ML19332G140

Proposed Tech Spec 3/4.4.5, Steam Generators.

ML19332G140
Person / Time
Site:	Summer
Issue date:	12/11/1989
From:	SOUTH CAROLINA ELECTRIC & GAS CO.
To:
Shared Package
ML19332G135	List: ML19332G134 ML19332G140
References
NUDOCS 8912200206
Download: ML19332G140 (10)

Text

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,  ; REACTOR C00L' ANT SYSTEM

.- $URVE!LLANCE REQUIREMENT $ (Continued) 4.4.5.4 Accootence Criteria y a. As used in this Specificatten: ' '

1. Imoerfection means an exception to the dimensions finish er centeur of a tube free that required by fabricatio,n drawings er specifications. E current testi insications below 2 5 of the nesinal tube wal thickness,if tectable, say be-considered as 1sperfections.

2. Deoradation means a service induced crackin0, wastage, wear er eral corresten occurring en either inside or outside of a ube.

d 3. Deoraded Tube means a tube containing taperfections greater t snan er equal to 23 of the nominal wall thickness caused by degradation.

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. . 4. 5 Deoradation osans the percentage of the tube well thickness affectee or removed by degradation.

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5. Defect means an imperfection of such severity that it exceeds l , sne ing er mpair limit. A tee containing a defect is 1

-defe vs.

6. /Muarino er Renafr Lin't seens the taperfection depth at er bey wntei sne tune saali no repaired (i.e. sleeving) er removed free service by ing and is 1 to 4 8 of the nominal tube wall thickness. p definitten not apply to the area of the tubesheet reglen below the distance provided the tube fs not aded (i.e., no indications of cracking) within the F*

di tance.

7. ***" k'" -

1. N" ' .,4 s. For the area in the upper weld joint, ery be 1 unless it can be clearl demonste ted by a vali-t, ten shall f1 technique that the degra tien is less than 4 ef the nominal well thickness of the sleeve for 30 imperfec-tiens er less than 45 assinal wall thickness of the tube for 0.D. imperfections.

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. b. For the area of the tube behind the sleeve and above the perweldjoint,tubeswith degradation shall be unless it can be clea demonstrated by a qualified hnique, that the degra ten is less than 48 of the nominal us11 thickness,

c. For the area below the upper weld joint.Jqr defect grester than 48 of the nominal sleeve well thickness shall be pi'.gged. -

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sule1ER - UNIT 1 3/44-14 Amendment No. W ' 59 a

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3 REACTOR COOLANT $YSTEN SURVIILLANCE REQUIREMENTS (Ontinued) ..

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F f. Unserviceable describes the condition of a tube if it leaks or contains a oefect large ene to affect its structural l

integrity in the event of an retipp Sesis Earthquake aine er feedvater less-of ct olant accident. e.e'a staas break as i pecified in 4.W. 3.c. above. -

c) F. Tube 21soection means en inspection of the steam generator tube I from t a point of entry (het leg side) com U-bend to the tap support of the cold leg.pletely around the i lo/. S'eeve Inspechien means an inspection of the sleeved pertion of I tie tuDe. Tn's inspection will include 3 inches of the parent tube directly obeve the upper weld, the upper weld which fems the new pressure boundary, and the sleeve asterial below th,e ,

upper weld, il Js. Roosired tube means a tube that has undergene a proctst that re 11snes be estape u w. wu.its serviceab111tg. a w Om-+uu.:

eer or more-

. of 4k khhp will The Combustion neering Inc. weld sleeve process will be used per report C -337-P.

rk % a + tm k.ex KWeh 5ke"- P*ceu d be.

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$lD01ER - UNIT 1 3/4 4-14a Amendment No. 59 i l

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REACTOR COOLANT $YSTEM ,

SURVEILLANCE REQUIREMENTS (Continued ,

... n.. / Preservice Insee:tfen means an insp' each tube in esca steen generator performed by eddy current a ction of the full length of l techniques prior to service to establish a baseline condition of the tubitu. This inspection shall be perfomed after the -

field hydros", etic test and prior to initial POWER OPERATION using the equipment and techniques expected to be used during subsequent inservice inspections.

13, )6. E* Distance is the distance into the tubesheet from the face l 4 of the tunesheet or the top of the-last hardroll, whichever is  ;

lower (further into the tubesheet) that has been conservatively chosen to be 1.5 inches. ,

H. )f. F* TUBE is the tube with degradation equal te or greater than soz, pelow the F8 distance and not degraded C1.e. , no indica- l tions of cracking) within the-F* distance. "he application of -

F* expires at the end of the fifth fuel cycle,  !

b. The stone ;cnerator shall be detamined OPERABLE after completing the correspondin of repair all tubes exceeding the plugging limit) g actions (p1 required by Ta le 4.4-2.

g 4.4.5.5 Reports i s. Within 15 days following the completten of each inservice inspection  ;

of staan generator tubes the number of tubes slugged or repaired in each steam generator shall be reported to the tennission in a special )

5 Report oursuant to Specification 8.g.t.

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b. The ceaplete results of the steam generator tube inservice inspection shell be submitted to the Commission in a Special Report pursuant to Specification 5.g.2 within 12 months following the completion of the inspection. This Special Report shall include , 1

1. Number and extent of tubes' inspected.

2. Location and percent'of well-thickness penettetton for each indication of an taperfection. ,

3. Identification of tubes plugged er repaired.

ce Results of steam generator tube inspections which fall into Category C 3 and require prompt notification of the Ceesission shall be reported pursuant to 10 CFR 50.7t(b)2(1) prior to resumption of plant operat an. A' report 8p svant to 10 CFR 50.73(a)2(ii) shall'be submitted to provide a desce tion of investigattens conducted to detafsine cause of the tube gradation and corrective'sessures taken to prevent recurrence. #

L d. The results of inspection / of F# tubes shall be rep #ted to the j E

l Ceanission of the unit following in a report to the Director.This report shall include:ONRR p the inspection.

1. Identification of F* tubes, and L 2. Location and size of the degradetion

.NRC approval of this report is not required prior to restart.

l SUl#1ER - UNIT 1 3/4 4-15 Amendment No. 35. M . 59

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3-ATTACHMENT 2 Description of Amendment Request and Safety Evaluation

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Attachment 2 to Document Control Desk Letter o Dece nber 11, 1989 Page 1 of 2 Description of Amendment Request:

Technical Specification 4.4.5.4.a.10. " Acceptance Criteria-Repaired Tube,"

presently allows steam generator tube repair using the Combustion Engineering sleeve process. The requested Technical Specification change will allow the use of B&W sleeves for steam generator tube repair. The change requires referencing B&W topical report BAW-2045P, " Recirculating Steam Generator Kinetic Sleeve Qualification for 3/4 Inch 0.D. Tubes," in Technical Specification Section 4.4.5.4.a.10. The topical war, submitted to the NRC by a letter dated June 9, 1988, from Mr. James H. Taylor r>f B&W to Mr. L. C.

Shao of the NRC. A supplement to the original B&W submittal was made on December 12, 1988, which contained anssers to NRC questions and transmitted a non-proprietary version of the topical. The currently allowed Combustion Engineering sleeve process will be retained in the Technical Specifications as an option.

The basis for steam generator tube surveillance and repair is to ensure that the structural integrity of the tubes is maintained. The sleeving process is one method of dispositioning a degraded tube. The advantage of sleeving versus plugging is that the tube is allowed to remain in service. The structural integrity of the tube is maintained with minimal reduction in flow and hear transfer capabilities. Therefore, the repaired tube functions in essentially the same manner as the original tube.

The proposed Technical Specification change is requested to provide SCE&G with another alternative for han/ ling degraded tubes. The B&W sleeve is qualified for two lengths. The shorter sleeve may be utilized in all steam generator tubes and is therefore more versatile than the currently approved Combustion Engineering sleeve.

Also, an editorial numbering / title revision is being made to Section 4.4.5.4.a.6 to more clearly delineate tube versus sleeve plugging or repair limits by adding item 4.4.5.4.a 7 and renumbering subsequent items.

Safety Evaluation:

Introduction:

The purpose of a sleeve is to repair a degraded steam generator tube in order to maintain the function and integrity of the tube. The sleeve functions in essentially the same manner as the original tube. B&W topical report BAW-2045P describes in detail the analytical methods used for design and qualification of the B&W sleeve. Table 4.1.1, " Summary of RSG Sleeve Requirements," lists the specifications (mainly ASME Boiler and Pressure Vessel code requirements) used in design, procurement and qualification of the sleeve. Table 4.2.2, " Steam Generator Design Transients," summarizes the transients used to establish sleeve loading. Details for key areas covered in the topical report are summarized below.

f Attachment 2 to Document Control Desk Letter December 11,19^J Page 2 of 2 Justification:

BAW-2045P contains the results of the sleeve design verification which included analysis and confirmatory testing to demonstrate the acceptability of the steam generator sleeving technique for defective tubes. The design and operating conditions specified for the sleeve bound the VCSNS steam generator design conditions. In general, the generic topical (BAW-20459) was written utilizing VCSNS specific design data.

The sleeve design described in BAW-2045P is qualified for two lengths, eleven inches and seventeen and one half inches. The lower end of each sleeve is located approximately 16 inches from the primary face of the tubesheet. The shorter sleeve may be utilized in all the steam generator tubes (including the peripheral tubes which typically do not permit the introduction of sleeves due to the close proximity of the bowl in that area). The longer sleeve extends further into the tube past the flow distribution baffle.

The sleeve material is thermally treated Alloy 690 Inconel with a specified minimum 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 BAW-2045P. Design and operati19 conditions listed in Table 4.2.1 of BAW-2045P bound those for VCSNS. The upper sleeve / tube joint is produced by a kinetic weld / expansion which is subsequently stress relieved. The joint is qualified as both a strength and seal weld. The lower joint may consist of either a kinetic weld in the tubesheet or a mechanically sealed joint produced by rolling the sleeve in the tubesheet. The lower joint is qualified for applicable loads without taking credit for the original strength of the tube rolled into the tubesheet. Therefore, the structural integrity of the tube is maintained by the sleeving process.  !

1 The adequacy of the sleeve to withstand cyclic loadings was demonstrated 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.

Based on Regulatory Guide 1.121 guidelines for tube degradation limits, a plugging limit of 40% of the original sleeve wall has been established. Eddy current techniques are available to perform necessary sleeve / tube inspections for defect detection and to verify proper installation of the sleeve. The available techniques are capable of providing 20% defect sensitivity in the required areas of the tube / sleeve pressure boundary. The inspection requirements currently contained in the Technical Specifications do not require any changes.

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l ATTACHMENT 3 Description of Amendment Request and No Significant Hazards Evaluation .

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Attachment 3 to Document C:ntrol Desk Letter

• December 11, 1989 "r '

Page 1 of 3 NO SIGNIFICANT HA7ARDS EVALUATION Description of Amendment Request:

Technical Specification 4.4.5.4.a.10. " Acceptance Criteria-Repaired Tube,"

presently allows steam generator tube repair using the Combustion Engineering i sleeve process. The requested Technical Specification change will allow the use of B&W sleeves for steam generator tube repair. The change requires referencing B&W topical report BAW-2045P, " Recirculating Steam Generator Kinetic Sleeve Qualification for 3/4 Inch 0.0. Tubes," in Technical Specification Section 4.4.5.4.a.10. The topical was submitted to the NRC by a letter dated June 9, 1988, from Mr. James H. Taylor of B&W to Mr. L. C.

Shao of the NRC. A supplement to the original B&W submittal was made on December 12, 1988 which contained answers to NRC questions and transmitted a non-proprietary version of the topical. The currently allowed Combustion Engineering sleeve process will be retained in the Technical Specifications as an option.

The basis for steam generator tube surveillance and repair is to ensure that the structural integrity of the tubes is maintained. The sleeving process is one method of dispositioning a degraded tube. The advantage of sleeving i versus plugging is that the tube is allowed to remain in service. The structural integrity of the tube is maintained with minimal reduction in flow and heat transfer capabilities. Therefore, the repaired tube functions in essentially the same manner as the original tube.

The proposed Technical Specification change is requested to provide SCE&G with another alternative for handling degraded tubes. The B&W sleeve is qualified for two lengths. The shorter sleeve may be utilized in all steam generator tubes and is therefore more versatile than the currently approved Combustion Engineering sleeve.

Also, an editorial numbering / title revision is being made to Section 4.4.5.4.a.6 to more clearly delineate tube versus sleeve plugging or repair limits by adding item 4.4.5.4.a.7 and renumbering subsequent items. 4

, No Significant Hazards Evaluation:

l The purpose of a sleeve is to repair a degraded steam generator tube in order to maintain the function and integrity of the tube. The sleeve functions in essentially the same manner as the original tube. B&W topical report BAW-l 2045P describes in detail the analytical methods used for design and qualification of the B&W sleeve. Table 4.1.1, " Summary of RSG Sleeve Requirements," lists the specifications (mainly ASME Boiler and Pressure Vesselcoderequirements)usedindesign,procurementandqualificationof the sleeve. Table 4.2.2 " Steam Generator Design Transients," summarizes the transients used to establish sleeve loading.

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Attachment 3 to Document Control Desk Letter O December 11, 1989 Page 2 of 3 l o

Pursuant to 10CFR50.91, the following analyses provide a determination that I the proposed change poses no significant hazard as defined by 10CFR50.92.

1) The proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated. ,

The steam generator tube rupture accident is the only previously evaluated accident which may have been significantly affected by this change. However, the steam generator sleeve has been analyzed and tested to the operating and design conditions of the original tube as documented in BAW-2045P. The topical report contains the design verification results from the analysis and confirmatory testing performed on the sleeve. The probability or consequences of previously evaluated accidents is not increased by this change since the sleeve meets the original tube design conditions and the structural integrity of the tube is maintained by the sleeving process.

In addition, the sleeve is less susceptible to the identified stress corrosion failure mechanisms of the original tube because of the use of an improved material Alloy 690 Inconel, and the B&W specified installation process. The continued integrity of the sleeve will be verified by the Technical Specification inspection requirements and the sleeve will oe plugged in accordance with Technical Specification 4.4.5.4.a.7 evaluation and acceptance criteria.

The numbering / title revision is purely editorial in nature and has no technical impact.

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2) The proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.

The purpose of the sleeve is to repair a degraded steam generator tube in order to maintain the function and integrty of the tube. The sleeve functions in essentially the same manner as the original tube and has been analyzed and tested for the steam generator design conditions.

Repairing the tube to a serviceable condition utilizing this sleeving process does not create the possibility of a new or different kind of accident since the sleeve is a passive component with failure mechanisms that should be similar to the original tube.

3) The proposed change does not involve a significant reduction in a margin of safety.

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! The potential for primary to secondary leakage is reduced by the addition of a steam generator tube sleeve. Also, the structural integrity of the tube is maintained by the sleeve and sleeve / tube weld.

l The proposed sleeving technique provides an increased margin of safety over plugging the tube and removing it from service. The effect of sleeve installation on steam generator performance was analyzed for heat

transfer, flow restriction and steam gener4 tion capacity. The results j show that plugging one tube is equivalent to the heat transfer reduction of sleeving 48 tubes, the primary flow reduction of sleeving 20 tubes, j and loss of steam generation capacity of sleeving 40 tubes. Therefore, l

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E 4 Attachment 3 to Document Control Desk Letter

. December 11,.1989

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Page 3 of 3 sleeving provides additional margin when compared to the plugging alternative.

<. Based on the preceding analysis, SCELG has determined that this change does not involve a significant hazards consideration.

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