Event Notification Report for June 23, 2013
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
06/22/2013 - 06/23/2013
EVENT NUMBERS
49143
Power Reactor
Event Number: 49143
Facility: DIABLO CANYON
Region: 4 State: CA
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: ADAM PECK
HQ OPS Officer: VINCE KLCO
Region: 4 State: CA
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: ADAM PECK
HQ OPS Officer: VINCE KLCO
Notification Date: 06/24/2013
Notification Time: 04:35 [ET]
Event Date: 06/23/2013
Event Time: 21:20 [PDT]
Last Update Date: 08/21/2013
Notification Time: 04:35 [ET]
Event Date: 06/23/2013
Event Time: 21:20 [PDT]
Last Update Date: 08/21/2013
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):
WAYNE WALKER (R4DO)
WAYNE WALKER (R4DO)
| 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 |
LOSS OF 230 KV OFFSITE POWER RESULTS IN THE AUTOMATIC START OF EMERGENCY DIESEL GENERATORS
"At 2120 PDT, Diablo Canyon Power Plant experienced a loss of the offsite 230 kV startup power source due to an offsite transmission system relay actuation, resulting in valid anticipatory starts of Units 1 and 2 three emergency diesel generators on each unit. All diesels successfully started but were not loaded. All systems operated as designed with no problems observed.
"The 230 kV startup power source is the only offsite power system designed to be immediately available following an accident. However, the safety related onsite emergency diesel system would have provided power to mitigate the consequences of an accident while the 230 kV was unavailable.
"Restoration of the 230 kV offsite power system is in progress."
The licensee will notify the NRC Resident Inspector.
* * * UPDATE FROM MICHAEL KENNEDY TO HOWIE CROUCH AT 1618 EDT ON 8/21/13 * * *
"230 kV was restored to Operable on 06/24/13 at 0200 PDT. Normal 500 kV Offsite Power remained operable and was unaffected by this event.
"Following further review, Diablo Canyon Power Plant (DCPP) has determined that the loss of the 230 kV system was not a condition that could have prevented fulfillment of the safety function of a system credited to mitigate the consequences of an accident. This power source is not considered to be a safety-related system that is credited to mitigate any accident as described in the DCPP UFSAR, Chapters 6 and 15 accident analyses. PG&E concludes that the emergency diesel generators are the only power source needed to fulfill the accident mitigation function, and they did not become inoperable as a result of this event."
The licensee will be notifying the NRC Resident Inspector. Notified R4DO (Werner).
"At 2120 PDT, Diablo Canyon Power Plant experienced a loss of the offsite 230 kV startup power source due to an offsite transmission system relay actuation, resulting in valid anticipatory starts of Units 1 and 2 three emergency diesel generators on each unit. All diesels successfully started but were not loaded. All systems operated as designed with no problems observed.
"The 230 kV startup power source is the only offsite power system designed to be immediately available following an accident. However, the safety related onsite emergency diesel system would have provided power to mitigate the consequences of an accident while the 230 kV was unavailable.
"Restoration of the 230 kV offsite power system is in progress."
The licensee will notify the NRC Resident Inspector.
* * * UPDATE FROM MICHAEL KENNEDY TO HOWIE CROUCH AT 1618 EDT ON 8/21/13 * * *
"230 kV was restored to Operable on 06/24/13 at 0200 PDT. Normal 500 kV Offsite Power remained operable and was unaffected by this event.
"Following further review, Diablo Canyon Power Plant (DCPP) has determined that the loss of the 230 kV system was not a condition that could have prevented fulfillment of the safety function of a system credited to mitigate the consequences of an accident. This power source is not considered to be a safety-related system that is credited to mitigate any accident as described in the DCPP UFSAR, Chapters 6 and 15 accident analyses. PG&E concludes that the emergency diesel generators are the only power source needed to fulfill the accident mitigation function, and they did not become inoperable as a result of this event."
The licensee will be notifying the NRC Resident Inspector. Notified R4DO (Werner).