ML19253A692

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Responds to IE Bulletin 79-11.All Overcurrent Trip Devices on DB-50 & DB-75 Breakers Have Been Tested & Calibr.Devices Are Now Calibr to New More Conservative Bands
ML19253A692
Person / Time
Site: Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date: 08/08/1979
From: Counsil W
CONNECTICUT YANKEE ATOMIC POWER CO.
To: Grier B
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
CYH-79-190, NUDOCS 7909110003
Download: ML19253A692 (1)


Text

Yk C CONNECTICUT YANKEE AT O MIC POWER COMPANY HADDAM NECK PLANT RR e t, BOX 127E. EAST H AMPTON, CONN. 06424 August 8, 1979 CYH-79-190 Docket No. 50-213 U. S. Nuclear Regulatory Commission Region I Office of Inspection and Enforcement 631 Park Avenue King of Prussia, Pennsylvania 19406 Attention:

Mr. Boyce Grier, Director

References:

1)

Facility Operating License No. DPR-61 Docket No. 50-213 IE Bulletin 79-11 2)

Letter W. G. Counsil to B. Grier, dated July 6, 1977, "IE Bulletin 79-11"

Dear Mr. Grier:

On July 6, 1979, we sent our response to you on the questions raised in IE Bulletin 79-11.

Item two of this Bulletin was not answered at that time because the material needed for this response was

ill being researched and evaluated.

As required in IE Bulletin 79-11 we have reviewed oIr past test data on all of our DB-50 and DB-75 breakers.

This review did point out that a number of these overcurrent trip devices were outside of the acceptance band.

Of the ones found outside of this acceptance band only a very few were found to be on the low side of the band.

Because of these findings we have tested and calibrated all of the overcurrent trip devices on these DB-50 and DB-75 breakers. These devices are now calibrated to new more conservative bands as suggested by the manufacturer.

The test procedures will be revised to incorporate these new tighter bands for all future testing of these breakers.

None of these devices were found with cracked or defective end caps, therefore these caps were not replaced.

Very truly yours, CCNNECTICUT YANKEE ATOMIC POWER COMPANY i

o ~ -orn

.30 c reJi]

W. G. Counsil, Vice-President 7909110CO 3 0