ML20135A831

Rev 1 to Final Rept, Repair of W Series 44 & 51 SG Tubes Using Leak Tight Sleeves

ML20135A831
Person / Time
Site:	Prairie Island
Issue date:	11/30/1996
From:	ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY, ASEA BROWN BOVERI, INC.
To:
Shared Package
ML19310D717	List: ML20135A819 ML20135A825 ML20135A831
References
CEN-629-NP, CEN-629-NP-R01, CEN-629-NP-R1, NUDOCS 9612040058
Download: ML20135A831 (183)

Text

B.4.12-2 4.12 STEAM GENERATOR TUBE SURVEILIANCE Bases continued plants have demonstrated the capability to reliably detect wastage type defects that have penetrated 20% of the original 0.050-inch wall thickness (Reference 2).

Plugging or sleeving is not required for tubes meeting the F* criteria.

The F* distance will be controlled by a combination of eddy current i

inspection and/or process control.

For a new additional roll expansion, the requirement will be at least 1.2 inches of new hard roll.

This is controlled by the length of the rollers (1.25 inch effective length).

The distance from the original roll transition zone is also controlled by the process in that the lower end of the new roll expansion is located one inch above the original roll expansion.

In the case of the new roll, eddy current examination will confirm there are no indications in the new roll region and that there is a new roll region with well defined upper and lower expansion transitions.

When eddy current examination, alone, must determine the F* distance, such as in the existing hard roll region, or when multiple lengths of j

additional hard rolls have been added, the eddy current uncertainty is j

qualified by testing against known standards. That value is expected to be 0.18 inches.

Therefore, the F* distance measured by eddy current 1

(sum of 1.07 and 0.18) will be conservatively set at 1.3 inches.

When more than one Alternate Repair Criteria are used, the summation of J

1eakage from all tubes left in service by all repair criteria must be less than the allowable leakage for the most limiting of those Alternate Repair Criteria.

Whenever the results of any steam generator tubing in-service inspection fall into Category C-3, these resules will be promptly reported to the Commission prior to resumption of plant operation.

Such cases will be considered by the Commission on a case-by-case basis and may result in a requirement for analysis, laboratory examinations, tests, additional eddy-current inspection, and revision of the Technical Specifications, if necessary.

Degraded steam generator tubes may be repaired by the installation of sleeves which span the section of degraded steam generator tubing. A steam generator tube with a sleeve installed meets the structural requirements of tubes which are not degraded.

The following sleeve designs have been found acceptable by the NRC Staff:

a.

Westinghouse Mechanical Sleeves (WCAP 10757) b.

Westinghouse Brazed Sleeves (WCAP-10820) c.

Combustion Engineering Leak Tight Sleeves (CEN-294-P, for sleeves installed prior to January 1, 1997) d.

Combustion Engineering Leak Tight Sleeves (CEN-629-P, for sleeves installed after January 1, 1997)

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NON-PROPRIETARY CEN-629-NP Revision 01 4

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COMBUSTION ENGINEERING, INC.

November,1996 4

l Repair of i

Westinghouse Series 44 and 51 i

Steam Generator Tubes i

i Using I2ak Tight Siseves t

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FINAL REPORT Combustion Engineering, Inc.

Nuclear Operations Windsor, Connecticut 9612040058 961127 PDR ADOCK 0500 292 P

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ABSTRACT j

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A technique is presented for repairing degraded steam generator tubes in pressurized water reactor Nuclear Steam Supply Systems (NSSS). The technique described alleviates the need

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for plugging steam generator tubes which have become corroded or are otherwise considered to have lost structural capability. The technique consists of installing a thermally treated Alloy 690 sleeve which spans the section or sections of the original steam generator tube which requires repair. The sleeve is welded to the tube near each end of the sleeve for repairs at the tube support plates or welded at the upper end and lower end or welded at the upper end and 4

j hard rolled at the lower end for repairs to the steam generator tube in the tube sheet region.

This report details analyses and testing performed to verify the adequacy of repair sleeves for installation in a 7/8 inch O.D. nuclear steam generator tube. These verifications show tube l

sleeving to be an acceptable repair technique.

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TABLE OF CONTENTS Section Iitle Eage

1.0 INTRODUCTION

1-1 1.1 PURPOSE l-1

1.2 BACKGROUND

l-2 1.3 ACRONYMS 1-2 i

2.0

SUMMARY

AND CONCLUSIONS 2-1 3.0 ACCEPTANCE CRITERIA 3-1

' 4.0 DESIGN DESCRIPTION OF SLEEVES AND INSTALLATION EQUIPMENT 4-1 4.1 SLEEVE DESIGN DESCRIPTION 4-1 4.2 SLEEVE MATERIAL SELECTION 4-1 4.3 SLEEVE-TUBE ASSEMBLY 4-2 4.4 PLUGGING OF A DEFECTIVE SLEEVED TUBE 4-4 4.5 SLEEVE INSTALLATION EQUIPMENT 4-4 i

4.5.1 Bemote Controlled Manioulator 4-4 4.5.2 Tool Delivery Eauioment 4-5 4.5.3 Tube Brushine - Cleanine Eauioment 4-6 4.5.4 Tube Size Rollinn Eauioment 4-6 4.5.5 Sleeve Exoansion Eauinment 4-6 4.5.6 Sleeve Weldine Eauipment 4-7 4.5.7 Nondestructive Examination 4-7 ii s: -

TABLE OF CONTENTS (Continued)

Section Title Page 4.5.8 Post-Weld Heat Treatment Eauinment 4-8 4.5.9 Sleeve Rolline Eauinment 4-8 4.5.10 Perinheral Sleeve Straichtening/ Installation Eauipment 4-9 4.6 ALARA CONSIDERATIONS 49

4.7 REFERENCES

TO SECTION 4.0 4-10 5.0 SLEEVE EXAMINATION PROGRAM 5-1 5.I ULTRASONIC INSPECTION 5-2 5.1.1 Summary and Conclusions 5-2 5.1.2 Ultrasonic Evaluation 5-3 5.1.3 Test Eauinment 5-3 5.2 EDDY CURRENT INSPECTION 5-4 5.2.1

Background

5-4 5.2.2 Plus Point Probe Oualification Study 5-5 5.3 VISUAL INSPECTION 5-5 5.3.1 Summary and Conclusions 5-6 5.3.2 Cleanine Inspection 5-7 5.3.3 Weld Examination 5-7

5.4 REFERENCES

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l TABLE OF CONTENTS (Continued) 4 Section Iillt East I

6.0 SLEEVE-TUBE CORROSION 'IEST PROGRAM 6-1 i

6.1

SUMMARY

AND CONCLUSIONS 6-1 1

6.2 TEST DESCRIPTION AND RESULTS 6-1 j

6.2.1 Primary Side tests 6-1 i

6.2.1.1 Pure Water Stress Corrosion Cracking Tests 6-3 j

.6.2.1.2 Above the Tubesheet (ATS) Weld Capsule Tests 6-3 6.2.1.3 TSP Sleeve Weld Capsule Tests 6-4 I

6.2.1.4 Summary-Primary Coolant Corrosion Performance 6-5 6.2.2 Secondary Side Tests

'6-6 6.2.2.1 Modified Huey Tests 6-6 6.2.2.2 Capsule Tests 6-7 6.2.2.3-Sodium Hydroxide Fault Autoclave Tests 6-8 6.2.2.4 Summary 6-9

6.3 REFERENCES

FOR SECTION 6.0 6-10 iV r

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TABLE OF CONTENTS (Continued)

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7.0 MECHANICAL TESTS OF SLEEVED STEAM GENERATOR 7-1 TUBES 7.1

SUMMARY

AND CONCLUSIONS 7-1 7.2 CONDITIONS TESTED 7-1 7.3 WELDED SLEEVE TEST PARAMETERS AND RESULTS 7-1 f

7.3.1 Axial Pull Tests 7-1 t

7.3.2 Collaose Testing 7-2 7.3.3 Burst Testine 7-3 7.3.4 Load Cycline Tests 7-3 8.0 STRUCTURAL ANALYSIS OF SLEEVE-TUBE ASSEMBLY 8-1 4

8.1

SUMMARY

AND CONCLUSIONS 8-1 4

8.1.1 Desien Sizing 8-1 8.1.2 Detailed Analysis Summary 8-1 8.2 LOADINGS CONSIDERED 8-7 8.2.1 Unoer Tube Weld Pull-Out Load 8-7 8.2.2 Lower Sleeve Rolled Section Push-Out Load 8-7 1

8.2.3 Weld Fatigue 8-8 1

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TABLE OF CONTENTS (continued)

SECTION TITLE PAGE 8.3 EVALUATION FOR ALLOWABLE SLEEVE WALL 8-8 DEGRADATION USING REGULATORY GUIDE 1.121 8.3.1 Normal Operation Safety Margins 8-8 8.3.2 Postulated Pine Ruoture Accidents 8-9 8.3.3 Average Minimum Weld Height Reauirements 8-11 l

8.4 EFFECTS OF TUBE LOCK-UP ON SLEEVE LOADING 8-12 8.4.1 Sleeved Tube in Operatine Steam Generator. Free at Tube Suocort 8-12 8.4.2 Sleeved Tube in " Worst" Case Envelooment. Free at Suonort Plate 8-13 8.4.3 Sleeved Tube in Ooeratine Steam Generator.

8-13 Lock-un at First Tube Sunoort 8.4.4 Sleeved Tube in " Worst" Case Envelooment.

8-14 lock-un at First Suonort Plate 8.4.5 Effect of Tube Prestress Prior to Sleeving 8-21 8.4.6 l_ower Sleeve Rolled or Weld Section Pushout 8-21 Due to Restrained Thermal Exoansion 8.5 SLEEVED TUBE VIBRATION CONSIDERATIONS 8-22 8.5.1 Effects of increased Stiffness 8-22 8.5.2 Effect of Severed Tube 8-22 8.6 STRUCTURAL ANALYSIS FOR NORMAL OPERATION 8-24 8.6.1 Fatigue Evaluation of Uoner Sleeve / Tube Weld 8-24 8.6.2 Fatigue Evaluation of Lower Sleeve Rolled Section 8-25 vi

TABLE OF CONTENTS (Continued)

SECTION TITLE PAGE i

8.6.3 Fatigue Evaluation of Irwer Stub Weld 8-28 8.6.4 Fatigue Evaluation of Sleeved Tube Plue Weld 8-29 1

8.7 REFERENCES

FOR SECTION 8.0 8-32 8A FATIGUE EVALUATION OF UPPER TUBE / SLEEVE WELD 8A-1 8B FATIGUE EVALUATION OF LOWER STUB WELD 88-1 8C FATIGUE EVALUATION OF SLEEVED TUBE PLUG WELD 8C-1 8D SLEEVE HISTORY DATA 8D-1 9.0 SLEEVE INSTALLATION VERIFICATION 9-1 9.1

SUMMARY

AND CONCLUSIONS 9-1 9.2 SLEEVE-TUBE INSTALLATION SEQUENCE 9-1 9.2.1 Full Deoth Tubesheet Sleeve With Welded Imwer Joint 9-1 l

9.2.2 Full Deoth Tubesheet Sleeve With Rolled Lower Joint 9-1 9.2.3 Tube Suonort Sleeve 9-2 9.3 WELD INTEGRITY 9-2 9.3.1 Cleaning Oualification 9-3 9.3.2 Exnansion Oualification 9-3 9.3.3 Weld Oualification 9-3 9.3.4 Ultrasonic Testing Oualification 9-4 9.3.5 Post Weld Heat Treat Oualification 9-4 9.3.6 Summarv 9-6 vii

4 TABLE OF CONTENTS (Continued)

SECTION TITLE PAGE 9.4 ROLLED JOINT INTEGRITY 9 9.5 COMMERCIAL SLEEVE INSTALLATION 9-7

9.6 REFERENCES

FOR SECTION 9.0 9-7 10.0 EFFECT OF SLEEVING ON OPERATION 10-1 l

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't LIST OF TABLES 4

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TABLE NO.

TABLE JMfg l-1 ACRONYMS USED IN REPORT l-3 2-1 INSTALLATIONS OF ABB-CENO WELDED SLEEVE 2-3 1

3-1 REPAIR SLEEVING CRITERIA 3-2 i

j 5-1 ACRONYMS USED IN ET ANALYSIS 5-8 f

6-1 STEAM GENERATOR TUBE SLEEVE CORROSION TESTS 6-2 i

6-2 SLEEVE / TUBE CAPSULE SCC TESTS 6-4 6-3 SECONDARY SIDE STEAM GENERATOR TUBE SLEEVE 6-8 CAPSULE TESTS j

7-1 SLEEVE-TUBE ASSEMBLY MECHANICALTESTING 7-5

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RESULTS i

8-1

SUMMARY

OF SLEEVE AND WELD ANALYSIS RESULTS 8-4 8-2

SUMMARY

OF LOWER JOINT (WELDED AND ROLLED)

DESIGN, ANALYSIS,AND TEST RESULTS 8-6 8-3A 30 INCH SLEEVE AX1AL MEMBER PHYSICAL PROPERTIES j

FOR OPERATING STEAM GENERATORS 8-15

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8-3B 30 INCH SLEEVE AXIAL MEMBER PHYSICAL PROPERTIES FOR " WORST" CASE ENVELOPMENT 8-16 e

i 8-4A AXIAL LOADS IN SLEEVE WITH TUBE NOT LOCKED INTO TUBE SUPPORT FOR OPERATING STEAM GENERATORS 8-17 i

8-4B AXIAL LOADS IN SLEEVE WITH TUBE N_DT LOCKED j

INTO TUBE SUPPORT FOR " WORST" CASE ENVELOPMENT 8-18 4

8-5A AXIAL LOADS IN SLEEVE WITH TUBE LOCKED INTO TUBE SUPPORT FOR OPERATING STEAM GENERATORS 8-19 8-5B AXIAL LOADS IN SLEEVE WITH TUBE LOCKED INTO l

TUBE SUPPORT FOR " WORST" CASE ENVELOPMENT 8-20 i

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LIST OF TABLES TABLE NO.

TABLE EAgj 8-6 UPPER SLEEVE WELD-TRANSIENTS CONSIDERED 8-26 i

8-7 LOWER SLEEVE SECTION-TRANSIENTS CONSIDERED 8-27 8-8 SLEEVED TUBE PLUG WELD-TRANSIENTS CONSIDERED 8-31 8A-1A STRESS RESULTS,100% STEADY STATE 8A-4 8A-1B STRESS RESULTS,0% STEADY STATE 8A-5 8A-lC STRESS RESULTS, REACTOR TRIP 8A-6 8A-2 FATIGUE EVALUATION 8A-7 8A-3A STRESS RESULTS,100% STEADY STATE (0.020" Weld) 8A-9 8A-3B STRESS RESULTS,0% STEADY STATE (0.020" Weld) 8A-10 8A-3C STRESS RESULTS, REACTOR TRIP (0.020" Weld)

- 8A-ll 8A-4A RANGE OF STRESS AT WORST LOCATIONS (0.020" Weld) 8A-12 8A-4B FATIGUE EVALUATION AT WORST LOCATIONS (0.020" Weld) 8A-13

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8B-1 STRESS RESULTS 8B-7 88-2 FATIGUE EVALUATION 8B-7 8C-1 STRESS RESULTS 8C-8 8C-2 FATIGUE EVALUATION 8C-10 9-1 0.875 0.D. SLEEVED TUBE PWHT DATA 9-9 9-2 0.750" O.D. SLEEVED TUBE PWHT DATA, TUBES LOCKED AT ALL SUPPORTS 9-10 9-3 ABB CENO S/G SLEEVE OPERATING HISTORY 9-11 10-1 HYDRAULIC EQUIVALENCE RATIOS 10-2 X

LIST OF FIGURES FIGURE NO.

TITLE PAGE 4-1A FULL DEPTH TUBESHEET SLEEVE FOR 4-11 A WELDED LOWER JOINT 4-1B FULL DEPTH TUBESIEET SLEEVE FOR 4-12 A ROLLED LOWER JOINT j

3 4-lC FULL DEPTH PERIPHERAL TUBSHEET SLEEVE 4-12A 4

4-2 TUBE SUPPORT SLEEVE 4-13 a

4-3 A FULL DEPTH TUBESHEET SLEEVE 4-14 A WELDED LOWER JOINT INSTALLATION 4-3B FULL DEPTH TUBESHEET SLEEVE 4-15 A ROLLED LOWER JOINT INSTALLATION 4-4 TUBE SUPPORT SLEEVE INSTALLATION 4-16 4-5 hfANIPULATOR AND TOOL DELIVERY SYSTEhi 4-17 4-6 TOOL DELIVERY EQUIPhENT 4-18 47 TUBE CLEANING EQUIPhENT 4-19 4-8 SLEEVE EXPANSION EQUIPhENT 4-20 4-9 SLEEVE WELDING HEAD ASSEhiBLY 4-21 4-10 SLEEVE WELDING HEAD POWER SUPPLY UNIT 4-22 4-11 ULTRASONIC TEST EQUIPhENT 4-23 4-12 VISUAL TEST EQUIPhENT 4-24 4-13 POST WELD HEAT TREAT EQUIPhENT 4-25 4-14 SLEEVE ROLLING EQUIPhfENT'- STRAIGHT 4-26 4-15 SLEEVE ROLLING EQUIPhENT - CURVED 4-27 Xi

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LIST OF FIGURES (Continued)

FIGURE NO.

TITLE PAGE 4-16 PERIPHERAL SLEEVE INSERTION EQUIPhENT 4-28 5-1 NDE PROCESS FLOW CHART 5-9 5-2 ET PROCESS FLOW CHART 5-10 5-3 UT B SCAN-ACCEPTABLE 5-11 5-4 UT B SCAN - REJECTABLE 5-12 5-5 UT PROBE 5-13 5-6 UT CALIBRATION STANDARD 5-14 61 PURE WATER CORROSION TEST SPECIhEN 6-11 62 ATS WELD CAPSULE TEST SPECIMEN 6-12 6-3 TSP WELD CAPSULE TEST SPECIMEN 6-13 6-4 CAUSTIC CORROSION AUTOCLAVE TEST SPECIhEN 6-14 l

8-1 WELDED SLEEVE / TUBE ASSEMBLY 8-34 8-2 SYSTEM SCHEMATIC FOR OPERATING STEAM GENERATOR 8-35 8-3 SYSTEM SCHEMATIC FOR " WORST" CASE ENVELOPMENT 8-36 8-4 STIFFNESS MODEL OF SLEEVE AND LOWER TUBE 8-37 8-5 STIFFNESS MODEL OF UPPER TUBE AND SURROUNDING TUBE 8-38 8-6 FINITE ELEhENT MODEL OF UPPER TUBE WELD 8-39 xii

l LIST OF FIGURES (Continued) i i

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TITLE PAGE l

l 8-7 FINITE ELEMENT MODEL OF LOWER STUB WELD 8-40 l

8-8 FINITE ELEMENT MODEL OF SLEEVED TUBE PLUG WELD 8-41 l

8-9 TUBESHEET PERFORATED PLATE LIGAMENT STRESSES 8-42 l

f 8A 1 NODE AND STRESS CUT IDENTIFICATION 8A-3 l

8A-2 NODE AND STRESS CUT IDENTIFICATION FOR 20 MIL WELD 8A-8 l

8B-1 LOWER STUB WELD MODEL (HOT STANDBY) 88-3 8B-2 LOWER STUB WELD MODEL (FULL POWER & THERMAL LOAD) 88-4 8B-3 LOWER STUB WELD MODEL (REACT. TRIP & THERM AL LOAD) 8B-5 8B-4 LOWER STUB WELD MODEL (SECONDARY LEAK TEST) 8B-6 i

8C-1 SLEEVED TUBE PLUG MODEL (FULL POWER) 8C-5 8C-2 SLEEVED TUBE PLUG MODEL (SECONDARY LEAK TEST) 8C-6 8C-3 SLEEVED TUBE PLUG MODEL (DETAILED VIEW) 8C-7 9-1 POST HEAT TREAT-BRUSHED SECTION 9-12 9-2 0.875 0.D. LOCKED TUBE TEST 9-13 l

9-3 0.875 0.D. LOCKED TUBE TEST, TEMPERATURE AND AXIAL LOAD PROFILE 9-14 9-4 0.750 0.D. LOCKED TUBE MOCKUP 9-15 9-5 0.750 O. D. TYPICAL TEMPERATURE PROFILES 9-16 l

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LIST OF APPENDICES l

1 APPENDIX NO.

NO.OF PAGES l

3 A

PROCESS AND WELD OPERATOR OUALIFICATION A-1 l

A.1 SLEEVE WELDING AND SLEEVE WELDER A-1 QUALIFICATION l

A.2 REFERENCES TO APPENDIX A A-1 i

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INTRODUCTION 1

l 1.1 PURPOSE The purpose of this report is to provide information sufficient to support a technical I

specification change allowing installation of repair sleeves in Westinghouse designed Series l

44 and 51 steam generators. This report demonstrates that reactor operation with sleeves j

installed in the steam generator tubes will not increase the probability or consequence of a postulated accident condition previously evaluated. Also it will not create the possibility of a new or different kind of accident and will not reduce the existing margin of safety.

ABB Combustion Engineering (ABB-CE) provides three types orleak tight sleeves for repair of 7/8 inch 0.D. steam generator tubes with partial depth rolled tubesheet joints or j

full depth rolled or expanded hbesheetjoints. The first two types span the parent steam generator tube within the tubesheet. One type of tubesheet sleeve is welded to the tube near both the upper and lower end of the sleeve. The second type of tubesheet sleeve is welded near the upper end and hard rolled into the tube within the steam generator l

tubesheet. A variation on these designs involves the use of a pre-curved sleeve to install a tubesheet sleeve at the periphery of the tube bundle. The steam generator tube with the installed sleeve meets the stmetural requirements of tubes which are not degraded.

l The third type of sleeve spans degraded areas of the steam generator tube at a tube support or in a free span section of tube. This leak tight sleeve is welded to the steam generator tube near each end of the sleeve. The steam generator tube with the installed welded sleeve meets the structural requirements of tubes which are not degraded.

Design criteria for all types of sleeves were prepared to ensure that all design and licensing requirements are considered. Extensive analyses and testing have been performed on the l

sleeve and sleeve to tubejoints to demonstrate that the design criter:a are met.

The effect of sleeve installation on steam generator heat removal capability and system flow rate are discussed in this report. Heat removal capability and system flow rate was considered for installation of one to three sleeves in a steam generator tube.

Plugs will be installed if sleeve installation is not successful or if there is unacceptable degradation of a sleeve or sleeved steam generator tube. Weled sleeve plugs or standard steam generator tube plugs may be used to take a sleeved tube cut of service.

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1.2 BACKGROUND

The operation of Pressurized Water Reactor (PWR) steam generators has in some 1

instances, resulted in localized corrosive attack on the inside (primary side) or outside 3

j (secondary side) of the steam generator tubing. This corrosive attack results in a reduction in steam generator tube wall thickness. Steam generator tubing has been i

designed with considerable margin between the actual wall thickness and the wall thickness required to meet structural requirements. Thus it has not been necessary to

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take corrective action unless structural limits were being approached.

Historically, the corrective action taken when steam generator tube wall degradation has been severe has been to install plugs at the inlet and outlet of the steam generator tube 4

l when the reduction in wal! thickness reached a calculated value referred to as a plugging j

criteria. Eddy current (ET) examination has been used to measure steam generator tubing degradation and the tube plugging criteria accounts for ET measurement i

uncertainty.

Installation of steam generator tube plugs removes the heat transfer surface of the i

plugged tube from service and leads to a reduction in the primary coolant flow rate i

available for core cooling. Installation of welded and/or welded and hard rolled steam j

generator sleeves does not significantly affect the heat transfer removal capability of the j

tube being sleeved and a large number of sleeves can be installed without significantly l

affecting primary flow rate 1.3 ACRONYMS Table 1-1 (along with Table 5-1) contains a list of the acronyms used throughout this J

report.

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TABLE 1-1 ACRONYMS USED IN REPOkT i

+ POINT: + Point

• ATS: Above Tube Sheet f

EFPH: Effective Full Power Hours EPPY: Effective Full Power Years I

ET: Eddy Current Testing ETZ: Expansion / Roll Transition Zone EW: Edge Weld 1

i FDTS: Full Depth Tubesheet I

LOF: Lack of Fusion PWHT: Post Weld Heat Treatment TS: Tube Support UT: Ultrasonic Testing VT: Visual Testing i

WTS: Welded Tubesheet 1

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SUMMARY

AND CONCLUSIONS J

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l The sleeve dimensions, materials and joints were designed to the applicable ASME Boiler and Pressure Vessel Code. An extensive analysis and test program was undertaken to prove the adequacy of both the welded and welded-hard rolled sleeve.

This program determined the effect of normal operating and postulated accident conditions on the sleeve-tube assembly, as well as the adequacy of the assembly to i

perform its intended function. The proposed sleeving provides for a substitution in kind i

for a portion of a steam generator tube. The proposed change has no significant effect on the configuration of the plant, and the change does not affect the way in which the plant is operated. Design criteria were established prior to performing the analysis and.

test program which, if met, would prove that these sleeve types are an acceptable repair technique. These criteria conformed to the stress limits and margins of safety of Section Ill of the ASME B&PV Code. The safety factors of 3 for normal operating conditions and 1.5 for accident conditions were applied. Based upon the results of the analytical and test programs described in this report these sleeve types fulfill their intended function as leak tight structural members and meet or exceed all the established design criteria.

Evaluation of the sleeved tubes indicates no detrimental effects on the sleeve-tube assembly resulting from reactor system flow, coolant chemistries, or thermal and pressure conditions. Structural analyses of the sleeve-tube assembly, using the demonstrated margins of safety, have established its integrity under normal and accident conditions. The structural analyses have been performed for sleeves which span the tube to a maximum length of [

] inches, sleeves which span a tube support or free span length of tube with a length of [

] inches and a combination of the sleeve types. The i

structural analyses performed are applicable to shorter tubesheet and tube tupport sleeves. The analyses for the different sleeve types and lengths are given in Section 8.

I Mechanical testing using ASME code stress allowables has been performed to support the analyses. Corrosion tests of typical sleeve-tube assemblies have been completed and reveal no evidence of sleeve or tube corrosion considered detrimental under anticipated service conditions.

Based upon the testing and analyses performed, the proposed sleeves do not result in a significant increase in the probability of occurrence or consequence of an accident previously evaluated, create the possibility for a new or different kind of accident, or result in a significant reduction in a margin of safety.

Welding development has been performed on clean tubing, dirty tubing which has been taken from pot boiler tests and contaminated tubing taken from a number of steam generators. ABB-CE installed their first welded sleeves in a demonstration program at 2-1

Ringhals Unit 2 in May 1984. ABB-CE's sleeving history is shown in Table 2-1. The success rate for all installed sleeves is 98%. Since 1985, no sleeve which has been accepted based on NDE has been removed from service due to service induced degradation.

If a steam generator tube which has been sleeved is found to require plugging to remove it from service a standard steam generator tube plug or a welded sleeve plug can be installed. An analysis is performed for the welded sleeve plug. No discussion or evaluation of the standard tube plug is provided as part of this document.

In conclusion, steam generator tube repair by installation of any of the three types of sleeves described herein is established as an acceptable method.

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TABLE 2-1 INSTALLATIONS OF ABB-CENO WELDED SLEEVE INSTALLED i

4 PLANT DATE QUANTITY TYPE

• KRSKO 6/%

273 TS 4

188 ETZ Byron 1 4/%

3527 ETZ-Prairie Island 1 2/%

253 WTS ANO2 10/95 711 ETZ Zion 1 10/95 911 WTS I

Zion 2 1/95 162 WTS j

KRSKO1 6/93 160 ETZ i

14 TS Ginna 4/93 51 WTS Zion 2 12/92 172 WTS 3

f Frairie Island 1 i1/92 158 WTS Ginna 4/92 175 WTS 63 Curved WTS Zion 1 4/92 124 WTS i

Kewaunee 3/92 16 Curved WTS Ringhals 3 7/91 46 ETZ j

22 TS i

Ginna 4/90 192 WTS 48 Curved WTS Zion 2 4/90 82 WTS Prairie Island 1 1/90 63 WTS Zica 1 9/89 445 WTS Ginna 4/89 395 WTS 107 Curved WTS Prairie Island 1 9/88 74 WTS i

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TABLE 2-1 (cont.)

1 JNSTALLATIONS OF ABB-CENO WELDED SLEEVE INSTALLED PLANT DATE QUANTITY TYPE Ringhals 2 5/87 571 WTS Prairie Island 1 4/87 27 WTS I

Ginna 2/87 105 WTS Zion 1 10/86 128 WTS Ringhals 2 5/86 599 WTS i

Ginna 2/86 36 WTS Ringhals 2 5/85 59 WTS Ringhals 2 5/84 18 WrS

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• Straight sleeves unless otherwise noted l

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ACCEPTANCE CRITERIA The objectives of installing sleeves in steam generator tubes are twofold. The sleeve must maintain structural integrity of the steam generator tube during normal operating and postulated accident conditions. Additionally, the sleeve must prevent leakage in the event of a through-wall defect in the steam generator tube. Numerous tests and analyses were performed to demonstrate the capability of the sleeves to perform these functions under normal operating and postulated accident conditions. Design and operating conditions used to bound the applicable steam generators are def~med as:

Primary Side:

594*F (operating) 2235 psig (openting)

(Hot Side) 650*F (design) 2500 psig (design)

Secondary Side:

506*F (100% load) 690* psig (100% load)

S50*F (design) 1085 psig (design)

Table 3-1 provides a summary of the criteria established for sleeving in order to demonstrate the acceptability of the sleeving techniques. Justification for each of the criterion is provided. Results indicating the minimum level with which the sleeves sur-passed the criteria are tabulated. The section of this report describing tests or analyses which verify the. characteristics for a particular criterion is referenced in the table.

• This value was conservatively chosen due to potential decrease in secondary side pressure.

i 3-1

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TABLE 3-1 REPAIR SLEEVING CRITERI A Criterion Justification Results Section 3

j 1.

Sleeve is leak tight leakage between 4.0 prinary and secondary side is prevented when steam generator tube is l

breached.

l 2.

Sleeve-tube assembly Sleeve tube assembly 8.0 functional integrity must meets applicable ASME j

be maintained for normal Code requirements.

operating and accident conditions.

3.

Axial load cycle 200 Bounds thermal cycle 7.3 pounds to 1700 pounds loading from normal j

for 1000 cycles, 200 operating and transient pounds to 2550 pounds cycling.

j for 1000 cycles without weld failure 4

4.

Pressurization of annulus Prevention of sleeve 7.3 l

between sleeve and tube failure for through wall does not collapse sleeve at defect in tube wall.

1500 psig.

l 5.

Pressurize sleeve to 4800 Factor of safety of three 8.3 l

psig without bursting.

(3) for normal operating i

(1600 psig delta pressure) conditions.

}

6.

Exposure of sleeve-tube Sleeve-tube assembly 6.0 i

sleeve assembly to required to function various primary and under coolant j

secondary chemistries chemistries without loss of functional i

integrity.

7.

Non-destructive Periodic examination of 5.0 i

examination of tube and tubes and sleeves sleeve to levels of required to verify 4

detectability required to structural adequacy show structural adequacy 8.

Welded sleeve installation Sleeve repair should not 10.0 4

does not significantly reduce power removal affect system flow rate or capability of reactor or j

heat transfer capability of steam generator below the steam generator, rated value.

3-2 L

4.

DESIGN DESCRIPTION OF SLEEVES AND INSTALLATION EQUIPMENT 4.1 SLEEVE DESIGN DESCRIPTION There are three (3) types of sleeves which may be installed in various combinations within a steam generator tube. These sleeves are shown in Figures 4-1, and 4-2. Each sleeve type has a nominal outside diameter of [

] inches and a nominal wall thickness of

[

] inches. The sleeve material is thermally treated Alloy 690. Each of the sleeve types includes a chamfer at both ends to prevent hang-up of equipment used to install the sleeve and to facilitate the inspection of the steam generator tube and sleeve.

The first type of sleeve, shown in Figure 4-1 A, spans the expansion transition zone and the full length of the tube within the tubesheet. This Full Depth Tubesheet (FDTS) sleeve with a welded lower joint is up to [

] inches long and chamfered at the upper end to prevent hang-up with equipment which is used to install or inspect the sleeve (or steam generator tube). [

]

The second type of sleeve, shown in Figure 4-1B, also spans the full length of the tube within the tubesheet. This Full Depth Tubesheet (FDTS) sleeve with a rolled lower joint is up to [

] inches long and includes [

]

A variation of these sleeves, the [

] sleeve is shown in Figure 4-1C.

This sleeve is preformed to a radius of curvature of approximately [

] inches over the majority of its length as part of the manufacturing process. This curvature allows the sleeve to be installed in peripheral tube locations where the primary head to tubesheet clearance would not permit the installation of a straight FDTS sleeve. [

]

The fourth type of sleeve, shown in Figure 4-2, spans a tube support. This Tube Support (TS) sleeve is [ ] inches in length. The sleeve spans a tube support elevation or can be used on a free span section of the tube. One or two TS sleeves may be used in a tube and may be used in a tube containing a FDTS sleeve.

4.2 SLEEVE MATERIAL SELECTION The thermally treated Alloy 690 tubing, from which the sleeves are fabricated, is procured to the requirements of the ASME Boiler and Pressure Vessel Code,Section II SB-163, Code Case N-20. Additional requirements are applied including a limit on Carbon conte 4-1

of 0.015 - 0.025% and a minimum annealing temperature of 1940*F (1060 C). The thermal treatment is specified at 1300*F (704*C) to impart greater corrosion resistance in potential faulted secondary side environments. The enhanced corrosion resistance is achieved in the thermal treatment by insuring the presence of grain boundary carbides and by reducing the residual stress level in the tubing.

During sleeve fabrication for a peripheral sleeve, an intermediate stress relief anneal is employed to reduce residual stresses induced during forming of the sleeve to the curved shape. This stress relief anneal is carried out at 1300*F for two hours. Upon stress relieving, the sleeve is ready for insertion and welding.

The mechanical properties of the sleeve material, particularly in the weld areas, are not affected by the forming or stress relieving since the top and bottom portions of the sleeve are not curved or restraightened. A four inch length at the top and two inch length at the bottom of the sleeve remains undisturbed with respect to bending and constitutes "as received" tubing stock. The minor exception to this statement is the additional two hours at 1300*F the ends are exposed to in sleeve stress relieving of the formed or curved configuration. This constitutes a time extension of the thermal treatment time employed at the tube mill which can be viewed as a positive exposure.

Sleeve expansion, flaring and welding takes place in sleeve ends that have not been curved and with tooling and processes duplicating those used for straight sleeve installation.

The principal selection criterion for the sleeve material was its resistance to stress corrosion cracking (SCC) in primary and caustic faulted secondary PWR environments.

j ABB-CE's justification for selection of this material and condition is based on the data contained in Reference 4.7.1.

1 l

4.3 SLEEVE-TUBE ASSEMBLY The installed sleeves are shown in Figures 4-3A,4-3B, and 4-4. The depth tubesheet (FDTS) sleeves span the tube in the expanded region, the creviced tubesheet region (where applicable), and the lower portion of the tube just above the secondary face of the tubesheet. If defects exist at a tube support as well as within the tubesheet, a FDTS sleeve and a Tube Support (TS) sleeve may be used.

The welded FDTS sleeve, shown in Figure 4-3A, is [

] inches in length or shorter. The bottom of the [

] inch sleeve is flush with the bottom of the steam generator tube and extends approximately [ ] inches above the secondary face. [

]

4-2

4 i

i L

j' The lower end of the sleeve is tapered prior to welding. The taper serves to provide tight contact with the tube for welding, i

l A weld is made at the upper end of the sleeve to join it to the steam generator tube.

Upper weld penetration into the steam generator tube is limited to less than 100% of the wall thickness with a minimum average weld height of 0.020 inches at the sleeve-tube J

interface. The upper sleeve to steam generator tube weld is centered approximately 1-1/2 inches below the end of the sleeve. If this upper weld is defective, it can be repaired by 3

j gas tungsten arc remelting of the original weld using the same welding procedure i

parameters as were employed for the original weld. The lower weld is a full penetration edge weld at the end of the sleeve and tube. If the lower weld is defective, it can also be repair we'ded.

The wedded and rolled FDTS sleeve is also [

] in length or shorter. The bottom of this sleeve is flush with the tube end for partial depth rolled tubesheet joints. The bottom of this sleeve is located approximately at the tubesheet neutral axis for full depth rolled or expanded tubesheet joints. The upper end of this [ ] inch FDTS sleeve is located [ ]

inches above the tube sheet upper face. [

]

The weld process, repair weld process and welding operators have been qualified for making upper and lower welds. The weld qualification documents are given in Appendix A.

The lower end of the welded and rolled FDTS sleeve is rolled into the tube within the tubesheet. The roll is controlled to provide a leak tight structural joint. A roll which does not meet the roll acceptance criteria can be repaired by rerolling at the same location.

The TS sleeve shown in Figure 4-4 is [ ] inches in length. It is approximately centered at a tube support plate. [

l

]

Weld penetration into the steam generator tube is limited to less than 100% of the wall thickness and the minimum average wt height is 0.020 inches at the sleeve to tube interface. The upper and lower welds are centered approximately 1 1/4 inches from the ends of the sleeve. If the weld is defective it can be repaired by gas tungsten are remelting of the original weld using the same welding procedure parameters employed for the original weld.

When it is considered to be of benefit (typically for units with 3/4" O.D. steam Eenerator tubes that are operating at temperatures above 600 F), a post weld heat treatment of the 4-3

sleeve weld will be added to the sleeve installation process. After the sleeve has been welded into the tube, the weld joint is heated in the range of [

] As described in Reference 4.7.5, this time and temperature combination is sufficient to reduce the level of residual stress in Alloy 600 while minimizing detrimental effects such as grain growth or sensitization. This treatment is similar to that utilized in some operating units to heat treat the tight radius U-bends.

Based on plant specific operaSg conditions (temperatures, pressures, chemistry, etc) and steam generator tube degradation history, post weld heat treatment may not be of any significant benefit. Five nca-post weld heat treated sleeves installed at Ringhals II (Westinghouse 51 series steam generator) in 1985 and 1986 were removed in January 1990 and extensively examined. These sleeves (and the parent tubing at the sleeve / tube joint) which had accumulated up to 22,000 Effective Full Power Hours (EFPH) of service, showed no field service degradation.

Qualification of the sleev welding process is in accordance with the procedure described in Appendix A.

4.4 PLUGGING OF A DEFECTIVE SLEEVED TUBE If a sleeve or sleeved tube is found to have an unrepairable defect, the tube can be taken out of service with welded sleeve plugs or standard steam generator tube plugs installed at both ends of the tube using approved methods. The Regulatory Guide 1.121 analysis for the sleeve is included in Section 8.3.

4.5 SLEEVE INSTALLATION PROCESS AND EQUIPMENT The equipment used for remote installation of sleeves in a steam generator is made up of the following basic systems. These systems are:

1. Remote Controlled Manipulator 4-4

. - -. - -......~ -.

T i

1 I

4 4

These systems, when used together, allow installation of the sleeves without personnel

)

(

entering the steam generator. In this way, personnel exposure to radiation is held to a minimum.

j The tooling and methods described in the following sections represent the present technology for leak tight sleeve installation. As technological advances are made in sleeve installation, the new tooling and/or processes may be utilized after they have been laboratory-verified to provide improved sleeve installation methods.

4.5.1 Remote Controlled Maninnlatnr The remote controlled manipulator (Figure 4-5) serves as a transport vehicle for inspection or repair equipment inside a steam generator primary head.

The manipulator consists of two major components; the manipulator leg and manipulator arm. The manipulator leg is installed between the tube sheet and bottom of the primary

{

head and provides axial (vertical) movement of the arm. The manipulator arm is divided into the head arm, probe arm and a swivel arm. Each arm is moved independently with encoder position controlled electric motors. The swivel arm allows motion for tool alignment in both square pitch and triangular pitch tube arrays. Computer control of the manipulator allows the operator to move sleeving tools from outside the manway and accurately position them against the tube sheet.

4.5.2 Tool Deliverv Eauinmeu!

The purpose of the tool delivery equipment is to support and vertically position the various tools required for the sleeving operation and to provide controlled rotation to some of the tools. Two different delivery systems may be used for the tool delivery. [

t l

]

The probe driver is a modified Zetec probe pusher or equivalent unit located outside the i

manway of the steam generator. A flexible conduit extending from the probe driver to an adaptor on the manipulator arm provides the guide path for the tools. The guide path j

adaptor is attached to the end of the manipulator arm by a dovetail fitting and manual lock.

The drive wheels of the probe driver deliver the tools to the required elevations within the j

tube. Where positioning is critical, a hardstop attached to the tool shaft locates the tool l

relative to the steam generator tube end.

l 4-5

I The tool delivery system for controlled tool rotation consists of two major components;

[

], Figure 4-6. The tool mounting plate is attached to the end of the manipulator arm by a dovetail fitting and manual lock. One or two sets of pneumatically operated fingers are used to draw-up and lock the tool mounting plate to the tube sheet. Proper alignment of the tool mounting plate to the tube i

sheet is assured through the actuation of three switches against the tube sheet. A spring loaded, air pressure release, quick change mount is provided on the face of the tool mounting platform for quick mounting of the probe pusher or the rolling tool elevator.

The probe pusher attaches to the tool mounting platform with the quick change mount.

The probe pusher includes two double sets of drive wheels and two idler wheels. The drive wheels are powered by electric motors to insert and remove the various sleeving tools and the sleeve into the steam generator tube. Vertical positioning of the tools is accomplished by hardstops and/or verified by visual means. Controlled rotation of the weld and non-destructive examination (NDE) tools is provided by an electric motor which rotates the probe pusher relative to the tool mounting platform.

4.5.3 Tube Brushing-Clenning Eauinment l

l 4.5.4 Tube Rolling Eau *nment 4.5.5 Sleeve Frnancion Eauinment 4-6

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4.5.6 Sleeve Welding Equinment l

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4-7

0 4.5.7 Nondestructive Framination Three types of nondestructive examination equipment are used during the sleeving process. They are as follows: eddy current test (ET) equipment, ultrasonic test (UT) equipment (Figure 4-11) and visual test (VT) equipment (Figure 4-12).

The ET inspection will be performed using the most recently developed eddy current probes and techniques for sleeving inspection. The eddy current probe presently being used is the new advanced + point rotating probe. Future probe designs may be used after suitable qualification demonstration has been performed. The ET fixture, with conduit, is used on the manipulator arm to position the probe.

Ultrasonic testing using an immersion technique with demineralized water as a couplant is used to inspect the tube to sleeve weld. A one-quarter inch diameter focusing transducer i

is positioned in the weld area and rotated by the probe pusher to scan the weld. A digital imaging system is used to acquire and store the inspection data.

Visual inspection of the steam generator tube to sleeve weld is accomplished with the use of a boroscope or micro camera system delivered and rotated by the probe pusher.

Inspection data is stored on video tape.

4.5.8 Post-Weld Heat Treatment Eauinment J

1 4.5.9 Slecyg.Rollino/Tanering Eauinment The sleeve rolling equipment is used to expand the FDTS sleeve (with rolled lower joint) into contact with the steam generator tube within the tubesheet, forming a strong leak tight joint. The sleeve tapering equipment is used to provide tight contact with the steam generator tube within the tubesheet for welding the FDTS sleeve (with welded lower 4-8

joint). The rolling tool is mounted on the manipulator and positioned within the tube by a hard stop on the roll tool shaft seating against the tube sheet. The rolling tool includes a dovetail attachment for quick mounting on the manipulator. The rolling tool mounted on the manipulator, [

] may be used in the central tubesheet region while a curved elevator [

] is used for the periphery. Although the curved elevator is used specifically for the periphery, it may be used at any tube location.

The rolling equipment consists of the air motor, tube expander, torque read-out, strip chart recorder and a torque calibration unit. The torque read-out and settings of the rolling tool are verified on the torque calibration unit prior to rolling of the sleeves. The rolling tool is located by a hardstop on the tool shaft. The hardstop positions the upper end of the tube expander within the portion of the sleeve which was hydraulically expanded during sleeve installation. The approximately 1-1/4 inch long roll is located at the nickel and metal oxide bands on the lower end of the FDTS sleeve. The sleeve is expanded to a torque which has been demonstrated by testing to provide a leak tight joint.

A record of the rolling tool torque is made for further evaluation of the rolling process on the individual sleeves. A rolled joint which fails to meet the acceptance criteria may be rerolled.

4.5.10 Perinheral Sleeve Installation Fouinment The tooling for installation of peripheral sleeves utilizes the proven technology of the tooning used for installation of straight Full Depth Tubesheet sleeves.

In addition to the equipment listed in 4.5, the installation of peripheral sleeves employs a sleeve straightening tool (Figure 4-16). The straightening tool consists of multiple rolls which straighten and deliver the sleeve into the tube. The curved sleeve, located on the ~

installation expansion tool, is installed with the straightening tool until the stops on the installation tool limit insertion. The expansion is formed in the' area of the upper weld which acts to hold the sleeve for subsequent operations.

In designing this sleeve particular attention was paid to minimizing the residual stresses in the straightened section of the sleeve. This involved specific requirements for the radius of curvature, fabrication process including heat treatment, and the design of the installation tooling. These processes produce a sleeve with post installation residual stress in the straightened portion of no more than [

].

Once the sleeve is straightened and installed in the steam generator tube the remaining operations are identical to those for the other FDTS sleeves.

4.6 ALARA CONSIDERATIONS The steam generator repair operation is designed to minimize personnel exposure during installation of sleeves. The manipulator is installed from the manway without entering the 4-9

1 i

=

steam generator. It is operated remotely from a control station outside the containment

{

building. The positioning accuracy of the manipulator is such that it can be remotely positioned without having to install templates in the steam generator.

l The tool delivery equipment is designed so that the dovetail fitting quickly attaches to the manipulator. The probe pusher is designed to quickly engage the individual sleeving tools. The tools are simple in design and all sleeving operations are performed remotely f

using tools held by the manipulator. Each tool can be changed at the manway in 10-15 l

J seconds. A tool operation is performed on several sleeves rather than performing each i

i tool operation on the same sleeve before proceeding to the next sleeve. This reduces the number of tool changes which are required. Spare tools are provided so that tool repair at the manway is not required. If tool repair is necessary, the tool is removed and sleeve I

operation continues using a spare tool. The tool may or may not be repaired during the outage but repair is performed in an area which does not have significant radiation.

l l

Air, water and electrical supply lines for the tooling are designed and mainta'med so that j

they do not become entangled during operation. This minimizes personnel exposure j

outside the steam generator All equipment is operated from outside the containment. 'Ihe l

l welding power source and programmer is stationed about a hundred feet from the steam generator in a low radiation area.

j Lead lined manway shield doors, both primary side and secondary (ventilation) side, are j

j also employed to reduce radiation exposure.

1 i

4.7 REFERENCES

TO SECTION 4.0 j

4.7.1 Allny 690 for Steam Generator Tubing Applications, EPRI Report NP-6997, October 1990.

l 4.7.2 Sedricks, A.. J., Schultz, J. W., and Cordovi, M. A., "Inconel Alloy 690 - A New i

Corrosion Resistant Material", Jannn Society of Corrosion Enoineerine,28,2 (1979).

j 4.7.3 Airey, G. P., " Optimization of Metallurgical Variables to Improve the Stress j

Corrosion Resistance ofInconel 600", Electric Power Research Institute Research i

Program RP1708-1 (1982).

l 4.7.4 Airey, G. P., Vaia, A. R., and Aspden, R. G., "A Stress Corrosion Cracking Evaluation ofInconel 690 for Steam Generator Tubing Applications", Nuclear i

Technnlogy, Ei, (November, 1981) 436.

]

4.7.5 Hunt, E.S. and Gorman, J.A., Snecincations for In-Situ Stress Relief of PWR Steam Generator Tube U-bends and Roll Trancition, EPRI Report NP-4364-LD, Electric Power Research Institute, Palo Alto, CA, December 1985.

j 4.7.6 Krupowicz, J. J., Scott, D. B., and Fink, G. C., " Corrosion Performance of i

Alternate Steam Generator Materials and Designs Vol. 2: Post Test Examinations

)

of a Seawater Faulted Alternative Materials Model Steam Generator," EPRI-NP-l 3044, July 1983.

4.7.7 G. Santarini et al, Recent Corrosion Results - Alloy 690, EPRI Alloy 690 Workshop, New Orleans, LA, April 12-14, 1989.

4-10

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FULL DEPTH TUBESHEET SLEEVE FOR A WELDED LOWER JOINT i

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i FIGURE 4-1B FULL DEPTH TUBESHEET SLEEVE FOR A ROLLED LOWER JOINT u

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FULL DEPTH TUBESHEET PERIPHERAL SLEEVE 4-12A

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FIGURE 4-2 TUBE SUP" ORT SLEEVE A-13

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FIGURE 4-3B FULL DEPTH TUBESHEET SLEEVE FOR A ROLLED LOWER JOINT INSTALLATION 1

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4 FIGURE 4-4 TUBE SUPPORT SLEEVE INSTALLATION 4-16

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FIGURE 4-5 MANIPULATOR AND TOOL DELIVERY SYSTEM 4-17

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FIGURE 4-6 TOOL DELIVERY EQUIPMENT 4-18

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FIGURE 4-7 TUBE CLEANING EQUIPMENT 4-19 l

0 FIGURE 4-8 SLEEVE EXPANSION EQUIPMENT 4-20

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l FIGURE 4-9 SLEEVE WELDING HEAD ASSEMBLY 4-21

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FIGURE 4-13 POST WELD HEAT TREAT EQUIPMENT 4-25

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FIGURE 4-16 PERIPHERAL SLEEVE INSERTION EOUTPhENT 4-28

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i 5.

SLEEVE EXAMINATION PROGRAM i

During the installation process, the sleeves are examined using a combination of visual I

testing (VT), ultrasonic testing (UT) and eddy current testing (ET) at different stages of the installation process. The general process is described in the flow charts presented in Figures 5-1 and 5-2, which are described below.

After the description of the inspection process, the individual inspection methods will j

be described in additional detail.

i

[

After completion of the brush cleaning step, the first inspection is a VT process on j-tubes to be sleeved to confirm adequate cleaning to proceed with the welding process.

Parent tube cleanliness has been identified as a critical feature of the overall welding -

j' process. A VT after cleaning is performed with a miniature remote camera inserted into the tube up to the elevation where the welding will be performed. The VT inspectors are trained using images of examples of acceptable and inadequate cleaning.

In simplest terms, the cleanliness requirement is the presence of " bright, shiny metal" j

in the region of the tube where welding will take place. If adequate cleaning is not confirmed by the remote VT, then the cleaning process is repeated until a suitable l

cleanliness is achieved. The extent of this inspection program is presently 100% of tubes to be sleeved. At such time that pr.ocess control is demonstrated to assure cleaning efficiency, a sampling program may be used.

i Upon confirmation of cleaning, the sleeve is inserted, expanded and welded. The next inspection is performed on the ATS weld by UT to confirm a leak tight bond has been achieved by the welding process. The weld height is not measured by the UT method, i

but rather is controlled by the welding process qualification. A confirmation of 360 degrees of weld bond is the acceptance criteria for the UT inspection. If a lack of fusion (LOF) through the weld height is detected, then the sleeve may be identified for

)

rewelding or plugged. After a reweld, the UT is repeated to confirm a leak tight weld. An acceptable UT result is required for any ATS weld left in service.

i 4

i Prior to the UT inspection, an optional VT-1 inspection of the ATS weld may be performed, but is not required. The VT-1, as defined in ASME Section XI, is suitable for detection of incomplete welds, blow holes and weld splattered geometric j

irregularities in the weld. Experience has shown that the UT and ET inspections are capable of detecting these conditions, so the VT is primarily useful to help resolve uncertainties in surface conditions detected by either the UT or ET inspections, if a j

i 1

l 5-1 4

-. ~.,

VT-1 inspection is performed and a blow hole or other potentially deleterious condition (with the exception of an incomplete weld) is detected, then a noncomformance report (NCR) must be generated. Blow holes identified as within the pressure boundary portion of the weld must be repaired. Blow holes not within the pressure boundary portion of the weld are identified for additional evaluation by the ET and UT inspections.

A VT-1 inspection of 100 % of all FDTS sleeve lower welds is required.

The final inspection is performed on all installed sleeves using the ET method with a

+ point probe, if post weld heat treatment is performed, this inspection must be performed after the heat treatment due to the possibility of additional signals from permeability variations caused by the heat treatment process. The entire length of the pressure boundary, including the pressure boundary portion of the parent tube behind the sleeve is inspected with the ET method. The details of the ET inspection are described in Section 5.2 and Figure 5-2 with the associated definitions in Table 5-1.

The sleeve to tube weld joints are qualified by process control as described in Appendix A. Checks are made to ensure that the welds meet these design requirements. The welding current and voltage are recorded as the weld head rotates inside the sleeve.

The recordings are examined after the welding sequence has been completed to verify l

that the essential parameters given in Reference 1 to Appendix A are met.

These descriptions of inspection techniques and tooling represent the current state-of-the-art practices. As new technology becomes available, advanced techniques may be substituted after a suitable qualification program has demonstrated equivalent or superior performance.

5.1 ULTRASONIC INSPECTION 5.1.1 Summary and Conclusions An ultrasonic inspection is performed on each sleeve to tube ATS weld to confirm a leak tight fusion. The test is performed using an ultrasonic crystal with a resonant frequency of [

] MHz (physical construction of the probe will reduce the effective output frequency to [

] MHz, typically. Actual output frequency is documented in the transducer certification package required by procedure.) The mechanical drive device performs a scan of the weld in 2 degree increments around 360 degrees with axial step increments of [

] inches; the scan path extends from above the weld so that the sleeve backwall is detected to below the weld until the backwall of the sleeve is detected. The inspection is demonstrated to detect a milled notch representing a weld lack of fusion (LOF) region of [

] inch or greater. The ultrasonic signal is 5-2

digitized and stored in order to provide a permanent record of the individual A scans (lower presentation on Figure 5-4), which are used to display plan view C scans (upper presentation on Figure 5-4) of he weld as well as cross sectional views in the axial t

direction (B' scans) and cross ational views (B scans). For each individual sleeve inspection, a calibration conM tion is available by monitoring the response to the sleeve back wall either above ci oelow the weld zone.

5.1.2 Ultrasonic Evaluation The basis of the UT inspection is the detection of a reflective surface at the sleeve to tube interface to detect a condition indicative of a lack of fusion. Sound is transmitted from the sleeve inner surface through the weld to the tube outer surface. Although the reflection from the tube outer surface is typically discernible in the recorded data, this is a sufficient, but not necessary indication of fusion. Geometric distortions in the weld region may preclude detection of this tube back wall as a consistent indicator of weld fusion.

In the data acquisition phase, a C scan is displayed for the operator with a [

] for monitoring reflections from the sleeve / tube interface. During analysis, both circumferential and axial cross sectional views of the ultrasonic reflectors are reviewed for evaluation of each weld. Detection of a [

] reflection is an indication of a complete weld.

In the absence of this signal, axial and circumferential cross sections (B and B' scans) data reviews are conducted. Locally, reflectors are compared to 20% of the sleeve backwall signal amplitude for determination of a local LOF. Using the B' scan axial cross section, a LOF condition through the weld height is discernible.

Using a combination of laboratory samples and removed tubes (Prairie Island, February,1996),

unbonds as narrow as 10 degrees are detectable using this B scan analysis techniques, as reported in References 5.4.1 and 5.4.2. Sample outputs from the UT results for an acceptable weld and unacceptable LOF condition are provided in Figures 5-3 (acceptable) and 5-4 (rejectable).

5.1.3 Test Eauioment The test equipment for the ultrasonic inspection comprises the following:

1. IntraSpect Ultrasonic Imaging System

2. Sleeve Weld UT Inspection Probe,15 MHz,0.250" diameter crystal, sized for sleeve ID, as depicted in Figure 5-5 5-3

3. Couplant supply system, integral with the probe and driver system

4. Position device for rotational and translational motion, include encoder feedback for each axis

5. Calibration standard with machined notches for initial set up, as depicted in Figure 5-6.

5.2 EDDY CURRENT INSPECTION 5.2.1 Background For the initial installation of sleeves, each sleeve will be inspected for a baseline and for acceptance. Over the years, the eddy current probe technology has evolved with ever increasing sensitivity in the probe response. Early sleeving programs used a cross wound bobbin coil design, which was later replaced by the I coil design and ultimately by the plus point probe design. The current practice uses the plus point probe design with the option of adopting future probe designs after suitable qualification demonstration has been performed. The description below discusses the most recent plus point probe design, which was extensively qualified for sleeve inspections in a

~

program that exceeded the requirements of the EPRI Steam Generator Inspection Guidelines, Appendix H in effect at this writing, as described in reference 5.4.3. This qualification used a detection threshold of 40% degradation of the sleeve wall thickness rather than the 60% allowed by Appendix H to add conservatism to the process.

The ET method is used to inspect the entire sleeve region pressure boundary which has four distinct regions:

4

1) the sleeve between the upper weld and lower joint (either roll or weld, depending on sleeve type)

2) the pressure boundary region of the steam generator tube behind the sleeve

3) the steam generator tube below the lower rolled joint for an FDTS sleeve

4) the unsleeved portion of the steam generator tube 4

i The first three regions are the subject of this discussion, the fourth region is handled as l

part of the normal tube inspection using the prevailing methods. If post weld heat treating is performed on the weld zone, the ET inspection is performed after the heat treatment.

5-4

5.2.2 Plus Point Probe Oualification Study The plus point ET technique was extensively qualified for each of the regions identified above using laboratory samples with EDM notches and laboratory produced weld imperfections. The details of the inspection samples and results for the weld zone indications are provided in references 5.4.1 and 5.4.2 and the Appendix H qualification report is provided in reference 5.4.3. The Appendix H qualification report provides the details for both the acquisition (ACTS) and analysis (ANTS) of the inspection data.

Site specific analysis guidelines have been developed and analysts are trained and tested on the specifics of the technique. In summary, the plus point technique was demonstrated to be able to detect relevant flaw mechanisms 40% throughwall and greater in each of the regions identified above.

Particular attention was paid to the ATS weld region of the sleeve. The detailed process for the initial installation inspection is shovm ir. the flow chart in Figure 5-2 with the companion list of acronyms in Table 5-1.

For the subsequent inservice inspections, reviews of previous inspection results may be used in lieu of the VT and UT reviews mentioned in the flow chart. Either the standard + point probe or the magnetically biased style may be used for the inspection. Experience has shown that one of the most common interfering signal sources in the weld region is caused by local permeability variations, which are greatly reduced by the partial magnetic saturation provided by the magnetically biased probe.

The ET indications are separated into two broad categories, surface and subsurface.

Surface indications are caused by minor weld sag which produces a signal classified as GEO for geometric. Local irregularities in the weld surface are classified as weld surface indications (WSI). In extreme cases, the WSI source could be a blow hole m i

the weld. Additional VT reviews are used to evaluate surface related indications prior to acceptance. With the aid of the VT data, WSI signals are resolved as blow holes outside or within the pressure boundary portion of the weld (BHA or BHB) or nondeleterious surface irregularities (WSS). If no surface condition is observed, then the signal is considered as a subsurface weld zone indication (WZl) and evaluated accordingly. For blow ho!es, the location relative to the pressure boundary is determined using a combination of the VT and UT results. Accordingly, the BHA (blow hole outside pressure boundary portion of the weld) condition is acceptable for service while the BHB (blow hole within the pressure boundary portion of the weld) is not.

The WZI signals may be caused by oxide inclusions in the weld or a partial void caused by a gas pocket during the welding process. Metallographic work, as reported in reference 5.4.1, has shown that these conditions occur at either the upper or lower edge 5-5

of the ATS weld on the sleeve outer surface. The oxide inclusion condition is generally precluded by proper cleaning, which is verified using VT before installing the sleeve. Minor voids may occur in a small percentage of welds even with proper cleaning, but generally are very shallow. No attempt is made to distinguish inclusions from voids, nor is there an attempt to measure depth or circumferential extent for these conditions. The only acceptance criteria is based on the location relative to the i

pressure bounday with indications outside the pressure boundary portion of the weld (WZA) acceptable for service and indications within the pressure boundary portion of 1

the weld (WZB) not acceptable for service. The ability to detennine the true location ofindications relative to the pressure boundary portion of the weld was demonstrated in the Appendix H qualification study and is reported in references 5.4.2 and 5.4.3.

The sleeve plugging criteria stated above provides at least a 12 % margin with respect to '

growth and ECT uncertainity. This is cor.sistent with the minimum allowable sleeve thickness determined in Section 8.0, an appropriate growth factor for Alloy 690 (given its excellent corrosion resistance in primary and secondary environments), and the success rate in detecting indications of 40% or greater (Reference 5.4.3).

Various other anomalous conditions may be reported by the ET analyst that would trigger an nonconformance report (NCR) and additional evaluation.

The other area of particular interest is the expansion transition zone above the weld.

Here the parent tube constitutes the pressure boundary. The ability to detect 40%

through wall flaws was demonstrated using EDM notches and is detailed in reference 5.4.3.

5.3 VISUAL INSPECTION 5.3.1 Summary and Conclusions There are three visual inspections associated with the sleeving process. The first inspection is performed after the brush cleaning process for the weld region. Tubes are inspected for cleanliness prior to sleeve installation. The second, optional inspection is performed after completion of the ATS weld and is conducted as a VT-1 inspection per Section XI of the ASME Code. The VT-1 inspection is performed when needed to resolve surface indications identified by the ET or UT inspections. The VT-1 inspection is also performed for rewelds. The third inspection is a required VT-1 performed on the FDTS sleeve lower weld.

The VT is performed remotely by means of a miniature CCD camera inserted into the tube with the results recorded on video tape. Visual aids are provided for the inspectors for evaluation of cleaning and weld quality. A training tape with examples t

5-6

l i

j i

of weld irregularities is provided and reviewed by the VT-1 inspectors. Conditions of interest include blow holes, incomplete welds, splatter, pits and burn through.

1 5.3.2 Cleanine Insoection 1

After the cleaning operation, the parent tube in the region where the weld will be made i

j is inspected for adequacy of cleaning. Approximately a two inch long zone is cleaned

)

and inspected. The acceptance criteria is bright, shiny metal to assure that thtre is no remaining oxide on the tube surface that could affect the weld quality by producing

{

inclusions. This process verification step is identified in the site specific traveller and is a QC check point required for each tube. The extent of this inspection program is presently 100% of tubes to be sleeved. At such time that process control is i

demonstrated to assure cleaning efficiency, a sampling program may be used.

t 5.3.3 Weld Examination i

4 The primary inspection methods for ATS weld and sleeve acceptance are the UT and I

ET methods described above. An additional VT-1 inspection of the weld is optional, l

unless required by the site procedure for specific situations, such as repair welds. The

]

VT-1 is also used as a supplemental technique to aid in the analysis of surface conditions reponed in either the UT or ET results. The primary inspection method for j

j a FDTS lower weld is a VT-1 inspetion of the weld. This is a required inspection for this type of weld.

I The CCD camera and right angle viewing mirror is insened into the sleeve. The l

camera system is checked using a 1/32" black line on an 18% neutral gray card. Also, j

a sleeve sample with a 0.020" diameter through hole is used to scale the image. The j

VT-1 results are recorded on video tape for permanent storage.

5.4 REFERENCES

5.4.1 ABB CENO CEN-628-P Rev 01-P, " Verification of the Stnictural Integrity of the ABB j

CENO Steam Generator Welded Sleeve, March,1996 (PROPRIETARY) 5.4.2 ABB CENO 96-3-9038T Rev 01, " POD Assessment for NDE of Sleeves",

June 14,1996 l

5.4.3 ABB CENO 96-OSW-003, "EPRI Steam Generator Examination Guidelines Appendix j

H Qualification for Eddy Current Plus-Point ProbeExamination of ABB CENO Welded i

Sleeves", April 27,1996 (PROPRIETARY) i i

l 5-7 i

1

d 1

TABLE 5-1 ACRONYMS USED IN ET ANALYSIS

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BHA: Blow Hole Outside Pressure Boundary i

l BHB: Blow Hole Within Pressure Boundary GEO: Geometric signal LOF: Lack Of Fusion NCR: NonConformance Report NDD: No Detectable Degradation PID: Positive ID retest RMB: Retest with Magnetically Biased probe UT: Ultrasonic Test VT-1: Visual Test, Type 1 per ASME Code,Section XI VT: Visual Test WEE: Weld at Edge of Expansion WOE: Weld Outside Expansion region WSI: Weld Surface Indication WSS: Weld Surface Signal WZA: Weld Zone indication Outside Pressure Boundary WZB: Weld Zone indication.Within Pressure Boundary WZl: Weld Zone Indication-subsurface or indeterminant 5-8

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5-14

6.

SLEEVE-TUBE CORROSION TEST PROGRAM ABB-CE has conducted a number of bench and autoclave tests to evaluate the corrosion resistance of the welded. sleeve joint. Of particular interest is the effect of the mechanical expansion / weld residual stresses and the condition of the weld and weld heat affected zone. Tests have been performed on welded joints with and without a post-weld heat treatment. An outline of these tests is shown in Table 6-1. [

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l 6.1

SUMMARY

AND CONCLUSIONS 6.2 TEST DESCRIPTION AND RESULTS 6.2.1 Primary Side Tests I

I 6-1

TABLE 6-1 STEAM GENERATQR TUBE SLEEVE CORROSION TESTS l

6-2 i

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l 6.2.1.1 Pure Water Stress Corrosion Cracking Tests i

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i 6.2.1.2 Above the Tubesheet (ATS) Weld Capsule Tests l

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Sample Condition Failure No.

Failure Time (Hrs) 4-j' i

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i 6.2.1.3 TSP Sleeve Weld Capsule Tests 6-4

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SECONDARY SIDE STEAM GENERATOR TUBE SLEEVE CAPSULE TESTS ENVIRONMENT EXPOSURE TIME RESULTS l

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l 6.2.2.3 Sodium Hydroxide Fault Autoclave Tests I

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6.2.2.4 Summary - Secondary Coolant Corrosion Performance i

f 6-9

6.3 REFERENCES

FOR SECTION 6.0 6.3.1 Statistical Analysis of Steam Generator Tube Degradation, EPRI Report NP-7493, September 1991.

6.3.2 Summary Report, Combustion Engineering Steam Generator Tube Sleeve Residual Stress Evaluation, TR-MCC-153, November 1989.

6.3.3 I. L. W. Wilson and R. G. Aspden, " Caustic Stress Corrosion Cracking of Iron-Nickel-Chromium Alloys." Stress Corrosion Cracking and Hydrogen Embrittlement of Iron Base Alloys, NACE, Houston, Texas, pp 1189-1204, 1977.

6.3.4 A. J. Sedriks, S. Floreen, and A. R. McIlree, "The Effect of Nickel Content on the Stress Corrosion Resistance of Fe-Cr-Ni in an Elevated Temperature Caustic Environment". Corrosion,Vol. 32, No. 4, pp 157-158, April 1976.

6.3.5 F. W. Pement,1. L. W. Wilson and R. G. Aspden, " Stress Corrosion Cracking Studies of High Nickel Austenitic Alloys in Several High Temperature Aqueous Solutions." MaterialsPerformance, Vol.19, pp 43-49 April 1980.

6.3.6 P. Berge and J. R. Donati, " Materials Requirements for Pressurized Water Reactor Steam Generator Tubing." NuclearTechnology, Vol. 55, pp 88-104, October 1981.

6.3.7 G. P. Airey, A. R. Vaia and R. G. Aspden, "A Stress Corrosion Cracking Evaluation of Inconel 690 for Steam Generator Tubing Applications." Nuclear Technology, Vol. 55, pp 436-448, November 1981.

6.3.8 J. R. Crum and R. C. Scarberry, " Corrosion Testing of Inconel Alloy 690 for PWR Steam Generators." Journal of Materials for Energy Systems, Vol. 4, No. 3, pp 125-130, December 1982.

6-10

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I 7.

MECHANICAL TESTS OF SLEEVED STEAM GENERATOR TUBES 7.1

SUMMARY

AND CONCLUSIONS Mechanical tests were performed on mockup steam generator tubes containing sleeves to provide qualified test data describing the basic properties of the completed i

assemblies. These tests determined axial load, collapse, burst and thermal cycling capability. A minimum of three tests of each type were performed.

i 4

7.2 CONDITIONS TESTED 1

7.3 WELDED SLEEVE TEST PARAMETERS AND RESULTS 7.3.1 Axial Pull Tests 7-1

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COMPONENT AND TEST RESULT RESULT (MINIMUM) l (MAXIMUM) e T

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1 A minimum of three tests of each type were performed.

7-5

+-

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8.0 STRUCTURAL ANALYSIS OF StFRVE-TURE AREMBLY His analysis establishes the structural adequacy of. the sleeve-tube assembly.

The i

methodology used is in accordance with the 1989 Edition of the ASME Boiler and Pressure i

Vessel Code, Section 111. De work was also performed in accordance with 10CFR50 Appendix B and other applicable U.S. Nuclear Regulatory Commission requirements.

e

. 8.1

SUMMARY

AND CONCLUSIONS I

Based on the analytical evaluation contamed in this secten and the mechanical test data i

contained in Section 7.0, it is concluded that the Full Depth Tube Sheet (FDTS) and the Tube Support (TS) sleeves described in this document, meet all the requirements stipulated in 3

Section 8.0 with substantial additional margins. In performing the analytical evaluation on the f

tube sleeves, the operating and design conditions for all of the Westinghouse operating plants j.

with 7/8 inch Inconel 600 tubes are considered (Reference 8.2).

1 l

8.1.1 Design Sizing L

i j

In accordance with ASME Code practice, the design requirements for tubing are covered by i

the specifications for the steam generator " vessel". The appropriate formula for calculating j

the minimum required tube or sleeve thickness is found in Paragraph NB-3324.1, tentative pressure thickness for cylindrical shells (Reference 8.1). The following calculation uses this i

j formula for the tube sleeve material which is Alloy 690 material with a specified minimum l

yield of 40.0 ksi.

i i

i i

i-i l

)

4 i

Where t = Minimum required wall thickness, in.

l P = Design Tubesheet differential pressure, ksi (max. value for plants, Ref. 8.2)

R = Inside Radius of sleeve, in. (maximum value for plants considered)

S. = Design Stress Intensity, S.I. @ 650 F maximum design (per Reference 8.15) j 8.1.2 Detailed Analysis Summarv l

When properly installed and welded within specified tolerances, the FDTS sleeve and its upper weld and lower weld or rolled joint (depending on the tube sleeve design), and the TS sleeve and its two primary welds possess considerable margin against pull-out for all loading

}

which can be postulated from operating, emergency, test, and faulted conditions.

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_ ABLE 8-1 T

SUMMARY

OF SIERVE AND WFin ANALYSIS RESULTS i

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• - The alle -loles listed in Table 8-1 are in accordance with the ASME Code (Refs. 8.1 and 8.15).

" - Simpi neo Elastic-Plastic Analysis used in the fatigue evaluation (Para. NB-3228.5 of Ref. 8.1).

"* - Whue the nununum tensile strength and yield strength are listed in Reference 8.15 as 80.0 ksi and 40 ksi, respectively, the actual material properties were found to be higher based on Reference 8.18. Typically, S, > 100 ksi and S, > 50 ksi at room ternperatures Based on the trendrag curves in Reference 8.19 for the above room temperature allowables, it can be expected that S, is greater than or equal to 90 ksi at 650*F. This value will be used to evaluate the accidetu conditions and the allowable sleeve wall degradation in Section 8.3.

8-4

FORMULAS FOR t,i.NERAL MEMBRANE STRESSES SUMMARIZED IN TABLE 8-1 (Note: All SI equations below are a derivation of the formula in Par. NB-3324.1 of Ref. 8.1.)

1. GENERAL PRIMARY MEMBRANE STRESS (DESIGN TUBESHEET DELTA PRESSURE)

2. MAIN STEAM LINE BREAK

3. PRIMARY PIPE BREAK (LOCA) l t

8-5

TABLE 8 2 i

SUMMARY

OF LOWER JOINT (WELDED AND ROI.IFn) DESIGN. ANALYSIS AND TEST RESULTS

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8.2 LOADINGS CONSIDERED in this section a number of potential failure modes are examined to determine the relative safety margins for selected events. Failure loads are calculated based on minimum dimensions and compared with mechanical testing results from Section 7.0. Bo:h calculated and measured loads are compared with the maximum postulated loads.

8.2.1 Uoner Sleeve Weld Pullout I md Assuming the parent tube is totally severed, the minimum load required to shear the upper tube weld is calculated.

The force required to pull the expanded sleeve through the unexpanded tube is conservatively neglected.

~'

In the event of a main steam line break (MSLB), the secondary pressure would drop in a short time interval. The primary pressure would rise briefly then follow the drop in secondary pressure. It is conservatively assumed that the full primary pressure remains when the secondary pressure reaches zero. Postulating a main steam line break (MSLB) accident, the maximum pullout load would be:

8.2.2 lowe Sleeve Rolled or Weld Section Pushout Imad Assuming the parent tube is totally severed, the minimum load required to rupture the lower rolled section is calculated. The minimum measured test value for the pushout load is 2000 lb. for the rolled section and 4914 lb. for the weld section. See Section 7 for details.

8-7 j

-=.

i Postuiating a loss of primary coolant accident (LOCA) during hot standby condition (0%

i Power), the maximum available load would be:

d l

Note that the LOCA pipe break accident is not controlling for this joint. See Section 8.4.6.

8.2.3 Weld Fatinue Since the factors of safety are quite high for loadings due to primary stress, the failure mechanism of greatest interest is the fatigue failure mode considering the variable axial l

loading of the sleeve during normal operating transients.

j in Section 8.6, fatigue evaluations of the upper weld and of the lower weld, which join the sleeve to the tube will be made. It is first necessary to determine the effects that tube lock-up within the tubesheet and tube supports have on the axial loads in the sleeve during normal operation. This subject is addressed in Section 8.4.

8.3 EVALUATION FOR ALLOWABLE SLEEVE WALL DEGRADATION USING REGULATORY GUIDE 1.121 NRC Regulatory Guide 1.121 (Reference 8.3) requires that a minimum acceptable tube (or sleeve) wall thickness be established to provide a basis for leaving a degraded tube in service.

For partial thru-wall attack from any source, the requirements fall into two categories, (a) normal operation safety margins, and (b) considerations related to postulated pipe rupture accidents.

8.3.1 Normal Operation Safety Margins it is the general intent of these requirements to maintain the same factors of safety in evaluating degraded tubes as those which were contained in the original construction code, ASME Boiler and Pressure Vessel Code, Section 111 (Reference 8.1).

For Inconel Alloy 600 and 690 tube or sleeve material the controlling safety margin is:

" Tubes with partial thru-wall cracks, wastage, or combinations of these should have a factor of safety against failure by bursting under normal operating conditions of not less than 3 at any tube location".

From Reference 8.2, the normal operating conditions for the " worst" case envelopment of steam generators are:

8-8

... _.. _. ~.. _..

Primary Pressure Pg = 2250 psia Secondary Pressure P = 705 psia Differential Pressure DP = Pg - Pm = 1545 psi Average Pressure P.3 = 0.5 (Pg + P ) = 1478 psia Assuming the parent tube is totally severed, the sleeve is required to cany the pressure loading.

The following terms are used in this evaluation.

I R;.= sleeve nominalinside radius Sy,. = minimum required yield strength (per U.S. NRC Reg. Guide 1.121, Ref. 8.3)

Sy,mn = minimum yield strength of sleeve (Sy = 35.2 ksi min. at 650 *F, Ref. 8.15) l l

l i

S.3.2 Postulated Pine Runture Accidents i

l NRC Regulatory Guide 1.121 requires the following:

"The margin of safety against tube failure under postulated accidents, such as a LOCA, steam line i

break, or feedwater line break concurrent with the safe shutdown earthquake (SSE), should be consistent with the margin of safety determined by the stress limits specified in NB-3225 of Section III of the ASME Boiler and Pressure Vessel Code" 4

8-9 0

s f

i

}

The above referenced ASME code paragraph deals with " faulted conditions", where for an elastic t

i analysis ofInconel 690 sleeves, a general membrane stress of 0.7 S. = 0.7(90.0) =

63.0 ksi is allowed.

i In conjunction with the NRC Regulatory Guide 1.121, the following accidents are postulated:

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8.4 EFFEC'IS OF TUBE LOCK-UP ON SLEEVE LOADING Objective: Conservatively determine the maximum axial loads on the sleeve (tension and compression) during normal operation.

General Assumptions: (See Figures 8-2 through 8-5 for details).

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8-12 i

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Sleeved Tube in Operating Steam Generator. Irrk-uo at First Tube Sunoort t

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8.4.4 Sleeved Tube in " Worst" Case Envelopment. lxrk-uo at First Tube Support j

8-14

TABLE 8-3A 30 INCII SLEEVE AXIAL MEMBER PIIYSICAL PROPERTIES FOR OPERATING STEAM GENERATORS I

8-15

3 TABLE 8-3B 30 INCII SLEEVE AXIAL MEMBER PIIYSICAL PROPERTIES FOR " WORST" CASE ENVELOPMENT i

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TABLE 8-4A 30 INCII SLEEVE AXIAL LOADS IN SLEEVE WITII TUBE NOT LOCKED INTO TUBE SUPPORT FOR OPERATING STEAM GENERATOR i

8-17

TABLE 8 4B 30 INCII SLEEVE AXI AL LOADS IN SLEEVE WITil TUBE NOT LOCKED INTO TUBE SUPPORT " WORST" CASE ENVELOPMENT i

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TABLE 8-SA 30 INCll SlIEVE AXIAL LOADS IN SLEEVE WITil TUBE LOCKED INTO TUBE SUPPORT FOR OPERATING STEAM GENERATOR t

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8-19

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TABLE 8-5B 30 INCII SLEEVE AXIAL LOADS IN SLEEVE WITII TUBE LOCKED INTO TUBE SUPPORT FOR " WORST" CASE ENVELOPMENT I

t 8-20

8.4.5 Effect of Tube Prestress Prior to Sleeving i

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1 8.4.6 Lower Sleeve Rolled or Weld Section Pushout Due to Restrained Thermal Exoansion e

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8.5 SLEEVED TUBE VIBRATION CONSIDERATIONS The vibration behavior is reviewed since the installation of a sleeve in a tube could affect the dynamic response characteristics of the tube.

8.5.1 Effects of increased Stiffness Stiffness and mass have opposing influences on tube vibration. While increased stiffness tends to raise the tube natural frequency, increased mass tends to lower it. ABB/CE's vibrational testing (Reference 8.6) demonstrated among other things, that a solid rod of the same O.D. as a tube will vibrate at nearly the same frequency. However, the displacements for the stiffer rod will be significantly less.

In addition, if any contact is made betwe'.n the tube and sleeve along their length, the increased damping will absorb more energy. The damping would have a significant effect on amplitude of vibration. In light of this damping effect and the other above mentioned effects resulting from a sleeve inside a tube. the vibration performance of the tube / sleeve assembly is superior over the original tube.

8.5.2 Effect of Severed Tube l

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I 8.6 STRUCTURAL ANALYSIS FOR NORMAL OPERATION A static elastic analysis of the sleeved tube assembly was performed according to the requirements stipulated in NB-3220 Section ill of the ASME Code Section. 'This section describes the methods used to analyze the upper tube weld, lower stub weld, and sleeved tube plug weld.

8.6.1. Fatigue Evaluation of Unoer Sleeve / Tube Weld 1

I i

8-24

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8.6.2 Evaluation of lower Sleeve Rolled Section s

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8-25

TABLE 8-6 VPPER St REVE Wrt n - TRANSIENTS CONSIDERFD 7

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8.6.4 Fatinue Evaluation of Sleeved Tube Plun Weld l

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SLEEVED TUBE PLUG WFID - TRANSIENTS CONSIDEREn (R;fc. -.= 8.17) i l

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8-31

8.7 REFERENCES

FOR SECTION 8.0 8.1 ASME Boiler and Pressure Vessel Code, Section 111 for Nuclear Power Plant Components, 1989 edition.

8.2 ABB/CE letter Report No. CSE-%115. " Tube Sleeve History Data for 7/8 inch Steam Generator Tubes", May 03,1996.

8.3 U.S. NRC Regulatory Guide 1.121, " Bases for Plugging Degraded PWR Steam Generator Tubes".

8.4 ABB/CE License Report CEN-331-P, Rev.1-P, " Zion I & 2 Steam Generator Tube Repair Using leak Tight Sleeves", June 03,1986.

8.5 "ANSYS" Finite Element Computer Code, Rev. 5.1, 1994 by Swanson Analysis Systems, Inc.

8.6

" Vibration in Nuclear Heat Exchangers Due to Liquid and Two-Phase Flow," By W.J.

Heilker and R.Q. Vincent, Journal of Engineering for Power, Volume 103, Pages 358-366, April 1981.

8.7 "ANSYS" Engineering Analysis System, User's Manual, Rev. 4.1, 1986, by John A.

Swanson.

8.8 EPRI NP-1479, "Effect of Out-of-Plane Denting loads on the Structural Integrity of Steam Generator Internals," Contractor: Combustion Engineering, August 1980.

8.9 ABB/CE Drawing No. C-SGN-218-038-01, " Welded Sleeve for 7/8" Diameter Westinghouse Steam Generator", January 1986.

8.10 ABB/CE Drawing No. C-SGN-218-059-04, " Welded Sleeve Installation - Westinghouse 7/8*

Diameter Tubes", February 1989.

8.11 Inconel 690, Huntington Alloys, Inc., Huntington, W. Virginia.

8.12

" Primary / Secondary Boundary Components Steady State Stress Evaluation", Prepared by Raymond Paul Wedler, Westinghouse Electric Corp., April 1%5 (REF-96-001).

8.13 Westinghouse Steam Generator Standard Information Package, January 04,1982 (REF-%

002).

8.14 ASME Boiler and Pressure Vessel Code, Section 11, Materials,1995 edition.

8-32 I

i l

8.15 ASME Boiler and Pressure Vessel Code Case N-20-3, "SB-163 Nickel-Chromium-Iron Tubing (Alloys 600 and 690)... at Specified Minimum Yield Strength of 40.0 ksi... Section Ill, Division 1, Class 1", November 30,1988.

j 8.16 ABB/CE Report No. TR-ESE-178, Rev. 1

" Palisades Steam Generator Tube / Sleeve l

Vibration Tests", October 05,1977 (REF-96-003).

i 8.17 ABB/CE Report No. CR-9417-CSE92-Il09 (CSE-92-281), " Evaluation of an Inconel 690 ABB/CE Welded Sleeve Tube' Plug for Application in Westinghouse Series 44/51 Steam Generators", August 10, 1992.

4 l

8.18 ABB/CE 1.etter Memo, E.P. Kurdziel to D.P. Siska, " Mill Test Results for I-690 Sleeve Material", dated August 8,1996.

8.19 Nuclear Systems Materials Handbook, Volume I " Design Data", Part I, Greap 4, Section 3 -

Inconel Alloy 600.

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1 APPENDIX 8A FATIGUE EVALUATION OF UPPER SLEEVE / TUBE WELD 8A-1

INTRODUCTION The analysis presented in this appendix is discussed in detail in Section 8.6.1 of this Report.

The results from the two (2) fmite element models considered are presented in this Appendix.

)

The model geometry is shown in Figure 8-6 of the Report. The only difference in the two models is the weld height and the number of elements. The [:

inch] weld height model is based on the design geometry minimum dimension. The [

inch] model is based on the minimum required axial weld length required for operating and accident conditions. All stresses and usage factors for both configurations are satisfactory when compared to allowables.

GENERAL DISCUSSION The lower end of the tube was assumed to be locked near the secondary side surface of the tubesheet. From Section 8.4, it was found that the sleeve develops higher compressive loadings if the tube is free to slide through the first support. Therefore, sliding at the tube-to support interface was conservatively assumed. The FEM model consists of 2-D isoparametric elements with an axisymmetric option. The ANSYS input and output data are included in. The transient conditions listed in Reference 8.4 are shown in Table 8-6 and are grouped as follows for simplicity of analysis:

The 200 cycles between ambient (room temperature) and hot standby represent the heatups and cooldowns.

The 20,500 cycles between hot standby and full power are the sum of 18,300 loading and unloading conditions and 2200 step load events./

The 600 cycles between full power and reactor trip are a combination of 400 trip, 80 loss of load and 40 loss of power cycles. " Loss of Flow", which is assumed to represent the greatest variation from full power, is utilized to define the " Trip" condition.

The axial loads determined from the thermal interaction in Section 8.4 are applied to the bottom of the sleeve FEM model. The pressure stresses and stresses due to radial thermal expansion are conservatively excluded since they result in tensile stress which relieve the compressive stresses resulting from the axial loads. The above described transients are combined in the worst case combinations in the fatigue evaluation.

For the [

] weld model, a stress concentration factor of four (4) is conservatively applied to the total stresses from the computer code output for the purpose of calculating peak stresses. The concentration factor is applied to the axial and radial stresses only since the shear stresses are relatively negligible. The concentration factor is applied at the sleeve outside surface located below the weld, the top and bottom of the weld, and to the inside surface of the tube location above the weld.

For the [

] weld tip region the stress concentration factor of four (4) is applied to the linearized stresses from the computer output. A stress concentration factor of four (4) is conservatively applied to the linearized membrane plus bending stresses for the axial, radial and shear stress components.

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i STRFRS RFRULTS 100% STEADY STATE m

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FATIGUE EVALUATION AT WORST LOCATION iit I

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TABLE 8A-3A STRESS RESULTS 100% STEADY STATE (0.020" Weld) l l'

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TABLE 8A-3C STRN RESULTS REACTOR TRIP (0.020" Weld)

N 8A-11 i

TABLE 8A-4A RANGE OF STRFRS AT WORST IDCATIONS (0.020" Weld) 8A-12

.. -.. - -.. -... -. -...... _ -. -. -.. _ ~.-

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FATIGUE EVALUATION AT WORST LOCATIONS (0.020" Weld) 4 1

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FATIGUE EVALUATION AT WORST IDCATIONS (0.020" Weld) '

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8A-14

3 APPENDIX 8B FATIGUE EVALUATION OF LOWER STUB WELD 8B-1

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i AXIAL LOAD DUE TO RESTRAINED THERMAL EXPANSION J-L i

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Y TUBE 5HEET SLt$e E jELD (REACTOR TRIP & THERt1AL LOAD)

FIGURE 8B-3 LOWER STUB WELD MODEL (REACTOR TRIP & THERMAL LOAD) 8B-5

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f APPENDIX SC FATIGUE EVALUATION OF SLEEVED TUBE PLUG WELD 8C-1 1

_- -. _ _. _. _ _ ~ _.. _... _. _ _ _ _ _. _ _ _ _ _ _ _ _. _ _

2 INTRODUCTION The analysis presented in this appendix was conducted utilizing Westinghouse Series 44 design I

geometry, operating transients and test loadings. However, the analysis is sufficient justification for i

the Series 51 steam generator tube plugging based on the following observations.

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i SLEEVED TUBE PLUG MODEL (DETAH FD VIEW) 8C-7 J

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APPENDIX 8D TUBE SLEEVE HISTORY DATA 8D-1

Jti.-30-1996 10:39 FROM RBB PLRCHASING DEPT.

TO 91 N 9530 P.02 1

i A._B._B

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i Inter-Office Correspondence To:

W. R. Gehwmar assy 03,1996 SomiummNaclearServue Cener l

cc:

D.P.Siska CSE-96-115 / Page 1 of 2 D. G. Sempmick i

T. M. Taylor i

SURTECT:

TUEE $[ZEVE RISTORY DATA POR 7/8 INCE STEAM GENERATOR 1TJEE5

)

REPERENCES:

l (1) CE NSPD.260f Rev. Of License Repart. "Ragbals 2 Summ Gausant him Rapsir Using Imak71 gin Siseves', Jammary 17,1985.

l (2) CEN-296f Rev. 34 IJccuse Report, " Pane Island Saam Genniaar Tube Repair Using IAak Tigla Sleeves", Janary 15,1985.

(3) CEN-313f Rev. 0 P Ijanse Report, 'D.C. Coot Unit 2 Samn F--==Tulz Rapsir Using IAnk lists Sleeves". .

W 26,1985.

(4) CEN-3314 Rev.1-P I.:ounse Esport,23cn 1 & 2 Seam Geograsr hbe Repair Using ImakTels Simeves', June 3,1986.

(5) CEN-413-P Rev. Of License Report, Eevannee Seam --hbe Regar UsingIsakTwin c

3 I

Sleeves", Jamary,1992.

l (6) ABB/CE Inanna1 Memo, J.E. Robers to A.D. Depenn. 'Indna Point 2 Tube Siceve Licensing Report",

ASG49 048. April 27,1989.

0) CEN-320f Rev. Of License Report. Ginna Saam=====mr him Repur Ushug ImatTigin Simeves".

r l

h= Nacicar Service Camer (SNSC) reviewed the past mbe sleeve repors k 7/8 inch sman generasor tubes.

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Rattriacos 1 tirough 7 comam the Secdon 8 mt='armi analysis as part of the hcense repora. A review was also inade of the seer 7/8 inch mesa generamr inbes. primarily, the Westingbones M/51 Seeies seam seneranus e see if their parsunsers

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would proshce a " worm" case menarian greater than those plans tuviewed in Redrrences 1 duough 7. Table 1 as the neu page cansans the meeseary parameem front the seven retrences an develop a "wrzst* case envelopment situation ihr Sarther stracetal analysis of 7/8 inch tube sleeves. Those "wors' case inans tar "operanag" planes with Inconst 600 seam i

generasor abes are nomd in Table 1 with an asernak (*). For a " single

• Wesungboose Plant sudy of aII 44/S1 mam guerasors (including those piams not in the seven references), the Rashals 2 Plant (whose naam generasers have since been 8tP aced wink anos contamag Incone1690 tubes) had the largest axial lcad on me abe sleeve. ~11m next largest axial lcad on l

j the tabe sleeve were the Zica 1 & 2 Plancs which still have Incone1600 mbes in the seam pasrators.

Sincerely, hah B.A.Be!!

j VERIFICATION STA11JS: COMP 1XII l

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The Sainty-Raland design in*=i==== ocamined in this domment has bem vedfled

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e be correct by assas of Design Review using ChucMis in QP-3.4 of QPM-101.

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TABLE 1:

INCONEL 690 TURE SLEEVE FOR 7/8" DIAMETER TUBE CSE-96-il5 / Page 2 of 2 PARAMETER Ringhals 2"#

Prairie Isid D.C. Cook 2

• Zion I&2" Kewaunee" S t Indian Point 2*

Ginna1""

Sic 51 51 51 44 44 Tube Sleeve Report issue Date I/85 1/85 9/85 6/86 1/92 4/89 N/A Design Tubesheet Differential 1600

• 1600

• 1600

• 1600

• 1600

• 1550 1550 Pressure (psi) Use Max.

Prunary Pressure @ 100% Power (psi) 2250

• 2250

• 2250

• 2250

• 2250

• 225C 2250

• Use Max.

Secorlary Press. @ 100% Power (psi) 885 750 820 720

• 740 770 797 Use Min.

Prunary Temp. @ 100% Power (*F) 616.3 590 606 594 617 5%

602 Sec. Temp." @ 100% Power (*F) 429 482 498 467 503 485 492 Prim.-Sec. Temp. @100% Power (*F) 187.3 108 108 127

• II4 III I10 Use Max. Difference 500 500 500 500 547 545 545 Primary Temp. @ Reactor Trip (*F) 429 540 540 540 557 540 540 Secondary Temp. @ Reactor Trip (*F)

Prim-Sec. Temp @XX % SS (*F) 71

-40 *

-40 *

-40 *

-10 5

5 Use Max. Difference l

Primary Temperature @ 0% SS (*F) 547

• 547

• 547

• 547

• N/A 547

• 547

• Use Max.

Secondary Temperature @ 0% SS (*F) 547

• 547

• 547

• 547

• N/A 547

• 547

• Um Max.

Span Length between Tubesheet & Ist 40.7 49.8

• 49.8

• 49.8

• 49.8

• 51.8

• St.8*

Support (in.) Use Max./ Min.

Seismic lead in Venical Direction N/A N/A N/A N/A N/A N/A N/A Use Max.

L Tubesheet Thickness w/ Cladding (in.)

21.22 21.22 21.22 21.22 21.18

• 22.25 22.25 Use Min.

Secondary Pressure During LOCA 1010 1085

• 1020 1020 1085

• 1085

• 1085

• Axial lead from Reference Report (ib.)

1602 1103 1263 1394 1197 1304 1271

• " Worst

• Case Envelopment of " operating" plants with inconel 600 steam generator tubes, Use Zion 1& 2 Data for worst case " operating

• Westinghouse 44/51 steam generators

" - Consideration fi>r downcomer/feedwater suluoling (1) Reference (I)

(2) Reference (2)

(3) Reference (3)

(4) Reference (4)

(5) Refererte (5)

(6) Reference (6)

(7) Reference (7)

(8) Replaced with steam generators containing inconel 690 tubes

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9.

SLEEVE INSTALLATION VERIFICATIQN l

9.1

SUMMARY

AND CONCLUSIONS The ABB-CENO welded sleeve installation process and sequence has been tested to ensure the installation of a sleeve which conforms to the design criteria described in Section 3. During this testing, actual steam generator conditions, such as the influence of tu' es locked at tube supports, have been considered in assessing the acceptablity of the various processes and the sequence in which they are performed.

Actual sleeve operating history, as well as the qualification test program described within this report indicate that the ABB CENO steam generator tube sleeve is capable i

of performing as well as, if not longer than, the original tube in which it has been

)

installed.

j 9.2 SLEEVE-TUBE INSTALLATION SEQUENCE 9.2.1 Full Deoth Tubesheet Sleeve with Welded Lower Joint i

The FDTS Sleeve with the welded lower joint is described in Section 4.3 and Figure 4-1 4A. Installation is accomplished using the processes described in Section 4.5 in the following sequence:

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4 1

4 9.2.2 Full Death Tubesheet Sleeve with Rolled Lower Joint 4

]

The FDTS Sleeve with the rolled lower joint is described in Section 4.3 and Figure 4-4B.

Installation is accomplished using the processes described in Section 4.5 in the i

following sequence:

9-1

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l 9.2.3 Tube Suonort Sleeve i

i The TS Sleeve is described in Section 4.3 'md Figure 4-5. Installation is accomplished j

using the processes described in Section 4.5 in the following sequence:

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9.3 WELD INTEGRITY i

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9.3.1 Cleaninn Oualification i

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9-2

A test program was conducted to establish the reduction of tube wall thickness after cleaning with the abrasive brush. Four oxidized tube samples were cleaned using a qualified brushing tool and process. It was determined that less than.0005 inches of metal was removed from each of the samples.

An additional test was conducted to determine whether the I.D. tube brushing would introduce noise interference on the bobbin coil eddy current test. A clean section of tubing was baseline tested to determine I.D. noise levels. The tubing was subsequently heat treated to produce an oxidation layer on the tube. One half of the tube section was then brushed to remove the oxide coating and the sample was retested with the bobbin coil. The results (Figure 9-1) show that the oxide does in fact generate a noise component. However, after the tubing is brushed, the noise level returns to that of the baseline (pre-heat treat) data.

9.3.2 Exoansion Oualification An extensive test program was performed to qualify the bladder expansion tool and process, which provides a tight sleeve / tube fit up in preparation for welding. This program considered tubing with thick, thin and nominal walls as well as tubing with different heat treatments (yield strengths).

9.3.3 Weld Oualification 9-3

1 9.3.4 Ultrasonic Testing Oualification Ultrasonic (U.T.) techniques are employed to confirm the presence of weld fusion into l

the tube. A test program was completed by ABB-CE to qualify the Ultrasonic i

Examination of sleeve / tube upper welds. Fourteen sleeve / tube weld specimens were i

prepared for this qualification program. Each weld was ultrasonically inspected and then hydrostatically tested to confirm U.T. results. Test results indicate complete correlation between ultrasonic and hydrostatic testing.

9.3.5 Post Weld Heat Treat Oualification The tubing used in some steam generators has been shown to be very susceptible to the effects of Primary Water Stress Corrosion Cracking (PWSCC). As a result, these utilities must minimize the residual stress induced in the steam generator tubing associated with any repair process. If sleeving is selected as the repair method, the 9-4

sleeve to tube weld joint as well as the weld heat affected zone and primary pressure boundary portion of the tube expansion requires annealing to minimize residual stresses. The Electric Power Research Institute (EPRI) has documented (Reference 4.7.4 of Section 4.7) evidence in support of the annealing process. It was determined that a 3 to 5 minute soak time at a tube temperature of 1300 to 1425 F was required to maximize tube life.

9.3.5.1 Instrumented Analysis of Locked Tubes 9-5

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A plot of the temperature profile and Se axial load measured are shown in Figure 9-3. The i

results of this test are shown in Table 9-3. Although no measurements were taken, no q

abrupt changes in the tube diameter were observed along the length of the tube. It was -

j concluded that the deformation experienced by the tube would not be detrimental either to i

the installation process, i.e.. in preventing the tool from being removed, or to the long term performance of the sleeve / tube joint as described in Section 5.

A similar test was performed on a two by four array of.750 inch O.D. x.042 inch wall tubes arranged in a square pitch and supported as shown in Figure 9-4. This configuration replicates the first three hot leg supports of a typical Westinghouse D3 Series generator j

while conservatively simulating aspects of a CE unit, in addition, this configuration is conservative when compared to a Westinghouse Series 44/51 steam generator. Four of the j

tubes were locked at their support (but not the FDB) location by tack welding in four i

locations. The other four were free from the tubesheet to Support Plate No. 8. Two Tube Support (TS) sleeves and a tubesheet sleeve were installed in each tube as shown in the -

figure. The tubes were instrumented with strain gages to determine the strain in the outer j

fibers. During the heat treatment of each sleeve the strain in the tube was recorded. A load cell was used to determine the total load in the upper most section of tube, in the case of

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this mockup, the heat treatment commenced at the upper most weld and proceeded toward the tubesheet. Both sleeve welds (where applicable) were treated prior to any strain gage i

)

measurements. A typical temperature / time plot is shown in Figure 9-5. The results of the j

test are shown in Table 9-2. As would be expected, the more times the tube segments experiences the heat treat cycle the greater the residual stress. Examination of the tube j

surfaces in the vicinity of the welds indicated [only a slight bulge of 0.002 - 0.005 inches in i

the tube O.D. There was no deformation in the tube near the end of the sleeve or elsewhere along the tube length. The amount of bowing in the shorter tube lengths was small and although no measurements were taken prior to releasing the load, the upper tube sections were sufficiently straight not to interfere with each other].

4 i

9.3.6 Summarv i

j in summary, ABB-CE has conducted a comprehensive development and verification i

program to ensure weld integrity of its leak tight sleeves. Experience has shown that oxide layers as visually confirmed to exist on the steam generator secondary side do not affect weld parameters and the abrasive cleaning method described in the report is i

effective in preparing the tube for welding.

i i

9-6

- -. _ -. -.. _ ~. -. _ _ -..

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9.4 ROLLED JOINT INTEGRITY A development program was conducted to ensure the rolled joint of the ETZ sleeve was

}'

leak tight and capable of withstanding the design loads. The sleeves were rolled into mock-ups consisting of steam generator tubes which had been rolled into blocks simulating the tube sheet. The sleeves were then tested to confirm the rolled joint was i

leak tight both before and after cyclic load testing. Tests of the rolled joint were also conducted where process parameters such as torque, tube diameter and roll location relative to the [ nickel and metal oxide bands l were varied. A test matrix was used to verify the sleeve installation with sleeve rolling process parameter tolerances. The test l

program confirmed that the rolled joint integrity is acceptable within the allowable l

rolling process tolerances, t

j 9.5 COMMERCIAL SLEEVE INSTALLATION i

ABB-CE's commercial sleeving experience is shown in Table 9-3. The success rate for all installed welded sleeves is 98%. Since 1985, no sleeve which has been accepted i

j based on U.T. and V.T. has been removed from service due to service related degradation.

.1 j

9.6 REFERENCES

FOR SECTION 9.0 4

b 9.6.1 Test Report on Steam Generator Tube Cleaning for Installation of Welded Sleeves TR-MCM-126.

9.6.2 An Investigation of the Installation of Welded Sleeves in R.E. Ginna Tubing, TR-MSD-128.

9.6.3 Sleeving Centrifugal Wire Brush Development and Life Test Report, TR-ESE-i l

705.

9.6.4 S.G. TSP /RTZ Sleeving-Tube I.D. Cleaning for 3/4 inch O.D. X.042/.043 Wall 1

Tubes, TR-ESE-860.

- 9.6.5 Steam Generator Sleeving - 3/4 inch Program, Bladder Expansion Pressure, TR-ESE-755.

j 9.6.6 Steam Generator Sleeving - 3/4 inch Program, Qualification of RTZ and TSP Sleeve Expansion Tools and Bladder Life Test TR-ESE-809.

4 9.6.7 Ultrasonic Examination of 3/4 inch O.D. S.G. Tube to Sleeve Upper Welds, TR-400-001.

^

9-7

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I 9.6.8 Qualification of the Post Weld Heat Treatment Tool for Westinghouse "D" Series Steam Generators,00000-ESE-830.

9.6.9 Qualification of the Roll Transition Zone (RTZ) Sleeve Rolled Joint. 00000-ESE-826.

4 4

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9-8 4

TABLE 9-1 0.875 O.D. SLEEVED TUBE PWHT DATA j

9-9

1 i

TABLE 9-2 j

0.750" O.D. SLEEVED TUBE PWHT DATA TUBES LOCKED AT ALL SUPPORTS

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TABLE 9-3 ABB CENO S/G SLEEVE OPERATING HISTORY

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FIGURE 9-1 POST HEAT TREAT - BRUSHED SECTION 9-12

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m MGURE 9 0.875 O.D. LOCKED TUBE TEST TEMPERATURE AND AXIAL LOAD PRORLE 9-14

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1 FIGURE 9-4 0.750 0.D. LOCKED TUBE MOCKUP 9-15 l

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I FIGURE 9-5 0.750 O.D. TYPICAL TEMPERATURE PROFITE9 9-16

10.0 EFFECT OF SLEEVING ON OPERATION Multiple plant specific analyses have been performed to determine the effects of installation of varying lengths and combinations of FDTS and tube support sleeves.

Sleeve lengths and various combinations of installed sleeves were used to evaluate the effect of sleeving on the hydraulic characteristics and heat transfer capability of steam generators. Using the head and flow characteristics of the pumps, in conjunction with

~ he primary system hydraulic resistances, system flow rates have been calculated as a t

function of the number of sleeved tubes and the types of sleeves installed. Similarly, curves are generated from calculations that show the percent reduction in system flowrate as a function of newly plugged tubes (per steam generator). These curves are derived from plant specific information based on the following steam generator conditions :

Number Of Open Tubes Per Steam Generator Number Of Tubes Sleeved Primary System Flowrate Primary Coolant Temperr.ture This information has been used to generate tables, such as Table 10-1, that provide hydraulic equivalency of plugs and installed sleeves, or the sleeve / plug ratio. Table 10-1 is provided as an approximation only and is based on assumed operating parameters and sleeve types for a Westinghouse Series 51 plant. It must be assumed that some variations in the sleeve / plug ratio will occur from plant to plant based on operating parameters and steam generator conditions.

The overall resistance to heat transfer between the primary and secondary side of the steam generator consists of primary side film resistance, the resistance to heat transfer through the tube wall, and the secondary side film resistance. ' Since the primary side film resistance is only a fraction of the total resistance and the change in flow rate is so small, the effect of this flow rate change on heat transfer is negligible.

When the sleeve is installed in the steam generator tube there is an annulus between the sleeve and tube except in the sleeve-tube weld regions. Hence, there is effectively little primary to secondary heat transfer in the region where the sleeve is installed. The loss in heat transfer area associated with sleeving is small when compared to the overall length of the tube.

In summary, installation of sleeves does not substantially affect the primary system flow rate or the heat transfer capability of the steam generators.

10-1 s

i d

TABLE 10-1 a

q TYPICAL SLEEVE TO PLUG EOUIVALENCY RATIO a

CASE CONFIGURATION RATIO (Sleeve / Plug)*

FDTS (1) i 2

FDTS (1) + TS (1) 3 FDTS (1) + TS (2)

• This ratio should be considered approximate due to plant to r' int variations.

I 10-2

l t

1 APPENDIX A t

PROCESS AND WELD OPERATOR OUALIFICATIONS l

i i

l l

A.1 SLEEVE WELDING AND SLEEVE WELDER OUALIFICATION Sleeve welding is qualified using an approved test procedure (Reference 1). The sleeving test procedure is in compliance with applicable sections of the ASME Code. Sleeve l

welders are qualified using test records in accordance with applicable sections of the-ASME Code.

l l

The test procedure specifies the requirements for performing the welds, the conditions (or l

changes) which require requalification, the method for examining the welded test assemblies and the requirements for qualifying the welding operators. Sleeve welding is l

qualified by performing six consecutive welds of each type which meet specified design l

requirements. Welders are qualified by performing two consecutive successful welds of i

l each type.

l

.i j

A.2. REFERENCES TO APPENDIX A l

l 1.

Welded Steam Generator Tube Sleeve Semi-Automatic Gas Tungsten Arc Detailed i

i Welding Procedure Qualification, Test Procedure 00000-MCM-050.

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