Event Notification Report for May 27, 2007
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/26/2007 - 05/27/2007
EVENT NUMBERS
43391
Power Reactor
Event Number: 43391
Facility: DIABLO CANYON
Region: 4 State: CA
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MATT COWARD
HQ OPS Officer: MARK ABRAMOVITZ
Region: 4 State: CA
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MATT COWARD
HQ OPS Officer: MARK ABRAMOVITZ
Notification Date: 05/27/2007
Notification Time: 18:08 [ET]
Event Date: 05/27/2007
Event Time: 11:17 [PDT]
Last Update Date: 05/31/2007
Notification Time: 18:08 [ET]
Event Date: 05/27/2007
Event Time: 11:17 [PDT]
Last Update Date: 05/31/2007
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):
CLAUDE JOHNSON (R4)
CLAUDE JOHNSON (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | M/R | N | 0 | Hot Standby | 0 | Hot Standby |
MANUAL REACTOR TRIP IN MODE 3 DURING CONTROL ROD TESTING
"On May 27, 2007, at 11:17 PDT, with Diablo Canyon Power Plant (DCPP) Unit 1 in Mode 3 (Hot Standby) during day 28 of refueling outage 14, operators manually actuated the reactor protection system. All rods fully inserted.
"Operators were performing Surveillance Test Procedure (STP) R-1 C 'Digital Rod Position Indictor Functional Test'. While control bank C was being re-inserted, at 42 steps withdrawn, rod N-13 indicated position changed to 24 steps withdrawn. In response to this 18 step deviation, and in accordance with STP R-1C, operators opened the reactor trip breakers.
"At the time of the event, the reactor coolant system remained at normal operating temperature and pressure, and all other shutdown and control rod banks remained fully inserted.
"This event is being reported as an 8-hour non-emergency event in accordance with 10 CFR 50.72(b)(3)(iv)(A) for a valid actuation of the reactor protection system."
Unit-1 is maintaining temperature with atmospheric steam dumps and aux feed water. Electrical power is from 500 KV backfeed (normal electrical shutdown lineup). Control rod N-13 was being tested along with seven other control rods.
The licensee notified the NRC Resident Inspector.
* * * UPDATE ON 05/27/07 AT 2301 EDT BY JOY SKAGGS TO MACKINNON * * *
"(STP) R-1C 'Digital Position Indicator Functional Test' was re-performed on control bank C to obtain additional information.
"At 1706 hours, while control bank C was being re-inserted, at 138 steps withdrawn, rod N-13 indication dropped to 126 steps withdrawn. Rod motion was stopped to gather data. All other shutdown and control banks remained fully inserted.
"At 1725 hours, operators manually actuated a reactor trip to fully insert all control bank C rods. All rods fully inserted.
"(STP) R-1C 'Digital Rod Position Indicator Functional Test' was re-performed on control bank C for further evaluation. At 1838 hours, while control bank C was being re-inserted, at 168 steps withdrawn, rod N-13 indication dropped to 150 steps withdrawn. Rod motion was stopped to gather data. All other shutdown and control banks remained fully inserted.
"At 1840 hours, operators manually actuated a reactor trip to fully insert all control bank C rods. All rods fully inserted.
"At the time of the event, the reactor coolant system remained at normal operating temperature and pressure, and all other shutdown and control rod banks remained fully inserted." R4DO (C. Johnson) notified.
The licensee will notify the NRC Resident Inspector.
* * * UPDATE PROVIDED BY LARRY PARKER TO JEFF ROTTON AT 0951 EDT ON 05/31/07 * * *
"On May 27, 2007, in response to the initial occurrence of Rod N-13 slipping at 11:17 PDT, PG&E contacted the vendor and researched operating experience to develop a troubleshooting plan. Management approved a plan based on the vendor recommendations, which consisted of exercising all rods successfully five cycles. It was acknowledged that additional slipping events could occur requiring mitigation by opening the reactor trip breakers. Upon implementation of this plan, two similar events occurred and are described in the update above [provided on 05/27 at 2301 EDT]. Following these events, Rod N-13 was successfully cycled five times without any deviation. Reactor startup was then allowed to proceed and there have been no further rod position deviation events."
The licensee notified the NRC Resident Inspector. Notified R4DO (C. Cain)
"On May 27, 2007, at 11:17 PDT, with Diablo Canyon Power Plant (DCPP) Unit 1 in Mode 3 (Hot Standby) during day 28 of refueling outage 14, operators manually actuated the reactor protection system. All rods fully inserted.
"Operators were performing Surveillance Test Procedure (STP) R-1 C 'Digital Rod Position Indictor Functional Test'. While control bank C was being re-inserted, at 42 steps withdrawn, rod N-13 indicated position changed to 24 steps withdrawn. In response to this 18 step deviation, and in accordance with STP R-1C, operators opened the reactor trip breakers.
"At the time of the event, the reactor coolant system remained at normal operating temperature and pressure, and all other shutdown and control rod banks remained fully inserted.
"This event is being reported as an 8-hour non-emergency event in accordance with 10 CFR 50.72(b)(3)(iv)(A) for a valid actuation of the reactor protection system."
Unit-1 is maintaining temperature with atmospheric steam dumps and aux feed water. Electrical power is from 500 KV backfeed (normal electrical shutdown lineup). Control rod N-13 was being tested along with seven other control rods.
The licensee notified the NRC Resident Inspector.
* * * UPDATE ON 05/27/07 AT 2301 EDT BY JOY SKAGGS TO MACKINNON * * *
"(STP) R-1C 'Digital Position Indicator Functional Test' was re-performed on control bank C to obtain additional information.
"At 1706 hours, while control bank C was being re-inserted, at 138 steps withdrawn, rod N-13 indication dropped to 126 steps withdrawn. Rod motion was stopped to gather data. All other shutdown and control banks remained fully inserted.
"At 1725 hours, operators manually actuated a reactor trip to fully insert all control bank C rods. All rods fully inserted.
"(STP) R-1C 'Digital Rod Position Indicator Functional Test' was re-performed on control bank C for further evaluation. At 1838 hours, while control bank C was being re-inserted, at 168 steps withdrawn, rod N-13 indication dropped to 150 steps withdrawn. Rod motion was stopped to gather data. All other shutdown and control banks remained fully inserted.
"At 1840 hours, operators manually actuated a reactor trip to fully insert all control bank C rods. All rods fully inserted.
"At the time of the event, the reactor coolant system remained at normal operating temperature and pressure, and all other shutdown and control rod banks remained fully inserted." R4DO (C. Johnson) notified.
The licensee will notify the NRC Resident Inspector.
* * * UPDATE PROVIDED BY LARRY PARKER TO JEFF ROTTON AT 0951 EDT ON 05/31/07 * * *
"On May 27, 2007, in response to the initial occurrence of Rod N-13 slipping at 11:17 PDT, PG&E contacted the vendor and researched operating experience to develop a troubleshooting plan. Management approved a plan based on the vendor recommendations, which consisted of exercising all rods successfully five cycles. It was acknowledged that additional slipping events could occur requiring mitigation by opening the reactor trip breakers. Upon implementation of this plan, two similar events occurred and are described in the update above [provided on 05/27 at 2301 EDT]. Following these events, Rod N-13 was successfully cycled five times without any deviation. Reactor startup was then allowed to proceed and there have been no further rod position deviation events."
The licensee notified the NRC Resident Inspector. Notified R4DO (C. Cain)