Event Notification Report for April 21, 2018
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
04/20/2018 - 04/21/2018
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 53355
Facility: WATTS BAR
Region: 2 State: TN
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: JUSTIN GALLAGHER
HQ OPS Officer: DAVID AIRD
Region: 2 State: TN
Unit: [1] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: JUSTIN GALLAGHER
HQ OPS Officer: DAVID AIRD
Notification Date: 04/22/2018
Notification Time: 02:34 [ET]
Event Date: 04/21/2018
Event Time: 21:52 [EDT]
Last Update Date: 05/09/2018
Notification Time: 02:34 [ET]
Event Date: 04/21/2018
Event Time: 21:52 [EDT]
Last Update Date: 05/09/2018
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(B) - POT RHR INOP
10 CFR Section:
50.72(b)(3)(v)(B) - POT RHR INOP
Person (Organization):
ALAN BLAMEY (R2DO)
ALAN BLAMEY (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 |
BOTH TRAINS OF RESIDUAL HEAT REMOVAL INOPERABLE
"On April 21, 2018 at 2152 EDT, Watts Bar Nuclear Plant (WBN) Unit 1 entered TS [Technical Specifications] LCO [Limiting Condition for Operation] 3.0.3 due to both trains of the Residual Heat Removal System (RHRS) becoming inoperable. During surveillance testing, the gas void values on Emergency Core Cooling System (ECCS) piping common to both trains did not meet acceptance criteria. This caused both RHRS trains to become inoperable. Operations subsequently vented the RHRS to meet the acceptance criteria and exited TS LCO 3.0.3 at 2222 EDT. More frequent surveillances will be conducted to monitor gas void volumes while additional analysis is being performed to determine corrective actions."
The NRC Resident Inspector has been notified.
* * * RETRACTION FROM ANTHONY PATE TO DONALD NORWOOD AT 1310 EDT ON 5/9/2018 * * *
"This event is being retracted. The initial report was based on a conservative acceptance criteria for gas accumulation adopted on April 19, 2018 when it was determined that the previously used acceptance criteria for gas accumulation in the ECCS was non-conservative. Additional analysis has subsequently been performed and determined that a higher gas accumulation acceptance criteria does not challenge operability. With a void of less than the acceptance criteria, in the event of ECCS actuation, the system piping support loads will remain within structural limits and the piping system will remain operable. Therefore, both trains of Unit 1 RHRS were operable and the previously reported 10 CFR 50.72(b)(3)(v)(B) event is being retracted.
"The NRC Resident Inspector has been informed of this event retraction."
Notified R2DO (Ehrhardt).
"On April 21, 2018 at 2152 EDT, Watts Bar Nuclear Plant (WBN) Unit 1 entered TS [Technical Specifications] LCO [Limiting Condition for Operation] 3.0.3 due to both trains of the Residual Heat Removal System (RHRS) becoming inoperable. During surveillance testing, the gas void values on Emergency Core Cooling System (ECCS) piping common to both trains did not meet acceptance criteria. This caused both RHRS trains to become inoperable. Operations subsequently vented the RHRS to meet the acceptance criteria and exited TS LCO 3.0.3 at 2222 EDT. More frequent surveillances will be conducted to monitor gas void volumes while additional analysis is being performed to determine corrective actions."
The NRC Resident Inspector has been notified.
* * * RETRACTION FROM ANTHONY PATE TO DONALD NORWOOD AT 1310 EDT ON 5/9/2018 * * *
"This event is being retracted. The initial report was based on a conservative acceptance criteria for gas accumulation adopted on April 19, 2018 when it was determined that the previously used acceptance criteria for gas accumulation in the ECCS was non-conservative. Additional analysis has subsequently been performed and determined that a higher gas accumulation acceptance criteria does not challenge operability. With a void of less than the acceptance criteria, in the event of ECCS actuation, the system piping support loads will remain within structural limits and the piping system will remain operable. Therefore, both trains of Unit 1 RHRS were operable and the previously reported 10 CFR 50.72(b)(3)(v)(B) event is being retracted.
"The NRC Resident Inspector has been informed of this event retraction."
Notified R2DO (Ehrhardt).
Non-Agreement State
Event Number: 53357
Rep Org: STERIS ISOMEDIX PUERTO RICO, INC.
Licensee: STERIS ISOMEDIX PUERTO RICO, INC.
Region: 1
City: VEGA ALTA State: PR
County:
License #: 52-24994-01
Agreement: N
Docket:
NRC Notified By: DAVID JACKSON
HQ OPS Officer: DONALD NORWOOD
Licensee: STERIS ISOMEDIX PUERTO RICO, INC.
Region: 1
City: VEGA ALTA State: PR
County:
License #: 52-24994-01
Agreement: N
Docket:
NRC Notified By: DAVID JACKSON
HQ OPS Officer: DONALD NORWOOD
Notification Date: 04/22/2018
Notification Time: 11:42 [ET]
Event Date: 04/21/2018
Event Time: 14:37 [AST]
Last Update Date: 04/22/2018
Notification Time: 11:42 [ET]
Event Date: 04/21/2018
Event Time: 14:37 [AST]
Last Update Date: 04/22/2018
Emergency Class: NON EMERGENCY
10 CFR Section:
36.83(a)(4) - FAILED CABLE/DRIVE
10 CFR Section:
36.83(a)(4) - FAILED CABLE/DRIVE
Person (Organization):
JON LILLIENDAHL (R1DO)
WILLIAM GOTT (IRD)
NMSS_EVENTS_NOTIFICATION (EMAIL)
JON LILLIENDAHL (R1DO)
WILLIAM GOTT (IRD)
NMSS_EVENTS_NOTIFICATION (EMAIL)
FAILURE OF SOURCE RACK DRIVE MECHANISM
The following is a synopsis of information received via E-mail:
On 4/21/2018 at 1437 AST, the irradiator faulted with a 'Source Pass Cylinder Fault.' Source rack No. 1 moved to safe position in the pool but rack No. 2 remained in the raised position. The Maintenance Manager was notified of the situation. After evaluating the problem with the rack, he found that the air from the source rack No. 2 hoist cylinder was not being released through SVP36 and SVP36A. The Operators loosened a pipe fitting and let air slowly bleed from the rack hoist cylinder. This brought rack No. 2 into a fully lowered position at 1446 AST.
The Maintenance Manager contacted the corporate, Radiation Safety Manager and the plant manager and informed them of the situation.
The Maintenance Manager removed SVP36 and SVP36A valves and took them to the maintenance shop. There was no debris or water found in the valves. Both valves were replaced.
The Maintenance Manager contacted the Plant Manager and the corporate RSM to inform them that the rack problem was caused by the valves not releasing and that valves had been replaced.
The Maintenance Manager restarted the irradiator and after one cycle stopped the irradiator to test the valves. The source racks lowered into the pool as designed.
Corrective Actions:
1. The solenoid valve vendor will be contacted Monday morning and backup-replacement valves for SVP35, SVP35A, SVP36 and SVP36A will be ordered.
2. Annual replacement of SVP35, SVP35A, SVP36 and SVP36A will be added as an annual PM task.
Further investigation into the source valve failure will continue and conclusions will be included in the written report to Region 1 within 30 days.
The irradiator is now operating as designed. No personnel were exposed, nor was there the possibility of exposure, to the source.
The following is a synopsis of information received via E-mail:
On 4/21/2018 at 1437 AST, the irradiator faulted with a 'Source Pass Cylinder Fault.' Source rack No. 1 moved to safe position in the pool but rack No. 2 remained in the raised position. The Maintenance Manager was notified of the situation. After evaluating the problem with the rack, he found that the air from the source rack No. 2 hoist cylinder was not being released through SVP36 and SVP36A. The Operators loosened a pipe fitting and let air slowly bleed from the rack hoist cylinder. This brought rack No. 2 into a fully lowered position at 1446 AST.
The Maintenance Manager contacted the corporate, Radiation Safety Manager and the plant manager and informed them of the situation.
The Maintenance Manager removed SVP36 and SVP36A valves and took them to the maintenance shop. There was no debris or water found in the valves. Both valves were replaced.
The Maintenance Manager contacted the Plant Manager and the corporate RSM to inform them that the rack problem was caused by the valves not releasing and that valves had been replaced.
The Maintenance Manager restarted the irradiator and after one cycle stopped the irradiator to test the valves. The source racks lowered into the pool as designed.
Corrective Actions:
1. The solenoid valve vendor will be contacted Monday morning and backup-replacement valves for SVP35, SVP35A, SVP36 and SVP36A will be ordered.
2. Annual replacement of SVP35, SVP35A, SVP36 and SVP36A will be added as an annual PM task.
Further investigation into the source valve failure will continue and conclusions will be included in the written report to Region 1 within 30 days.
The irradiator is now operating as designed. No personnel were exposed, nor was there the possibility of exposure, to the source.