Event Notification Report for December 28, 2000
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
12/27/2000 - 12/28/2000
EVENT NUMBERS
37637
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 37637
Facility: COOPER
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: STEVE WHEELER
HQ OPS Officer: BOB STRANSKY
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: STEVE WHEELER
HQ OPS Officer: BOB STRANSKY
Notification Date: 12/28/2000
Notification Time: 12:21 [ET]
Event Date: 12/28/2000
Event Time: 07:41 [CST]
Last Update Date: 01/05/2001
Notification Time: 12:21 [ET]
Event Date: 12/28/2000
Event Time: 07:41 [CST]
Last Update Date: 01/05/2001
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(ii) - ESF ACTUATION
10 CFR Section:
50.72(b)(2)(ii) - ESF ACTUATION
Person (Organization):
CHARLES MARSCHALL (R4)
CHARLES MARSCHALL (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 |
CONTROL BUILDING VENTILATION ISOLATION
"At 0741 CST the Control Building Emergency Filtration System automatically initiated on a Control Building Intake Gas High Activity alarm. The cause of the Gas High Activity alarm is under investigation."
The NRC resident inspector has been informed of this event by the licensee.
* * * UPDATE ON 12/29/00, 0024 ET BY MYERS TAKEN BY MACKINNON * * *
During the day, trouble shooting was performed to determine the source of the actuation at 0741 CST today. Surveillance Procedure 6.PRM.317, CONTROL ROOM AIR SAMPLING SYSTEM ELECTRONIC CALIBRATION, was performed, and all indications were within specification. A source check of the gaseous channel was also performed per Instrument Operating Procedure 4.17, and the response of the monitor was normal. Air sampling was conducted, and no indications of abnormal radiation were identified. The Control Room Emergency Filtration System was returned to the standby lineup.
At 1933, the Control Room Emergency Filtration System again initiated on a high gaseous activity signal. All equipment functioned as required. The Control Building Ventilation Radiation Monitor has been declared inoperable, and the Control Room Emergency Filtration System remains in service, aligned in the accident mode.
The NRC Resident Inspector was notified.
Note: The Control Building Ventilation Radiation Monitor consists of three channels, with two required to be operable. The Iodine channel is also presently inoperable. The actuation logic requires only one channel of the three to initiate Control Room Isolation and start the Emergency Booster (pressurization) fan.
Noble gas sample was taken at 2142 CST. All readings were normal. NRC R4DO (C. Marschall) notified.
* * * UPDATE ON 1/5/01 @ 1113 BY VAN DER KAMP TO GOULD * * * RETRACTION
Event Number 37637 reported a condition at Cooper Nuclear Station (CNS) where the Control Room Emergency Filtration System (CREPS) automatically initiated on a Control Building Intake Gas High Activity alarm. Surveillance testing found no abnormalities with the system and air sampling found no indications of abnormal radiation levels. A subsequent identical event occurred later the same day and was reported to the NRC Operations Center in an update.
Subsequent troubleshooting has found a solder connection, that connects gas monitor components to ground, had come apart. Discussions with the manufacturer of the monitor confirm that the loss of ground can cause spiking in the displayed background reading.
CNS investigation has found that the initiation of the CREPS was due to an invalid signal, i.e., not due to an actual elevated radioactive concentration. Per 10CFR50.72(b)(2)(ii), invalid actuations of CREFS are not required to be reported and EN 37637 is retracted.
The NRC Resident Inspector will be notified of this event by the licensee.
The Reg 4 RDO(Johnson) was notified.
"At 0741 CST the Control Building Emergency Filtration System automatically initiated on a Control Building Intake Gas High Activity alarm. The cause of the Gas High Activity alarm is under investigation."
The NRC resident inspector has been informed of this event by the licensee.
* * * UPDATE ON 12/29/00, 0024 ET BY MYERS TAKEN BY MACKINNON * * *
During the day, trouble shooting was performed to determine the source of the actuation at 0741 CST today. Surveillance Procedure 6.PRM.317, CONTROL ROOM AIR SAMPLING SYSTEM ELECTRONIC CALIBRATION, was performed, and all indications were within specification. A source check of the gaseous channel was also performed per Instrument Operating Procedure 4.17, and the response of the monitor was normal. Air sampling was conducted, and no indications of abnormal radiation were identified. The Control Room Emergency Filtration System was returned to the standby lineup.
At 1933, the Control Room Emergency Filtration System again initiated on a high gaseous activity signal. All equipment functioned as required. The Control Building Ventilation Radiation Monitor has been declared inoperable, and the Control Room Emergency Filtration System remains in service, aligned in the accident mode.
The NRC Resident Inspector was notified.
Note: The Control Building Ventilation Radiation Monitor consists of three channels, with two required to be operable. The Iodine channel is also presently inoperable. The actuation logic requires only one channel of the three to initiate Control Room Isolation and start the Emergency Booster (pressurization) fan.
Noble gas sample was taken at 2142 CST. All readings were normal. NRC R4DO (C. Marschall) notified.
* * * UPDATE ON 1/5/01 @ 1113 BY VAN DER KAMP TO GOULD * * * RETRACTION
Event Number 37637 reported a condition at Cooper Nuclear Station (CNS) where the Control Room Emergency Filtration System (CREPS) automatically initiated on a Control Building Intake Gas High Activity alarm. Surveillance testing found no abnormalities with the system and air sampling found no indications of abnormal radiation levels. A subsequent identical event occurred later the same day and was reported to the NRC Operations Center in an update.
Subsequent troubleshooting has found a solder connection, that connects gas monitor components to ground, had come apart. Discussions with the manufacturer of the monitor confirm that the loss of ground can cause spiking in the displayed background reading.
CNS investigation has found that the initiation of the CREPS was due to an invalid signal, i.e., not due to an actual elevated radioactive concentration. Per 10CFR50.72(b)(2)(ii), invalid actuations of CREFS are not required to be reported and EN 37637 is retracted.
The NRC Resident Inspector will be notified of this event by the licensee.
The Reg 4 RDO(Johnson) was notified.