ML20136B526

Proposed Tech Specs,Requesting Approval of Alternative Sleeving Repair Process for SG Tubes at Plant

ML20136B526
Person / Time
Site:	Maine Yankee
Issue date:	03/05/1997
From:	Maine Yankee
To:
Shared Package
ML20136B523	List: ML20136B516 ML20136B526
References
NUDOCS 9703110011
Download: ML20136B526 (6)

Text

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l ATTACHMENT B Proposed Technical Specification Pages '

4.10-3. 4.10-5 and 4.10-6 l

9703110311 970305 PDR ADL'CK 05000309 -

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D. Acceotance Criteria .

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. 1. As used in this Specification. l (a) Imoerfection means an exception to the dimensions, finish or contour of a tube or tube sleeve from that required by fabrication drawing or specifications. Eddy-current testing indications below 20% of the nominal tube or tube sleeve wall thickness may be ,

considered as imperfections.

(b)

Dearadation means a service-induced cracking. wastage,

wear or 1 general corrosion occurring on either insioe or outside of a tube or tube sleeve. l (c) Dearaded Tube means a tube or tube sleeve containing imperfections greater than or equal to 20% of the nominal tube or tube sleeve wall thickness caused by degradation.

(d) %Dearadation means the percentage of the tube or tube sleeve wall thickness affected ro removed by degradation.

(e) Defect means an imperfection of such severity that it exceeds the repair limit. A defective tube is a tube containing a defect that has not been repaired by sleeving or a sleeved tube that has a defect in the sleeve.

(f) Reoair Limit means the imperfection depth at or beyond which the tube shall be removed from service by plugging or repaired by sleeving in the affected area because it may become unserviceable prior to the next inspection and is equal to 40% of the nominal tube wall thickness. For a tube that has been previously sleeved, through wall penetrations or imperfection depths of greater than or equal to 40% of the sleeve nominal wall thickness for Combustion Engineering sleeves [39% of the sleeve nominal wall thickness for Westinghouse laser welded sleeves or 20% of the sleeve nominal wall thickness for Framatome Electrosleeves*] shall be defined as the repair limit.

(g) Unserviceable describes the condition of a tube if it leaks or contains a defect large enough to affect its structural integrity in the event of a steam line break, feedwater line break, Operating Basis Earthquake, or a loss-of-coolant accident as specified in 4.10.C.3 above.

(h) Tube Insoection means an inspection of the steam generator tube from the point of entry (hot leg side) completely around the U-bend to the top support of the cold leg. For a tube that has been repaired by sleeving, the tube inspection shall include the sleeved portion of the tube.

(i) Critical Area means an area of the steam generator where degraded and/or defective tubes exist due to a steam generator physical and/or operating characteristic which would promote tube degradation in that identified area.

(j) Tube Reoair means either plugging or sleeving by mechanical.

l electrodeposition, or welded methods which will maintain a tube in service or return a tube to service.

Amendment No. 28,68,84, M9, %9 4.10-3 i

TABLE 4.10-2 *

-STEM GENERATOR TUBE INSPECTIONS ' -

ilST SMPLE INSPECTION 2ND SMPLE INSPECTION 3R0 SMPLE INSPECTION -

Sample Size Result Action Required Result Action Required Result Action Required

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A minimum of C-1 None N/A N/A N/A N/A St tubes per C-2 Plug or Sleeve (1) C-1 None N/A N/A i S.G. defective tubes and i inspect additional 25% i' tubes in this S.G.

C-2 Plug or sleeve 2 defective C-1 None tubes and r

Inspect additional 45% tubes C-2 Plug or sleeve defective tubes 2

in this S.G. .

C-3 Perform action for C-3 result i of first sample C-3 Perform action for C-3 N/A N/A result of first sample l C-3 Ins W all tubes in this All other S.G.s None N/A N/A 5.G. plug or sleeve 2 are C-1 defective tubes and Some S.G.s C-2 Perfcm action for C-2 N/A N/A Inspect 25% tubes each but no result of second sample l S.G. additional S.G.  ;

are C-3 Report to NRC pursuant to Additional S.G. Inspect all tubes in each N/A N/A- f l

10 CFR 50.72(b)(2) is C-3 S.G. and plug or sleeve' 1 defective tubes. Report to NRC pursuant to 10 CFR [

50.72(b)(2) l I

S-3N/n Percent where N is the number of steam generators in the unit. and n is the nurrber of steam generators inspected during an inspection (1) Sleeving repair of tubes shall be in accordance with the sleeve design. Installation techniques, and Inspection program identified in the proprietary }

Combustion Engineering Report CEN-618-P. Maine Yankee Nuclear Power Plant Steam Generator Tube Repair Using Leak Tight Sleeves Revision 0, dated l October 1994 or in the proprietary Westinghouse Electric Corporation Reports WCAP=13698. Rev. 2: " Laser Welded Sleeves for % Inch Diameter Tube Feedring-  !

Type and Westinghouse Preheater Steam Generators dated April 1995 and WCAP-14346.-Rev. 1; " Specific Application of Laser Welded Sleeves for the Maine  !

Yankee Nuclear Power Plant Steam Generator ~ dated April 1995. or in the proprietary Framatome Technologies Report BAW-10219P Revision 1. dated March [

1996.  :

t Amendment No. 28. 84. 448, 149. 450 4.10-5  :

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Basis: The Surveillance Requirement for inspection of the steam generator tubes ensure that the structural integrity of this portion of the RCS will be {

maintained. The program for inservice inspection of steam generator tubes is based on a modification of Regulatory Guide 1.83, Revision 1. Inservice )

inspection of steam generator tubing is essential in order to maintain surveillance of the conditions of tubes in the event that there is evidence of mechanical damage or progressive degradation due to design, manufacturing errors, or inservice conditions that lead to corrosion.

Inservice inspection of steam generator tubing also provides a means of characterizing the nature and cause of any tube or tube sleeve degradation so that corrective measures can be taken.

The plant is expected to be operated in a manner such that the primary and secondary coolant will be maintained within those chemistry limits found to result in negligible corrosion of the steam generator t'ubes. If the l primary or secondary coolant chemistry is not maintained within these '

limits, localized corrosion may likely result in stress corrosion cracking.

Steam generator tubes with imperfections that exceed the repair limit may i be repaired by the installation of sleeves which span the region of defect. l A steam generator tube sleeve is designed to meet the structural l requirements of tube which are not degraded. Maine Yankee has been I analyzed for the use of the Combustion Engineering sleeves as specified in the report CEN 618,P, " Maine Yankee Nuclear Power Plant Steam Generator l Tube Repair Using Leak Tight Sleeves", Revision 0, dated October 1994.

Maine Yankee has also been analyzed for the use of Westinghouse Laser Welded Sleeves as specified in the two reports, WCAP-13698, Rev, 2. " Laser Welded Sleeves for % inch Diameter Tube Feedring-Type and Westinghouse Preheater Steam Generators", dated April 1995, and WCAP-14346, Rev. 1,

" Specific Application of Laser Welded Sleeves for the Maine Yankee Nuclear Power Plant Steam Generators," dated April 1995, Maine Yankee has also been analyzed for the use of Framatome Technologies Electrosleeves" as specified in the Report BAW-10219P, "Electrosleeving" Qualification for PWR Recirculating Steam Generator Tube Repair", Revision 1, dated March l 1996.

Wastage-type defects are unlikely with proper chemistry treatment of the primary and secondary coolant. However, even if a defect should develop in service, it will be found during scheduled inservice steam generator tube examinations. Plugging or sleeving repair will be required for all tubes or sleeves with imperfections exceeding 40% of the tube or sleeve nominal wall thickness for Combustion Engineering sleeves [39% of the sleeve nominal wall thickness for Westinghouse laser welded sleeves; 20% of the sleeve nominal wall thickness for Framatome Electrosleeves".]

In the past, Maine Yankee as well as other licensees has experienced steam generator tube degradation in specific localized areas. The exception permits inspecting 100% of the localized area and a representative sample of remaining tubes, when degradation of tubes in the localized area would otherwise cause the inspection results to be classified C-3.

Amendment No. 28, 84, 449, MG 4.10-6

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l ATTACHMENT C Proposed Technical Specification Pages l 4.10-7 l I

I (This page applies only if Maine Yankee Proposed Change No. 169 is approved before this Proposed Change)

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-Unscheduled inspections of steam generators during the shutdown following a primary-to-secondary tube leak are foct: sed on finding the. leaking tube and identifying i ddditi6nal defects similar to the leaking tube. These inspections do not affect nor >

do they substitute for existing routine inservice inspections. They do not change any inservice inspection sampling requirements or criteria.

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1 Amendment No. 4.10-7 I 1