ML19330B979

Interim Deficiency Rept Re Failure of Klockner-Moeller Starter Relay.Failure Caused by Use of Improper Screw on Terminal Connections.Investigation Continuing.Final Rept Should Be Submitted by 801002

ML19330B979
Person / Time
Site:	Grand Gulf
Issue date:	08/01/1980
From:	Mcgaughy J MISSISSIPPI POWER & LIGHT CO.
To:
References
REF-PT21-80-245-001 AECM-80-176, NUDOCS 8008070339
Download: ML19330B979 (2)

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: MISSISSIPPI POWER & LIGHT COMPANY

' *; Helping Build Mississippi

.mma P. O. B O X 16 4 0, J A C K S O N. MI S SIS SIP PI 3 9 2 0 5 NUCLEAR PRooUCT1CN CEP ARTMENT August 1, 1980 Office of Inspection & Enforcement _,

U. S. Nuclear Regulatory Cor=11ssion 3 Region II i 101 Marietta Street, N.W. _,

Suite 3100 Atlanta, Georgia 30303 .

Attention: Mr. J. P. O'Reilly, Director ~ -[

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SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 02' /15525/15526

'RD-80/ 2, Status Report, Klockner-Moeller Starter Relay AECM-80/176 On July 2, 1980, Mississippi Power & Light notified Mr. F.

Cantrell of your office of a Potentially Reportable Deficiency (PRD) concerning a Klockner-Moeller 480 V MCC Starter Relay.

Our investigation of this deficiency is not cesplete. Attached is a report detailing the current status of the investigation.

We expect to determine reportability and submit a fina) report by October 2, 1980.

Yours truly,

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2 J. P. McGaughy, Jr.

Assistant Vice President, Nuclear Production ATR:st Attachment ec: Mr. N. L. Sta=pley Mr. Victor Stello, Directo #

Mr. R. B. McGehee Divisien of Inspection & Enforcecent Mr. T. 3. Ccnner U. S. Nuclear Regulatorf Cec =ission Washingten, D.C. 20555 (3sv1'

.a o o 8 0 7oWBameer uiteie Scu:n utiiicies System [

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Attrchm:nt to AECM-80/176 Page 1 of 1 STATUS REPORT FOR PRD-80/36 I. Description of Deficiency During testing of the Lube Oil Conditioning and Storage System, a non-safety related system, a vapor exhaust fan failed to start.

An investigation of the cause disclosed a nonconforming DILO NA contactor in a Klockner-Moeller 480 volt circuit breaker.

The failure was caused by the use of a 3/8 inch length screw in place of a 1/4 inch length screw. When tightened the longer screw bottomed out before the terminal connection was tight.

The resulting loose connection caused the circuit breaker te fail.

II. Safety Implications The Klockner-Moeller 480 volt circuit breaker is used in both safety and non-safety related systems. An inspection of 20 con-tactors stored in the warehouse and of 82 installed contactors did not disclose any additional loose terminals.

The investigation has revealed the existence of two (2) types of DILO-22-NA contactors. One, with a green plunger, uses 3/8 inch length screws in all connections; the second, with an orange plunger, uses 3/8 inch length screws except for the relay holding coil connection which uses a 1/4 inch length screw. The green plunger type appears to be an older production model.

III. Corrective Actions Taken Examples of both style contactors have been sent to the vendor for investigation and evaluation.

Maintenance instructions will be developed to specify steps to insure the holding coil ter=inal screws are the proper length.

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