ML20024B746

Final Deficiency Rept Re Heat Sink Failures on Loop Power Supply Cards & Contact Bounce in Mercury Relay Utilized on Temp Channel Test Cards of Westinghouse 7300 Process Protection Sys.Initially Reported on 830603

ML20024B746
Person / Time
Site:	Marble Hill
Issue date:	06/30/1983
From:	Shields S PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, S83-29, SVP-0104-83, SVP-104-83, NUDOCS 8307110306
Download: ML20024B746 (2)

Text

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PUBLIC SERVICE INDIANA S. W. Shields June 30, 1983 Senior Vice President .

S83-29

• • '**' UISI "

SVP-0104-83 Mr. James G. Keppler, Docket Nos.: STN 50-546 Regional Administrator STN 50-547 U. S. Nttelear Regulatory Commission Construction Permit Nos :

Region III CPPR - 170 799 Roosevelt Road CPPR - 171 Glen Ellyn, Illinois 60137 Marble Hill Nuclear Generating Station - Units 1 and 2

Dear Mr. Keppler:

On June 3,1983, Mr. L. G. Yeager of Public Service Company of Indiana, Inc. (PSI) notified your office of a potentially reportable item as required by 10 CFR 50.55(e). This item involves two potential problems with the Westinghouse 7300 Process Protection System. The first potential problem is with heat sink failures on the loop power supply (NLP) cards.

Westinghouse has determined that NLP printed circuit cards shipped from Westinghouse Industry Electronics Division (WIED) between August 1, 1980, and September 1, 1982, were equipped with a thermal heat sink assembly on the inverter transistors that are subject to potential failures in the adhesive bond in the thermal link assembly. The adhesive bond is between an insulating washer and the thermal link. Failure of the bond can cause the heat sink plate to separate from the thermal links and fall off of the printed circuit board. The plate is conductive metal and under certain circumstances could cause shorting of low level signals if it became wedged between cards in the card frame. The second potential problem involves contact bounce in the mercury relay utilized on the temperature channel test (NTC) cards. This intermittent contact bounce will result in signal saturation of the downstream resistance temperature detector amplifier (NRA) card in the T-hot and T-cold circuits of the Westinghouse 7300 Process Protection System. Westinghouse has determined that the Marble Hill units utilize slow response resistance temperature detectors with no downstream signal filtering. Delayed Overtemperature-Delta T and Overpower-Delta T trips could, therefore, be experienced with the current design. This problem only occurs as a result of contact bounce induced by a seismic event.

8307110306 830630 PDR ADOCK 05000546 dl/L S PDR 8%

P. O. Box 190, New Washington, Indiana 47162 812. 289.3000

$637

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i PUSUC Letter: .J. G. Keppler= June 30, 1983 S83-29 SVP-0104-83

~With regard to the NLP card heat sink issue, preltninary indications are that ino potentially defective NLP cards -have been shipped to the Marble Hill units.

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Westinghouse plans to have their site personnel inspect the hardware currently in the field to confirm this finding. If any of the potentially

' defective NLP cards are found,. Westinghouse has committed to provide replacements. On the NTC= card relay ~ issue, Westinghouse has committed to-provide the Marble Hill units with replacement relays prior to plant operation.'

This letter is intended to fulfill the requirements of a final report as required by 10 CFR 50.55(e). If you have any questions regarding this

-matter, please contact me at your convenience.

Sincerely, ema-S. W. Shields

-SWS/LGY/bak cc: Director of Inspection and Enforcement U. S. Nuclear Regulatory Commission

. Washington, D. C. 20555 J. E. Konklin

'J. F. Schapker i

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