Event Notification Report for November 01, 2014
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
10/31/2014 - 11/01/2014
EVENT NUMBERS
50587
50587
Power Reactor
Event Number: 50587
Facility: COOK
Region: 3 State: MI
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: PERRY GRAHAM
HQ OPS Officer: DANIEL MILLS
Region: 3 State: MI
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: PERRY GRAHAM
HQ OPS Officer: DANIEL MILLS
Notification Date: 11/01/2014
Notification Time: 05:03 [ET]
Event Date: 11/01/2014
Event Time: 02:48 [EDT]
Last Update Date: 11/01/2014
Notification Time: 05:03 [ET]
Event Date: 11/01/2014
Event Time: 02:48 [EDT]
Last Update Date: 11/01/2014
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
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
CHRISTINE LIPA (R3DO)
CHRISTINE LIPA (R3DO)
| 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 |
| 2 | M/R | Y | 50 | Power Operation | 0 | Hot Standby |
DUAL UNIT MANUAL REACTOR TRIPS DUE TO LOWERING CONDENSER VACUUM AND DEGRADED FOREBAY
"On November 1, 2014, at 0249 [EDT], DC Cook Unit 1 reactor was manually tripped and at 0248 [EDT] DC Cook Unit 2 was manually tripped due lowering condenser vacuum caused by degraded forebay conditions (observed thick grass and sand). U-1 and U-2 entered Abnormal Operating Procedure for Degraded Forebay on November 1, 2014 at 0153 [EDT]. Conditions degraded in U-1 and U-2 until all but 2 screens in each unit were tripped on overload and main condenser vacuum was lowering. U-1 and U-2 met criteria in the Degraded Forebay procedure to remove the units from service and remove all circulating water pumps from service.
"This event is reportable under 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation, as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report.
"The electrical grid is stable. Unit 1 and Unit 2 are being supplied by offsite power. All control rods fully inserted in both units. Decay heat is being removed by steam generator PORVs. Preliminary evaluation indicates all plant systems functioned normally following the reactor trip with the exception of U-1 turbine driven auxiliary feed pump. DC Cook Unit 1 and Unit 2 remain stable in Mode 3 while conducting the post trip review. No radioactive release is in progress as a result of this event.
"Additional information received determined the Unit 1 turbine driven auxiliary feedwater pump tripped for unknown reasons. Feedwater flow to all steam generators was maintained by the U-1 east and west motor driven auxiliary feedwater pumps.
"U-2 reactor power was lowered from 100 percent to 50 percent over the hour prior to the trip in accordance with the Degraded Forebay Procedure.
"The DC Cook NRC Resident Inspector has been notified."
* * * UPDATE PROVIDED BY RICHARD HARRIS TO JEFF ROTTON AT 0945 EDT ON 11/01/2014 * * *
At 0921 EDT, DC Cook issued a press release regarding the event described earlier.
The licensee notified the NRC Resident Inspector.
Notified R3DO (Lipa)
"On November 1, 2014, at 0249 [EDT], DC Cook Unit 1 reactor was manually tripped and at 0248 [EDT] DC Cook Unit 2 was manually tripped due lowering condenser vacuum caused by degraded forebay conditions (observed thick grass and sand). U-1 and U-2 entered Abnormal Operating Procedure for Degraded Forebay on November 1, 2014 at 0153 [EDT]. Conditions degraded in U-1 and U-2 until all but 2 screens in each unit were tripped on overload and main condenser vacuum was lowering. U-1 and U-2 met criteria in the Degraded Forebay procedure to remove the units from service and remove all circulating water pumps from service.
"This event is reportable under 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation, as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report.
"The electrical grid is stable. Unit 1 and Unit 2 are being supplied by offsite power. All control rods fully inserted in both units. Decay heat is being removed by steam generator PORVs. Preliminary evaluation indicates all plant systems functioned normally following the reactor trip with the exception of U-1 turbine driven auxiliary feed pump. DC Cook Unit 1 and Unit 2 remain stable in Mode 3 while conducting the post trip review. No radioactive release is in progress as a result of this event.
"Additional information received determined the Unit 1 turbine driven auxiliary feedwater pump tripped for unknown reasons. Feedwater flow to all steam generators was maintained by the U-1 east and west motor driven auxiliary feedwater pumps.
"U-2 reactor power was lowered from 100 percent to 50 percent over the hour prior to the trip in accordance with the Degraded Forebay Procedure.
"The DC Cook NRC Resident Inspector has been notified."
* * * UPDATE PROVIDED BY RICHARD HARRIS TO JEFF ROTTON AT 0945 EDT ON 11/01/2014 * * *
At 0921 EDT, DC Cook issued a press release regarding the event described earlier.
The licensee notified the NRC Resident Inspector.
Notified R3DO (Lipa)