ML20072Q647

Application for Amends to Licenses NPF-35 & NPF-52,allowing Option of Using B&W Kinetic Sleeving Process for 3/4-inch OD Tube Repair Described in Topical Rept BAW-2045(P)-A

ML20072Q647
Person / Time
Site:	Catawba
Issue date:	12/19/1990
From:	Tuckman M DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20072Q650	List: ML20072Q647 ML20072Q660
References
NUDOCS 9012260273
Download: ML20072Q647 (10)

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_ Oake 1%u er Ctunpany S!S Tecurn

' huclear Predaction Dept Ytce1 % dent

. PO flux H'HI hueirar Operutwns Charlotte h C 26201 1007 (TulklihiMI l l

DUKE POWER December 19, 1990 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Subject Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50-414 Proposed Technical Specification Amendment to Allow the Use of the Babcock & Wilcox (B&W) Kinetic Sleeving Process for Steam Generator Tube Repair Gentlement This letter contains a proposed amendment to the Technical Specifications for Catauba Nuclear Station (Facility Operating License Nos. NPF-35 and NPF-52) to allow the option of using the B&W Kinetic Sleeving Process for 3/4 Inch OD Tube repair described in Topical Report BAW-2045(P)-A.

This revision will provide Catawba with an alternative other than plugging for bandling defective steam generator tubes.

Attachment No. 1 contains the justification / description / technical discussion, a no significant hazards analysis, and an environmental impact' analysis. The proposed changes to the Technical Specifications in the form of marked pages are identified in Attachment No. 2.

Catawba Unit 1 is scheduled for a refueling outate in early March 1991. It

-is known that tube plugging will be required during this outage. in

-order to minimize the impact of plugned tubes on primary flow margin and heat transfer, we would like to utilize the B&W sleeving process, Therefore, we request the staff review and approve this request prior to

' March 1,==1991.

!A~similar amendment request was approved for McGuire Nuclear Station on April 17, 1990.

Very truly yours,

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M. S. Tuckman, Vice President Nuclear Operations Attachments i LTB/30/lcs

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9012260273 901219 PDR ADOCK 05000413 / -

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.U. S. Nuclear Regulatory Commission i ,

December 19. 1990 Page 2 xc _ W/ Attachments Mr. S. D. Ebneter, Administrator U. S. Nuclear Regulatory Commission, Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 l

Mr. R. E. Martin, Project Manager Office of Nucioar Reactor Regulation, USNRC U. S. Nuclear Regulatory _ Commission One White Flint North, Mail Stop 9H3 Washington", D.C. 20555 Mr. W. T. Orders Senior Resident Inspector, USNRC Catawba Nuclear Station M & M Nuclear Consultants 1221 Avenue of the Americas New York, New York 10020

'American Nuclear Insurers

.c/o Dottle.Sherman, ANI Library 270 Farmington Avenue Farmington, CT 06032 INPO Records Center Suite 1500 1100 circle 75 Parkway ,

Atlanta,_Coorgia 30339 t

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a U.S. Nuclear Hogulatory Commission

• December 19, 1990 Page 3 M. S. Tuckman, being duly sworn, states that he is Vice President of Duke Power Company; that he is authorized on the part. of said Company to sign and file with the U.S. Nuclear Regulatory Commission this revision to the Catawba Nuclear Station Technical Specifications. License Nos. NPF-35 and NPF-521 and, that all statements and matters set forth therein are true and correct to the best of his knowledge.

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M. S. Tuckman, Vice President Nuclear Operations l

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Subscribed and sworn to before me this 18th day of December, 1990.

-xYA> b Not ry Public )

My Commission Expires:

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Attachment No. 1 Duke Power Company Catawba Nuclear Station Technical Discussion, No Significant Hazards Analysis, and Environmental Analysis Justification / Description / Technical Discussion Currently, the Catawba Technical Specificat. ion (TS) 4.4.5.4 states that a steam generator tube containing a defect is a defective tube. A defect is defined as an imperfection of such severity that it exceeds the plugging limit. The plugging limit for Catawba is the imperfection depth at or beyond which the tube shall be removed from service and is equal to 40% of the nominal wall thickness. The exception to this criterion applies to imperfections in the region of the tube located within the tube sheet below what is known as F

• distance (1.60 inches into the tube sheet from the top). Tubes with indications below this minimum distance may be left in service without plugging. This is due to the reinforcing effect of the tube to-tube sheet joint on tube integrity and pull-out.

With the forthcoming outage in March, 1991 Duke Power would like to be l able to utilize tube sleeving as an alternate to plugging. The advantage of tube sleeving versus tube plugging is that the tube will '

remain in service and the structural integrity of the tube is maintained with minimal reduction in flow and heat transfer capabilities. The repaired tube functions in essentially the same manner as the original tube. Therefore, Duke Power requests the NRC provide approval to allow Catawba the option of using the Babcock & Wilcox (B&W) Kinetic Sleeving Process for Steam Generator Tube Repair. This TS revision will provide Catawba with-a desirable alternative for handling degraded steam generator tubes.

The tube sleeving technique which Duke Power wishes to uso at Catawba

' Nuclear Station is described in B&W Topical Report BAW-2045(P)-A,

" Recirculating Steam Generator Kinetic Sleeve Qualification For 3/4 Inch OD Tubes". This report was submitted to the NRC by B&W Ictter dat.ed June 9, 1989 and supplemented on December 12, 1989. This report received NRC approval by letter dated January 4,1990 (James Richardson, NRC Director of Division of Engineering Technology to J.H. Taylor of B&W).

The following changes to the TSs are requested to support the use of the the B&W tube sleeving process (see Attachment No. 2):

+ Change TS 4.4.5.i.a.1 to include sleeve under Imperfection criteria; 4 Change TS 4.4.5.4.a.2 to include sleeve under Degradation critoria; 1_

Attachment No. 1 i

+ Change TS 4.4.5.4.a.3 to include sleeve under Degraded Tube criteria; 4 Change TS 4.4.5.4.a.4 to include sleeve under % degradation criteria; 4 Change TS 4.4.5.4.a 5 to include sleeve under Defect criteria;

+ Change TS 4.4.5.4.a.6 from Plugging Limit to Repair Limit and add tube sleeving as an alternate to tube plugging, clarify F* tube requirements, and identify the B&W process to be used for tube sleeving.

+ Change TS 4.4.5.4.a.7 to include sleeve under unserviceable criteria;

+ Change TS 4,4,5.4.b to allow sleeving as an alternate to plugging tubes that exceed the repair limit.

+ Change TS 4.4.5.4.a.12 to change plugging limit to repair limit;

+ Change TS 4.4.5.5.b.3 to add a requirement to report repaired tubes as well ar plugged tubes; and, 4 Change the TS Bases 3/4.4.5, Steam Generators to add tube repair by sleeving and to address F* tube requirements with respect to sleeving.

These changes incorporate tube sleeving into the existing surveillance requirements specified in the TSs.

The purpose of the sleeving process is to repair a degraded steam generator tube in order to maintain the function and the integrity of the tube. The sleeve functions essentially in the same manner aa the original tube. B&W Topical Report BAW-2045(P)-A describes in detail the analytical methods used for design and qualificatioi. of the B&W sleeve. The Topical also contains the results of the sleeve design verification which included analysis and confirmatory testing to demonstrate the acceptability of the steam generator slooving technique for defective tubes. The design and operating conditions specified for the sleeve bound the Catawba steam generator design conditions.

The sleeve design described in Topical Report BAW-2045(P)-A is qualified for two lengths, 11 inches and 17.5 inches. The lower end of each sleeve is located approximately 16 inches from the primary face of the tube sheet (reference Figure 5.1.1 of the Topical Report). The shorter sleeve may be utilized in all the steam generator tubes (including the peripheral tubes which typically do not allow the introduction of sleeves due to the close proximity of the steam generator bowl in that area). The longer sleeve extends further into the tube and spans the secondary face of the tube sheet as well as the flow distribution baffle which is 8 inches above the tube sheet.

Attachment No. 1 The sleeve material is thermally treated Alloy 690 Inconel with a specified wall thickness of 0.039 inches. The required minimum thickness is 0.027 inches based on primary side design pressure. This material has been demonstrated to be much more resistant to corrosion phenomenon as detailed in Topical Report BAW-2045(P)-A.

The upper sleeve / tube joint is produced by a kinetic weld / expansion which is subsequently stress relieved. The lower joint is either a kinetic weld in the tube sheet or a mechanically sealed joint produce'd by rolling the sleeve in the tube sheet. Therefore, the structural integrity of the tube is maintained by the sleeving process.

The adequacy of the sleeve to withstand cyclic loadings was demonstrated by B&W using fatigue testing. Fatigue testing consisted of cyclic vibration, pressure, thermal, and axial loading. These tests were performed to demonstrate the structural adequacy of the installed sleeve. In all cases, the results of the tests indicated that the sleeve conformed to the design requirements of the steam generators. Table 4.2.2, " Steam Generator Design Transients" of the Topical Report summarizes the transients used to

. establish sleeve loading. The design and operating conditions for which the sleeve has been designed are listed in Table 4.2.1, " Design &

Operating Conditions."

Catawba currently has a program for inservice inspection based on a modification of Regulatory Guide 1.83, Revision 1. If a defect mechanism should develop in service, it will be detected during routinely scheduled inservice steam generator tube examinations. Repair will be required for all tubes or sleeves with imperfections exceeding the repair limit of 40% of the tube or sleeve nominal wall thickness por the TSs. Defective steam generator tubes can be repaired by the installation of sleeves which span the area of degradation, and serve as a replacement pressure boundary for the degraded portion of the tube, allowing the tube to remain in service.

Steam generator tube inspections have demonstrated the capability to reliably detect wastage type degradation that has penetrated 20% of the original tube wall thickness. For tubes with degradation below the F*

distance,,and not degraded within the F* distance, repair is not required.

If a tube is sleeved due to degradation in the F* distance, then any defects in the tube below the sloove will remain in service without repair.

No Significant Hazards Analysis As required by 10 CFR 50.91, the following analysis is provided concerning whether the proposed amendment request involves a significant hazards consideration as defined in 10 CFR 50.92. Standards for determination that an amendment request does not involve a significant hazards consideration are if the operation of the facility in accordance with the proposed amendment would not:

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Attaclanont No. I 1). Involvo a significant increase in the probability or consequences of an accident previously evaluated; or,

2) Create the possibility of a new or different kind of accident from any previously evaluated; or,

3) Involve a significant reduction in a margin of safety.

Operation of Catawba in accordance with the proposed amendment would not involve a significant increase in the probability or consequences of an accident previously evaluated. Considering the function of the sleeve, the

-principal accident associated with this amendment is the steam generator tube rupture accident. 'The steam generator sleeve has been analyzed and tested to the operating and design conditions of the original tube as documented in Topical Report BAW-2045(P)-A. The Topical Report contains the design verification results from tho analysis and confirmatory testing performed on the sloovo. The probability or consequences of this previously evaluated accident does not involve a significant increano since the sleevo meets the original tube design conditions and the structural integrity of the tube is maintained by the slooving process, and surveillance requirements. The sleeve is less susceptible-to the identified stress corrosion failure mechanisms of the original tubo because of the B&W specified installation process and the use of improved material (Alloy

-inconel 690); therefore, the potential for. primary to secondary-leakage is also reduced by the addition of a steam generator tube sleeve. The continued integrity of the sleeve will be verified by TS inspection requirements and the sleeve will be plugged in accordance with TSs. if necessary.

Operation of Catawba in accordance with the proposed amendment would not create the possibility of a.new or different kind of accident from any accident previously evaluated. Tho purpose of the sleeve is to repair a defective steam generator tube to maintain the function and integrity of the tube-as opposed-to plugging and removing the-tube-from service. The s1 cove functionsLin essentially t he same manner as the original tube and has been-analyzed and tested for steam generator design conditions. The sleeve is

~1oss susceptible to the: identified stress corrosion failure mechanisms of the original tube because of the B&W specified installation process and the use of improved material (Alloy Inconel 690); therefore, the potential for primary to secondary leakage is also reduced.by the addition of a steam generator tubo sloove. The continued integrity of the sloove will be

-verified by TS inspection requirements and tho' sleeve will be plugged in

accordance-with TSs, if nocessary. Repairing a steam generator tubo to a serviceable condition utilizing the proposed sleeva process does not create the possibility of a new or different type of accident since'the sleevo is a passive component with postulated failures that are similar to the original tube.

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, At tachment No.1 Operation of Catawba in accordance with the proposed amendment would not involve a significant reduction in a margin of safety. The structural integrity of the tube is maintained by the installation of the sleeve and the sleeve / tube weld. The potential for primary to secondary leakage is reduced by the addition of the steam generator tube sleeve. The sleeve is made of Alloy 690 and is not subject to the same f ailure mechanisms of the original t ube.

The Catawba LOCA analysis in Chapter 15 of the FSAR takes into account the effect of plugged tubes on primary coolant flow. The LOCA analysis assumes a worst case where 10% of the tubes are plugged. The effects of sleeve installation (versus tube plugging) on steam generator performance, heat transfer, flow restriction, and steam generation capacity were analyzed and described in the B&W Topical Report. The results show that plugging one tube is equivalent to the heat transfer reduction of sleeving 48 tubes, the primary flow reduction of sleeving 20 tubes, and the loss of steam generation capacity of slooving 40 tubes. In summary, the tube sleeving does not result in a reduction of the margin assumed in the LOCA analysis since it is bounded by the

-limits for tube plugging.

Environmental Impact Analysis one of the major design objectives'of the B&W steam generator tube sleeving process was to minimize personnel exposure. The rcsults of a personnel exposure study are presented in Section 7.2 of the Topical Report-BAW-2045(P)-A. The conclusion-is that tube slooving provides a radiological economic alternative to plugging and removing tubes from service.

The sleeving process does result in radioactive waste whien is considered disposable and cannot be reused. The solid volume produced during the-installation of 50 sleeves is approximately 0.75 cubic feet. This waste consists-of nylon tubing, stress relief heaters, roll expanders, cleaning

' hones, and water. The cleaning hones (less than one percent of the waste) are the_only components that will come in contact with the primary system.

This contact will result in an expected hone radiation reading of approximately 1-2 R/hr after the usabic life of the hone. The remainder of the waste is considered to be extremely low level waste. The cicaning water will be' retrieved and piped to the station radioactive waste water treatment system. Approximately one gallon per each tube will be required.

Additional wastes will be produced consisting of protective clothing, tape, plastic bags, and other materials normally used in a radioactive

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' Attachment. No. 1 onvironment.- This waste la also considered extremely low level waste and will be processed and disposed of in a low level waste burial l facility. The amount _of waste created using the sleeving process is I

. comparable to that_ created by tube plugging..

The proposed amendment does not involve a significant hazards consideration,  !

nor increase the types and amounts of offluents or waste that may be released offsite, nor increase individual or cumulative occupational.

radiation exposures. Therefore, the proposed TS amendment meets the j criteria given in 10 CFR 51.22(c)(9) for a categorical exclusion from the <

requirement for an Environmental Impact Statement.

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Attachment No. 2

, 1 Duke Power Company-l' l'roposed Changes to Catawba Technical Specifications F

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