ML19316D472

Forwards Results of Steam Generator Tube Plugging as Part of Inservice Insp & Required by Tech Spec 4.4.5.5.b.Special Rept of Results Will Be Submitted by 890703

ML19316D472
Person / Time
Site:	Sequoyah
Issue date:	07/18/1988
From:	Gridley R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8807260389
Download: ML19316D472 (5)

Text

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. 0 TENNESSEE VALLEY AUTHO RITY KNOXVILLE, TENNESSEE 379o2 SN 157B Lookout Place

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U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 '

Gentlemen:

In the Matter of Tennessee Valley Authority ) Docket No. 50-327 SEQUOYAH NUCLEAR PLANT (SQN) - UNIT 1 STEAM GENERATOR TUBE PLUGGING In accordance with the requirements of SQN unit 1 technical specification 4.4.5.0, an in-service inspection was performed on approximately 20 percent of the tubes in steam generators 1 and 4 with none of the inspected tubes being determined defective. As required by technical specification 4.4.5.5.b, a special report of the results of this in-service inspection will be submitted on or before July 3, 1989.

Independent of the in-service inspection, TVA performed a self-imposed eddy current examination of all rows 1 and 2 tube U-bend regions in all four steam generators utilizing an optimized probe design (motorized rotating pancake coil probe). This examination was performed for the detection of defects in close radius U-bends; however, this examination does not conform to the American Society of Mechanical EngineersSection XI Code nor Regulatory Guide 1.83 requirements. Enclosure 1 provides a listing of steam generator t.ubes that have been plugged recently based on the results of these examinations.

There are 50 unit 1, row 1, tubes that were plugged because of imperfections greater than 40 percent of the tube wall thickness. An additional 12 tubes were deplugged and replugged with a permanently installed plug. Also, the steam generator 1, row 10, column 44 tube was stabilized and preventively plugged based on identification as being susceptible to excessive flow-induced vibration if dented at the top support plate.

The summary statement of the commitment.contained in this letter is provided in enclosure 2. Please direct questions concerning this issue to Kathy S. latitaker at (615) 870-7748.

Very truly yours, TENNESSEE VALLEY AUTHORITY 8807260389 880718 /,i M

PDR ADOCK 05000327 R. Gridley, Director G PNU Nuclear Licensing and Regulatory Affairs q]}

Enclosures ]

cc: See page 2 {

I Ar Equal Opportunity Employer

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1 U.S. Nuclear Regulatory Commission l_{hlhhh cc (Enclocures):

Ms. S. C. Black, Assistant Director  ;

for Projects l TVA Projects Division l U.S. Nuclear Regulatory Commission i One White Flint, North

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11555 Rockville Pike  !

Rockville, Maryland 20852 1 Mr. F. R. McCoy, Assistant Director i for Inspection Programs  !

TVA Projects Division I U.S. Nuclear Regulat ory Commission Region 11 101 Marietta Street, NW, Suite 2900  ;

Atlanta, Georgia 30323 i

l Sequoyah Resident inspector Sequoyah Nuclear Plant 1 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 l

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ENCLOSURE 1 )

SQN Unit 1 Steam Generator Tubes Plugged July 1988 Steam Generator 1  ;

Row Column Indication Location Reason for Plugging 1 17 N/A N/A See note 1

" " " l 1 20 1 40 > 40% U-Bend Eddy Current Indication 7 47 1 61 N/A N/A See note 1 1 69 1 71 > 4 0% U-Bend Eddy Current Indication 1 73 1 81 N/A N/A See note 1 10 44 See note 2 1

Steam Generator 2 1 12 > 40% U-Bend Eddy Current Indication -

1 13 1 21 1 22 1 25 >

1 39

> 1 43 N/A N/A See note 1 1 45 i 3 1 63 1 75 > 40% U-Bend Eddy Current Indication Steam Cenerator 3 1

1 8 > 40% U-Bend Eddy Current Indication 7 gg o o ..

1 20 g 77 .. . ..

j 1 24 I 1 30 .. ..  ;

1 31 1 35 1 39  ;

I 44 l l

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steam Generator 3 (continued) p Row . Column Indication.- Location Reason'for Plugging 1 45 N/A . N/A See note'1 .j 1- 47 > 40% U-Bend Eddy Current Indication. -l 1e 54 i 1 57 - - -

l 1 60  ;

g gy .. .. ..

63 1 i

3- yg .. ..

l 1 79 .. .;

1 .g3 ,

l' 84 N/A N/A See note 1  !

1 86  !

1 1 88 > 40% U-Bend Eddy Currer.t Indication- I 1 gg- . .

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-i Steam Generator 4 1 9 > 4 0% U-Bend Eddy Current Indication 1 13 .. ..

1 33 ..

, 1 34 . . . ..

1 3.

1 38 {

1 41  !

1 42 " "

l 1- 45 "

j 1 49 .-

1 1 54 "'

, 1 57 "

l 1 73 i 1 88 N/A N/A See note 1 4 1 89 > 40% U-Bend Eddy Current. Indication

1 ,o .. .

1 92 **

1 93 "

i g g4 ..

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! j Note 1: Combustion Engineering,.Inc., tube plugs were removed, and- I Westinghouse Electric Corporation mechanical plugs were installed.

Note 2: A thermal/hydraulic analysis identified this tube as being susceptible to excessive flow-induced vibration if dented.at the top support plate.

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ENCLOSURE 2 List of Commitments  !

1. As required by technical specification 4.4.5.5.b, a special report of the results of this inspection will be submitted on or before July 3,1989.

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