ML20247B462

Forwards Technical Bulletin 12 Addressing Problem Found at Illinois Power W/Power Semiconductor Clamps Used in Elgar Inverters.Procedure for Tightening Clamps Was Incorrect. Correct Method Involves Use of Force Gauge

ML20247B462
Person / Time
Site:	Clinton
Issue date:	03/27/1998
From:	Moshenrose T ELGAR CORP.
To:	Adams W, Debernardo R, Hill J NIAGARA MOHAWK POWER CORP., NORTHEAST NUCLEAR ENERGY CO., POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK
References
NUDOCS 9805080042
Download: ML20247B462 (6)

Text

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l March 27,1998 0

File: TB12 Mr. uFirstNamen cLastNamen aUtility_Namen l

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Reference- (1). Licensee Event Report, Clinton Power Station. Docket 05000461, Division 2 Nuclear Protection System Inverter Not in Accordance with the Plant's Design {

Basis Due to Various Deficiencies, dated 2/26/98, {

i i

Subject:

Technical Bulletin # 12: Installation of Power Semiconductor Clamps  ;

Dear Mr. nLastNamen:

Technical Bulletin # 12 addresses a problem found at Illinois Power with the power semiconductor clamps used in the Elgar inverters. The procedure for tightening the clamps at Illinois Powei was incorrect. The technique used a torque wrench for applying and verifying the compressive force on th clamps, which is incorrect The correct method for tightening the clamps involves the use of a force gauge to indicate a proper compressive force on the clamp.

Note:

The semiconductor clamps must be tightened using the approved forte gauget the use of a torque wrench is pawhibited.

Elgar recommends that, if the torque wrench method has been used, the power semiconductor c be removed and new clamps be installed as soon as practical using the procedure called out in the technical bulletin. In addition, the power semiconductors, secured by clamps that have been tightened using a torque wrench, be replaced, since internal damage may have resulted from the excessive force.

AAer reviewing this techrical bulletin, please send back a signed copy of this memo to F.lgar in

! that the technical bulletin has been received and acknowledged by the plant.

i i Ifyou have any questions regarding this bulletin, please contact me by phone at 619-458-0245, by F at 619 678-4441, or by e-mail at tomm@ cigar.com L

Sincerely,

\\

blbmd $ Ym Thomas A. Moshenrose Acknowledged' Manager, Nuclear Customer Service Date. _ . _ .

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M AR - 2 *7 - BO 16 30 FRoM. ELGAR ID 61967e4441 PACE 3 TECHNICAL BULLETIN #12 Sho21 1 of 1 Date: March 27,1998

Subject:

'rechnical Bulletin # 12: Installation of Power Semiconductor Clamps

Reference:

(1) Licensee Event Report, Clinton Power Station, Docket 05000461, Division 2 Nuclear Protection System inverter Not in Accordance with the Plant's Design liasis Due to Various Deficiencies, dated 2/26/98.

Description:

Per the Licensee Event Report (Reference 1), the compressive force applied to the heatsink clamp hardware for the SCRs and power diodes in the Elgar inverter had been applied and verified incorre causing loose connections.

A torque wrench at a value of 90-100 inch pounds was used to apply and verify the compressive force on the heatsink clamp The compressive force resulting from the use of the torque wrench was excessive The application of the excessive force caused the spring bars in the clamp to Hex beyond their yield point resulting in inadequate force applied to the installed SCRs and diodes Note:

The semiconductor clamps must be tightened using the approved force gauge; the_

__use of a torque wrench is prohibited.

Action:

Flgar recommends that the SCR and diode clamps be tightened using a fbrce gauge (Elgar P/N 846 SCR-MB) and the following procedure-

1. Check each hearsink surface for nicks, scratches, and flatness.

2 Apply a thin film of thermal compound. (Note A thick will adversely affect the electrical and thermal resistances )

1 Refer to the device preparation sheet for further surface preparation instructions.

4.

With the semiconductor positively in pince on the heatsink (i.e., the power semiconductor centered on the alignment pin), pince the clamp in position with the bolts through the holes in the heatsink t Tightened the nuts evenly until fmger-tight.

Tighten cach bolt % turn at a time, ahernating between bolts, using a 9/16 inch socket wrench Atter each %

turn of the bolts, place the force gauge fumly against the spring When the proper flat edges line up on the upper portion of the force gauge, the clamp is properly tightened. Note If the bolts have been tightened beyond the proper Rat edges on the gauge, the bolts must be loosened to finger tight and the process of tightening iepeated if the clamps have been tightened usmg a torque wrench. they should be replaced at the earliest convenient time using the above procedure to install the new clamp in addition, if the clamp has been installed using a torque wrench at a value of 90-100 inch pounds, it is piobable that the power semiconductor has been damaged by the excessive force applied. Therefoic, it is funher recommended that, if a torque wrench has been used to tighten the clamps, the powcr semiconductors be replaced also Products Affected: All Elgar inserters and uninterruptible power supplies APPR0VALS CUSTOMER SERVICE DATE ENGINEERING DATE QUAUTY DATE

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MAR-27-90 16:30 FRoM ELCAR ids S196784441 PACE 4

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Mr. Walter Adams Mr. David Bazinet Niagara Mohawk Power Corporation Northeast Nuclear Energy Company Nine Mile Point Unit 2 Connecticut Yankee P. O Box 63, Laks Road '

P. O Box 127E, Lycoming, NY 13093 East Hampton, CT 064243099 Mr. Richard DeBernardo Mr Therman Caner Northeast Nuclear Energy Company North Atlantic Energy Services Millstone Nuclear Station 3 Seabrook Station Rope Ferry Road (Route 156) P. O. Box 300 Wattrford,CT 06385 Seabrook, NH 03874 Mr. John Hill Mr. Jack Nystrom New York Power Authority Northern States Power Indian Point 3 Monticello Nuclear Station P. O. Box 215 2807 W. Highway 75 Buchanan, NY 10511 Monticello, MN 55362 Mr. Donald Flegle Mr. Innan Lee Omaha Public Power District Portland General  !

! Fort Calhoun Station Trojan Nuclear Power Plant '

P. O Box 399 71760 Columbia River liighway Fort Calhoun, NE 68023 Rainier, OR 97048 Mr. Tar Singh Mr. Charles Johnson l Sacramento Murdcipal Utility District Southern Calitbrnia Edsion Company Rancho Seco Power Plant San Onofre Nuclear Generating Station 14440 Twin Cities Road P O. Box 128 Ilerald, CA 95638 San Clemente, CA 92674 l- Mr. Alan Bryan Mr. Steve Kerstiens Southern Nuclear Operating Company Southern Nuclear Operating Company Plant E.1. Hatch Nuclear Plant Vogtle Electric Generating Plant liighway # 1 P. O. Box 1600 P. O. Box 439 Waynesboro, GA 30830 Baxley, GA 31513 Mr JeffLaMarca Mr Rick Herman TU Electric Company Washington Public Power Comanche Peak Steam Electric Station }

WNP 2 P. O. Box 1002 i P. O Box 968 i Glen Rose, TX 76043 Richland, WA 993520968 l

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MAR-27-98 1Ga39 FROMs ELCAR ids GISG7eqqql PACE 5 Mr. John Slinkard ,

Mr. Steven Barbera Consumers Energy Company Arizona Public Service Company Palisades Nuclear Plant Palo Verde 27780 Bluestar Me'morial H' wy.

CovIrt, MI 49043 5401 S. Wintersburg Tonopah, AZ 853547529 )

Mr. Frank Modlin Mr. William Slack Carolina Power & Light l Cleveland Electric illuminating Company Robinson Nuclear Plant {

Perry Nuclear Station 3581 West Entrance Road {

10 Center Road liartsville, SC 29550 I Perry, OH 44081

- Mr. Rick Brock Mr. Thomas Tremel Duke Power Company

, Duquesne Light Company Oconce Nuclear Station Beaver Valley Station Hwy.130 P, O. Box 4 Senec:, SC 29679 Shippingport, PA 15077 Mr Thomas Carpenter Mr. John Meibaum

Entergy Operations Entergy Operations River Bend Station Waterford 1 Power Plant P. O. Box 220 P. O. Box B St. Francisville, I,A 7t)775 Killona, l.A 70066075l Mr Joseph Tnngali Mr Douglas Dayton Florida Power & Light South Texas Project Nucleai Operating Company l St Lucie Nuclear Plant South Texas Project Electric Generating Station P. O. Box 128

' P. O Box 289 Ft. Picree, FL 3345 t Wadsworth, TX 77483 Mr. Burt Schoonover Mr Mark Wagner South Texas Project Nuclear Operating Company lilinois Power Company i

South Texas Project Electric Generating Station Clinton Power Station l- P O. Box 289 P. O Box 678 Wadsworth, TX 774M Clinton,IL 61727 i

l Mr' Donald Lukach Mr. Harold Ingels tilinois Power Company IES Utilities Company Clinton Power Station Duane Arnold Energy Center P. O. Box 678

' Clinton, IL 61727 3277 DAEC Road Palo, I A 52324

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om ec-<wwwmu ems e Mr: Jonathan Malloy Wisconsin Electric Company Point Beach Nuclear Plant l 6610 Nuclear Road Two Rivers, WI 54241 l

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