Event Notification Report for January 08, 2020
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
01/07/2020 - 01/08/2020
EVENT NUMBERS
54467
Part 21
Event Number: 54467
Rep Org: ENGINE SYSTEMS, INC
Licensee: ENGINE SYSTEMS, INC.
Region: 1
City: ROCKY MOUNT State: NC
County:
License #:
Agreement: Y
Docket:
NRC Notified By: DAN ROBERTS
HQ OPS Officer: BRIAN LIN
Licensee: ENGINE SYSTEMS, INC.
Region: 1
City: ROCKY MOUNT State: NC
County:
License #:
Agreement: Y
Docket:
NRC Notified By: DAN ROBERTS
HQ OPS Officer: BRIAN LIN
Notification Date: 01/08/2020
Notification Time: 16:44 [ET]
Event Date: 01/08/2020
Event Time: 00:00 [EST]
Last Update Date: 01/08/2020
Notification Time: 16:44 [ET]
Event Date: 01/08/2020
Event Time: 00:00 [EST]
Last Update Date: 01/08/2020
Emergency Class: NON EMERGENCY
10 CFR Section:
21.21(d)(3)(i) - DEFECTS AND NONCOMPLIANCE
10 CFR Section:
21.21(d)(3)(i) - DEFECTS AND NONCOMPLIANCE
Person (Organization):
STEVEN RUDISAIL (R2DO)
JOHN HANNA (R3DO)
- PART 21/50.55 REACTORS (EMAIL)
STEVEN RUDISAIL (R2DO)
JOHN HANNA (R3DO)
- PART 21/50.55 REACTORS (EMAIL)
PART 21 - INADEQUATE SELENIUM SURGE SUPPRESSOR THREAD MODIFICATION
The following is a summary of information that was received via facsimile:
On November 14, 2019, Engine Systems, Inc. obtained information of a defect or failure to comply associated with selenium surge suppressors. Three batches of suppressors supplied by Engine Services, Inc. between 2011 and 2013 utilize a thread modification that is inadequate for the application. The design specifies the use of a single 1/4-20 x 2-3/4" long bolt to compress the stack of selenium cells as well as mount the suppressor. Contrary to this requirement, the manufacturer used a #8-32 screw through the body of the stack and added a modified bolt to obtain the required 1/4-20 mounting threads. The modified bolt consisted of a 1/4-20 x 5/8" long bolt that was drilled and tapped in the head to accept #8-32 threads. An attempt to install the selenium surge suppressor by tightening the corresponding mounting nut may result in failure of the modified bolt threads.
Use of this thread modifier significantly reduces the strength of the mounting threads. Failure of the mounting threads creates the possibility of the suppressor dislodging with the potential to electrically short between the positive and negative plates of the rectifier assembly. An electrical short would affect output of the voltage regulator system, which may prevent the emergency diesel generator set from performing its safety-related function. This issue is therefore considered to be a reportable defect as defined by 10 CFR Part 21.
The affected part number is 8403049. A list of affected customers include: Point Beach Nuclear Plant and Surry Power Station.
The following is a summary of information that was received via facsimile:
On November 14, 2019, Engine Systems, Inc. obtained information of a defect or failure to comply associated with selenium surge suppressors. Three batches of suppressors supplied by Engine Services, Inc. between 2011 and 2013 utilize a thread modification that is inadequate for the application. The design specifies the use of a single 1/4-20 x 2-3/4" long bolt to compress the stack of selenium cells as well as mount the suppressor. Contrary to this requirement, the manufacturer used a #8-32 screw through the body of the stack and added a modified bolt to obtain the required 1/4-20 mounting threads. The modified bolt consisted of a 1/4-20 x 5/8" long bolt that was drilled and tapped in the head to accept #8-32 threads. An attempt to install the selenium surge suppressor by tightening the corresponding mounting nut may result in failure of the modified bolt threads.
Use of this thread modifier significantly reduces the strength of the mounting threads. Failure of the mounting threads creates the possibility of the suppressor dislodging with the potential to electrically short between the positive and negative plates of the rectifier assembly. An electrical short would affect output of the voltage regulator system, which may prevent the emergency diesel generator set from performing its safety-related function. This issue is therefore considered to be a reportable defect as defined by 10 CFR Part 21.
The affected part number is 8403049. A list of affected customers include: Point Beach Nuclear Plant and Surry Power Station.