Event Notification Report for May 30, 2016
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/29/2016 - 05/30/2016
EVENT NUMBERS
51965
Power Reactor
Event Number: 51965
Facility: DIABLO CANYON
Region: 4 State: CA
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: RUSS CRUZEN
HQ OPS Officer: JEFF HERRERA
Region: 4 State: CA
Unit: [] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: RUSS CRUZEN
HQ OPS Officer: JEFF HERRERA
Notification Date: 05/30/2016
Notification Time: 19:11 [ET]
Event Date: 05/30/2016
Event Time: 09:30 [PDT]
Last Update Date: 05/30/2016
Notification Time: 19:11 [ET]
Event Date: 05/30/2016
Event Time: 09:30 [PDT]
Last Update Date: 05/30/2016
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
GREG WERNER (R4DO)
GREG WERNER (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | N | 0 | Hot Shutdown | 0 | Hot Shutdown |
MANUAL OPENING OF REACTOR TRIP BREAKERS DUE TO ROD POSITION ERROR GREATER THAN 12 STEPS
"On 5/30/2016 at 0930 [PDT], Unit 2 was in its 19th refueling outage in Mode 4 (hot shutdown, reactor subcritical). Routine post-maintenance testing of digital rod position indication (DRPI) was in progress in accordance with Surveillance Test Procedure (STP) R-1C. Rod Shutdown Bank A was being withdrawn. With Shutdown Bank A Group 1 demand indicating 14 steps, and Group 2 demand indicating 13 steps, Bank A DRPI indicated 12 steps but control rod B4 DRPI indication remained at Step 0. With the bank demand position exceeding rod B4's DRPI indication by greater than 12 steps, Operators manually opened the Reactor Trip Breakers, placing all the rods in a known position due to an inoperable DRPI system. All systems actuated as required and rods fully inserted.
"Manual initiation of a reactor trip where the actuation is not part of a pre-planned evolution is reportable under 10 CFR 50.72 (b)(3)(iv)(A). While the reactor trip was initiated in accordance with the STP's instructions, the manual actuation was not a preplanned outcome of the STP.
"Subsequently, it was determined that rod B4 had remained on the bottom at Step 0 as indicated by DRPI. A moveable gripper fuse was blown, preventing that rod from being withdrawn. The blown fuse was replaced and testing continued in accordance with the procedure.
"There was no impact to public, employee, or plant safety.
"The NRC Resident Inspector was notified."
"On 5/30/2016 at 0930 [PDT], Unit 2 was in its 19th refueling outage in Mode 4 (hot shutdown, reactor subcritical). Routine post-maintenance testing of digital rod position indication (DRPI) was in progress in accordance with Surveillance Test Procedure (STP) R-1C. Rod Shutdown Bank A was being withdrawn. With Shutdown Bank A Group 1 demand indicating 14 steps, and Group 2 demand indicating 13 steps, Bank A DRPI indicated 12 steps but control rod B4 DRPI indication remained at Step 0. With the bank demand position exceeding rod B4's DRPI indication by greater than 12 steps, Operators manually opened the Reactor Trip Breakers, placing all the rods in a known position due to an inoperable DRPI system. All systems actuated as required and rods fully inserted.
"Manual initiation of a reactor trip where the actuation is not part of a pre-planned evolution is reportable under 10 CFR 50.72 (b)(3)(iv)(A). While the reactor trip was initiated in accordance with the STP's instructions, the manual actuation was not a preplanned outcome of the STP.
"Subsequently, it was determined that rod B4 had remained on the bottom at Step 0 as indicated by DRPI. A moveable gripper fuse was blown, preventing that rod from being withdrawn. The blown fuse was replaced and testing continued in accordance with the procedure.
"There was no impact to public, employee, or plant safety.
"The NRC Resident Inspector was notified."