ML19332G062
| ML19332G062 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 12/13/1989 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8912200108 | |
| Download: ML19332G062 (2) | |
Text
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ELECTRIC CHARLES CENTER. P. O. BOX 1476 + BALTlMORE, MARYLAND 21203 i
Gronot C. CRttL vice P.cssor=1 wveu. car..v December 13,1989 (300 960 e495 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit No.1; Docket No. 50-317 Reoort of Steam Generator Tube Plunninn Gentlemen:
As required by Technical Specification 4.4.5.5, this letter reports the number of tubes plugged in the Calvert Cliffs Steam Generator No.12 during the current Unit I outage.
Two tubes were found to have indications which exceeded the Technical Specification plugging limit of 40% penetration. One of these tubes was plugged due to a through-wall defect leading to a primary-to-secondary leak. The other tube was taken out of service via plugging due to a $5% wall loss indication on the outside diameter.
The tube plugging information is tabulated as follows:
ROW LINE REASON FOR Pl.UGGING 1
141 Tube primary-to-secondary leak of 30-60 drops per minute at ilTS-SF+0.2 inches.
75 93 Eddy current testing indication of 55% wall loss originatint on the outside diameter of the tube at ilTS-SF+1.3 inches.
Over the last eight years Steam Generator No.12 has experienced a sporadic primary-to-l secondary leak. Prior to 1988, the leak rate varied from just detectable to a maximum of 10 GPD. After the Unit I refueling outage in the Spring of 1988, the leak rate increased from 10 GPD to 30 G PD, When Unit I was shutdown to evaluate the condition of the pressurizer heater sleeves, BG&E decided to perform a leak test on Steam Generator No.12.
Prior to the Steam Generator No.12 leak test, a primary side visual examination of the L
hot leg channel head found a 30-60 drop per minute leak from the tube on Row I Line 141. A video inspection of this tube revealed a pin hole leak at the tube roll transition just above the secondary side of the hot leg tubesheet, in addition, a bobbin coil eddy current examination confirmed the through-wall defect. The eddy current data was analyzed using the " turbo mix" software. The tube was plut,ged July 17, 1989.
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" Doe:me:t C:: trol Desk December 13,1989 Page 2 Unit 1 1988 eddy current outage data was re-evaluated using ' turbo mix" analysis. This review found one additional tube, Row 75 Line 93, with a 55 % 0.D.
wall loss indication, 1.3 inches above the hot leg tubesheet secondary face. This tube was plugged September 22, 1989.
Should you have any further questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours,
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GCC/ PSF /bjd cc:
D. A. Brune, Esquire J. E.
Silberg, Esquire R. A.Capra,NRC S. A.McNeil,NRC W. T. Russell, NRC J. E. Beall, NRC T. Magette, DNR i
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