ML20084D178

Final Deficiency Rept Re Improperly Assembled Foxboro Power Generation Control Complex Panel Filler Assemblies.Initially Reported on 840314.All Screws in Panels Checked & Tightened to Required Torque

ML20084D178
Person / Time
Site:	Nine Mile Point
Issue date:	04/16/1984
From:	Mangan C NIAGARA MOHAWK POWER CORP.
To:	Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
(NMP2L-0031), (NMP2L-31), 55(E)-84-12, NUDOCS 8405010210
Download: ML20084D178 (2)

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- o NuMOHAWK Y NIAGARA NIAGAR A MOH AWK POWER CORPeR ATION nJO (k[ DCULT VAND Af ST CWM;lf,f NY IVn2/TFIIh40NE(lisi 474 1511 April 16,1984 (NMP2L 0031)

Mr. R. W. Starostecki, Director U.S. Nuclear Regulatory Commission Region 1 Division of Project and Resident Programs 631 Park Avenue King of Prussia, PA 19406

SUBJECT:

Nine Mile Point Unit 2 Docket No. 50-410 Enclosed is a final report in accordance with 10CFR50.55(e) for the problem concqrning Power Generation Control Complex (PGCC) panel filler assemblies (55(e)-84-12).

This problem was reported via telecon between Mr. T. Loomis, Nine Mile Point Unit 2 Licensing, and Mr. S. Collins of your staff on March 14, 1984.

Very truly yours, J

C. V. Mangan Vice President Nuclear Licensing and Engineering CVM/TRL:lf Enclosure cc:

Director of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, DC 20555 R. Grann (Hesident Inspector) 0400010210 n40416 PDFt ADOCK 03000410 0

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NIAGARA M0 HAWK POWER CORPORATION NINE MILE POINT - UNIT 2 DOCKET NC. 50-410 Final Report for a Problem Concerning Power Generation Control Complex (PGCC) Panel Filler Assemblies (55(e)-84-12)

Description of the Problem The Foxboro Company informed us that during the period from December 1, 1982, to April 6, 1983, ten panel filler assemblies, Model No. 00126SA, were assembled improperly, and nine subject filler assemblies were supplied to Nine Mile Point Unit 2.

These panels are used in PGCC. A panel filler assembly has eight screws holding the filler and load plates together. These screws are required to be tightened to 24 to 28 lb/ft torque.

The Foxboro Company has indicated that the assemblies with screws tightened to less than the required torque may separate during a seismic event.

The screws in the subject nine assemblies were inspected.

The inspection indicated that eight assemblies had some improperly torque screws.

This inspection and the completion of corrective action detailed below have been documented on Stone and Webster Quality Assurance Inspection Report No.

E4015639.

Analysis of Safety implications If an assembly would have separated, a possibility exists that it could have damaged the terminal block wiring and thus could have adversely affected the intended safety function of the panel. Malfunctioning of the panels could

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have jeopardized the design function of systems such as service water system and hydrogen recombiner system.

In addition, the separation of an assembly would have changed the dynamic characteristics of the panel which could have resulted in an increase in stresses in the panel during a seismic event.

The probability of the above happening has not been ascertained.

To prevent this problem from occuring, the below stated corrective action has been performed.

Corrective Action All screws in the panels in question have been checked and tightened to the required torque.

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