Part 21 Report - 1998-242
ACCESSION #: 9805080042
Elgar FAX COVER SHEET Sorensen
(800) 733-5427 Division of ELGAR
(619) 450-0085 (800) 525-2024
(619) 450-0085
9250 Brown Deer Road, San Diego, CA 92121, U.S.A
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Elgar Administration Fax: 619/458-0257
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March 27, 1998
File: TB12
Mr. <<(FirstName>> <<(LastName>>
<<(Utility_Name>>
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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.
Subject: Technical Bulletin # 12: Installation of Power
Semiconductor Clamps
Dear Mr. <>
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 Power was incorrect. The
technique used a torque wrench for applying and verifying the compressive
force on the 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 force
gauge; the use of a torque wrench is prohibited.
Elgar recommends that, if the torque wrench method has been used, the
power semiconductor clamps 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.
After reviewing this technical bulletin, please send back a signed copy
of this memo to Elgar indicating that the technical bulletin has been
received and acknowledged by the plant.
If you have any questions regarding this bulletin, please contact me by
phone at 619-458-0245, by FAX at 619-678-4441, or by e-mail at
tomm@elgar.com.
Sincerely,
Thomas A. Moshenrose Acknowledged:
Manager, Nuclear Customer Service Date:
ELGAR TECHNICAL BULLETIN #12 Sheet 1 of 1
Date: March 27, 1998
Subject: Technical 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 Basis 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 incorrectly
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 flex 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: Elgar recommends that the SCR and diode clamps be tightened
using a force gauge (Elgar P/N 846-SCR-MB) and the following
procedure:
1. Check each heatsink 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.)
3. Refer to the device preparation sheet for further surface
preparation instructions.
4. With the semiconductor positively in place on the heatsink (i.e.,
the power semiconductor centered on the alignment pin), place the
clamp in position with the bolts through the holes in the heatsink.
5. Tightened the nuts evenly until finger-tight.
Tighten each bolt 1/4 turn at a time, alternating between bolts, using a
9/16 inch socket wrench. After each 1/4 turn of the bolts, place the
force gauge firmly 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 flat
edges on the gauge, the bolts must be loosened to finger-tight and the
process of tightening repeated. If the clamps have been tightened using
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 probable that the power semiconductor
has been damaged by the excessive force applied. Therefore, it is
further recommended that, if a torque wrench has been used to tighten the
clamps, the power semiconductors be replaced also.
Products Affected: All Elgar inverters and uninterruptible power
supplies.
APPROVALS
CUSTOMER SERVICE DATE ENGINEERING DATE QUALITY DATE
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, Lake Road P. O. Box 127E,
Lycoming, NY 13093 East Hampton, CT 064243099
Mr. Richard DeBernardo Mr. Therman Carter
Northeast Nuclear Energy Company North Atlantic Energy Services
Millstone Nuclear Station 3 Seabrook Station
Rope Ferry Road (Route 156) P. O. Box 300
Waterford, 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 Highway
Fort Calhoun, NE 68023 Rainier, OR 97048
Mr. Tar Singh Mr. Charles Johnson
Sacramento Municipal Utility District Southern California Edsion
Company
Rancho Seco Power Plant San Onofre Nuclear Generating
Station
14440 Twin Cities Road P. O. Box 128
Herald, CA 95638 San Clemente, CA 92674
Mr. Alan Bryan Mr. Steve Kerstiens
Southern Nuclear Operating Company Southern Nuclear Operating
Company
Plant E. I. Hatch Nuclear Plant Vogtle Electric Generating Plant
Highway # 1 P. O. Box 1600
P. O. Box 439 Waynesboro, GA 30830
Baxley, GA 31513
Mr. Jeff LaMarca Mr. Rick Herman
TU Electric Company Washington Public Power
Comanche Peak Steam Electric Station WNP 2
P. O. Box 1002 P. O. Box 968
Glen Rose, TX 76043 Richland, WA 993520968
Mr. John Slinkard
Consumers Energy Company
Palisades Nuclear Plant
27780 Bluestar Memorial Hwy.
Covert, MI 49043
Mr. Frank Modlin
Carolina Power & Light
Robinson Nuclear Plant
3581 West Entrance Road
Hartsville, SC 29550
Mr. Rick Brock
Duke Power Company
Oconee Nuclear Station
Hwy. 130
Seneca, SC 29679
Mr. Thomas Carpenter
Entergy Operations
River Bend Station
P. O. Box 4220
St. Francisville, LA 70775
Mr. Joseph Tringali
Florida Power & Light
St. Lucie Nuclear Plant
P. O. Box 128
Ft. Pierce, FL 33454
Mr. Burt Schoonover
South Texas Project Nuclear Operating Company
South Texas Project Electric Generating Station
P. O. Box 289
Wadsworth, TX 77483
Mr. Donald Lukach
Illinois Power Company
Clinton Power Station
P. O. Box 678
Clinton, IL 61727
Mr. Steven Barbera
Arizona Public Service Company
Palo Verde
5401 S. Wintersburg
Tonopah, AZ 853547529
Mr. William Slack
Cleveland Electric Illuminating Company
Perry Nuclear Station
10 Center Road
Perry, OH 44081
Mr. Thomas Tremel
Duquesne Light Company
Beaver Valley Station
P. O. Box 4
Shippingport, PA 15077
Mr. John Meibaum
Entergy Operations
Waterford 3 Power Plant
P. O. Box B
Killona, LA 700660751
Mr. Douglas Dayton
South Texas Project Nuclear Operating Company
South Texas Project Electric Generating Station
P. O. Box 289
Wadsworth, TX 77483
Mr. Mark Wagner
Illinois Power Company
Clinton Power Station
P. O. Box 678
Clinton, IL 61727
Mr. Harold Ingels
IES Utilities Company
Duane Arnold Energy Center
3277 DAEC Road
Palo, IA 52324
Mr. Jonathan Malloy
Wisconsin Electric Company
Point Beach Nuclear Plant
6610 Nuclear Road
Two Rivers, WI 54241
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