Event Notification Report for June 18, 2012
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
06/17/2012 - 06/18/2012
EVENT NUMBERS
48204
Power Reactor
Event Number: 48204
Facility: WATTS BAR
Region: 2 State: TN
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MICHAEL BOTTORFF
HQ OPS Officer: MARK ABRAMOVITZ
Region: 2 State: TN
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: MICHAEL BOTTORFF
HQ OPS Officer: MARK ABRAMOVITZ
Notification Date: 08/17/2012
Notification Time: 14:11 [ET]
Event Date: 06/18/2012
Event Time: 23:49 [EDT]
Last Update Date: 08/17/2012
Notification Time: 14:11 [ET]
Event Date: 06/18/2012
Event Time: 23:49 [EDT]
Last Update Date: 08/17/2012
Emergency Class: NON EMERGENCY
10 CFR Section:
50.73(a)(1) - INVALID SPECIF SYSTEM ACTUATION
10 CFR Section:
50.73(a)(1) - INVALID SPECIF SYSTEM ACTUATION
Person (Organization):
EUGENE GUTHRIE (R2DO)
EUGENE GUTHRIE (R2DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
INVALID ACTUATION OF CONTAINMENT VENTILATION ISOLATION
"Watts Bar Nuclear Plant's (WBN's) containment ventilation isolation systems provide the means of isolating ventilation systems that pass through containment penetrations to confine to the containment any radioactivity that may be released following a design basis event. The containment ventilation system isolates following a manual or automatic safety injection signal, high containment purge exhaust radiation levels, or manual actuation.
"On 6/18/12 at 2349 EDT, a B train containment ventilation isolation signal was received in the Main Control Room due to an invalid high radiation signal from a containment purge exhaust radiation monitor (1-RM-131). Corrective action replaced the 1-RM-131 ratemeter following the 6/18/12 B train containment ventilation isolation. However, on 7/2/12 at 1252 EDT, a second B train containment ventilation isolation signal was received in the Main Control Room due to another invalid high radiation signal from 1-RM-131. An investigation found that 1-RM-131 was spiking repeatedly due to a defective Power On indicating light socket which affected the 120 VAC power circuit that is common with the 24 volt power supply. 120 VAC signal fluctuations could affect the 24 volt power supply signal to the rate meter causing output spikes. Corrective action replaced the defective Power On indicating light socket on 7/3/12.
"This event notification is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A) as a 60 day telephone notification of the invalid initiation of a containment isolation signal. The specific system and train that was actuated was B train containment ventilation isolation. The system functioned as designed and the complete train operated.
"WBN's NRC Resident Inspector has been notified."
"Watts Bar Nuclear Plant's (WBN's) containment ventilation isolation systems provide the means of isolating ventilation systems that pass through containment penetrations to confine to the containment any radioactivity that may be released following a design basis event. The containment ventilation system isolates following a manual or automatic safety injection signal, high containment purge exhaust radiation levels, or manual actuation.
"On 6/18/12 at 2349 EDT, a B train containment ventilation isolation signal was received in the Main Control Room due to an invalid high radiation signal from a containment purge exhaust radiation monitor (1-RM-131). Corrective action replaced the 1-RM-131 ratemeter following the 6/18/12 B train containment ventilation isolation. However, on 7/2/12 at 1252 EDT, a second B train containment ventilation isolation signal was received in the Main Control Room due to another invalid high radiation signal from 1-RM-131. An investigation found that 1-RM-131 was spiking repeatedly due to a defective Power On indicating light socket which affected the 120 VAC power circuit that is common with the 24 volt power supply. 120 VAC signal fluctuations could affect the 24 volt power supply signal to the rate meter causing output spikes. Corrective action replaced the defective Power On indicating light socket on 7/3/12.
"This event notification is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A) as a 60 day telephone notification of the invalid initiation of a containment isolation signal. The specific system and train that was actuated was B train containment ventilation isolation. The system functioned as designed and the complete train operated.
"WBN's NRC Resident Inspector has been notified."