ML20084L782

RO 50-237/1974-27A update.Three-yr Study of Use of phosphorus-bronze in Place of Teflon as Bushing Matl in torus-to-drywell Vacuum Breakers Provides No Justification for Replacement of Teflon Bushings

ML20084L782
Person / Time
Site:	Dresden
Issue date:	12/15/1976
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20084L783	List: ML20084L782 ML20084L786 ML20084L789
References
76-883, NUDOCS 8305230721
Download: ML20084L782 (1)

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h[ggfygg BBS LTR.Jf76-S83 December 15, 1976 to s

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Mr. James G. Keppler, Regiond Director oID Directorate of Regulatory Operations - Region III s

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1 01~en Ellyn, Illinois 60137

SUBJECT:

Dresden Station Torus-to-Dryuell Vacuum Breaker Bushings

REFERENCES:

1) Letter from'B. B. Stephenson to J. F. O' Leary dated July 29, 1974 (Abnormal Occurrence report no.

50-237/1974-27)

2) Drawing number: M-25 REPORT NUMBER:

50-237/1974-27A REPORT DATE: December 15, 1976 OCCURRENCE DATE: July 20, 1974 FACILITY: Dresden Nucicar Power Station, Morris, Illinois The referenced Abnormal Occurrence report stated that a study was in progress to evaluate the possibic use of phosphorus-bronze in place of teflon as a bushing material in the torus-to-drywell vacuum breakers on Unita 2 and 3.

The vacuum breaker performance has been monitored for approximately three years. During this period three binding problems have been experienced; two with teflon bushings and one with phosphorus-bronze bushings.

Based on the results thus far there is no justification for replacement of the teflon bushings with phosphorus-bronze bushings. Additionally, based on the reduced frequency of failures,'no other action is planned at this time.

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. Superintendent Dresden Nuclear Power Station BBS:CES:jo ec: Director of Inspection & Enforcement Director of Emagement Information & Program Control File /NRC I SOM 0305230721 761215 PDR ADOCK 05000237

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