Event Notification Report for February 11, 2009
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
02/10/2009 - 02/11/2009
EVENT NUMBERS
44846
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 44846
Facility: PALO VERDE
Region: 4 State: AZ
Unit: [1] [2] [3]
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: TIM GAFFNEY
HQ OPS Officer: PETE SNYDER
Region: 4 State: AZ
Unit: [1] [2] [3]
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: TIM GAFFNEY
HQ OPS Officer: PETE SNYDER
Notification Date: 02/11/2009
Notification Time: 19:31 [ET]
Event Date: 02/11/2009
Event Time: 13:18 [MST]
Last Update Date: 02/12/2009
Notification Time: 19:31 [ET]
Event Date: 02/11/2009
Event Time: 13:18 [MST]
Last Update Date: 02/12/2009
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
10 CFR Section:
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
Person (Organization):
GEOFFREY MILLER (R4)
GEOFFREY MILLER (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
| 3 | N | Y | 100 | Power Operation | 100 | Power Operation |
POSSIBLY INADEQUATE BACKUP NITROGEN SUPPLY FOR ATMOSPHERIC DUMP OPERATION
"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 of under the reporting requirements of 10 CFR 50.73.
"Palo Verde Nuclear Station declared all three Unit's atmospheric dump valves (ADV) inoperable at 1318 MST. The reason for the inoperability is the discovery by engineering personnel that the ADV backup nitrogen capacity, required to operate the valves to mitigate certain accident scenarios, was not adequate.
"There are 4 ADVs (one on each steam line with two steam lines per steam generator) for each of the three units. Engineering review of a loss of offsite power event determined that the current nitrogen supply of 13.3 hours will not be adequate to get the plant to shutdown cooling entry conditions during a natural circulation asymmetric cooldown (i.e. Feedwater Line Break, Main Steam Line Break, and Steam Generator Tube Rupture).
"Actions are in progress to restore the operability of the ADVs. If unsuccessful, all three units will be required by the Technical Specifications to be in Mode 3, Hot Shutdown, by 1918 MST on February 12, 2009."
The licensee notified the NRC Resident Inspector.
* * * RETRACTION FROM RAY BUZARD TO PETE SNYDER AT 1840 ON 2/12/09 * * *
"This is a retraction of the condition reported in EN # 44846 on February 11, 2009 at 19:31 EST. Upon further review of the condition, engineering personnel have determined that the ADV nitrogen supply was adequate to mitigate the consequences of the postulated events and the ADVs were declared operable at 04:30 MST on February 12, 2009. Therefore, no reportable condition existed."
The licensee notified the NRC Resident Inspector. Notified R4DO (Miller).
"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 of under the reporting requirements of 10 CFR 50.73.
"Palo Verde Nuclear Station declared all three Unit's atmospheric dump valves (ADV) inoperable at 1318 MST. The reason for the inoperability is the discovery by engineering personnel that the ADV backup nitrogen capacity, required to operate the valves to mitigate certain accident scenarios, was not adequate.
"There are 4 ADVs (one on each steam line with two steam lines per steam generator) for each of the three units. Engineering review of a loss of offsite power event determined that the current nitrogen supply of 13.3 hours will not be adequate to get the plant to shutdown cooling entry conditions during a natural circulation asymmetric cooldown (i.e. Feedwater Line Break, Main Steam Line Break, and Steam Generator Tube Rupture).
"Actions are in progress to restore the operability of the ADVs. If unsuccessful, all three units will be required by the Technical Specifications to be in Mode 3, Hot Shutdown, by 1918 MST on February 12, 2009."
The licensee notified the NRC Resident Inspector.
* * * RETRACTION FROM RAY BUZARD TO PETE SNYDER AT 1840 ON 2/12/09 * * *
"This is a retraction of the condition reported in EN # 44846 on February 11, 2009 at 19:31 EST. Upon further review of the condition, engineering personnel have determined that the ADV nitrogen supply was adequate to mitigate the consequences of the postulated events and the ADVs were declared operable at 04:30 MST on February 12, 2009. Therefore, no reportable condition existed."
The licensee notified the NRC Resident Inspector. Notified R4DO (Miller).