| U.S. Nuclear Regulatory Commission
Operations Center Event Reports For
07/11/2017 - 07/12/2017 ** EVENT NUMBERS ** |
 | Part 21 | Event Number: 48797 | Rep Org: FLOWSERVE
Licensee: ANCHOR DARLING
Region: 1
City: RALEIGH State: NC
County:
License #:
Agreement: Y
Docket:
NRC Notified By: JAMES TUCKER
HQ OPS Officer: BILL HUFFMAN | Notification Date: 03/01/2013
Notification Time: 11:12 [ET]
Event Date: 12/29/2012
Event Time: [EST]
Last Update Date: 07/11/2017 | Emergency Class: NON EMERGENCY
10 CFR Section:
21.21(d)(3)(i) - DEFECTS AND NONCOMPLIANCE
| Person (Organization):
ART BURRITT (R1DO)
RANDY MUSSER (R2DO)
JAMNES CAMERON (R3DO)
DON ALLEN (R4DO)
NRC HQ PART 21 GROUP (EMAI)
| Event Text PART 21 - WEDGE PIN FAILURE IN ANCHOR DARLING MOTOR OPERATED DOUBLE DISC GATE VALVES WITH THREADED STEM TO UPPER WEDGE CONNECTIONS
The following is a summary of information received from Flowserve via facsimile:
"This is to notify the US Nuclear Regulatory Commission that, in accordance with the provisions of 10CFR Part 21, we have identified a potential issue and are submitting our evaluation of the event.
"Flowserve has been working with the Tennessee Valley Authority's (TVA) Browns Ferry Nuclear Plant to investigate the failure of a Size 10, Class 900 Anchor/Darling motor-operated double-disc gate valve. The failure was due to the shearing of the wedge pin which serves a joint locking function at the threaded interface between the valve stem and upper wedge. The pin is designed to ensure that the joint does not loosen due to vibration and other secondary loads. On some valve designs, the pin also is used to attach the disc retainers to the upper wedge. The pin shearing allowed rotation of the stem during the closing stroke when the valve was seating and ultimately resulted in loss of the stem to upper wedge joint integrity.
"Flowserve has completed an evaluation of the failure and concluded the root cause of the wedge pin failure was excessive load on the pin. The stem operating torque exceeded the torque to tighten the stem into the upper wedge before installation of the wedge pin. The additional stem torque produced a load on the wedge pin creating a stress which exceeded the pin shear strength causing the failure. The recommended assembly stem torque did not envelope the operating torque for the TVA application providing the potential for an over load situation and ultimate failure. The operating torque for the TVA valve was unusually high due to the fast closing time of the actuator and very conservative closing thrust margin.
"This situation can potentially occur on any Anchor/Darling type double-disc gate valve with a threaded stem to upper wedge connection, typically size 2.5" and larger, operated by an actuator that applies torque on the stem to produce the required valve operating thrust. An operating stem torque greater than the assembly stem torque can provide the opportunity for excessive pin load and potentially failure.
"We have reviewed our records, and the only similar wedge pin failure that we can identify, in addition to the Browns Ferry problems, is a sheared wedge pin at LaSalle Nuclear Station in 1993. Our investigation of the LaSalle failure concluded that the wedge pin failed due to excessive torque in the opening direction due to bonnet over pressurization.
"Flowserve recommends that all critical Anchor/Darling Double-Disc Gate valves with threaded stem to upper wedge connections and actuators that produce a torque on the stem be evaluated for potential wedge pin failure. Valves with electric motor actuators which produce high output torques are the most susceptible to failure. Valves which were assembled with stem torques that exceed the operating torque are not candidates for failure.
"Below is a list, based on our records, of customers, utilities and nuclear plants which were supplied with Anchor/Darling Double-Disc Gate valves with motor actuators on contracts with ASME Section III and/or 10 CFR 21 imposed.
"Flowserve plans to provide each of the customers identified [below] with a copy of this notification letter."
The following facilities in the United States may be affected:
ANO 1, Browns Ferry, Brunswick, Callaway, Catawba, Clinton, Columbia, Cook, Cooper, Crystal River, Dresden, Diablo Canyon, Duane Arnold, Fitzpatrick, Fort Calhoun, Grand Gulf, Hatch, Indian Point, Kewaunee, LaSalle, Limerick, Maine Yankee, Millstone, Monticello, Nine Mile, North Anna, Oconee, Oyster Creek, Peach Bottom, Perry, Pilgrim, Prairie Island, Quad Cities, River Bend, Robinson, San Onofre, St. Lucie, Surry, Three Mile Island 2, Waterford, VC Summer, Vermont Yankee, Wolf Creek.
See Related Part 21 EN #48650.
* * * UPDATE AT 1537 EDT ON 7/11/17 FROM AMY OATHOUT TO JEFF HERRERA * * *
The following is a summary of a report provided by Flowserve via email:
This is to notify the US Nuclear Regulatory Commission that, in accordance with the provisions of 10 CFR Part 21, Flowserve has gained additional insight and information concerning the referenced previously reported issue based on a recent incident at the LaSalle County Station, Unit 2 involving a similar valve.
Evaluation of a similar incident at LaSalle added an element not addressed in the previous evaluation regarding the limitation of a pressed-on stem collar to support the actuator thrust and maintain the stem-wedge preload.
Valve evaluations and actions resulting from the previous notification are applicable and still apply. This notification includes additional information for maintaining the stem preload that was not addressed previously. The actuator thrust as well as the torque must be reviewed to insure the preload is maintained.
A list of customers, utilities and nuclear plants which were supplied with Anchor/Darling DD Gate valves with motor actuators on contracts with Section 111 and/or 10CFR21 was provided. This list added a few sites not included on the list provided with the original notification.
For questions or additional information please contact:
Joseph Carter
Manager, Quality Assurance
Flowserve Corporation, FCD
Raleigh, NC
919-831-3220
Notified R1DO(Dimitriadis), R2DO(Bonser), R3DO(Peterson), R4DO(Proulx), Part 21 group (via email). |
| Agreement State | Event Number: 52838 | Rep Org: SC DIV OF HEALTH & ENV CONTROL
Licensee: CLEMSON UNIVERSITY
Region: 1
City: CLEMSON State: SC
County:
License #: 540
Agreement: Y
Docket:
NRC Notified By: ANDREW M. ROXBURGH
HQ OPS Officer: DONG HWA PARK | Notification Date: 07/03/2017
Notification Time: 11:22 [ET]
Event Date: 12/12/2013
Event Time: [EDT]
Last Update Date: 07/03/2017 | Emergency Class: NON EMERGENCY
10 CFR Section:
AGREEMENT STATE
| Person (Organization):
RAY POWELL (R1DO)
NMSS_EVENTS_NOTIFICA (EMAI)
| Event Text AGREEMENT STATE REPORT - UNPLANNED CONTAMINATION
The following report was received from the South Carolina Department of Health and Environmental Control via e-mail:
"This event was first reported to the State as an allegation but is now being reported as an incident because of our recent IMPEP [Integrated Materials Performance Evaluation Program] review.
"The unplanned contamination was because of the dissolution of a Po-210 Static Eliminator containing 125 microcuries. The contamination was discovered when a Graduate Research Assistance was surveying himself upon exiting the lab. The RSO was notified and the lab was thoroughly decontaminated. The laboratory was posted and access was restricted. The licensee was required to report this incident within 24 hours of discovery because the unplanned contamination caused a restricted area to be closed for more than 24 hours." |
| Power Reactor | Event Number: 52848 | Facility: COLUMBIA GENERATING STATION
Region: 4 State: WA
Unit: [2] [ ] [ ]
RX Type: [2] GE-5
NRC Notified By: SID MORRISON
HQ OPS Officer: JEFF HERRERA | Notification Date: 07/11/2017
Notification Time: 17:45 [ET]
Event Date: 07/11/2017
Event Time: 07:50 [PDT]
Last Update Date: 07/11/2017 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
| Person (Organization):
DAVID PROULX (R4DO)
|
| Unit | SCRAM Code | RX CRIT | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode | | 2 | N | Y | 100 | Power Operation | 100 | Power Operation | Event Text FLOW INDICATING SWITCH FOR HIGH PRESSURE CORE SPRAY UNRELIABLE INDICATION
"This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function. On July 11th, 2017, it was discovered that the flow indicating switch for the high pressure core spray (HPCS) minimum flow valve was providing unreliable indication. There was no flow through the line at the time the condition was discovered. This switch provides the flow signal to the HPCS minimum flow valve logic.
"The switch was declared inoperable and the required actions of Technical Specification 3.3.5.1 were entered. This condition could have prevented the HPCS system, a single train safety system, from performing its specified safety function. Troubleshooting is underway to determine the cause of and correct the condition." | |