ML20077C280

Deficiency Rept Re Defective Yokes P/N 342849 Mfg by Copes- Vulcan,Inc.Affected Utilities Notified & Defective Yokes Will Be replaced.Copes-Vulcan Also re-inspected All Yokes in Inventory & Verified Yokes Acceptability

ML20077C280
Person / Time
Site:	Point Beach, Sequoyah, Farley
Issue date:	11/21/1994
From:	Scarpelli J COPES-VULCAN, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-94 NUDOCS 9412010115
Download: ML20077C280 (2)

Text

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h' COPES-VULCAN, INC.

P O BOX 577

• LAKE CITY, PENNSYLVANIA 16423-0577

• PHONE (814) 7741500

• FAX (814) 7741682 November 21, 1994 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555

SUBJECT:

Defective Yokes, P/N 342849 manufactured by Copes-Vulcan, Inc., Lake City, PA REF: FAX message to NRC Op Center dated Nov. 3, 1994 Copes-Vulcan has been informed by Tennessee Valley Authority (TVA) that yokes, P/N 342849, supplied for the upgrade of existing air operated actuators at the Sequoyah Nuclear Plant do not have an acceptable thread form for the 1/2"-13 UNC-2B tapped holes. On November 3, 1994, Copes-Vulcan subsequently notified three (3) utilities of this defect.

This problem was discovered during the assembly process while attempting to secure the mating component to the yoke. Application of specified assembly torque could not be achieved as the mating component would lose engagement with the 1/2"-13 UNC-2B thread in the yoke before the required torque was applied.

The source of the problem has been traced to a manufacturing operation which was configured to use a roll tap to form the 1/2"-13 UNC-2B threads. For the subject yokes, a cutting tap was incorrectly used for the threading operation. This caused the minor diameter of the thread to be oversize as the base material was cut, rather than formed (mechanically displaced) to create the thread.

An investigation into the affected yokes has limited the usage to nine (9) yokes at TVA, one (1) yoke at Wisconsin Power and one (1) yoke at Farley Southern Company. The TVA yokes have not been installed at this time and the Wisconsin Power, Point Beach, actuator which may contain a defective yoke, would perform its fail safe mode as delivered as would the valve at Farley. All eleven (11) yokes will be replaced.

Copes-Vulcan re-inspected all yokes in inventory and verified their acceptability.

Cordially, 290003 p/Iy d r J.R. Scarpelli Director Quality Assurance JRS/pjg Attachment fjj20ggy}ggg]j66 fiff;)D' S PDR jv i

. 1 COPES-VULCAN, INC.

MARTIN & RICE AVENUES

, LAKE CITY, PA 16423 USA PHONE: 814-774-1708 l FAX: 814-774-1682 DATE: November 3, 1994 NO. OF PAGES SENT 1 FROM: J.R. Scarcelli QUALITY ASSURANCE DEPARTMENT TO: COMPANY TVA - Secuoyah ATTENTION Steve Gillev FAX NO. 615-843-8750 Copes-Vulcan, Lake City, Pennsylvania, has been informed by Tennessee Valley ;cathority, Sequoyah, that nine (9) yokes, P/N 342849, supplied to tnur as part of an upgrade program, have discrepant 1/2-13UNC taped holes which could impact the ability to operate if installed.

Copes-Vulcan has traced the problem to a manufacturing operation which drills the holes oversize and then uses a roll tap to re-form the threads. If a roll tap is not used, the thread minor diameter is oversize to the point of weakening the thread. This is what happened in this instance.

An investigation into the affected yokes has limited the usage to nine (9) yokes at TVA, one (1) yoke at Wisconsin Power and one (1) yoke at Farley Southern Company. The TVA yokes have not been installed at this time and the Wisconsin Power, Point Beach, actuator which may contain a defective yoke, would perform its fail safe mode as delivered as would the valve at Farley.

The affected utilities have been notified as of November 3, 1994.

A written report as required by 10CFR21 will be issued.

- M/

J.R. Scarpelli Director Quality Assurance JRS/pjg

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