ML20087G345

Forwards Calvert Cliffs Unit 1,Insp of Steam Generators 11 & 12, Final Rept

ML20087G345
Person / Time
Site:	Calvert Cliffs
Issue date:	03/06/1984
From:	Lundvall A BALTIMORE GAS & ELECTRIC CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20087G349	List: ML20087G345 ML20087G350
References
NUDOCS 8403190408
Download: ML20087G345 (2)

Text

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e BALTIMORE GAS AND ELECTRIC CHARLES CENTER.P.O. BOX 1475 BALTIMORE, MARYLAND 21203 ARTMum E. LUNOVALL,.JR.

wee rm.mv March 6,1984 SUPPLY U.S. Nuclear Regulatoty Commission Region I

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631 Park Avenue King of Prussia, PA '19406 ATTENTION:

Mr. Thomas E. Murley, Director

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit No.1; Docket No. 50-317 1983 Results of Steam Generator Eddy Current Examinations

REFERENCE:

(a)

Unit 1 Technical Specification 4.4.5.5 ENCLOSURES: (1)

Unit i Eddy Current inspection of #11 & #12 Steam Generators, Final Rep' ort - Prepared by Zetec, Incorporated, October 1983 (2)

Combustion Engineering Series 67 Steam Generator Tube Sheet Pattern (3)

Tubes Plugged #11 & #12 Steam Generators Gentlemen:

Reference (a) requires that we report, on an annual basis, all steam generator tube exarninations conducted in the past year, listing the tubes examined, degradation noted, ar.d identity of tubes plugged.

Calvert Cliffs Steam Generators are Series 67 Combustion Engineering units.

Tube locations are referenced to.ne hot leg or cold leg tub ~ heet as shown in Enclosure (2).

The hot leg tube sheet is divided'into quadrants #2 (rig.. ' and #3 (left) with Line No. I dwn the center. Whereas the cold leg tube sheet is divided into quadrants #1 (left) and

1. 4 Pight) vzith Line No.1 in the center. Both steam generators at Calvert Cliffs Unit 1

- were examined by the multi-frequency eddy current method during 1983. Examinations were conducted in accordance with the requirements specified in reference (a) and

- tiegulatory Guide i.83. Enclosure (1) lists the tubes examined and the indications found.

During the fall 1983 Unit 1 outage, #11 & #12 steam generators were examined. Tubes were probed from the hot leg side of the generator with full length tube examinations being performed.

Service induced degradation was found in #11 & #12 steam generators. The imperfections found were all of a small volume and area nature. The indications were not localized in a particular area of the tube bundle.

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. Eddy current results of. #15. eam generator showed that of the 1,044 tubes examined, one.was defective (imperfection 2 ; 40% wall loss),10 were degraded (2 20% wall loss),

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- seven had. imperfections 4 20% wall thickness, and 143 tubes contained service induced A*

denting. In 130 of the 143 dented tubes, the denting occurred at the ninth support on the L

~ hot leg side of the tube bundle. Of.the 1,044 total tubes examined, 611 were selected 4

' from the region where the ninth support exists. The average dent size of the tubes L

, dented in the ninth' support of #11 steam generator. was_.871 mits. 'All of the dented

' tubes ~ allowed passage of the eddy current probe.

Eddy current results of #12 steam generator showed that of the 1,043 tubas examined, itwo were defective, sixLwere degraded,' nine had imperfections / 20% wall thickness, E

and 220 tubes contained service. Induced denting. In 191 of the 220 dented tubes, the L

. denting occurred at the ninth support on the hot leg side of the tube bundle. Of the 1,048 L,

total tubes examined,632 were selected from the region where the ninth support exists.

9 The average dent size of.the tubes dented in the ninth support of #12 steam generator p

was 2.36 mils. - All of the dented tubes allowed passage of the eddy. current probe.

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= As stated above, one tube in #11 steam generator and two tubes in #12 steam generator l,

contained. defects which exceeded the plugging limit ;of 40% loss of nominal wall

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thickness. These tubes were removed from service by plugging each end with mechanical tube plugs.11n. addition,-. portions of two steam ' enerator tubes which contained' eddy g

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- current indiations of less than 40% wall loss were removed from #11 steam generator for detailed metallurgical ' examination. These tubes were also removed from service by l'

~ lugging the hot and cold' leg tube ends with mechanical tube plugs. Enclosure (3) lists p

the, tubes plugged during the fall 1983 Unit 1 outage along with the reason for plugging the tube.

'Should Lyou have further -questions regarding'this matter, please do not hesitate to contact us.

Sincerely 'youts,-

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~ Enclosures H

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3. A. Biddison, Esquire (w/o Enclosure) m G. F. Trowbridge, Esquire D. H. Jaffe, NRC R. E. Architzel, NRC :

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