Event Notification Report for April 15, 2012
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
04/14/2012 - 04/15/2012
EVENT NUMBERS
47837
Power Reactor
Event Number: 47837
Facility: PALO VERDE
Region: 4 State: AZ
Unit: [] [] [3]
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: MICHAEL KOHRT
HQ OPS Officer: JOHN KNOKE
Region: 4 State: AZ
Unit: [] [] [3]
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: MICHAEL KOHRT
HQ OPS Officer: JOHN KNOKE
Notification Date: 04/15/2012
Notification Time: 17:13 [ET]
Event Date: 04/15/2012
Event Time: 12:20 [MST]
Last Update Date: 04/15/2012
Notification Time: 17:13 [ET]
Event Date: 04/15/2012
Event Time: 12:20 [MST]
Last Update Date: 04/15/2012
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
Person (Organization):
VINCENT GADDY (R4DO)
VINCENT GADDY (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 3 | M/R | Y | 0 | Startup | 0 | Hot Standby |
MANUAL REACTOR TRIP DUE TO CONTROL ROD DEVIATION DURING STARTUP
"The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73.
"On April 15, 2012 at approximately 1220 Mountain Standard Time (MST), Palo Verde Unit 3 was manually tripped during low power physics testing.
"While conducting low power physics testing following a refueling outage, Regulating Group 1 rods were being inserted while simultaneously diluting to maintain a constant power level below the Point of Adding Heat. While inserting rods one rod deviated from its subgroup when it stopped moving. The Reactor Operator immediately ceased rod motion and the dilution was stopped. The residual positive reactivity in the core caused a corresponding reactor power increase that approached procedural power limits set forth in the low power physics testing procedure. Based on these indications, operators initiated a manual reactor trip.
"Following the reactor trip, all CEAs inserted fully into the core. All systems operated as expected and this event was diagnosed as an uncomplicated reactor trip. No emergency plan classification was required per the Emergency Plan. Safety related busses remained powered during the event from offsite power and the offsite power grid is stable. No major equipment was inoperable prior to the event that contributed to the event or complicated operator response. Unit 3 is stable and in Mode 3 feeding Steam Generators with Auxiliary Feedwater Pump 'N'. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant or the health and safety of the public.
"The NRC Resident Inspector was informed of the Unit 3 reactor trip."
The electrical lineup remained normal. Decay heat is being removed via the steam bypass to the main condenser.
"The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73.
"On April 15, 2012 at approximately 1220 Mountain Standard Time (MST), Palo Verde Unit 3 was manually tripped during low power physics testing.
"While conducting low power physics testing following a refueling outage, Regulating Group 1 rods were being inserted while simultaneously diluting to maintain a constant power level below the Point of Adding Heat. While inserting rods one rod deviated from its subgroup when it stopped moving. The Reactor Operator immediately ceased rod motion and the dilution was stopped. The residual positive reactivity in the core caused a corresponding reactor power increase that approached procedural power limits set forth in the low power physics testing procedure. Based on these indications, operators initiated a manual reactor trip.
"Following the reactor trip, all CEAs inserted fully into the core. All systems operated as expected and this event was diagnosed as an uncomplicated reactor trip. No emergency plan classification was required per the Emergency Plan. Safety related busses remained powered during the event from offsite power and the offsite power grid is stable. No major equipment was inoperable prior to the event that contributed to the event or complicated operator response. Unit 3 is stable and in Mode 3 feeding Steam Generators with Auxiliary Feedwater Pump 'N'. The event did not result in any challenges to fission product barriers and there were no adverse safety consequences as a result of this event. The event did not adversely affect the safe operation of the plant or the health and safety of the public.
"The NRC Resident Inspector was informed of the Unit 3 reactor trip."
The electrical lineup remained normal. Decay heat is being removed via the steam bypass to the main condenser.