ML20084R937

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Discusses RO on 740114 Re Lack of Acceptable Repeatability of Existing Barksdale Condenser Low Vacuum Scram Switches. Barksdale Switches Were to Be Replaced w/Static-O-Ring Corp Vacuum Switches,However After Testing,Switches Undesirable
ML20084R937
Person / Time
Site: Dresden Constellation icon.png
Issue date: 08/31/1976
From: Stephenson B
COMMONWEALTH EDISON CO.
To: James Keppler
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19289B380 List:
References
76-642, NUDOCS 8306160075
Download: ML20084R937 (1)


Text

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Commonwr"'] Edison p ,

Dresden Nucteddsr Statlin \

RR.#1 Morris, liiinois 60450 Telephono 815/942-2920 ,

" ' BBS Ltr. #76-6421 . August 31, 1976 [ 1 u f '

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SEP y IO76x ig gi j {Hr.JamesG.Keppler,RegionalDirector y, . ,,,, 9.s.  %

=j Directorate of Regulatory Operations - Region,1,.ll.nc , c - h, y.;U.S. Nuclear Regulatory Commission  !

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799 Roosevelt Road 2' ' M Glen Ellyn, Illinois 60137 no p. . m <j , m g u , ,,

SUBJECT:

Dresden Unit-3 Condenser Low Vacuum Scram Swltches

References:

1) Letter to J.F. O' Leary from W.P. Wo'rden dated January 22, 1974
2) P & ID H-346 Report Date: August 31, 1976 Occurrence Date: January' 14, 1974 INTRODUCTION Under " Corrective Action" of the Abnormal Occurrence report referenced above, it was stated that the existing Barksdale condenser low vacuum scram switches appeared to lack acceptable repeatability. To correct the problen, the Barksdale switches were to be replaced with Static-0-Ring Corporation vacuum switches which had proved to be very reliable in similar applications.

RESOLUTION

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After qual 1.tative testing, the proposed substitution of the Static-0-Ring i  !~

switch'was'Judg'ed to be undesirable becauser of the , switch's seismic limita- ge 3..si t e .

tions. Furthermore, the performance of the condenser low vacuum scram switches over the intervening 34-month period indicates that the Barksdale switches have s tab i l i zed l,s igni f i can'tl y. The maximum drift exhibited by any of these

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,switchesovertfisperiodhasbeen0.6inHgj,whichoccurredonceonPS503C.;.a -. ,

,,', By adjusting thes'e switches ' to the Dresden setpoi.nt band of 23.7 + 0.2 in Hg,.;m 1,,a ,

m; nc all setpoint variations have remained well within Technical Specification . , , , , , .

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i limits. Since"the existing Barksdale switches on Unit-3 appear to be performing ,i._<

as designed, no corrective action is deemed necessary. - --~.

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J' B.B. Stephenson 8306160075 770411 Station Superintendent PDR ADOCK 05000249 S PDR Dresden Nucicar Power Station BBS:WEil:bbc SEP 101976 ,%.

COPY SENT REGION M i ~

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