ML19305E315
| ML19305E315 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 04/15/1980 |
| From: | Davidson D CLEVELAND ELECTRIC ILLUMINATING CO. |
| To: | |
| References | |
| NUDOCS 8004230353 | |
| Download: ML19305E315 (3) | |
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,qg ILLUMINATING BLOG. e PU8UC SQUARE e CLEVELAND. ohio 44101 e TELEPHONE (216) 623 ".J50 e Mall ADDRESS: P. o. BOX S000
'U Dalwyn R. Davidson vlCE PRESrOENT SYSTEV ENGINEERING AND CONSTRUCTION April 15, 1980 Mr. James G. Keppler Director Region III Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 RE: Perry Nuclear Power Plant Final Report on 4.16kV Switchgear
Dear Mr. Keppler:
This letter constitutes the final report required by 10CFR50.35(e) on the deficiency concerning ITE 4.16kV Switchgear. This item wa-first dis-cussed in a telephone conversation between Mr. W. J. Kacer of The Cleveland Electric Illuminating Company and Mr. Jim Konklin of the NRC Region III, Office of Inspection and Enforcement on October 23, 1979. An interim report was later written on November 23, 1979.
Description of Deficiency ITE Corporation was contracted by The Cleveland Electric Illuminating Company to manufacture Class IE 4.16kV Switchgear for Perry Nuclear Power Riant.
Initial inspection of four (4) units revealed the existence of cracks and tears in the bottom of the steel enclosures where the metal is bent to allow mounting to embedded channels.
Subsequent inspections of all remaining units revealed that 52 of the 80 cubicles inspected had similar cracks and/or tears. Discussion of this problem with ITE revealed that the cause of the cracks in the frames were attributed to the low level, seismic inputs, substantial reinforcement was required in order to survive the seismic environment. One method of reinforcement was to install angle iron supports at the four corners of the unit. An alternate method was to join three units together thereby reinforcing each other.
A minimum of three units is required to survive the equivalent seismic environment.
Analysis of Safety Implication l
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Due to the nature of the cracks and tears, it was felt that the defect could travel the entire length of the bend. This could cause the switch-gear to become dislodged from the floor and possibly affect the safe i
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4 Mr. James G. Keppler April 15, 1980 operation or shutdown of the nuclear power plant during or after a seismic event.
Corrective Action To correct the defects in the switchgeor frames, a 1/16" hole was drilled 1/2" ahead of the cracks on the bend line of the sheetmetal in order to prevent any further traveling of the cracks or te. s.
A 1/4" fillet weld was then run along the bend line from the drilled hole over the entire crack and then to the end of the switchgear frame. To support the adequacy of the recommended corrective action, threc (3) test pieces of 12 gauge steel were prepared as shown in Attachment A.
The flat piece of steel broke at 10,000 pounds, the fo..ed 90 bend broke along the bend line at 9,600 pounds and the fillet w' eld repair of the cr.ack broke along the edge of the' weld at 9,600 pounds. This test demonstrated that the welded crack wa.s as strong as the parent metal, and therefore, would not affect the seismic qualification of the switchgear itself.
In order to prevent the reoccurrence of this type of problem, a minimum of three (3) switchgear frames will be bolted together and mounted on a single skid for all future shipments. In addition, all units will be bolted together during installation to aid in the seismic capabilities of the equipment.
Summary In spite of the large percentage of cubicles which was found to contain cracks and/or tears, the repairs themselves were relatively easy to make.
It has further been demonstrated that these repairs were as strong as the base metal and would not jeopardize the seismic qualification of the equip-ment.
It is, therefore, felt that the facts stated in this report and our assessment of actual test results justify our position that repaired cracks no longer constitute a significant deficiency.
Very truly yours Dalwy Davidson Vice President System Engineering and Construction DRD:rmw cc:
ictor Stello, Director Office of Inspection and Enforcement l
U.S. Nuclear Regulatory Commission Washington, D.C.
20555
r Test of Formed "V" Filled Weld Corners Test #1 - Pull test of a flat piece of 12 gage steel sample 2" in width.
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Sample broke at 10,000 lbs.
l Tesc #2 - Pull test of a formed 90' bend across a 2" wide,12 gage steel sample.
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Sample broke at 9,600 lbs.
Test #3 - Pull test of fillet weld across a 2" wide piece of 12 gage steel.
Fillet Weld t
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i Sample broke along edge of we'id at 9,600 lbs.
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