ML20084N882

AO 50-249/75-34:on 750807,isolation Condenser High Flow Switches 1349A & B Exhibited Instrument Setpoint Drift.Cause Unknown.Switches Reset

ML20084N882
Person / Time
Site:	Dresden
Issue date:	08/15/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20084N886	List: ML20084N882 ML20084N890
References
506-75, NUDOCS 8306090102
Download: ML20084N882 (2)

Text

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Rolcrenecc: 1) Rec.tictory Guisle 3.16 Rev.1 Aprendi:: A

2) Ectificatien of Recien III cf U. S. Nuclce Reculatory Co~r:iscien Telephone:

73. F. Johnson, U30 hrs. on Lucust 8, 1975 Telc;-=:

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on Aucast 8, 1975.

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1.ucant 7,1975 acility: Dresden Uuclear Pcuer Stition, I.:orric, Illinois 60h50 r,,.ny

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An inrtru ent setmint ri-if t of icolttion cendenner hich flov suitebec 1349A a E occi~ rcd on Urit-3.

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-Unit-3 *: e in. the cold chutdown mode for a refuelinc~ outace.

D7."",3TFTION CP OCCU'F:*302 At n,mproximately 1500 heurn en Aucant 7,1975, during routino steveillence of dif-ferentini r'dtchna U49A !.: P, both m itches ucro found with retroints above the Technical Crocific, tion li;ait of $ 32" H 0.

Switch 149A var found at.36" H O, and 2

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D:l'rMAT7CN CP APDFCl? CAUC2 0F 0"CD.'CICE I

No definitive cauce een be cotabliched at thic time. Surveillanecc have not been perfot cd on the ncitchen during the outage. 1.'aview of prior surveillancen hno g

indicJted that tbo cetrointn of thene catches are cubject to' a clow drift.

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S:: itches 13hoA e E were found uith acceptable setpointa during the routine 11, 1975, cene 36 days before Unit-3 was surveillance co". ducted on D rehIt 4.c considered unlikely thst the evitches' cct-clut do ci for refueli c.

points exceeded 'Neh. 0 cc. li-ite ' tile the unit van operatinc, given the 7

Analysis of the past perfo-nance of the 150-dar cr'n 'cotucon curveillrnees.th?.t cetroint &ift occurs very cradually. The phenoncnon critebec indicate of dercearin7 inctr r ent co woint values after extended cutacec was noted on Enrkrdale pre cice cuitd ec (recert no. 50-2~7/75-17 dated Orch 27,1975).

Enced en the de:~oa-:"ared relia':ility of c *itchen 1349A & B uben cheaked it 4.0 concluded that this occurrence in no way rou*inely dri-:- ^reration,

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