ML20011F187

Submits Results of Apr-Jul 1989 Inservice Insp of Steam Generator Tube Plugging.Of 16,947 Tubes examined,212 Tubes Had Indications of 20% or Greater through-wall Degradation w/11 Exceeding Plugging Limit

ML20011F187
Person / Time
Site:	Calvert Cliffs
Issue date:	02/21/1990
From:	Creel G BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9003020033
Download: ML20011F187 (5)

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0 BALTIMORE GAS AND ELECTRIC CH ARLES CENTER. P. O. BOX 1476 + BALTIMOR E, MARYLAND 21203 Gtomot C. CRett v,cc p.c. or,

February 21, 1990 W e6can rwsmov noo eeo. ss U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:

Document Control Desk i

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit No. 2; Docket No. 50-318 Report of Steam Generator Tube Plunninn

REFERENCE:

(a) Calvert Cliffs Unit 2 Technical Specification 4.4.5.5 Gentlemen:

As required by Reference (a), this letter reports the number of tubes plugged in the Calvert Cliffs Unit 2 Steam Generators during the recent April through July, 1989 Inservice inspection. Eleven tubes were found to have indications which exceeded the Technical Specification plugging limit of 40% loss of nominal wall thickness. An additional 11 tubes were plugged as a preventive measure. Of the 22 tubes plugged during this inservice inspection,12 tubes were plugged in Steam Generator #21 and 10 tubes were plugged in Steam Generator #22.

Attachments (1) and (2) list the tubes plugged during the 1989 Unit 2 Refueling Outage along with the reason for plugging each tube. Attachment (3) is a sketch indicating i

Steam Generator support locations and nomenclature.

All of the tubes in service in each Steam Generator were examined. The 100% inspection required a total of 16,947 tubes to be examined. Of the 16,947 tubes t;xamined, 212 tubes had indications cf' 20% or greater through-wall degradation. As stated above, 11 of these indications exceeded the plugging limit. Six tubes were plugged in Steam Generator #21 and 5 tubes were plugged in Steam Generator #22 for this reason.

As a preventive measure,11 additional tubes with indications in the sludge pile, upper supports or free span areas were plugged. Of these additional iI tubes taken out of y

service, 6 were in Steam Generator #21 and 5 were in Steam Generator #22.

Previous metallurgical examination of Unit I tubing has shown degradation in the sludge pile area was-caused by Intergranualar Attack (IGA). Five tubes in the sludge pile region with indications less than the plugging limit were plugged because of the potential for a local active IGA mechanism just above the tube sheet, in the upper U-bend support area, previous metallurgical examination of Unit I tubing has shown degradation in this area was caused by mechanical wear. Five tubes in the 9003020033 900221 9Ibb gDR ADOCK 05000318 0

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Doe:: ment C;;; trol Desk February 21, 1990 Page 2 U-bend region with indications less than the plugging limit were plugged due to the

- possibility of an active mechanical wear mechanism.

One tube was plugged as a precaution due to outer diameter wall loss of 36% in the free span area. Previous examination of this tube in 1987 had found no detectable degradation.

Should you have any further questions regarding this matter, we will be pleased to discuss them with you.

l Very truly yours,

/- -eg;sg /

$9 d[(,w

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GCC/DWM/bjd Attachments cc:

D. A. Brune, Esquire J. E.

Silberg, Esquire R. A.Capra, NRC D. G. Mcdonald, Jr., NRC W. T. Russell, NRC J. E. Beall, NRC T. Magette, DNR i

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ATTACHMENT (1)

STEAM GENF_R ATOR #21 TUBES PLUGGED DURING THE 1989 OUTAGE ROW LINE RE ASON FOR PLUGGING 129 Eddy current testing indication of 51% wall loss originating on the outside diameter of the tube at HTS - SF + 0.60 inches.

9 145 Eddy current testing distorted indication originating on the outside diameter of the tube at VM + 0.00 inches.

43 75 Eddy current testing indication of 60% wall loss originating an the outside diameter of the tube at CTS - SF + 6.60 inches.

53 33 Eddy current testing indication of $8% wall loss originating on the outside diameter of the tube at HTS - SF + 0.90 inches.

58 32 Eddy current testing distorted indication originating on the outside diameter of the tube at IITS - SF + 0.70 inches.

71 123 Eddy current testing indication of 55% wall loss originating on the outside diameter of the tube at IITS - SF + 0.70 inches.

96 122 Eddy current testing indications of 39%, 32%, and 16% wall loss originating on the outside diameter of the tube at CTS - SF + 2.20, 0.80, and 3,30 inches respectively.

104 126 Eddy current testing distorted indication originating on the outside diameter of the tube at CTS - SF + 1.80 inches.

117 109 Eddy current testing distorted indication originating on the outside i

diameter of the tube at CTS - SF + 0.70 inches.

121 105 Eddy current testing distorted indication originating on the outside diameter of the tube at CTS - SF + 1.10 inches.

123 57-Eddy current testing indication of 64% wall loss originating on the outside diameter of the tube at CTS - SF + 1.50 inches.

t 136 102 Eddy current testing indication of 48% wall loss originating on the outside diameter of the tube at CTS - SF + 5.10 inches, b. -.

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3 A*ITACHMENT (2)

STEAM GENERATOR #22 TUBES PLUGGED DURING Tile 1989 OUTAGE t:

JLQE 1.INE R E ASON FOR PLUGGING i

25 63 Eddy current testing indication of 36% wall loss originating on the outside diameter of the tube at C3 + 6.90 inches.

34 38 Eddy current testing indication of 95% wall loss originating on the outside diameter of the tube at IITS - SF + 6.00 inches, 1

34 94 Eddy current testing indication of 36% wall loss originating on the j

outside diameter of the tube at Dit + 0.00 inches.

35 75 Eddy current testing indication of 28% wall loss originating on the outside diameter of the tube at Dil + 0.00 inches.

58 22 Eddy current testing indication of 51% wall loss originating on the outsWe diameter of the tube at VM + 0.00 inches.

58 98 Eddy current testing indication of 85% wall loss originating on the outside diameter of the tube at IITS - SF + 0.80 inches.

64 52 Eddy current testing indication of 38% wall loss originating on the outside diameter of the tube at VM + 0.00 inches.

81 23 Eddy current testing indication of 49% wall loss originating on the outside diameter of the tube at VM + 0.00 inches.

86 74 Eddy current testing indication of 44% wall loss originating on the outside diameter of the tube at ilTS - SF + 0.60 inches.

94 26 Eddy current testing indication of 38% wall loss originating on the outside diameter of the tube at VM + 0.00 inches.

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