ML19259A729

Interim Rept Re Status of Class 1E Station Battery Racks Made by Exide.Vendor Plans to Add Isolation Bars to the Racks to Avoid Failures.Testing by Exide to Be Completed Aug 1979 with Rept Anticipated by Sept 1979

ML19259A729
Person / Time
Site:	Midland
Issue date:	01/05/1979
From:	Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
References
HOWE-3-79, NUDOCS 7901100220
Download: ML19259A729 (2)

Text

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G=3 NN, Consumers -

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g Stephen H. Howell Senior Vice PresiJcnt ceneral of fices: 1945 West Parnali Road, Jackson, Michigan 49201 e (S17) 788-0453 January 5, 1979 Hove-3-79 Mr J G Keppler, Regional Director Cffice of Inspection and Enforcement Region III US Huelear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL c0137 MIDLA'ID NUCLEAR PLAUT -

U'IIT UO 1, DOCKET EO 50-329 UNIT UO 2, DOCKE'" UO 50-330 CLASS 1E STATION BATTEEY

Reference:

Letter, S E Eovell to J G eppler; !!idland nuclear Plant; Unit No 1, Docket No 50-329; Unit no 2, Docket No 50-330; Class lE Station Battery; Hove-235-78; dated november li,1978 The referenced letter was an interin 50.55'e) report. This letter is also an interim report.

Description of Discrepancy In accordance with the requirements of Title 10 of the Code of Federal Regulations, Part 21 (10 CFR 21), Exide, the vendor for t'le subject equip-ment, advised the URC that as a result of seismic analysis performed on the Class 1E battery racks, an additional isolation bar must be added at two-cell increments in order to mitigate the buildup of horizontal momentum during a seismic event. Exide has stated that their analysis was made of a horizontal seismic lc9 ding of the magnitudes to he anticipated. Considering the mass of the "G" celi, their analysis showed that the loading would be transmitted through the intercell connectors down the row of cells with the constrained end cell subjected to this total noment. This loading could cause the end cell to suffer damage.

Safety Tmplications Exide further stated that the failure mode, if this deficiency was not detected, vould be to the end cell in that the terminal post and cover coC 4 not stand the forces and would fail with a probable disruption to the circuit. A circuit disruption would be classified as a failure of the battery to perfcrm its in-tended safety function.

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• 2 Hove-3-79

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Corrective Action The corrective action has been initiated by Exide to add isolation bars to the racks after installation. The isolation bar in currently being designed by Exide. Drr. wings showing this change were received Decenter lb,1978, and are currently undergoing engineering review. The assenblies are to be available for retrofit h weeks after drawing approval. It was cricinally reported by Exide that the isolation bars vould be available by December 10, 1978.

Reportability Based cn the anticipated failure mode, Exide felt that this was a potential problen with possible .=afety implicat:'on and therefore was considered to be reportable under 10 CFR 21.

Actual seismic testing by Exide of their prototype G cell and battery rack assembly is scheduled to be completed in August 1979 with the report antici-pated to be received by September 1979 Another report, either interin or final, vill be supplied by January 31, 1979

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CC: *' Director of Office of Inspection & Enforcement Att: !ir. John G. Davis, Acting Director, USNRC (15)

Director, Office of E!anagement Information and Program Control, USHRC (1)