOMAS KOZAK (R3)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
1 M/R Y 100 Power Operation 0 Hot Standby

Event Text

MANUAL REACTOR TRIP DUE TO CONDENSATE PUMP AND FEEDWATER PUMP TRIP

"At 1425 on April 14, 2006, a lockout trip of 11 Condensate Pump occurred. The condensate pump trip caused an expected lockout trip of 11 Main Feedwater Pump trip. With the loss of 50% of feedwater pump capacity, the Shift Supervisor directed a manual Unit 1 reactor trip. The manual reactor trip was successful and all systems responded as expected. The reactor protection system actuation is reportable under 10CFR 50.72(b)(2). A reactor trip from full power results in an expected steam generator narrow range level shrink to 0%. This resultant narrow range steam generator level caused an expected Auxiliary Feedwater System Actuation. Both 11 and 12 Auxiliary Feedwater Pumps started as expected. Auxiliary feedwater actuation is reportable under10CFR 50.72(b)(3).

"Investigation is underway to determine the cause of 11 Condensate Pump lockout.

"Plant operations are underway per emergency procedure 1ES-0.1, Reactor Trip Recovery, and 1C1.3, Unit 1 Shutdown, to stabilize the plant in Mode 3, Hot Standby."

All control rods fully inserted. Steam generators are discharging steam to the condenser steam dump system. The Auxiliary Feedwater Pumps are maintaining Steam Generator level. The electrical grid is stable.

The licensee will notify the NRC Resident Inspector.

To top of page
Power Reactor Event Number: 42505
Facility: RIVER BEND
Region: 4 State: LA
Unit: [1] [ ] [ ]
RX Type: [1] GE-6
NRC Notified By: VERNON CARLSON
HQ OPS Officer: MARK ABRAMOVITZ
Notification Date: 04/15/2006
Notification Time: 20:52 [ET]
Event Date: 04/15/2006
Event Time: 16:15 [CDT]
Last Update Date: 04/16/2006
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
Person (Organization):
TROY PRUETT (R4)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
1 A/R Y 100 Power Operation 0 Hot Shutdown

Event Text

REACTOR SCRAM FROM 100% POWER

"At 1615 CDT time on April 15th, 2006 with the Reactor at 100% power, River Bend Station experienced a reactor scram resulting from a RPS actuation. All plant systems performed as designed. The reactor is stable with pressure and temperature being controlled by feed water system and main steam bypass valves, respectively. The cause of the scram is not known at this time. The plant is conducting causal investigations to fully understand the cause of the plant scram."

All control rods fully inserted, no safety valves lifted, and no Emergency Safety Feature actuations occurred on the scram. The electrical grid is stable.

The licensee notified the NRC Resident Inspector.

* * * UPDATE AT 1033 EDT ON 4/16/06 FROM KENNETH HIGGINBOTHAM TO S. SANDIN * * *

"River Bend Station status on 04/16/2006: The unit is in Mode 3, Hot Shutdown, and stable. Investigation of the plant trip found an optical isolator in the control circuit for the end-of-cycle recirculation pump trip failed causing both recirculation pumps to shift to slow speed. The pump downshift placed reactor power and flow into the exclusion region of the power to flow map. The reactor received trip signals from APRM E & H heat flux exceeding their corresponding trip set points. The optical isolator is being replaced. Plant restart will commence pending successful replacement of the optical isolator."

The licensee informed the NRC Resident Inspector. Notified R4DO (Pruett).

To top of page
Power Reactor Event Number: 42506
Facility: VOGTLE
Region: 2 State: GA
Unit: [1] [ ] [ ]
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: STEVE PHILLIPS
HQ OPS Officer: STEVE SANDIN
Notification Date: 04/17/2006
Notification Time: 01:20 [ET]
Event Date: 04/17/2006
Event Time: 00:26 [EDT]
Last Update Date: 04/17/2006
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
ROBERT HAAG (R2)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
1 M/R Y 33 Power Operation 0 Hot Standby

Event Text

UNIT 1 MANUALLY TRIPPED DUE TO FAILURE OF A MAIN FEED REGULATING VALVE TO CONTROL STEAM GENERATOR LEVEL

"Unit 1 reactor was manually tripped from 33% RTP due to the Loop 3 Main Feed Regulating Valve (MFRV) 1LV-0530 not controlling steam generator level in manual or AUTO.

"A unit shutdown was in progress at the time of the trip due to concerns with the Loop 3 MFRV. The unit shutdown had commenced from 100% power on 04/16/2006 at 1603 hrs.

"All systems functioned as required on the reactor trip including a feedwater isolation and the Loop 3 MRFV closing as expected. The unit is presently in Mode 3 at normal operating temperature and pressure. An investigation team is being assembled concerning the Loop 3 MFRV."

All control rods fully inserted. No primary or secondary reliefs/safeties lifted during the transient. Unit 1 is currently in Mode 3 Hot Standby controlling Steam Generator Water Level using Auxiliary Feedwater supplied by both Motor Driven and the Steam Driven pumps. Decay Heat is being removed via the Bypass Valves to the Main Condenser. Offsite power is stable and all EDGs are available, if necessary.

The licensee informed the NRC Resident Inspector.

Page Last Reviewed/Updated Friday, March 30, 2012
Friday, March 30, 2012