05000348/LER-1979-035-01, /01T-0:on 790824,Westinghouse Notified Util of Potential Heat Sink Shorting to 7300 Rack Card Guides within 7300 Process Instrumentation & Control Printed Card Circuits.Caused by Mfg Defect.Cards Replaced

/01T-0:on 790824,Westinghouse Notified Util of Potential Heat Sink Shorting to 7300 Rack Card Guides within 7300 Process Instrumentation & Control Printed Card Circuits.Caused by Mfg Defect.Cards Replaced

ML19207C446
Person / Time
Site:	Farley
Issue date:	09/06/1979
From:	Hairston W ALABAMA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19207C442	List: 05000348/LER-1979-035, Forwards LER 79-035/01T-0 05000348/LER-1979-035-01, /01T-0:on 790824,Westinghouse Notified Util of Potential Heat Sink Shorting to 7300 Rack Card Guides within 7300 Process Instrumentation & Control Printed Card Circuits.Caused by Mfg Defect.Cards Replaced
References
LER-79-035-01T, LER-79-35-1T, NUDOCS 7909110632
Download: ML19207C446 (2)

LER-1979-035, /01T-0:on 790824,Westinghouse Notified Util of Potential Heat Sink Shorting to 7300 Rack Card Guides within 7300 Process Instrumentation & Control Printed Card Circuits.Caused by Mfg Defect.Cards Replaced

Event date:
Report date:
3481979035R01 - NRC Website

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w is t COCK E T NU*.tdER bd LJ EVENT OATE 34 75 R EPOH T DAT E 60 4T cEsCnmTicN AND PROG ABLE CONSEGUENCES h Ev2:

l Westinghouse notified Alabama Power Company that-certain 7300 Process I & C printed

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g,3 l guides. An inspection of the FNP Unit 1 7300 racks, revealed 23 of the Westinghouse

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40 41 42 43 44 47 cAUSE DESCRIPTION AND CORoECTIVE ACTIONS h o j lThis occurrence is attributable to a manufacturing defect.

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ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PLANT DOCKET NO. 50-348 ATTACHMENT TO LER 79-035/01T-0 Facility:

Joseph M. Farley Unit 1 Report Date:

9/6/79 Event Date:

8/24/79 Identification of Etent:

Certain process I & C printed circuit cards have manufacturing defects (heat sink clearance).

Conditions Prior to Event

The unit was in Mode 5.

Description of Event

Westinghouse notified Alabama Power Company that certain 7300 Process I & C printed circuit cards could have problems with regard to heat sink shorting to 7300 rack card guides.

An inspection of the FHP Unit 1 7300 racks, revealed 23 of the Westinghouse identified cards, 14 (12 NLL and 2 NMD) of which were located in the protection racks. None of the card heat sinks were touching the card guides, however, the clearances on all but one of the cards were less than allowed by manufacturing tolerances.

It was determined on S/24/79 that this condition was potentially reportable under Tech. Spec. 6.9.1.8.i.

Designation of Apparent Cause:

This occurrence is attributable to a manufacturing defect.

Analysis of Event

A small possibility exists that vibration from a seismic event could cause card guide rubbing of the card heat sinks.

If such rubbing were to wear through the heat si.nk anodized coating and a short occurred between the heat sink and card guide, the card calibration would shift. The health and safety of the public were not affected by this event.

4

Corrective Action

1.

The defective cards are being removed and replaced with defect-free cards.

2.

Operability will be verified by the satisfactory performance of surveillance tests.

Failure Data:

None I

I 940 355