United States Nuclear Regulatory Commission - Protecting People and the Environment

Event Notification Report for July 11, 2013

U.S. Nuclear Regulatory Commission
Operations Center

Event Reports For
07/10/2013 - 07/11/2013

** EVENT NUMBERS **


49039 49183 49184

To top of page
!!!!! THIS EVENT HAS BEEN RETRACTED. THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor Event Number: 49039
Facility: MILLSTONE
Region: 1 State: CT
Unit: [ ] [ ] [3]
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: MICHAEL WEISE
HQ OPS Officer: MARK ABRAMOVITZ
Notification Date: 05/16/2013
Notification Time: 10:20 [ET]
Event Date: 05/16/2013
Event Time: 02:56 [EDT]
Last Update Date: 07/10/2013
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
DAN SCHROEDER (R1DO)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
3 N N 0 Hot Standby 0 Hot Standby

Event Text

MANUAL REACTOR TRIP DURING CONTROL ROD TESTING

"On May 16, 2013, at 0256 EDT, while in Mode 3 (subcritical), operators manually opened the reactor trip breakers as directed by procedure. During rod drop testing, demand position and digital rod position indication did not agree within procedural limits. As directed by procedure, operators opened the reactor trip breakers. The cause of the discrepancy is under investigation. The plant responded as expected and all rods inserted as required. The plant remains stable in Mode 3.

"This condition is reportable pursuant to 10 CFR 50.72(b)(3)(iv).

"The NRC Senior Resident Inspector has been notified."


* * * RETRACTION FROM TODD STRINGFELLOW TO DANIEL MILLS ON 7/10/2013 AT 1418 EDT * * *

"The purpose of this call is to retract the report made on May 16, 2013, Event Number 49039. Operators manually opened the reactor trip breakers in MODE 3 during hot control rod drop testing as directed by procedure. The condition has been determined to be an invalid actuation of the RPS since boron concentration, and not control rods, were being relied upon for safety function during rod testing. The details of the engineering review will be provided to the NRC Senior Resident Inspector."

Notified R1DO (Cook).

To top of page
Power Reactor Event Number: 49183
Facility: MILLSTONE
Region: 1 State: CT
Unit: [ ] [ ] [3]
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: TODD STRINGFELLOW
HQ OPS Officer: DANIEL MILLS
Notification Date: 07/10/2013
Notification Time: 12:46 [ET]
Event Date: 07/10/2013
Event Time: 05:13 [EDT]
Last Update Date: 07/10/2013
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(xiii) - LOSS COMM/ASMT/RESPONSE
Person (Organization):
WILLIAM COOK (R1DO)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
3 N Y 100 Power Operation 100 Power Operation

Event Text

LOSS OF ASSESSMENT CAPABILITY DUE TO FAILURE OF A & B MAIN STEAM LINE RADIATION MONITORS

"A and B Main Steam Line Radiation Monitors 3MSS-RE75 and 76 have failed and were declared inoperable at 0513 hours July 10, 2013. Repairs have been completed and A and B Main Steam Line Radiation Monitors 3MSS-RE75 and 3MSS-RE76 were returned to service at 0900 hours July 10, 2013. The unit is in Mode 1.

"This event is reportable pursuant to 10 CFR 50.72(b)(3)(xiii) as is any event that results in a major loss of emergency assessment capability, off-site response capability, or off-site communications capability.

"The licensee informed the State of Connecticut, Waterford dispatch, and the NRC Resident Inspector."

To top of page
Power Reactor Event Number: 49184
Facility: DIABLO CANYON
Region: 4 State: CA
Unit: [ ] [2] [ ]
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MICHAEL QUITTER
HQ OPS Officer: DANIEL MILLS
Notification Date: 07/10/2013
Notification Time: 16:13 [ET]
Event Date: 07/10/2013
Event Time: 09:50 [PDT]
Last Update Date: 07/10/2013
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
50.72(b)(2)(xi) - OFFSITE NOTIFICATION
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
DAVID PROULX (R4DO)

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

Event Text

UNIT 2 AUTOMATIC REACTOR TRIP

"On July 10, 2013, at 0950 PDT, the Diablo Canyon Power Plant Unit 2 500kV line differential relay actuated. This action tripped the turbine and opened the generator output breakers to isolate the generator. With the turbine tripped and Unit 2 operating above the P-9 50% power permissive, a reactor trip was initiated from the reactor protection system.

"All plant equipment responded as designed. All three Unit 2 Auxiliary Feedwater pumps started, the Containment Fan Cooling units started and ran in slow speed, and the standby Auxiliary Saltwater train started, all as expected.

"Unit 2 is stable at normal operating temperature and pressure. All power transferred to the plant startup source without incident. Condenser vacuum was maintained.

"The preliminary cause of the differential relay actuation was a flashover of Phase A 500 kV to ground across the Phase A lightning arrestor during maintenance activities to wash the 500 kV insulators.

"NRC Resident Inspector has been informed of this event.

"A press release is planned for local media."

Decay heat is being removed by steam dumps to the condenser. No relief valves lifted during the transient. The steam generators are being supplied by the auxiliary feedwater pumps. There were no injuries to personnel. Unit 1 was not affected.

Page Last Reviewed/Updated Thursday, July 11, 2013
Thursday, July 11, 2013