ML20195D693
| ML20195D693 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 10/31/1998 |
| From: | FRAMATOME |
| To: | |
| Shared Package | |
| ML20195D679 | List: |
| References | |
| BAW-10219, BAW-10219-R03, BAW-10219-R3, NUDOCS 9811180134 | |
| Download: ML20195D693 (250) | |
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BAW-10219 REV.03 OCTOBER 1998 ELECTROSLEEVING QUALIFICATION FOR PWR RECIRCULATING STEAM GENERATOR TUBE REPAIR i
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NON-PROPRIETARY FRAMATOME TECHNOLOGIES, INC.
P.O. BOX 10935 LYNCHBURG,VA 24506-0935 COPY NO.
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FTl NON-PROPRIETARY This document is the non-proprietary vers!on of the proprietary document BAW-10219P-03. In order for this document to meet the non-proprietary criteria, certain blocks of information were with-held based on the following criteria.
(b) The information reveals data or material concerning FTl research or development plans or programs of present or potential competitive advantage to FTI.
(c) The use of the information by a competitor would decrease his expenditures,in time or resources,in designing, producing or marketing a similar product.
(d) The information consists of test data or other similar data concerning a process, method or component, the application of which results in a competitive advantage to FTI.
(e) The inforniation reveals special aspects of a process method, component or the like, the exclusive use of which results in a competitive advantage to i;TI.
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BAW-10219 REV.03 OCTOBER 1998 ELECTROSLEEVING QUALIFICATION FOR PWR RECIRCULATING STEAM GENERATOR TUBE REPAIR FRAMATOME TECHNOLOGIES, INC.
P.O. BOX 10935 LYNCHBURG,VA 24506-0935
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FTl Non-Proprinttry FTl NON-PROPRIETARY This document is the non-proprietary version of the proprietary document BAW 10219P-03. In order for this document to meet the non-proprietary criteria, certain blocks of information were with-held based on the following criteria.
The information reveals data or material concerning FTl research or (b) development plans or programs of present or potential competitive advantage to FTl.
The use of the information by a competitor would decrease his (c) expenditures, in time or resources, in designing, producing or marketing a similar product.
(d) The information consists of test data or other similar data concerning a process, method or component, the application of which results in a competitive advantage to FTI.
The information reveals special aspects of a process method, (e) component or the like, the exclusive use of which results in a competitive advantage to FTl.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary RECORD OF REVISION Rev/Date Section Descriotion 03/ 10/98 ALL The text has been completely rewritten and includes additional test results, analyses, and nondestructive examination qualification. The following Requests for Additional Information (referenced by NRC request date) have been incorporated.
RAI 7/2/96 Question 1 Section 6.5 Question 2 Sections 6.6 and 8.6 Question 3 Sections 6.6 and 7.4 Question 5 Sections 10.4 and 11.8 (new sample sets)
Question 6 Sections 11.8 and 11.9 (new sample sets)
RAI 7/25/96 Question 1 Section 11.9 Question 2 Sections 11.8 thru 11.10 and Section 12 (new sample sets)
Question 3 Sections 11.2.1 and 11.8 (new sample sets)
Question 4 Section 11.8.5 (new sample set)
Question 5 Table 12.5.2 Question 6 Sections 6.3,10.1.2, and 10.7 Question 7 Sections 3 and 4 Question 8 Sections 6.3,10.1.2, and 10.2 Question 9 Sections 10.3 and 10.4 Question 10 Sections 10.3 and 10.4 Question 11 Sections 3 and 11.10 RAI 12/17/96 Question 1 Sections 11.2.1,11.7, and 11.9 Question 2 Sections 8.5,11.8 thru 11.10 (new sample sets) and Section 12 Question 3 Section 11.2.1 and 11.8 thru 11.12 (new sample sets)
Question 4 Section 11.8 (new sample sets) and Table 12.5.2 Question 5 Sections 11.2.4 and 11.2.5 Question 6 Sections 11.3 and 11.9 Question 7 Sections 11.10 and Section 12 FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propristtry RECORD OF REVISION (Cont'd)
Section Description Rev/Date RAI 4/28/97_
03/ 10/98 Sections 11.9,11.11, and 11.12 Question 1 Question 2 Table 12.5.3 Question 3 Table 11.9.3 and Section 11.9.10 Question 5 Section 7.5 Question 6 Tables 11.9.2,11.9.6,11.9.7 and Section 11.9.3 Question 7 Section 11.8.5 and Table 11.8.13 (new sample set)
Question 9 Table 3.1 Questica 10 Sections 11.8 thru 11.12 (news sample sets) and Secticn 12 RAI 8/13/97 Question 1 Sections 11.9 thru 11.11 and Section 12 Question 2 Section 12 Question 4 Section 11.7,11.9, and 11.10 Question 5 Section 11.9 Question 6 Section 11.10 RAI 12/12/97.
Question 1 Sections 11.7.3,11.9 and 11.11 Question 4 Section 11.3.3 and 11.9.3 Question 5 Section 11.7.3 Question 7 Sections 5, 8,10,11, and 12 (primarily)
Question 9 Section 11.4.2 Question 10 Table 11.9.1 Question 11 Section 11.9.3 Question 12 Section 8.5 and Section 12 Question 13 Sections 11.8 thru 11.11 (new sample sets)
Question 14 Section 11.7.3 and 11.11 Question 15 Section 11.10 While not allinclusive, the following changes provide technical information to clarify the qualification of the repair process.
3.0 Table 3.1 Updated nickel sleeve installation.
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FTl Non-Proprietary RECORD OF REVISION (Cont'd) :
Rev/Date Section Descriotion 03/ 10/98 4A 4.2 Added Reference to 5/8" tubing.
Table 4.2.1 Added Code Case N-569.
D. 0 5.2 Expanded installation steps description, added process variable monitoring.
BA 8.2 Added information related to peripheral tube.
Table 8.5.1 Revised to reflect structural limits for TSP peripheral tubes near wrapper wedge supports.
Figure 8.5.1 Added normalized burst pressure correlation.
9.0 9.2.2.4 Added Section.
9.4 Added Section.
10.0 10.1 Added reference to Code Case N-569.
10.3 Added Section, 10.4 Added Section.
10.8 Added Section.
12.0 New Section.
13.0 Was Section 12 in Rev. 01. ,
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FTl Non-Proprietary TAplE OF CONTENTS ,
PAGE l i
1.0 -EXECUTIVE
SUMMARY
1-1 I
2.0 INTRODUCTION
2-1
3.0 BACKGROUND
3-1 4.0 DESIGN CRITERIA 4-1 4.1 Qualification Methodology 4-1 4.2 Design and Qualification Requirements 4-3 )
4.3 Sleeve Design Conditions 4-5 5.0 SLEEVE DESIGN 5-1 5.1 Design Description 5-1 5.2 Process Description 5-5 6.0 DESIGN VERIFICATION - MATERIAL PROPERTIES 6-1 1 I
6.1 Tensile Strength 6-1 6.2 Modulus of Elasticity 6-4 i 6.3 Ductility / Adhesion 6-6 6.4 Fatigue Life 6-8 i 6.5 Thermal Stability 6-10 l 6.6 Creep Properties 6-18 1 6.7 Burst Strength 6-29 6.8 Thermodynamic Properties 6-31
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7.0 DESIGN VERIFICATION - MECHANICAL TESTING 7-1 7.1 Locked Tube Testing 7-1 7.2 Fatigue Testing 7-4 7.3 Testing of Degraded Sleeves 7-8
-7.4 Creep-Fatigue Experimental Analysis 7-18 7.5 Leak Testing of Minimum Bond Length 7-21 7.6 Tube-to-Tubesheet Pull-Out Load Testing 7-21 7.7 Mechanical Testing Summary 7-22 8.0 DESIGN VERIFICATION - ANALYSES 8-1 8.1 Pressure Boundary Thickness 8-1 8.2 Fatigue Test Loads 8-3 8,3 Flow-Induced Vibration 8-11 8.4 Thermal / Hydraulic 8-13 8.5 Sleeve Structural Limits 8-15 l
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FTl Non-Propristary TABLE OF CONTENTS (Cont'dl PAGE 8.0 DESIGN VERIFICATION - ANALYSES (Cont'd) 8-23 Creep Analysis 8-35 8.6 8.7 Design Summary 9-1 9.0 DESIGN VERIFICATION - CORROSION 9-1 I General Corrosion Properties 9-9 9.1 l Primary Side Corrosion Evaluation 9-23 9.2 l Secondary Side Corrosion Evaluation 9-50 9.3 l Exposure to Mercury at Room Temperature 9-51 9.4 9.5 Corrorhn Evaluation Summary 10-1 10.0 SLEEVE INSTALLATION 10-1 Installation Procedure 10-3 10.1 Process Verification 10 4 10.2 10.3 Electrosfeeving Chemical Procurement and Quality Assurance 10 5 Process 10.4 Electrosleeving Process Detrimental Materials Control 10-6 10.5 Installation System / Tooling 10-10 10-12 10.6 ALARA 10-13 10.7 Sleeving Experience 10.8 Waste Processing 11-1 11.0 NONDESTRUCTIVE EXAMINATION 11-1 NDE Requirements 11-4 11.1 11.2 NDE Methodology Evaluation 11-7 11-11 11.3 Ultrasonic Testing 8ackground 11.4 Ultrasonic System Description 11-16 11.5 UT Acquisition Parameters 11-17 11-21 11.6 UT Data Presentation 11-35 11.7 UT Analysis Techniques Qualification Program for Longitudinal Wave UT 11-57 11.8 11-77 11.9 Qualification Program for Shear Wave UT 11-82 11.10 UT Qualification Results 11.11 Advanced UT Analysis Evaluation 11-89 11.12 Technique Application 11-90 11.13 NDE Qualification Conclusions FRAMATOME TECHNOl.OGIES, INC.
FTl Non-Proprietary TABLE OF CONTENTS (Cont'd)
PAGE J 12.0 PLUGGING LIMIT DEFINITION 12-1
- 12.1 Repair Limit for Uniform Thinning Degradation 12-2 12.2 Repair Limit for Sleeve Pitting and Disbond 12-3 2
12.3 Repair Limit for Cracking Degradation Using Conventional UT Methods 12-5 12.4 Repair Limit for Cracking Degradation Using Advanced UT Methods 12-8 12.5 Electrosfeeve" Plugging Limits 12-11
13.0 REFERENCES
13-1 i
Appendi,: A PWR DESIGN INFORMATION A-1 !
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FTl Non-Propristrry LIST OF TABLES PAGE 37 Steam Generator Nickel Plating and Electrosleeving Experience 3.1 4-4 4.2.1 Summary of Applicable Codes and Standards -
5-1 5.1.1 Steam Generator Tube and Electrosleeve" Nominal Dimensions l 5-6 5.2.1 Process Variables 6-3 ASME Code, Section lit, Minimum Design Strength Values 6.1.1 6-10 6.4.1 Fatigue Testing Results 6-17 Summary of Microhardness Determination on Strain-Annealed 6.5.1 Electrosleeves 6-23 6.6.1 Creep Test Specimens - Constant Axial Load Creep Test 6-30 6.7.1 FTl Burst Test Results at Room Temperature 6-30 6.7.2 OHT Burst Test Results at 581*F 7-3 7.1.1 Locked Tube Test Results 7-3 7.1.2 Calculated Loads for Locked Tubes 7-6 7.2.1 Fatigue Testing Specimens 7-7 Summary of Minimum Bond Fatigue Test Load Ranges 7.2.2 7-11 7.3.I Plugging Criteria Fatigue Test Specimens 7-12 Circumferential Defect Fatigue Test Loads 7.3.2 7-14 7.3.3 Axial Defect Fatigue Test Loads
' 7-15 Fatigue Inspection Interval [.,
)ee 7.3.4 7-17 7.3.5 Plugging Criteria Burst Specimens 7-19 7.4.1 Creep-Fatigue Testing Results 8-2 8.1.1 Tune / Sleeve Dimensions 8-3 8.1.2 Primary Membrane Stress Intensity Range 8-7 8.2.1 Summary of Minimum Bond Fatigue Test Load Ranges FRAMATOME TECHNOLOGIES, INC.
FTl Non-Proprietary LIST OF TABLES (Cont'd)
PAGE
'8.2.2 -C 3 Fatigue Test Loads 8-9 8.2.3 - [., 3 Fatigue Test Loads 8-11
'8.3.1 Flow induced Vibration Analyses Results 8 12 8.4.1 Thermal / Hydraulic Effects of Sleeves in Steam Generator Tubes 8-14 8.5.1 Electrosleeve" Structural Limits Level A Conditions 8-16 8.5.2 ' Electrosleeve" Structural Limits Level D Conditions 8-17 8.5.3 ' Electrosleeve" Draft Reg. Guide 1.121 Structural Limits Burst and 8-19 Leakage Limits 8.5.4 ' Electrosleeve" Structural Acceptance Standard 8-21 8.6.1 (- ] Electrosleeve* Installed in the Tube Free Span 8-28 8.6.2 [- 3 Electrosleeve" installed at Top of Tubesheet 8-30 8.6.3 (,, I 8-33 8.7.1 - . Acceptable Wall Thicknesses for an installed Sleeve 8-35 9.1.1 Summary of Literature Survey - Nickel and Alloy 600 General 9-2 Corrosion Rates in Various Environments 9.2.1 Primary Side Matrix Chemistry 9-9' 9.2.2 Primary Side Chemistry Comparison 9-11 9.3.1 Secondary Side Matrix Chemistry 9-25 9.3.2 Secondary Side Chemistry Comparison 9-26 ,
9.3.3 Summary of Crack Propagation Tests 9 28 l 9.3.4 - Maximum SCC Penetrations in Alloy 600 Control Specimens 9 33 9.3.5 Secondary Side Capsule Tests 9-37 9.3.6 Summary of Heat Transfer Sludge Corrosion Tests 9-40 9.3.7 - Composition % Weight of Sludge Mixture and Other Chemical 9-43 Species Used to Fill the Sludge Simulant Holders FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propristtry LIST OF TABLES (Cont'd)
PAGE 9-53 9.5.1 Summar) >f Material Susceptibility (Accelerated) Tests 9-55 9.5.2 Summary of Primary Water Corrosion Testing 9-56 9.5.3 Summary of Secondary Side Corrosion Tests 10-11 10.6.1 Sleeve ALARA Evaluation (100 sleeves)
Average Area Dose Rates Electroformed Sleeve Exposure l
11-10 11.3.1 Transducer and Flaw Type Comparison 11-34 11.7.1 Typical Full Skip Normalization Values 11-37 11.8.1 Parent Tube OD Pit Sample Set 11-38 11.8.2 Parent Tube OD Pit Sizing Result 11-41 11.8.3 Sleeve OD Pit Data Set 11-42 11.8.4 Sleeve OD Pitting Results - 3/4" Tube 11-42 11.8.5 Sleeve OD Pitting Results - 7/8" Tube 11-45 11.8.6 Disbond Sample Set 11-46 11.8.7 Two Pitch Extent Sizing Error Bounds 11-47 11.8.8 Disbond Circumferential Excent Sizing Result Disbond Axial Extent Sizing Results 1'-48 11.8.9 11-51 11.8.10 ID Pit Sample Set 11-53 11.8.11 ID Pit Sample Set Detection Results 11 55 11.8.12 Combined Wall Thickness Data Set 11-56 11.8.13 Combined Wall Thickness Results 11-61 11.9.1 Summary of Dent Depths 11-63 11.9.2 EDM Sample Data Set 11-64 11.9.3 Laboratory Induced SCC Sample Set FRAMATOME TECHNOLOGIES, INC.
FTl Non-Proprietary LIST OF TABLES (Cont'd)
PAGE 11.9.4 In-Service SCC Sample Set - Not Sleeved 11-65 11.9.5 In-Service SCC Sample Set - Sleeved 11-66 11.9.6 Axial EDM Sample Results 11-68 -
11.9.7 Circumferential EDM Sample Results 11-69 11.9.8 Laboratory SCC Sample Results - Pre-Sleeve 11-70 11.9.9 Laboratory SCC Sample Results - Post-Sleeve 11-71 11.9.10 In-Service SCC Sample Results - Not Sleeved 11-73 ;
11.9.11 In-Service SCC Sample Results - Sleeved Analysis Comparison 11-75 c
11.9.12 In-Service SCC Sample Results Pre- vs. Post Sleeving [ ]4 11-76 11.10.1 Summary of Flaw Detection 11-78 11.10.2 Summary of Sizing Performance 11-81 11.11.1 Mode Converted Signal Sizing Results Using EDM Notch Data 11-83 11.11.2 Comparison of Conventional TOF Analysis to MCS Analysis 11-84 Using EDM Notch Data as Presented in Table 11.11.1 11.11.3 Summary of FSN Remaining Wall Values 11-88 12.1.1 Repair Limits for Unifprm Thinning [ 12-3 3 Based on UT Sizing i
12.2.1 Repair Limits for OD Pitting [ 12-4 J' Based On UT Sizing C 3" 1 12.3.1 Repair Limits [ 12-7 l 12.3.2 Repair Limits [ 12-7 e,e.
12.4.1 Repair Limits [ 12-9
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FTl Non-Propristery LIST OF TABLES (Cont'd) PAGE
]c,e 12-11 C 3.CRepair LimitsC 12.5.1 12-12 12.5.2 Electrosteeve" Plugging Limits 12-13 12.5.3 Repair Limit Based on UT Sizing [ ]"
A-2 A.1 W-D Design Information A-6 A.2 W-E Design Information A-10 A.3 CE SYS 80 Design Information A-13 A.4 Westinghouse 7/8" Tubing S/G Design Information A-18 Combustion Engineering 3/4" x 0.048" Tubing S/G Design Information A5 A-25 A.6 W-F Design Information FRAMATOME TECHNOLOGIES, INC.
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l l FTl Non-Proprietary LIST OF FIGURES PAGE 1 l 3.1 Electroplated Tubes Pulled From Doel-2 3-4 I 5.1.1 Electrosleeve" Pressure Boundary 5-2 5.1.2 Typical RSG TSP and TS Sleeve Arrangement 5-4 I l
6.1.1 Material Test Specimen Designs - Tensile, Fatigue, Young's Modulus 6-2 Specimens 6.1.2 Typical Tensile Properties vs. Temperature 6-3 6.2.1 Elastic Modulus vs. Temperature 6-5 6.3.1 Reverse Bend Specimen 6-7 6.4.1 Electrosteeve* Material Fatigue Test Data 6-9 6.5.1 Material Test Specimen Designs - Thermal Stability Specimens 6-11 6.5.2 Electrosleeve" Thermal Stability Test Results( 6-12
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6.5.3 Electrosleeve*[ Values [ 6-13
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6.5.4 [ "j Activation Energy 6-14 b b 6.5.5 { ] Thermal { ~] Mechanism 6-15 b
6.5.6 Electrosleeve" Activation Energy ( ] 6-16 6.6.1 Standard Creep Specimen 6-19 6.6.2 Circumferentially Notched Creep Specimen 6-20 6.6.3 Mechanical Test Specimen Designs - Minimum Bond Fatigue 6-21 and Burst Specimens 6.6.4 Creep Test Results 6-25 6.6.5 Electrosteeve" Typical Fracture Surface Fractography 6-27
-7.1.1 Typical Locked Tube Mockup Test Rig 7-2 7.2.1- Mechanical Test Specimen Designs (Minimum Bond Fatigue and 7-5 Burst Specimens) 7.3.1 Mechanical Test Specimen Designs (Plugging Criteria Fatigue 7-10 Specimens)
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FTl Non-Propristtry LIST OF FIGURES (Qont'd)
PAGE 7-16 7.3.2 Mechanical Test Specimen Designs (Plugging Criteria Burst Specimens) 7-20 7.4.1 Typical Creep-Fatigue Surface Fractography 8-5 8.2.1 Peripheral Tubes Affected by TSP-to-Wrepper Supports b
.3 8-18 8.5.1 Norma!ized Burst Pressure {
8-22 8.5.2 Typical Electrosteeve* Pressure Boundary c 8-24 8.6.1 [ 3 Strain (%) vs. Time C
8-26 8.6.2 Tube Defects Modeled[., 3
- c. 8-31 8.6.3 ANSYS vs.[ 3 Test Data 8-32 8.6.4 [
9-30 9.3.1 Secondary Side Capsule Tests 9-35 9.3.2 Capsule Furnace Setup 9-36 9.3.3 Capsule Testing For Faulted Secondary Side Environments 9-41 9.3.4 Refreshed Autoclave Loop 9-42 9.3.5 Steam Generator Electrosleeved Tube Mockup For Sludge and Faulted Chemistry Tests 10-8 10.5.1 Electrosleeve* Installation System Schematic 10-13 10.7.1 Electrosleeve" Installation Experience 11-2 11.1.1 Electrosleeve" NDE Regions 11-8 11.3.1 UT Wave "V" Path 11-12 11.4.1 UT-360 System Diagram - Data Station 11-13 11.4.2 UT-360 System Diagram - Containment 11-15 11.4.3 UT-360 System Diagram - Probe Head 11-19 ,
11.6.1 Typical C-Scan Map FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary I
- LIST OF FIGURES (Cont'd) ;
4 PAGE
.11.6.2 Typical A-Scan Presentation 11-20 )
- i. '11.7.1 Half Skip Signal Reflection Position 11-24 2
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11.7.2 Full Skip Signal Reflection Position 11-24 11.7.3 Loss of Full Skip Signal with Electrosleeve" 11-25 11;7.4 Target Motion TOF 11-27 11.7.5 TOF Calculation for OD Corner Reflection 11-28 J 11.7.6 [ J' 11-30 11.7.7 C
- . { 3 11-33 i
l .11.10.1 Crack Detection POD 11-79
,11.11.1
{ fTechnique[ f' 11-85 11.11.2 [ iRegression 11-86 c,e
-11.11 3 [ ] Analysis 11-87 11.12.1 UT OD Initiated Crack Sizing Logic 11-89 i l
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FTl N:n-Propri2t:ry LIST OF ACRONYMS / TERMS A/D Analog to Digital Converter ADB Acceptable Disbond AECB Atenic Energy Control Board ALARA As Low As Reasonably Achievable ANO-2 Arkansas Nuclear One Unit 2 ANSYS ANSYS Analysis System Software (Finite Element Mode)
ASME American Society of Mechanical Engineers ASME B&PV American Society of Mechanical Engineers, Boiler and Pressure Vessel Code ASTM American Society of Testing Materials AVT All Volatile Treatment AX EDM Axial EDM Notch CD ConcentratelDryer Unit CE Combustion Engineering CE SYS 80 Combustion Engineering System 80 RSG CFR Code of Federal Regulations COA Certificate of Analysis COC Certificate of Conformance DE Destructive Examination DFO Differential Focus Optical DI Deionized Water DOR Depth of Reflection DSC Differential Scanning Calorimetry DSM Degradation-Specific Management E Modulus of Elasticity i ECT Eddy Current Testing EDM Electrode Discharge Machining EFPY Effective Full Power Years EMAT Electromagnetic Acoustic Transducer EPRI Electric Power Research Institute FESEM Field Emission Scanning Electron Microscopy FIV Flow-Induced Vibration FSM Fluid-Elastic Stability Margin
[ J' FTl Framatome Technologies, Incorporated GB Grain Boundary HP Hewlett-Packard 1
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k FTl Non-Proprietary LIST OF ACRONYMS / TERMS (Cont'd)
HTMA . High Temperature Mill Annealed ID inside Diameter IGA Intergranular Attack IGSCC. Intergranular Stress Corrosion Cracking ISl in-Service inspection LCL Lower Confidence Limit j LOCA Loss of Coolant Accident LOW Lake Ontario Water LTMA Low Temperature Mill Anneal I MCRR Ministry of Consumer and Commercial Relations ;
'b MSDS Material Safety Data Sheet l MSLB Main Steam Line Break l MULTEQ FORTRAN Software developed by EPRI (Multiple Equations) )
MUX Multiplex MWT Mean Wall Thickness-NCR Nonconformance Report l NDD No Detectable Degradation NDE Ncndestructive Examination NlC NDE Integrated Control NRC Nuclear Regulatory Commission OBE Operational Bases Earthquake OD Outside Diameter ODSCC Outside Diameter Stress Corrosion Cracking OHT Ontario Hydro Technologies, Inc.
OTSG Once Through Steam Generator P , Puo,,, Internal Burst Pressure, P, ,,,,, External Collapse Pressure P. Primary Stress
' POD Probability of Detection PWR Pressurized Water Reactor PWSCC Primary Water Stress Corrosion Cracking QA Quality Assurance OADP Quality Assurance Data Package QCIR Quality Control Inspection Report RAI Request for Additional Information (NRC acronym)
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FTl Non-Pr:pri;trry LIST OF ACRONYMS / TERMS (Cont'd)
RCS Reactor Coolant System RG 1.121 NRC Draft Regulatory Guide 1.121 RMSE Root Mean Squared Error RO Reverse Osmosis RSG Recirculating Steam Generator RT Room Temperature RUB Reverse U-bend RWR Remaining Wall Resolution SCC Stress Corrosion Cracking SG Steam Generator S,,, Allowable Stress Intensity SPS Sleeve Procedure Specification SSE Safe Shutdown Earthquake ST Sleeved Tube Su, Son,,,,,,, Ultimate Tensile Strength Sy, Syo Yield Strength TIG Tungsten inert Gas TOF Time of Flight Tp Exothermic Peak Temperature TS Tubesheet TSP Tube Support Plate TSS Tubesheet Sleeve TTS Top of Tubesheet TW Through-Wall UF Ultra-Filtration UT Ultrasonic Testing VHN Vickers Microhardness Number VT Virgin Tube W-51 Westinghouse Model 51 RSG W-D Westinghouse Model D RSG W-E Westinghouse Model E RSG W-F Westinghouse Model F RSG WT Witness Tube
%TW Percent Through-Wall FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary 1.0 EXECUTIVE
SUMMARY
i Nickel plating has been used as a repair and preventive-maintenance technique for metal l
components, including nuclear steam generator tubing, affected by primary water stress
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corrosion cracking. The Electrosleeve""', which takes advantage of the chemical and l material properties of nickel, represents the next generation of steam generator repair. i
' A process and resulting sleeve have been developed to repair Alloy 600 tubing in l 1
recirculating steam generators (RSGs) designed by Combustion Engineering or Westinghouse. l The Electrosleeve" is a layer, or sleeve, of high-purity nickel (>99.5%) that is 1 electrochemically deposited on the inner surface of the tube. Since the nickel bonds directly to the tube, the repair is leak tight. Further, the process does not deform the parent tube or affect its material microstructure; therefore, stress relieving is not I
required after the sleeve has been installed. The Electrosteeve" can be placed in any
, tube of the RSG and anywhere within the tube except in the U-bend.
Insta!!ing the Electrosleeve" uses a four-step process. The first step is cleaning the inside surface of the tube. Depositing a very thin layer of nickel (nickel strike) is the second phase of the process. This step prevents repassivation of the bonding surface and establishes a transition layer between the parent tube and the Electrosleeve*,
Forming the sleeve is the third step; the fourth involves nondestructively examining (NDE) the sleeve using ultrasonic testing (UT).
Framatome Technologies, Inc. (FTI) has qualified the Ele atrosteeve" by characterizing its material properties, performing structural analyses, and mechanical and corrosion tests to verify its performance in the operating environment of a steam generator. The material properties of the ultra-fine-grained nickel sleeve were characterized by testing as recommended by the ASME Boiler and Pressure Vessel Code, Section lll Appendices and ASTM specifications. These tests established the sleeve's tensile strength, ductility, modulus of elasticity, fatigue and creep characteristics, thermal stability, burst strength, and thermal-dynamic properties.
- The results from the above-mentioned tests were used in subsequent structural analyses i
and mechanical-qualification tests. Criteria were also established to set the extent to which a sleeve can be degraded before the tube must be repaired or removed from service.
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FTl Non-Pr:prietary l
The qualification process also required that an accurate and repeatable NDE method b used to verify the sleeve's proper installation. Typically, eddy current testing (ECT) is used to examine repairs in steam generators.[ ,, g,c,,,
. a various NDE techniques were assessed to determine the best type for this application. UT provided the most accurate tool for verifying the sleeve's position and integrity.
The development and qualification program has shown that the Electrosfeeve* and associated inspection process meet all of the requirements for application in steam generator repair.
"' Electrosleeve" is a trademark of Ontario Hydro Technologies, Inc.
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l FTl Non-Proprietary
2.0 INTRODUCTION
To repair recirculating steam generators (RSGs) with degraded Aitoy 600 tubing, the Electrosleeve**, an electroformed sleeve, was developed and qualified. This report documents the design analyses, mechanical testing, corrosion evaluation, nondestructive examination, installation process, and ALARA (As Low As Reasonably Achievable) aspects of the sleeve design.
Sleeving is a method used to repair defective steam generator tubes to keep them in service. Typically, sleeves were designed with sleeve-to-tube joints that were either welded, brazed, rolled, and/or hydraulically expanded. However, these joints created another set of problems in the tubes, which often required performing post-installation stress relief. Therefore, the focus of sleeve design shifted to repair methods that would produce minimal residual effects on the parent tube. The result was the electroplated sleeve, an electrodeposition of conventional (large-grained) nickel (> 99% pure) on the inner surface of the tube. This sleeve, while not a complete structural repair, required no welding or deformation of the parent tube, yet provided the leak limiting benefits of previous sleeve repair options.
The Electrosleeve" represents the next generation of steam generator tube repair. It is an electroformed sleeve consisting of ultra-fine-grained nickel electrochemically deposited on the inner surface of a degraded tube to form a structural repair. The electrochemical deposition of nickel provides a continuous metallurgical bond between the tube and sleeve that eliminates all leak paths and crevices. The nickel utilized in the Electrosleeve" repair process, once deposited, is referred to as a nanostructured material. Nanostructured sleeve material has a grain structure with mean diameters of less than 300 nanometers (nm). This grain structure provides unique properties including enhanced corrosion and wear properties along with improved hardness, strength, ductility, and thermal stability that exceed those of conventional nickel electroplating. The grain structure (-250 grains /0.001 inch) produces the enhanced strength while the microalloying sets the thermal stability.
The Electrosleeve" provides a structural, leak-tight seal while minimizing residual stresses on the parent tube. Because the electroformation of the nickel imparts low stresses on the prrent tube, installing the sleeve does not deform the parent tube or change the microstructure; thus, the design does not require post-installation stress relief. In addition to maintaining the tube in service, the continuous metallurgical bond maintains the heat transfer area over the length of the sleeve. The strength and FRAMATOME TECHNOLOGIES, INC.
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I FTl Non-Proprietary installation also provide a free path through the sleeve for future needs. . Thus, the structural repair using an Electrosteeve" minimizes thermal-hydraulic losses and maximizes heat transfer performance.
"8 Electrosfeeve* is a registered trademark of Ontario Hydro Technologies, Inc. (OHT).
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3.0 BACKGROUND
Recirculating steam generators (RSGs) were typically fabricated with tubing made of mill-annealed nickel-chromium-iron (Ni-Cr-Fe) Alloy 600. The cracking of low- l temperature mill-annealed (LTMA) tubes due to high tensile stresses was identified in the late 1970's and early 1980's. Primary water stress corrosion cracking (PWSCC) occurred in low row U-bends and in the expansion roll transitions of tubing expanded l into the tubesheet. U-bend stress relief [13.9] and preventive shot peening [13.8] were l
develeped for plants identified as having a high potential for PWSCC. However, the French and Belgians reported that shot peening was not as effective when performed after the plant was in operation as when performed prior to the plant operation [13.10].
The decrease in performance was attributed to the presence of small cracks that
)
initiated during operation prior to the peening operation. Thus, other repair methods i were required to keep tubes in service.
Subsequently, plants began experiencing degradation by outside diameter stress i corrosion cracking (ODSCC) at both roll and explosive expansion transitions, in addition, 1 secondary side corrosion began to emerge at the tube support plate (TSP) intersections.
The types of tubes experiencing various degradation modes included high-temperature mill-annealed (HTMA) tubes as well.
Identification of these degradation mechanisms led to the development of numerous sleeve designs in the industry. The overall objective of these sleeve designs was to provide a structural repair by spanning the degraded region of the tube. The typical sleeve design was the tube-within-a-tube concept, with structural joints formed by various means at each end of the sleeve. The joints required permanent deformation of the sleeve and tube for welded (leak-tight) or mechanical (leak-limiting) sleeve installation. The tube deformation produced residual stress in the tube. In addition to the deformation residual stresses, welded joints produced residual stresses in the heat-affected zone. These joints had to be stress relieved to reduce the potential of any type of stress corrosion cracking (SCC). For a mcchenical joint, stress relief can negate the leak-limiting capability of the joint; therefore, some residual stress must remain to ensure the integrity of the joint.
Since the originalinstallation of many of these sleeves, some tubes have been found locked (restrained) at the TSPs due to mechanisms such as the buildup of corrosion products. This impairs the ability to perform an effective stress relief (approximately 1400*F for five minutes) of tube-sleeve joints. In some of these instances, rather than FRAMATOME TECHNOLOGIES, INC.
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FTl N:n-Proprist:ry reducing stress, stress relief could lead to either localized yielding or buckling of the tube (Iow yield stress at 1400 F) or a redistribution of residual stresses. If the joint yields axially because the thermal growth caused by the stress relief is restrained by the locked tube support, the thermally induced deformation will result in a residual tensile stress as the temperature from the stress relief heater returns to ambient.
In 1993, Laborelec-Belgium confirmed the effect of residual stresses with an intensive SCC testing program of steam generator tubes repaired with welded sleeves. This study evaluated all types of welding: tungsten inert gas (TIG) overlap or fillet, laser, and kinetic
[13.43). The study concluded that the risk of develocing new cracks in the parent tube at the upper joint of a welded tube-sleeve assembly was high for a tubing material highly susceptible to PWSCC. The risk was a concern because of the circumferential orientation of the new cracks and the difficulty of detecting them in the complex geometry of the joint.
To eliminate these concerns, Framatome Technologies, Inc. (FTI) in cooperation with OHT, developed the Electrosleeve". The process deposits a layer of nearly pure nickel (with traces of phosphorus) on the inside diameter of degraded tubes to provide a structural, leak-tight repair that requires no stress relief. The Electrosleeve" will span defects within the tube at the baffle plates, the tube support plates, at or near the secondary face of the tubesheet, or in free-span regions of steam generators. Further information on the technology can be found in Reference 13.66 where it is concluded that homogenous nickel-phosphorus alloys displayed corrosion resistance superior to their crystalline counterparts. Comparisons of corrosion performance indicate that Ni-P alleys are cuperior to pure nickel and to 316L stainiess steel at high (> 0.45 volts) potential.
Electrodeposition of pure nickel, a stable material, is a precursor technology closely related to Electrosfeeve* that, as documented by Dini [13.67], has been discussed and researched extensively. (This reference provides a comprehensive background on Since 1985, processes, testing, and troubleshooting in electrodeposition technology.)
Framatome (Europe) has been using nickel electroplating as a remedial technique to repair steam generator tubing with PWSCC. The primary goal of this technique is to arrest the degradation process of the tube wall by depositing a Icyer of nickel plating capable of bridging PWSCC in a steam generator tube. This process has also been to seal the roll transition area to inhibi'. or prevent the initiation of PWSCC. Some of these repairs have been performed over through-wall flaws. The through-wall flaw was defined by observed leakage.
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^
The Electric Power Research Institute (EPRI) has documented the use of electroplated nickel to successfully repair European steam generator tubes affected by PWSCC
[13.12]. From 1985-1992, Framatome successfully installed electroplated nickel in more than 1,000 tubes at various plants in Europe [13.39]. The repair method has been successfully used to prevent cracking as well as to repair existing 100% through-wall cracks within the parent tube. Greater than 95% of these electroplat .-j nickel sleeves remained in service for the life of the steam generator, with no corapromising l degradation or cracking. (A small percentage of tubes have been plugged since the first l large commercial application in 1988 at Doel-2, but none were due to any defect or degradation of the nickel sleeving.) !
To evaluate the performance of the electroplated nickel skeves, two tubes with through-
)
4 wall cracks were pulled from Doel-2 after nine months and two years of operation, respectively. The tubes we.re ultrasonically tested and destructively examined (Figure 3.1). The results verified that the cracking did not propagate into the nickel sleeve.
(Reference 13.56 shows the metallographic sections of these tubes.)
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l FTl Non Propristcry FIGURE 3.1 ELECTROPLATED TUBES PULLED FROM DOEL-2
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Tube 21/59 pulled after 2 years of service FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary ,
- i. t At the EUROCORR '96 conference, Laborelec representatives presented additional
) information about the Belgian experience on repairing steam generator tubes [13.69].
] The operating experience of plants with nickel-plated tubes compared favorably to other sleeve repair techniques (mechanical, welded, and laser-welded sleeving). .
- In North America, operating experience with nickel plating has been equally favorable, r The Framatome nickel-plating technique was first used in the U.S. at Baltimore Gas &
7 Electric's Calvert Cliffs Unit 1 in 1994 (13.37), where one hundred eighteen (118)
[ pressurizer heater nozzles were plated to a thickness of 8 mils. The same technology j was used again in 1998 at Florida Power & Ught's St. Lucie Unit 1 to plate one hundred 7
).
twenty (120) pressurizer heater nozzles to a thickness of 10 mils. A 10-mil layer of !
nickel was qualified to seal a 1/2-inch through-wall crack for more than 120 fatigue i cycles.
1 i
OHT successfully installed the next generation of nickel-plated sleeve, the i
Electrosleeve*, in various steam generators in the Pickering plants. Initially, the sleeves b were installed as part of the development phase, and the parent tubes were either plugged or pulled for evaluation. In May 1994, fourteen (14) electrosteeves were j installed in Pickering Unit 5 and left in service. After one year of operation, the j electrosleeves were inspected. The results showed no degradation or significant j changes due to the environmental conditions of operation. As a result, the Atomic
- Energy Control Board (AECB) granted authorization to leave the electrosfeeves in l operation. As of August 1998, all fourteen (14) tubes were still in operation.
I
- in 1995, FTlinstalled nine electrosfeeves in a steam generator at Oconee Unit 1. These i sleeves were installed as part of the development program to gain experience with the !
1~
- sleeving equipment and field procedures. All of the sleeves were successfully installed
- as confirmed by ultrasonic testing (UT). Since the Electrosfeeve* was not licensed in the U.S. at that time, these tubes were subsequently plugged. Table 3.1 provides a
- summary of Framatome nickel plating and Ontario Hydro electrosfeeving experience in operating steam generators.
- Two U.S. uJiities have independently hired consultants to provide additional technical
- review of the Electrosleeve* qualification program. These consultants participated in p
. technical presentations and received copies of the topical report (December 1995 and
] March 1996). Both consultants found the electrosleeving process acceptable.
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FTl N::n-Pr:prietzry The term "Electrosleeve*" specifically refers to nanocrystalline microalloyed nickel that is electrochemically deposited on the steam generator tube. Electrosleeving material has the necessary strength and thermal stability to qualify as a structural repair. Nickel plating refers to the process currently used in Europe that utilizes a thin (~0.004 inch) layer of nickel to either prevent PWSCC or to inhibit further growth of existing PWSCC.
Nickel plating uses high purity nickel, but the material does not have nanocrystalline structure and is not microalloyed for thermal stability. Nickel plating, as currently used in Europe and adapted for pressurizer heater nozzles, is not qualified as a structural repair.
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FTl Non-Proprietary TABLE 3.1 '
STEAM GENERATOR NICKEL PLATING AND ELECTROSLEEVING EXPERIENCE PLANTNENDOR YEAR TUBES TUBES ACTIONS COMMENTS NI-PLATED IN-SERVICE TAKEN Doel-2 1985 10 1 3 plugged,3 pulled, R&D field baseline program; large through-wall cracks; some leaked due to micro nickel pits; lab (Framatome) and 3 repaired (1990) exam results: bridged cracks, no internal corrosion Doel-2 1986 81 56 13 plugged. 3 pulled. R&D field baseline program; large through-wall cracks; some leaked due to nickel hardness (Framatome) and 9 repaired (1990) (nickel cracked over Alloy 600 cracks > 0.39 inch) i Doel-2* 1988 33 33 First commercial application; large through-wall cracks; visual inspections in 1988,1989,and ,
(Framatome) 1990 with a 40X baroscope; conclusions: no leaks, no visible corrosion, no erosion Doel-3*'" 1988 11 11* Large through-wa!! cracks in parent tubing: UT inspected in 1988 (baseline), 1989,1990,and (Framatome) 1991; conclusion: cracks have not propagated into nickel plating !
Ringhals-3'3"* 1990 10 10* UT (long. and circum.) baseline in 1990 to qualify UT relative to ET; UT 1991 and 1992; (Framatome) conclusion: cracks have not propegated Doel-2'* 1990 345 337 8 plugged (not related Local re-expansion (2 inches) in the tubesheet entirely protected by Ni-plating on 4 inches (2 mils (Framatome) to nickel plating) thick); visual and ET inspected in 1990 (baseline)
Tihange-2* 1992 602 602m Plating in parallet on all three SGs (Framatome)
Pickering-6 May 1 0 Trial run of Electrosleeve* Process not approved yet by AEC8 and MCCR so tubes plugged.
(OHT) 1993 Pickenng-8 October 9 0 9 electrosleeves installed in BOS and 8011; process not approved yet by AEC8 and MCCR so (OHT) 1993 tubes plugged.
Pickering-1 Nov 8 0 8 electrosfeeves installed in 3 tubes; 3 sleeves unacceptable due to disbonded areas. Process not (OHT) 1993 approved yet by AEC8 and MCCR so tubes plugged.
Pickering-5 May 46 14 4 tubes pulled 90% electrosfeeves acceptable. 28 of 46 sleeves installed in mockup iocated on SG platform.
(OHT) 1994 As of August of 1998, all 14 electrosleeved tubes in SG are still in operation.
Tihange-2 1993 565 565* On all three SGs. More than 500 tubes in 1993 and 118 tubes in 1995 electroplated .
(Frematome) 1995 118 118*
Tihange-2 1996 600 600" 600 tubes electroplated in May 1996 outage. SG change-out performed in 1998.
(Framatome) !
i' Oconee-1 1995 9 O All 9 electrosfeeved, 9 electrosleeves anstalled in SG tubes, process not yet approved by NRC. 9 tubes plugged.
(FTl/OHT) then plugged NOTES:
(1) Crack sizes at Doel-2: 0.2 to 0.3 inch; frequently up to 0.5 inch (5) Crack sizes at Tihange-2: 0.35 to 0.47 inch (2) Crack sizes at Doel-3: 0.4 inch (6) Steam generator replacement was made at Doel-3 in 1993, in Ringhals-3 in 1995 & in Thiange-2 in 1998.
(3) Crack sizes at Ringhais-3: 0.1 to 0.2 inch (7) Tubes in service refers to the remaining duration of service until SG change-out.
(4) No cracks; high work hardened area FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary h 4.0 DESIGN CRITERIA i ,
a The design criteria used to evaluate the Electrosleeve" are detailed in this section. !
These criteria define the design and qualification requirements of the Electrosleeve".
l l 4.1 Qualification Methodology i l t
l The first step in qualifying the Electrosleeve" for use in repairing degraded pressurized :
1 i water reactor (PWR) steam generator tubing involved specifying the requirements, '
! regulatory or others, that are imposed on the sleeve in its installed condition. If the
! current standard did not apply explicitly to the Electrosteeve*, then it was still followed l l as a guideline. Next, the material properties of the Electrosfeeve" were determined per the ASME Boiler and Pressure Vessel Code and the ASTM guidelines. For this topical report, the term "ASME Code" refers to the ASME Boiler and Pressure Vessel Code (ASME B&PV). The terms may be used interchangeably.
The following methodology was used to qualify the Electrosleeve*:
- Define the design requirements for the steam generator tube repair,
- Develop the applicable material properties per the requirements of the ASME i Code, Section lil [13.2], ;
- Prepare a design analysis of the tube repair per the requirements of the ASME Code, Section 111 [13.2], and
- Evaluate the tube repair to the requirements of the Nuclear Regulatory l Commission (NRC) Draft Regulatory Guide 1.121 (RG 1.121) (13.6].
The design requirements for the Electrosleeve" are defined in Section 4.2.
l The tests done to establish the material properties are presented in Section 6.0. The ;
material properties were developed per the following methodology:
i
- Determine the allowable stress intensity value (S,n) per the methodology of ASME l Code, Section Ill, Apperidix lil-2110(b). 1 i
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FTl Non-Propristrry
- Perform tensile testing per ASTM E8 and E21 [13.13,13.14],
- Perform creep testing per ASTM E139 [13.22),
- Perform bend testing per ASTM E290 [13.20], and
- Verify the thermal stability of the electrochemically deposited nickel at the design temperature of 650*F.
- Determine the design fatigue curve for tha elecimchemically deposited nickel and apply the appropriate ASME Code, Senion til safety factors (2 on stress, 20 on cycles).
- Determine the appropriate fatigue strength reduction f actors applicable to the "as-formed" surface finish.
- Determine the additional physical properties associated with the ultra-fine-grained nickel material.
The design analyses for the Electrosleeve" were performed using ASME Code, Section ill as a guideline and followed the methodology outlined below:
- Determine the minimum required sleeve thickness using ASME Code, Section Ill, Subsection NB as a guide. The design stress intensity value determined in Section 6.0 was used.
- Determine the structuralloading associated with the tube repair including repair of locked tubes and tubes with 100% through-wall defects. Evaluate the structuralloads and installed sleeve configurations per the stress and fatigue limits in ASME Code, Section Ill.
- Determine the minimum sleeve attachment length using the experimental analysis techniques of ASME Code, Section lit, Appendix 11.
Additional qualification evaluations included:
- Flow-leduced Vibration (FIV),
- Corrosion (Primary and Secondary Side Environments),
- Nondestructive Examination Techniques, and
- RG 1.121 Evaluation.
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! FTi Non-Proprietary i
- The purpose of this report is to show that the Electrosteeve" is qualified to structurally repair the RSG tubing designs in service today. Qualification testing and/or analysis was l I
performed on three sizes of tubing (11/16",3/4", and 7/8"). In the cases where a '
bounding condition and size were determined, the results were expanded to encompass the other sizes of tubine. Material test results are presented for 1/2" and 5/8" size tubing along with results for.11/16",3/4", and 7/8" Alloy 600 tubes. ;
l l 4.2 -Design and Qualification Requirements i 3
The'electroformed sleeve is designed for application in PWR stearn generators with .
I
- . tubing having the following nominal dimensions
- i l
I e 11/16" OD x 0.040" wall, l
- e 3/4" OD x 0.042"/0.043'/0.048". walls, and j e 7/8" OD x 0.050" wall. l A sleeve has also been designed (described in a separate topical) for once through steam generator (OTSG) 5/8" OD x 0.037" wall tubes.
i !
l
- The operating conditions of the RSGs form the design basis for the operating conditions !
~
of the sleeve. The sleeve must meet the following design requirements:
- Span defects in the parent tube at top of tubesheet (TTS) and TSP locations, e Provide a structural repair for the parent tube at these locations, j e' Provide a leak-tight seal for primary to secondary side water, and
,- e Minimize residual stress in the parent tube to minimize the possibility of primary and secondary side intergranular stress corrosion cracking (IGSCC).
i
{ = The design and qualification of the sleeve utilized applicable industry codes and i-standards as summarized in Table 4.2.1. The ASME Code is the basic governing document for numerous aspects of the design including determining test loads,
- performing structural analyses, procuring material, establishing the sleeve procedure qualification, and preparing the sleeve procedure specification (SPS) (Section 10.0).
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FTl Non-Propristcry TABLE 4.2.1
SUMMARY
OF APPLICABLE CODES AND STANDAHDS m APPLICATION CRITERIA Structural Design of the Sleeve ASME B&PV Code,
- Sleeve / Tube Loads Section 111 [13.21
- Analyses Sleeve Plugging Limit NRC Draft Reg. Guide 1.121(13.61 ASME B&PV Code, Material Procurement Sections 11 and til [13.1,13.21 Section XI, Code Case N-569 [13.4]
ASME B&PV Code, Electroformed Sleeve Material Section XI, Code Case N-569 [13.4]
Qualification ASME Standards [13.13-13.28] ~
ASME B&PV Code, Sleeve NDE Sections V and XI [13.3,13.4]
Code Case N-504-1 [13.7)
Section XI, Code Case N-569 [13.4]
Procedure Qualification EPRI Checklist [13.11]
NOTES:
(1) The ASME B&PV Code Section ill does not address nanocrystalline nickel material. Therefore, these Code sections were followed as a guideline for developing the Electrosteeve" FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary At present, nickel is not identified as an approved materialin the Code for ASME, Section Ill, Class I, systems. However, electrodeposition has been identified in ASME,Section XI, Code Case N 569, as a tube repair method. Therefore, material testing (as recommended by Code Case N-569) has been performed per the guidance of ASME, Section 111 and ASTM to establish material design properties. Similarly, the sleeve procedure qualification has been performed following the guidance of ASME,Section XI, Code Case N-569.
4.3 Sleeve Design Conditions The design and operating conditions for the RSG are imposed on the sleeves. The tables in Appendix A detail the operating conditions for which the sleeve has been designed.
Analyses and tests were performed for the worst-case bounding conditions. The sleeve has been designed to encompass the following types of steam generators:
- Westinghouse Models D, E, F, 33,44,51,and
+ Combustion Engineering (CE) Models 67, 80, 3410, Arkansas Nuclear One Unit-2 (ANO-2), and Ft. Calhoun.
t Design transients for steam generators were used to establish loading transients for the sleeve. Section 8.0 discusses how these transients were used to establish the sleeve loading transients and cycles. Operating pressure and thermalloading ranges were used to establish the worst-case conditions, considering both unlocked and locked tube conditions. For the locked tube condition, the tubss were considered Iccked at all tube support plates, which is the most conservative assumption.
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- 5.0 SLEEVE DESIGN i
The physical design of the Electrosteeve"is described in this section. A brief description of the installation and a list of the key process parameters are also included.
5.1 Design Description An electroformed sleeve is an electrochemical deposition of ultra-fine-grained nickel material on the inside diameter of a degraded steam generator tube. Table 5.1.1 summarizes the dimensions of an installed Electrosfeeve" in the RSG designs. Because the thickness of the sleeve depends on the rate of deposition, the actual sizes of
, installed sleeves may vary. If the installed sleeve does not meet the target design parameters, justification or testing must be performed as required to leave the sleeve in service.
J- TABLE 5.1.1 STEAM GENERATOR TUBE AND ELECTROSLEEVE"
. NOMINAL DIMENSIONS j TUBE NOMINAL SLEEVE STEAM OD TUBE WALL SLEEVE WALL LENGTH SLEEVE GENERATOR (INCH) (INCH) (INCH) 1 (INCH) LOCATION i Westinghouse F 0.G88 0.040 { j'* Tubesheet (TS) '- #
I Midspan, TS? m 6 Westinghouse D, E 0.750 0.043 V f>*
{ TS Midspan, TSP _ ,
CE SYS 80 0.750 0.042 N g fe' TS -
)
Midspan, TSP , l All CE SGs 0.750 0.048 E (except CE SYS 80)
{ ]" TS r Midspan, TSP L ;
Westinghouse 33, 0.875 0.050 TS '- M 44, & 51 { ]"
Midspan, TSP FRAMATOME TECHNOLOGIES, INC. ,
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FTl Non-ProprietEry For the purposes of qualifying this repair process, any reference to the length of a sleeve refers to the length between the tapered transitions including the minimum bond lengths.
The tapered transitions are not considered part of the pressure boundary region of the sleeve (Figure 5.1.1).
FIGURE 5.1.1 ELECTROSLEEVE" PRESSURE BOUNDARY l
l ALLOY 600-+
PARENT TUBE
>J O
\{1 ELECTROSLEEVE
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FTl Non-Proprietary Figure 5.1.2 depicts a typicalinstalled Electrosfeeve". The sleeve is designed to repair tubes by spanning the degraded region. The sleeve can be installed at any straight section of tubing including the expansion transitions, all of the TSP intersections, and the free-span areas. The electroformed repair is leak-tight because the nickel is bonded to the tube.
l l
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FTl Non-Prepristiry FIGURE 5.1.2 l TYPICAL RSG TSP AND TS SLEEVE ARRANGEMENT l
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1 FTl Non Proprietary The material used for the sleeve is high purity nickel (>99.5%). Nickel has excellent bonding characteristics with the Alloy 600 base metal. The Electrosteeve" composition does not release activated species such as cobalt and has excellent material properties, including ductility, as discussed in Section 6.0 of this report.
The design enables the sleeve to act as the primary pressure boundary and maintains its structuralintegrity under operatirsg and accident conditions, installation of the sleeve has no effect on the parent-tube material microstructure. Residual stresses generated in the tube are low, thereby eliminating post-installation stress relief.
5.2 Process Description !
The process steps for installing an Electrosleeve" are summarized below with a more detahed description presented in Section 10.0.
- Tube marking and position definition
- Mechanical tube cleaning
- Electrosfeeve" probe positioning f
. r- 9 c.# .
~
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Electroforming ( yc,e
{ ge,e Flush with DI water e Probe removal e Nondestructive Examination (Ultrasonic, Eddy Current)
After the tubes are marked and the position defined, the tubes are mechanically cleaned with a vacuum-assisted rotating scraper or hone. The cleaning removes loose oxides in order to reduce the level of radioactive contamination of the waste streams. A specially designed probe is then installed at the desired location and remains in place for the following steps:[ ]e. nickel forming. Acid j cleaning and activation prepares the tube surface by electroetching or " dissolving" the surface oxide layer to improve the contact and adherence of the nickel layer to the tube inside diameter (ID). [ I FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propristcry C 3 C ,e.
' As shown in Table 5.2.1, a number of parameters are monitored and controlled to ensure proper sleeve installation. In addition, a witness tube (WT) located on the steam generator platform can be electroformed in parallel with the actual steam generator tubes. The WT can then be examined to verify correct electroforming has occurred in the tubes.
TABLE 5.2.1 PROCESS VARIABLES RECOMMENDED RECOMMENDED DATA PARAMETER STORAGE FREQUENCY MONITORING
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, FTl Non-Proprietary 6.0 DESIGN VERIFICATION - MATERIAL PROPERTIES The Electrosleeve* is a nanocrystalline material installed in situ on the tube inside surface using an electrochemical deposition process. This section describes the tests performed to establish the properties of the Electrosleeve" material. ASTM and ASME standards were used in the development and qualification of the material. The material properties of the electrochemically deposited nickel material are independent of the parent tube inside diameter and thickness as shown by supporting data presented in the following sections. For the purposes of this section and other design j verification sections of this report, a specimen is defined as a tube with an l
Electrosteeve" installed on the inside diameter.
I 6.1 Tensile Strength i j
l h,c b,e l
, Tensile tests were performed at[ ] temperature [ Jto j determine yield strength, ultimate strength, and elongation of the electrochemically l deposited nickel material.[ Ispecimens were tested to ensure l
\
statistically significant results. FTl tested four sizes of Alloy 600 tubes:
. 5/8" OD x 0.034" wall, e 3/4" OD x 0.043" wall,
Additionally, OHT performed tensile tests of ultra-fine-grained nickel material deposited
- in 1/2" OD x 0.049" wall Monel 400 tubes [ ].h C'
, The test specimens were fabricated as shown in Figure 6.1.1 and tested per ASTM procedures [13.13,13.14]. The results of the tensile tests were tabulated for each of 4
the temperatures tested by FTl and co.,bined with the results of OHT. These data were evaluated per the ASME Code Section ill to establish the design properties for 1
the nanocrystalline nickel material at a range of temperatures, including operating i temperatures.
FRAMATOME TECHNOLOGIES, INC.
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- _ _ _ . _ - - ~ - " - - - - - - - - - - _ . , _ _ _ _
FTl Non-Proprietary FIGURE 6.1.1 MATERIAL TEST SPECIMEN DESIGNS"1 TENSILE. FATIGUE. YOUNG'S MODULUS SPECIMENS l
ALLOY 600 4- ELECTROSLEEVdy TUB U)
Note 2->
w eeswwgssawe wsA y AiewweseistMAR
/
N N
/ mv*** ***#e Masswvs9miwe avg j Nw T
[
- g L
NOTES:
(1)
Electrosteeves were installed in the following tube sizes for testing:
5/8" OD x 0.034" wall 3/4" OD x 0.043" wall 3/4" OD x 0.048" wall 7/8" OD x 0.050" wall (2) Nominal sleeve-to-tube bond length:
5/8" OD tubes: C E 3/4" and 7/8" OD tubes: [ ]'t FRAM ATOME TECHNOLOGIES, INC.
62
- FTl N
- n-Proprietary The ASME Code, Section lll minimum design strength values at various temperatures are tabulated in Table 6.1.1. The typical yield and ultimate strength versus i temperature curves are shown in Figure 6.1.2.
TABLE 6.1.1 ASME CODE. SECTION 111. MINIMUM DESIGN STRENGTH VALUES
[ Experimentally Determined per References 13.2 and 13.4)
Temperature S,w Sm S.
('F) (ksi) (ksi) (ksi)
T -ff,*2 L J FIGURE 6.1.2 TYPICAL TENSILE PROPERTIES VS. TEMPERATURE I ld, s,c,e l
L d ,
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FTl Non Pr:pri:t:ry l
6.2 Modulus of Elasticity
)
j specimens were tested to determine the modulus of elasticity for the '
{material per ASTM procedure [13.15]. Of those, FTl tested four Alloy 600 tube sizes with installed electrosleeves:
- S/8" OD x 0.034" wall,
. 3/4" OD x 0.043" wall, e 3/4" OD x 0.048" wall, and
. 7/8" OD x 0.050" wall.
The specimen design is illustrated in Figure 6.1.1.
b The specimens were loaded uniaxially with load and strain measured at( 3 distinct points within the elastic region. A linear regression was performed on the data points.
The loading and regression process was repeated twice and averaged. The same specimen was then heated to a different temperature and the loading was repeated.
Modulus of elasticity (Young's Modulus) testing {
} Io,c,e, The testing showed that the modulus of elasticity for the electrochemically deposited nickel material does not depend on the size of the tube. Figure 6.2.1 presents the typical testing results for Young's Modulus versus temperature for all tube sizes. The variation in the average testing result for Young's Modulus versus the ASME Code value for Nickel 201 (Ni 2oil over the typical RSG operating temperature range (70*F to :
625'F) is approximately 6%. These results show the Young's Modulus value for Ni 2oi is representative of the Electrosleeve" nanocrystalline nickel material. Thus, the Young's Modulus of Ni2 oi i s used [13.2].
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4 FTl N:n-Proprl:ttry 1
FIGURE 6.2.1
.El.ASTIC MODULUS VS. TEMPERATURE i
~~) % C,
- dt j
f "1
1
.L J i
i i
i-5 ,
i i
i 4 ..
i-FRAMATOME TECHNOLOGIES, INC.
6 .-. .
FTl Non-Propristrry 6.3 Ductility / Adhesion The bonding strength of the electrodeposited nickel to the tube generally depends on sufficient cleanliness of the parent tube material and an adequate nickel pre-film layer.
A vacuum-assisted rotating and translating hone or scraper is used to clean the tube surface. An electrochemical surface activation step follows the mechan. cal cleaning step to remove any remaining oxides { ]the tube material. The I
exposed clean tube surf ace is immediately pre-filmed with nickel to prevent the surf ac from passivating before the sleeve is installed. Process controls and monitoring of variables, such as applied current and voltage, provide assurance that the process cleaning and pre-filming are within specified ranges.
The Alloy 600 cleaning / surf ace activation process was qualified using furnace-oxidized tubing. The activation step alone was then used to clean the surface of pulled steam generator tube samples to verify that this step, without mechanical cleaning, would remove the tube surface oxides. The activation and pre-film steps are discussed in detailin Section 10.0. UT inspection verified that the electrosleeves were 100%
bonded when inspected by UT.
Ductility is a controlled material property dependent on the deposition parameters. To verify the ductility and adhesion of the electrochemically deposited nickel material,
[ ] specimens were tested per ASTM procedure [13.20,13.21].
Specimens were f abricated by electrosfeeving e, a tube and then cutting it longitudinal in half. The specimens were then bent over a[ ]Cemandrel with the nickel sleeve outside diameter in tension, as shown in Figure 6.3.1. After being bent, the sleeves were visually inspected for areas of separation and cracking. None of the qualification specimen installed per normal process procedures showed any defects. Therefore, ductility and adhesion characteristics of the electrochemically deposited nickel mate were verified and deemed acceptable (Reference 13.4). The ductility of the electrochemically deposited nickel material is further demonstrated by the ductile f ailures the material exhibited during the tensile tests (Section 6.1), creep tests (Section 6.6), and burst tests (Section 6.7).
FRAMATOME TECHNOl.OGIES, INC.
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i l
FTl Non-Proprietary
}
FIGURE 6.3.1 REVERSE BEND SPECIMEN I
l l
l '
%f -
-g i N/ .
+
l f
i I
\ .
l -__
The above illustrations - from left to right - show a drawing of the reverse bend test set-up j cnd a photograph of a reverse bend specimen, t
i i
1 i
FRAMATOME TECHNOLOGIES, INC.
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4
FTl Non-Propristcry 6.4 Fatigue Life The work presented here represents the only documented systematic study of the fatigue performance of nanostructured materials. A comprehensive review the literature as to how grain size (i.e., 210 micrometers ( m)) affects the fatigue performance of conventional nickel and nickel-based alloys found that as g decreased, the resistance to fatigue crack initiation increased as did the f atig propagation rate.
These results indicate nanostructured materials would be expected to display high cycle fatigue performance (initiation controlled process) and possibly s I
compromised low cycle fatigue resistance (propagation controlled process).
6,c
]electrosleeved tube specimens Fatigue testing was performed on[ ll d to establish a design f atigue curve. FTl tested four Alloy 600 tube sizes with insta electrosfeeves:
. 5/8" OD x 0.034" wall,
. 3/4" OD x 0.043" wall,
. 3/4" OD x 0.048" wall, and
. 7/8" OD x 0.050" wall.
In addition, OHT performed fatigue testing on thirty (30) electrosleeved tube specimens using 1/2" OD x 0.049" wall Monel 400 tubes.
Specimens with the as-plated inside surface condition and specimens inside surf ace were tested. All of the specimens were machined on the OD to rem the tube and the sleeve OD was polished.
Fatigue testing was performed at room temperature in accordance with AST The testing was performed with fully reversed strain, or procedures [13.16 - 13.19).
load, on each specimen (R =-1) [13.19] from full axial tension to full axial compression. Ranges of frequencies were tested to encompass the expecte subjective conditions an actual sleeve would experience.
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4 FTl Non-Proprietary
. Strain amplitude data for each test specimen were tabulated, multiplied by the elastic modulus to convert to stress, and plotted against the cycles-to-failure. The stress versus cycles-to-failure values for all plated specimens were fitted to a curve obtained by applying a least squares fit. ASME Code safety factors were applied to the normalized data. Combining the results of both of these adjusted curves resulted in a single, bounding design fatigue curve. Figure 6.4.1 illustrates the fatigue data for the Electrosleeve" material using a modulus of elasticity [ ].d
, FIGURE 6.4.1 ELECTROSLEEVE" MATERIAL FATIGUE TEST DATA '
~
f l b, c,d,e.
i i
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i l
i b
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FTl Non-Propristcry Fatigue testing of the Electrosleeve" material was conducted at both room and elevated temperatures. Table 6.4.1 shows the material maintains its fatigue resistance in the temperature range tested.
l TABLE 6.4.1 1 FATIGUE TESTING RESULTS STRAIN AMPLITUDE CYCLES TO TEMPERATURE
(%) FAILURE
('F) m b,c, d C
J L
6.5 Thermal Stability Thermal stability of the Electrosteeve" material is important because of long-term with (forty years) thermal exposure to operating temperatures
'ipset excursions up to the design temperature of 650 F. The principal strengthening mechanism for the Electrosleeve* materialis the Hall-Petch mechanism (i.e., grain refinement) [13.60,13.611. Previous studies have shown that nanocrystalline nickel may exhibit a driving force for grain growth several orders of magnitude greater than that for conventional polycrystalline nickel materials [13.62]. Therefore, the primary thermal effect on ths Electrosteeve" material would be a reduction in mechanical strength, b,c,cl The effect of annealing time [ ]on the Vickers Hardness Measurements (VHN) of the Electrosleeve" material was determined. Electrosfeeve material with the following alloys were evaluated:
. Nanocrystalline pure nickel' C,0.
e Nanocrystalline nickel [ ], and
. Nanocrystalline nickel [ ]?'E FRAMATOME TECHNOLOGIES, INC.
6-10
l i
FTl Non-Proprietary bC g
6,c
{ ]electrosleeved tubes were used to fabricate [ ] test specimens
, (three fabricated from each tube). Figure 6.5.1 shows the test specimen configuration. Each test configuration used five test specimens. The hardness values reported are at the mid walllocation of the Electrosteeve" material. Each data point represents a minimum of four readings from each of the five specimens. VHN values
, are in accordance with ASTM procedure [13.23]. The Electrosfeeve" materials used l had a plated hardness { ].d 8 i
l l
FIGURE 6.5.1 MATERIAL TEST SPECIMEN DESIGNS l l
THERMAL STABILITY SPECIMENS l
SLEEVE HARDNESS I MEASURED MIDWALL l j
I
/ A l
__ M 1/2" V
TUBE FRAMATOME TECHNOLOGIES, INC.
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FTl N n-Pr pristrry Figure 6.5.2 sh ws that pure nanocrystalline nickel decays rapidly [
within the first few hours of annealing. This reduction is
[
[
representative of rapid grain growth leading to a resultant grain size consistent with that of conventional p lycrystals (i.e.,10 - 30 pm). The nanocrystalline nickel
] dkosphorus [ hows no evidence of hardness decay containing [
within the total test period evaluated (i.e., approximately 10 months). The influence of minor solute additions on retarding grain growth in nanostructured nickel was previously documented [13.62,13.63] and attributed to:
. Solute drag effects on the grain boundaries, e Reduction in grain boundary (GB) energy from solute segregation, and
. Zener drag effects associated with the possible formation of nano-precipitates
[13.62,13.63,13.74].
FIGURE 6.5.2 ELECTROfLEEVE" THERMAi. STABILITY TEST RESULTS AT 650 F c
l~ )l n
a n ..
3 -
n n --
n n
.. il "h 2:
_h
n -
.. It g ,h ll f
I ..
e g ,
II I *
- : := .. : "9 (, j 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E 4 Y* I",*{*ku SQ l+ Ni-(0.0% P) A Ni- 'P) E Ni- . P) l L J L I FRAMATOME TECHNOLOGIES, INC.
6-12
FTl Non-Proprietary The margin of safety for the thermal stability of the Electrosleeve" material was determined using differential scanning calorimetry (DSC) measurements. Figure 6.5.3 is a typical DSC scan for the Electrosleeve" material. The DSC scan detected an exothermic peak at approximately 580'C (1076'F). The results of the DSC analysis shown in Figure 6.5.4 are in the form of a Kissinger plot (13.64]. In the peak temperature (T,) range of 560 C - 580 C (1040"F - 1076'F) with heating rates ranging from 30 - 100 K/ min., the shifts in the exothermic peaks are shown to yield an apparent activation energy of 59 kcal/ mole.
FIGURE 6.5.3 c, ELECTROSLEEVE" [ ~] VALUES ( )
C,8 f 7 L l FRAMATOME TECHNOLOGIES, INC.
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FTl N:n-Prrpritt:ry l
FIGURg 6.5.4
{ ] ACTIVATION ENERGY
-8.5 I .' l l
'O=-59 'kcal/ mole a
i ,
'n -a E --
j '.9.5 - ,
.E ,
-10.5 l l l l 0.00115 0.00116 0.00117 0.00118 0.00119 o.0012 1/rp, K d
1 P
By using DSC, Mehta, et. al., evaluated the thermal stability of a (Ni - 1.2 wt% P) alloy having an average grain size of 10 nm [13.65]. The exothermic peak was found to be ;
360'C (680'F) and the activation energy was found to be approximately 52 kcal/mol.
These values were attributed to the onset of rapid grain growth associated with a i
transition from' solute drag as the primary stabilizing influence at lower temperatures to i
(
a weaker grain boundary pinning by NiaP precipitates at the elevated temperatures.
The higher values of activation energy and peak temperature reported for the Electrosleeve" material are primarily attributed to a larger grain size (i.e.,100 nm) leading to a reduced driving force for grain growth.
c, C Figure 6.5.5 shows schematically the expected mechanism for thermal [ ]
l of the Electrosleeve" material. At temperatures below T, (i.e., approximately 560*C or 1040*F), the Electrosfeeve" material structure is primarily stabilized by the presence of continuous phosphorous at the grain boundaries. At temperatures above T,, the precipitate NiaP can form readily and results in phosphorous depletion at grain [
boundaries. Grain boundaries can then migrate; however, depending upon i temperature, they may be pinned by the NiaP. At higher temperatures, the grain boundaries may break away from the precipitates and grain growth may continue. The process described predicted increasing activation energy with decreasing temperature.
Some evidence for this phenomenon is seen in Figure 6.5.6 which shows activation l energy values determined from microhardness measurements performed on thermally t
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary aged Electrosteeve'" material in the temperature range of 400*C - 600 C (752'F -
1112'F). The Arrhenius dependence (i.e., the reciprocal of time for the onset of hardness decay) is the basis of the activation energy shown in Figure 6.5.6.
C FIGURE 6.5.5 e
{ } THERMAL (, ] MECHANISM
- P as GS segregant ' .FormasonofN!3Ppredpitates
- GB migra5cn a break-away from N!3P
- Pdepleton at GB's apinningbyN3P
\/g/ . '
~
~
- bj ' ls i
A
/
- l */i\s .
f' - a s
/ \*/ \ , s 1
1 1
, . Increasing T
- Decreasing Q i.
1 t
g t
! FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Pr:pri;t:ry FIGURE 6.5.6 c
] , <3, ELECTROSLIl EVE" ACTIVATION ENERGY [
, . . . . i . . . .l -
-e
-80 I! ' ' ' ' '
O ::
'l
.E ::
b x
~0i:~ [
b,c,d,e
>, '6 0 : :
m i.
E '50 7 m ::
40 b
~
'c O -.
3 ..
.$ 30 h t ::
< 20 L .J While DSC analysis provides an approximate assessment of thermal stability associated with rapid grain growth processes the values of activation energy displayed in Figure 6.5.6 are more representative of the actual service conditions of an installed Electrosfeeeve" in a steam generator. Figure 6.5.6 shows that, for long-term exposure to temperatures of approximately 350 C (662'F), the activation energy for grain growth of the Electrosleeeve" materialis above 70 kcal/ mole. This proves the excellent thermal stability of the Electrosfeeve* material at operating temperatures.
The testing results summarized in Figure 6.5.2 demonstrate that the Electrosleeve" materialis fully stable at the PWR design temperature of 650 F and at the lower operational temperatures. Additional testing at 675'F verified thermal stability.
However, thermal destabilization will not result in catastrophic deterioration of the Electrosfeeve" material. Thermal destabilization will occur as a gradual reduction in the mechanical properties similar to conventional Nim.
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1 l
FT! Non-Proprietary 4
Resistance to Strain Induced Recrvstallization I s
Due to the cold-work stored energy, strained materials tend to undergo recrystallization 1
accompanied by a commensurate decrease in mechanical strength at temperatures well below those required for the onset of normal grain growth. C-ring' specimens o electrosleeved Alloy 600 tubing subjected [ 3 nominal strain I
were used to assess the susceptibility of Electrosfeeve" material to strain-induced recrystallization. These strain values were into the plastic regime. The specimens were then thermally treated ( 3.b>C After the specimens were thermally treated, the microhardness was determined in the sleeve region near the Alloy 600 interface where the maximum deformation is expected. The results are summarized in Table 6.5.1.
l TABLE 6.5.1
SUMMARY
OF MICROHARDNESS DETERMINATION ON STRAIN-ANNEALED ELECTROSLEEVES HARDNESS HARDNESS
' APPLIED STRAIN AT AT
(%) (VHN) (VHN) r 1 d '
4 L ._]
}
The results showed no evidence that recrystallization occurred in any of the specimens since the hardness of recrystallized nickel is expected to be less [ ]Nhe hardness values are consistent with the normal variance in hardness noted with plated material.
l FRAMATOME TECHNOLOGIES, INC.
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FTl Ncn-Propristtry 6.6 Creep Properties The effect of decreasing grain size on creep deformation has been well documented with steady-state creep rates generall/ increasing with decreasing grain size.
However, with the exception of the work presented here, to date there have only been l a few studies on the creep performance of nanostructured materials. Wang and co-l f
workers recently demonstrated that nanocrystalline nickel with a grain size of less than 40 nm can exhibit grain boundary sliding deformation at room ternperature [13.4G1. At average grain sizes greater than 40 nm, dislocation mechanisms (i.e., power law creep) were shown to be operative, intrinsic intergranular creep cracking is the predominant mode of premature creep failure for engineering materials. A recent study showed that geometric constraints associated with decreasing grain size could render nanostructured materials highly resistant and possibly immune to this mode of creep failure (13.47]. This resistance is likely manifested as:
- The exclusive appearance of ductile fracture features in failed creep specimens, e Minimal time-dependent total strain at failure, and
. Extended creep life despite possibly enhanced steady-state creep rates.
A series of constant load creep tests was performed using ASTM E139 [13.22) as a guideline to determine the creep behavior of the Electrosleeve" material. Creep testing determines deformation as a function of time and the time to fracture at an elevated temperature when sufficient load is present. Constant-load creep testing is performed in a controlled environment at constant temperature. The measured deformation for a defined gauge length provides a strain-versus-time data presentation that represents the creep phenomena. Selecting a mathematical equation to model this phenomena is a significant challenge. The applicable literature presents many options for modeling creep [13.30,13.31, and 13.381 and finite element codes [13.32] have creep calculation capability for analysis. Section 8.6 presents an evaluation of the data and analysis. Figures 6.6.1 and 6.6.2 are typical fabrication drawings of the creep test specimens.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary Four types of creep specimens were tested:
Standard Soecimen: This specimen (Figure 6.6.1) was a standard tensile specimen. The tube was machined to produce a nominal gaga length. This specimen was used to establish creep rates.
FIGURE 6.6.1 STANDARD CREEP SPECIMEN TM ELECTROSLEEVE ALLOY 600 TUBE Note 1--> 4--- Note 2 g,3 csu w #% y Aswawwwwys ei
%. /
/
t %
5#tsWWM%m+ ++Vg **9we*hWWW r 7 b,C,6 J
NOTES: e, (1) The sleeve-to-tube bond length was nominally [ 3 long, except for the e
minimum bond specimen, which had a[ ] bond length.
(2) The wali thickness of the sleev:r tearied from{ ]e, depending on the specimen.
1 1
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FTl N n-Pr:pristcry e Cire. Notched Soecimen: This specimen (Figure 6.6.2) was a "best effort" creation to evaluate factors associated with notch sensitivity. The specimen was fabricated by machining a 360* circumferential,100% through-wall EDM notch in the Alloy 600 parent tube. The width of the notch was specifigd as
[ fMth a radius at the bottom of the EDM notch of3Lo'r less.
FIGURE 6.6.2 CIRCUMFERENTIALLY NOTCHED CREEP SPECIMEN EDM NOTCH ALLOY 600 ELECTROSLEEVE Note 1 Note 2 TUBE
" v Mqn#Gk(%i16i%%%is#ssk242m%wh1 b%wedsV4ssWM4anMegg%ssysiigeg
' /
N A
/ N 1h**www* #wwwwwumeM [63mtymesga m my Awgsmghwgg C 3 L,C,C.
L J NOTES:
j (1) EDM notch specimens had a 360* circumferential notch,[ ,
3*%, e C (2) The wall thickness of the sleeve varied [ ,3 , ,C.
l depending on the specimen.
I
{
l 1
l l
l FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary Minimum Bond Soecimen: This specimen (Figure 6.6.3) was fabricated by machining the tube and sleeve such that og a small sleeve-to-tube bond length existed (nominally [ ]In'ck, minimum [ ] inch). This specimen was used to evaluate any interaction between a min: mum bond and creep. This specimen was subjected to experimental fatigue tests consisting of axial load cycling and thermal cycling prior to creep testing. Refer to Section 7.4 for a description of these tests.
FIGURE 6.6.3 MECHANICAL TEST SPECIMEN DESIGNS MINIMUM BOND FATIGUE AND BURST SPECIMENS TUBE BOND LENGTH'" SLEEV
--> 4-r mwu % ne-" f-> aanmaa /
s x
$$$$$>@ihtRWG4 V %#9 TRsROW890$
V '
6, c.
L -4 NOTES:
(1) The sleeve to tube bond length for the minimum bond fatigue specimens was nominally [ ]SS FRAM ATOME TECHNOLOGIES, INC.
6-71
FTl N:n-Pr:pri;ttry C-Rina Soecimen: These specimens were fabricated from an installed
- ~
3 ,bc.
Electrosleeve* and were loaded to OD tensile strains of ['
L Y'khe s ecimens were put into a [ ftlaOH (caustic) corrosion test
](h e Section 9.3.1.2). The specimens exhibited 100% through-
[
wall SCC cracks in the Alloy 600 tube. The Alloy 600 cracks were blunted at the nickel surface. No cracking was observed in the nickel material. While the primary purpose of this test was to show corrosion resistance, it also served to show creep cracking did not occur at an SCC crack tip under high stress.
Table 6.6.1 lists the creep test specimens. Tests performed at temperatures [
b
]w, c.ere used to evaluate the influence of temperature. Figure 6.6.4 presents typical creep test [ g
]. The standard specimen geometries exhibited ducti!e failures with typical elongation ( ].'
1 i
i l
l l
l l
l l
l l
l FRAMATOME TECHNOLOGIES, INC.
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l l
FTl Non-Proprietary j i
TA8LF. 6.6.1 l CREEP TEST SPECIMENS CONSTANT AXIAL LOAD CREEP TESTonzi r I C q >4 1
4 7
L J NOTES:
(s:e next page) l FRAMATOME TECHNOLOGIES, INC.
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FTl N n-Propristzry TABLE 6.6.1 (Cont'd)
CREEP TEST SPECIMENS CONSTANT AXIAL LOAD WITH PRESSURE CREEP TESTouri cd i
r
,4 L
CREEP TEST SAMPLE PREPARATION FOR FATIGUE
, c,d c
L --.)
NOTES:
(1) All creep testing for material verification is complete.
(2) All tests were performed at constant temperature and constant load.
(3) Specimen types are defined as follows:
- a. Standard: Standard creep test specimen per Figure 6.6.1.
- b. Circ Notch: A 360,100% through-wall notch machined on the tube ([
3)*/fer Figure 6.6.2.
- c. Min Bond: The sample had a nominal sleeve to tube bond length C. ]6,c per Figure 6.6.3.
(4) Microstructural exam result: fully ductile morphology; no evidence of intergranular-sliding, voids, cavltation, or fracture.
(5) Prior to constant load creep test, this sample was fatigue cycled for a logding sequence equivalent to 40 effective full power years (EFPY) with a factor of[ ] on the number of test cycles.
(6) Sample removed from creep test to perform fatigue test.
(7) This creep test was discontinued since sufficient data had been accumulated for the specimen.
(8) Strain was not measured due to specimen design.
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FTl Non-Preprl:ttry FIGURE 6.6.4 CREEP TEST RESULTS C,b l
/
_I FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propristtry Creep fracture f aces on specimens designated 34-060, CT-007, and 34-023 were examined by high resolution field emission scanning electron microscopy (FESEM) to elucidate the nature of the fracture mode. The high-resolution capability of the FESEM was utilized to identify any possible contributions from grain boundaries to the fracture processes of the ultra-fine-grained Electrosleeve" material (approximately 100 nm grain size). Figure 6.6.5 shows photomicrographs of the fracture faces of specimens34-053 and CT-007 at magnifications ranging from 5000X to 110,000X.
l
~
FRAMATOME TECHNOl.OGIES, INC.
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FTl Non Proprietary l
FIGURE 6.6.5 ELECTROSLEEVE* TYPICAL FRACTURE SURFACE FRACTOGRAPHY
- <y -
j .,.
Gj ,
4 , y
.'3
=>yg
. N' s og% \ .
A gg- .
~-
~;
w.;-;1
- fab' ;.J i 'ML Magnified 5,000X Magnified 30,000X Serial No.34-023 Serial No.34-023 W Mu fV
, At t
/
b bi Q; h
i W -
.s.} .
Magnified 30,000X Magnified 110,000X Serial No. CT-007 Serial No. CT 007 FRAM ATOME TECHNOLOGIES, INC.
6-27
FTl Ncn-Prepristtry The creep fracture f aces examined had some unique differences in loading cond:tions:
- CT-007 was a standard tension specimen that failed in tension.
.34-023, a minimum bond sample, was first exposed to f atigue loadings and then creep tested to failure.
.34-060, an EDM circumferential notch sample, was exposed to an axialload in conjunction with internal pressure and then creep tested to failure.
Photomicrographs recorded at magnifications of approximately 5000X show that the fracture f aces of all specimens examined are entirely ductile in nature and possess classical microvoid coalescence features. Inspection at higher magnification
(>70,000X) reveals the ultrafine grain structure of the material. No evidence of grain boundary cavitation or fracture was evident in any of the fracture f aces examined, indeed, the grain boundary regions appear " raised" relative to the grain interiors, whereas intergranular fracture would typically yield " ditched" grain boundary regions, in summary, fractographic analysis of specimens34-060, CT-007, and 34-023 demonstrated that creep failures are entirely ductile in nature with no evidence of operative intergranular failure mechanisms.
Extrinsic creep cracking is the creep-assisted propagation of a pre-existing flaw (crack) in the material of interest (e.g., Electrosfeeve"). Although the resistance of nanestructured materials to extrinsic creep cracking has yet to be addressed elsewhere, considerable evidence existt that the bi-material interface comprising the nanostructured Electrosteeve" and Alloy 600 parent tubing poses a formidable barrier to crack penetration and propagation. Sugimura, et. al., have considered the general case of crack propagation in a bi-material system in which the two materials have similar elastic properties but different plestic properties (i.e., yield strength) [13.48].
The authors show by both geometric considerations and experimental data that when a crack in the material having the lower yield strength (e.g., Alley 600) approaches a bi-material interf ace, crack tip shielding will occur, which inhibits crack penetration into toe material of higher yield strength (e.g., Electrosteeve"). Further evidence for the extrinsic creep cracking resistance of the Electrosleeve" was obtained from the caustic SCC test results as presented in Section 9.3.i.2. These results demonstrate that SCC-induced sharp cracks in Alloy 600 were " blunted" upon encountering the FRAMATOME TECHNOLOGIES, INC.
6-28
. . ~ .. . -. . .. ..-. . . .. ..
FTl Non-Proprietary Electrosleeve"' for extended periods of time under both high stress and elevated temperature conditions (i.e., creep conditions). l l
6.7 Burst Strength \
i Burst testing was performed on eleven (11) Electrosleeve" cpecimens. Figure 6.6.3 shows the specimen design. Each specimen had a machined gauge length to accurately test the burst characteristics of the electrochemically deposited nickel material.
The specimens were pressurized using a hydraulic pressure generator at room temperature. Per EPRI guidelines [13.68), the specimens were internally pressurized at a rate of 200 to 2000 psi per second. Table 6.7.1 shows the results for the different sizes of specimens tested. For supplementalinformation, Table 6.7.2 contains OHT results for burst testing at a temperature of 581'F for electrosleeved specimens installed in 1/2" x 0.049" Monel 400 tubes. The data indicate that the electroformed sleeve material burst pressure can be calculated by classical burst pressure formulas such as:
P. = 2tS, / D o where: P, = calculated minimum burst pressure t = actual thickness So = actual ultimate tensile strength D. = outside diameter FRAMATOME TECHNOLOGIES, INC.
6 29
FTl Non-Propristtry TABLE 6.7.1 FTl BURST TEST RESULTS AT ROOM TEMPERATURE C,d 9
L TABLE 6.7.2 OHT BURST TEST RESULTS [ )
c,d 7
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_J FRAMATOME TECHNOLOGIES, INC.
6-30
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FTl Non-Proprietary 6.8 Thermodynamic Properties Testing performed on nanocrystalline nickel (13.33] showed that the measured
]
temperature-dependent properties (linear coefficient of thermal expension r#, isobaric heat capacity) of nanocrystalline nickel produced by electrodeposition compared well with the results obtained for conventional polycrystalline nickel material. Therefore, the physical properties of Niroi from Reference 13.2 were used to determine the j coefficient of thermal expansion, thermal conductivity, specific heat, and density of the nanocrystalline material. .
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l 6-31
FTl Non-Proprietary 7.0 DESIGN VERIFICATION - MECHANICAL TESTING The Electrosleeve" qualification program combined analysis and mechanical testing to meet the sleeve qualification requirements presented in Section 4.0. This section summarizes the mechanical testing; Section 8.0 presents the analysis results. Together, Sections 7.0 and 8.0 demonstrate that the installed Electrosleeve" is qualified for application in all RSG designs and their operating conditions.
7.1 Locked Tube Testing 1.ocked tube testing was performed to measure the loads induced on a locked parent tube as a result of the electrosleeving installation process. Four mockups were tested:
three measuring 3/4" x 0.043" wall and one that measured 7/8" x 0.050" wall. Each mockup had tubes that were roll expanded and welded into the TS and TSP, reinforced with tie rods, instrumented with strain gages and thermocouples, and sleeved in the TS and freespan. Figure 7.1.1 depicts a typical mockup used in the locked tube testing.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propriatary FIGURE 7.1.1 TYPICAL LOCKED TUBE MOCKUP TEST RIG WDA TSP I I .l(
A ' t;
I_I-!
V
'E N STRAIN G AGES AND THERMOCOUPLE
( THREADED ROD 4 ALLOY 600 TUBING C
F 1 STR AIN G AGES AND
~g p gis . ( THERMOCOUPLE N
-y L J INSTALLED SLEEVES
, STRAIN GAGE M
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7-2
FTl Non-Proprietary Table 7.1.1 shows the results for a 4-inch long Electrosleeve" installed in the freespan.
TABLE 7.1.1 LOCKED TUBE TEST RESULTS LOCKED TUBE SPAN TESTING AVERAGE TUBE AXfAL TUBE OD TEST LENGTH AXfAL TENSION LOAD TENSILE STRESS (INCHES) (INCHES) (LBS) (KSI) 3/4 I 7be 7/8 t ;
The results of the locked tube testing for the 3/4" and 7/8" tubes were used to calculate a typicallocked tube loading for the 11/16" tube. The loads were then normalized to a typical span length for each tube size. The tube axial stress outside the sleeved regicn was also calculated.
boC The calculated results for a [ ) Electrosleeve* installed completely within the tube span are presented in Table 7.1.2.
TABLE 7.1.2 CALCULATED LOADS FOR LOCKED TUBES TUBE TYPICAL LOCKED TYPICAL LOCKED TUBE TYPICAL LOCKED TUBE OD TUBE SPAN LENGTH AXlAL TENSION LOAD AXIAL TENSILE STRESS (INCHES) (INCHES) (LBS) (KSI) 11/16 I l 3/4 fik 7/8 L .J To determine the effect of different sleeve lengths or of multiple installed sleeves within a particular span, the axial span load and stress may be ratioed by the actual length of the installed sleeve (s) versus the[ ]le'ngth. These stresses are considered low and thus not significant.
I FRAMATOME TECHNOLOGIES, INC.
7-3
FTl Non-Proprist ry 7.2 Fatigue Testing Section ill of the ASME B&PV Code does not provide design rules for sleeves fabricated in situ by electrochemically deposited material, in such cases, the ASME B&PV Code, Section Ill, Appendix 11 [13.21 allows the use of experimental stress analysis to substantiate the critical, or governing, stresses. The adequacy of the installed material and its bond to the tube to withstand operational pressure and thermal cyclic loadings was demonstrated by means of fatigue testing per the ASME B&PV Code, Section ill, f Article 11-1500 (13.21 i
The Electrosleeve" is designed to accommodate allloads that any steam generator tube i
can experience due to normal plant conditions and all anticipated transients specified for the steam generator. Appendix A summarizes the expected transient conditions that were used to qualify the Electrosteeve" design. The fatigue testing loads associated with these transients are reported in Section 8.2.
The minimum bond specimen illustrated in Figure 7.2.1 (this figure is the same as Figure 6.6.3) addresses the situation where significant degradation and metalloss of the parent tube occurs (e.g., wastage, gross intergranular attack (IGA). The sample was machined so that the minimum acceptable bond length between the tube and Electrosteeve" was bc h present. The nominal bond length in the samples was[ 3, w. ile some samples had a[ ]b$d. The testing described below verified that the Electrosleeve* and the minimum bond length will carry the loads imposed in service for the various steam generator designs.
FRAMATOME TECHNOLOGIES, INC.
7-4
FTl Non-Proprietary FIGURE 7.2.1 MECHANICAL TEST SPECIMEN DESIGNS MINIMUM BOND FATIGUE AND BURST SPECIMENS'2 TUBE BOND LENGTH"' SLEEV
-+ b r ,c 4R4@ 02MWA 4- ' "
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(1) The sleeve to tube bond length for the minimum bond fatigue specimens was nominally
[ }.bC (2) The tube and sleeve sizes for the test specimens are given in Table 7.2.1 and Section 7.3.
FRAM ATOME TECHNOLOGIES, INC.
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FTl Non-Propristtry Eight specimens were tested, two of each tube size, as described below:
TABLE 7.2.1 FATIGUE TESTING SPECIMENS SLEEVE WALL NUMBER OF THICKNESS TUBE SIZE TEST SPECIMENS (INCHES)
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2 5/8" OD x 0.034" wall 8 2 3/4". OD x 0.043" wall 2 3/4" OD x 0.048" wall L )
2 7/8" OD x 0.050" wall The minimum bond fatigue test specimens were tested with loadings that represent th design life of an installed sleeve and are given in Table 7.2.2.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non Proprietary TABLE 7.2.2
SUMMARY
OF MINIMUM BOND FATlGUE TEST LOAD RANGESnx2 I b;Cd
] j L J FRAMATOME TECHNOLOGIES, INC.
7-7
FTl Non-Propri1tesy in accordance with the methodology outlined in ASME Section XI, these test specimens were subjected to temperature and pressure cycles to demonstrate structural integrity.
Thermal cycling was performed to determine if the differences in the thermal expansion coufficients for the sleeve and the tube would adversely affect the sleeve-to-tube joint.
The thermal cycling involved heating the specimens [
' ]6,c. The pressure cycling involved internally pressurizing the
) ' he sleeve-to-tube joint was specimens C, ultrasonically examined after test completion to verify that the Electrosleeve" did not separate from the tube.
The axial cycling was performed at room temperature to the test loads described in Section 8.2. The test loads were based on the highest set of operating tube loads anticipated. considering locked or unlocked tubes at the tube support plates. The test loads and cycles were increased to account for the number of test specimens per the requirements of ASME Code, Section lil, Appendix II.
The acceptance criteria used for the axial cycle testing were for the specimers to complete the required cycling with no failure. Failure is defined "as a propagation of a crack through the entire thickness, such as would produce a measurable leak in a pressure retaining member" [13.21. This criterion applies to the exposed Electrosfeeve" material as well as the sleeve-to-tube bond.
As the fatigue tests were completed, the specimens were examined visually and tested ultrasonically for bond or sleeve f ailure.[ [ specimens were acceptable with no evidence of degradation or leakage.
7.3 Testing of Degraded Sleeves A series of f atigue tests was performed on mechanically degraded sleeves to establish 1.121 (13.6].
plugging criteria per the guidelines of (he NRC Draft Regulatory Guide effort" for this Test specimens with[ ) $f)M notches were used as a "begkhis testing testing. The EDM nctched specimens had a radius [ ].
was done to support development of plugging criteria as discussed in Section 12.0.
Two types of tests were performed on the degraded sleeves, fatigue and burst.
1 FRAMATOME TECHNOLOGIES, INC.
7-8
L FTl Non-Proprietary l
7.3.1 Plugging Criteria Fatigue Tests The analysis for a degraded sleeve considered two types of flaws, a 360' circumferential flaw and an infinitely long axial flaw. The i ws were considered c, e.
to extend [ )cthrough-wall of the parent tube and[ ] nto the wall thickness i of the sleeve.
Based on these flaws, cyclic test loads were developed to represent design basis transients (Section 8.2). Eight test specimens were fabricated and subjected to i these test loacs. The specimens were fabricated as shown in Figure 7.3.1 and are listed in Table 7.3.1. Tables 7.3.2 and 7.3.3 define the test loads. The sleeves with axial defects were tested by cycling internal pressure. Similarly, the sleeves with circumferential defects were tested with cyclic axial loads. The required loads for the 11/16" OD tube are shown for comparison.
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j 7-9 I i
r FTl N:n-Pr.cpriet:ry FIGURE 7.3.1 MECHANICAL TEST SPECIMEN DESIGNS PLUGGING CRITERIA FATIGUE SPECIMENS CIRCUMFERENTIAL EDM NOTCH"'
TUBE SLEEVE y A 4-'
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w e s x WM$58n%*w a@wmwn%'wst4satwm;emma wwgggg l SECTION B - B l B+
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b,c (1) The circumferential EDM notch extended 360' around the specimen and( ]into the wall thicknass of the sleeve. C ].% C-(2) The axial EDM notch was{ 'o'ng and extended [. 3$r$o the wall thickness of the sleeve. C 3. <C FRAMATOME TECHNOLOGIES, INC.
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PLUGGING CRITERIA FATIGUE TEST SPECIMENS b;c3 6.
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1 (1) Refer to Figure 7.3.1 for a sketch of the defect.
FRAMATOME TECHNOLOGIES, INC.
7-11 I
FTl Non-Prepri;tiry TABLE 7.3.2 CIRCUMFERENTIAL DEFECT FATIGUE TEST LOADS 11/16" OD X 0.040" TUBE SIZE "'
INTERIOR LOCKED TUBE LOAD SET FOR 40 EFPY AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES AX1AL LOAD SET (Ibs)
]
PERIPHERAL LOCKED TUBE LOAD SET FOR 40 EFPY AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES AXIAL LOAD SET (Ibs)
%c 3/4" OD x 0.042"/0.043"/0.048" TUBE SIZE INTERIOR LOCKED TUBE LOAD SET FOR 40 EFPY AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES AXlAL LOAD SET (Ibs) m c.
r
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t2 PERIPHERAL LOCKED TUBE LOAD SET TESTED >
AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES AXIAL LOAD SET (Ibs)
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J FRAMATOME TECHNOLOGIES, INC.
7-12
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FTl Non-Proprietary TABLE 7.3.2 (Cont'd)
CIRCUMFERENTIAL DEFECT FATIGUE TEST LOADS 7/8" OD x 0.050" TUBE SIZE INTERIOR LOCKED TUBE LOAD SET FOR 40 EFPY AXlAL LOAD SET (Ibs) AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES Tc PERIPHERAL LOCKED TUBE LOAD SET TESTED
- AXIAL LOAD SET (Ibs) AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES r- rc 1
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NOTES:
(1) The fatigue qualification for an 11/16" tube was performed by comparison of these test loads and the testing performed using the 3/4" and 7/8" OD tubes.
(2) All test specimens were cycled to failure or 40 EFPY (whichever occurred first) using a load set representing an interior locked tube and were then conservatively cycled through the load set representing a peripheral locked tube. Each specimen had a 360",
[ tube represent the minimum time to failure.
]ttirkugh-wall defect in the sleeve. The total test cycles shown for the peripheral FRAMATOME TECHNOLOGIES, INC.
7-13
FTl Non-Pr:priittry TABLE 7.3.3 AXIAL DEFECT FATIGUE TEST LOADS PR' ESSURE RANGE TOTAL TEST CYCLES PARENT TUBE SIZE (psi)
I l 11/16" tube"' x 0.040" wall ge;g 3/4" tubei2x3' x 0.042",
0.043" 0.048" wall 7/8" tubei2" ' x 0.050" wall L J NOTES:
(1) The fatigue qualification for an 11/16" tube size was performed by comparison of the test loads and the testing performed using 3/4" and 7/8" OD tubes.
(2) The total test cycles shown represent the minimum failure time for any specimen of this type tested, b, C.
(3) Each specimen had a 1 inch long axial,[ ] through-wall (TW) defect in the s!eese.
100% of the tube was removed. See Figure 7.3.1.
FRAMATOME TECHNOLOGIES, INC.
7-14
FTl Non-Proprietary The test loads were developed to allow testing to proceed in steps with each step representir.g two years of operating life. The test steps were repeated until the specimens failed or reached forty (40) years of service life. The failure point can be used to define the inspection interval for the defective sleeve. Failure of the sleeves with axial defects was defined as detecting leakage through the sleeve defect. Failure of the sleeves with circumferential defects was defined as structural breakage at the flaw.
Table 7.3.4 shows the results of the defective sleeve fatigue tests. An
- 4. c Electrosfeeve" with a[ 3through-wall defect has a maximum inspection interval of:
TABLE 7.3.4 FATIGUE INSPECTION INTERVAL FATIGUE TUBE SIZE DEFECT TYPE INSPECTION i
INTERVAL (EFPY) 3/4" x 0.042/0.043/0.048" F 7 7/8" x 0.050" h,cf e 3/4" x 0.042"/0.C43"/O.048" 7/8" x 0.050" g j 7.3.2 Plugging Criteria Burst Testing The tube burst pressure must be greater than the limiting pressure defined by three times normal operating differential pressure or 1.43 times the worst case faulted differential pressure per Draft Regulatory Guide 1.121 [13.6]. Burst tests were performed on sleeved tubes to demonstrate that this margin is available in sleeves with defects.
Test specimens were fabricated with two types gf flaws in the sleeve, axial and pitting flaws. The flaws extended [ ] [ 3into the sleeve wall. Figure 7.3.2 depicts the test cpecimens. Five specimens were burst tested. The tests '
were performed at room temperature and at operating temperature.
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FRAMATOME TECHNOLOGIES, INC. I 7-15 l
FTl Ncn-Prrpri;tiry FIGURE 7.3.2 MECHANICAL TEST SPECIMEN DESIGNS PLUGGING CRITERIA BURST SPECIMENS AXtAL EDM NOTCH,
[ 3jTW INTO SLEEVE - SLEEVE TUBE A
[ 7 1 I m Nw%s%%%h_____ _msmummw Ahh%w%M%%%%%%%%%ww%%%%%%% M WEf SECTION A-A l c f
.040" WIDE AXIAL EDM NOTCM, TUBE E 'I'TW J INTO SLEEVE SLEEVE c J' s_
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FTl Non-Proprietary The specimens, along with burst test results, are listed in Table 7.3.5.
TABLE 7.3.5 PLUGGING CRITERIA BURST SPECIMENSir SPECIMEN TEST CALCULATED BURST NUMBER TUBE SIZE SLEEVE DEFECT TEM P.'" BURST PRESSURE
("F) PRESSURE (ksi)
(ksi) 754225-78-059 7/8" OD x I ~~l 0.050 Qc, d 754225-78-060 7/8" OD x 0.050" 754225-78-063 7/8" OD x 0.050" 754225-78-064 7/8" OD x 0.050" 754225-78-065 7/8" OD x 0.050" L -a NOTES:
(1) Refer to Figure 7.3.2 for a sketch of the axial defect.
(2)
Tube wall was complately removed from t(e test specimens. The sleeve
] in'cf thickness for these specimens was [
(3) The actual test temperature is reported (RT = Room Temperature).
(4) % through-wall = Percent through-wall of the sleeve.
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l FRAMATOME TECHNOLOGIES, INC.
l 7-17
FTl N:n-Pr:prl:tzry 7.4 Creep-Fatigue Experimental Analysis
)Ospecimens were tested to determine the effect of creep fatigue int
[test results (Table 7.4.1) showed sufficient margin in the design of the Electrosleeve" to accommodate the combined effects of fatigue and creep that an installed Electrosleeve" could experience in a steam generator. Additionally, the frar.ture faces of specimens
} were examined. Phetomicrographs at relatively
{
low magnification (Figure 7.4.1) show that the fracture-face features of the specimens were entirely ductile. Further, the fractographic analysis of specimens 766037-CT-006 and 766037-34-051 revealed the creep failures to be entirely ductile with no evidence l
of operative intergranular failure mechanisms.
l FRAMATOME TECHNOLOGIES, INC.
7-18
i FTl Non-Proprietary l TABLE 7.4.1 CREEP-FATIGUE TESTING RESULTS Sample Tube Size Creep / Fatigue Testing C 3 3/4" x 0.043" 1. C 3 creep test [
[ Figure 6.6.1] 3
- 2. 40 EFPY W-D modellocked tube load fatigue test at 650 F.
- 3. [ ] fatigue tested [,
J to failure C
[ ) 7/8" x 0.050" 1. f. ] thermal cycles [ 3.
(Minimum bond 2. 40 EFPY fatigue test using locked tube sample with 1/4" loads C J.
sleeve-to-tube bond) 3. [ 3 creep testl
[ Figure 7.2.1] 3-
- 4. 40 EFPY fatigue test using locked tube loads [ J.
- 5. C, ,3 fatigue tested E
3to failure C 3-p q 3/4" x 0.043" 1. [ ] creep tested C
[ Figure 6.6.21 l
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%c,d FRAMATOME TECHNOLOGIES, INC.
7-19
FTl Non-Proprietary FIGURE 7.4.1 TYPICAL CREEP-FATIGUE SURFACE FRACTOGRAPHY c.
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FRAM ATOME TECHNOLOGIES, INC.
7-20
FTl Non-Proprietary 7.5 Leak Testing of Minimum Bond Length C
Leak testing was performed at room temperature on[ 3electrosleeved 11/16" OD Alloy 600 tubes. After the sleeves were installed, the specimens were UT inspected.
Then, the tube material was removed as shown in Figure 7.2.1. The specimens were subjected to a primary side hydrotest at 4200 psig and then to a thirty (30) minute leak test at 2500 psig. No visible leakage was observed.
in addition, after the minimum bond fatigue testing described in Section 7.2 was completed, a 7/8" OD sample was subjected to rapid thermal shock cycles. The specimen was heated above 600*F and then the inside surface of the electrosleeved tube was subjected to a high-velocity cold-water flush. The specimen cooled to room temperature in approximately 5 to 10 seconds. After experiencing ten thermal shock cycles, the specimen was UT inspected and showed no loss of bonding. The specimen was then subjected to a primary-side hydrotest at 4200 psig followed by a thirty (30) minute leak test at 2500 psig. No visible leakage was observed.
These test results are consistent with the design objectives of a " sealed" sleeve installation and support the total bonding verified by the UT inspection.
7.6 Tube-to-Tubesheet Pull-Out Load Testing The repair of a degraded tube at the top of a tubesheet can affect the strength of the tube-to-tubesheet contact engagement in the tubesheet bore. To evaluate the post-sleeved engagement strength, samples were fabricated to evaluate the axial tube pull-out load. Tube specimens were roll expanded into the full length of four-inch tubesheet blocks. Four tubes were rolled into tubesheet mockups (i.e., two gth 3/4" x 0.043" wall tubes and two with 7/8" x 0.050" wall tubes). An [ ,] Electrosteeve" was installed (centered over the[ Nubesheet block) into one of each size mockup.
The slee"Lextended ( Jhast each end of the tubesheet block. The v center
[ 3 length of each mockup was cut away. The sleeve extended C 3 p.ast g
each end of the tubesheet block. Thus, the[ dockups yielded [ fs'IEieved and[ 3 unsleeved samples.
FRAM ATOME TECHNOLOGIES, INC.
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FTI Non-Proprietary bC All[ 3s,amples were then heat treated at 650*F for ten hours. The tube section was then pulled out of the tubesheet block (pull test performed at room temperature) and the removalload for the sleeved specimens was compared to the removalload for the similar unsleeved samples. The addition of the Electrosfeeve" increased the average joint strength of the four test specimens by approximately 10%. This increase in joint strength is attributed to the added stiffness of the composite tube section to resist the Poisson effect of the axial tube loading. Since the coefficient of thermal expansion of nickel is higher than that of the Alloy 600 or the carbon steel tubesheet, the joint strength will also increase at operating temperature.
Thus, the installation of the Electrosfeeve" does not require any change in the effective tube-to-tubesheet rolled joint length. The installation of the Electrosleeve" should also increase the tube-to-tubesheet joint strength for other tube expansion methods.
7.7 Mechanical Testing Summary The mechanical design verification tests were performed to show that the Electrosleeve" is structurally capable of withstanding actual in-service loading conditions. The results of the conservative tests reported in this section envelop the expected worst case conditions.
The burst tests demonstrate that the Electrosfeeve" is ductile and has burst characteristics similar to undegraded tubes. The burst tests also showed that a sleeved tube with a [ ]tIrIugh-wall defect in the sleeve will withstand faulted condition loadings.
The locked tube tests showed that the electrosfeeving process is unaffected by locked tubes. Further, no significant loads are generated in the parent tube from the installation process.
The series of experimental fatigue tests confirmed the structuralintegrity of the electrochemically deposited nickel sleeve material, with the following conclusions being drawn:
- Testing tubes with 100% through wall defects showed the sleeve would last for its specified design life.
FRAMATOME TECHNOLOGIES, INC.
7-22
l FTl Non-Proprietary i b, c-e Testing tubes with 100% through-wall defects, including [ 3through-wall l
defects in the sleeve, showed that a sleeve with a f. 3 defect would last longer
- than the specified five year inspection interval.
l e A nominal bond length ( )b,c,will carry all loading conditions and prevent leakage.
l
- Thermal, pressure, and axial loads have no detrimental effects on either the bond l or the sleeve strength characteristics.
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FTl Non-Proprietary 8.0 DESIGN VERIFICATION - ANAL.YSES
(
l Design analyses were performed for the Electrosleeve" to verify it conforms to the
~ qualification requirements identified in 6ection 4.0. Ths design analyses consist of:
- Pressure bour dary minimum thickness calculation,
- Analyses to support fatigue testing per Appendix 11 of the ASME Code,
- Analyses of flow-induced vibration of sleeved tubes, !
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Analyses of the effect of a sleeve on heat transfer and primary fluid flow,
- Analyses of a degraded sleeve, and
- Analysis of creep.
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The analyses were performed on the different sizes of steam generator tubing outlined in Section 4.0. The results are presented in Sections 8.1 through 8.6.
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8.1 Pressure Boundary Thickness Based on the material test results for the electroformed nickel matcrial, a design stress intensity value (S ) of 30 ksi at 650'F was established in Section 6.1. This Sm value was used to evaluate the structural adequacy of the various sleeve sizes for pressure thickness and external pressure in accordance with the ASME B&PV Code. Using the primary side design pressure (per NB-3324 [13.21), the minimum sleeve thickness for each design is given in Table 8.1.1.
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FTl Non-Propristtry TABLE 8.1.1 TUBE / SLEEVE DIMENSIONS ELECTROSLEEVE'"
NOMINAL TUBE ClZE Nominal Minimum Nominal PLANT OD Thickness Thickness OD Thickness (inch) (inch) (inch)
(inch) (inch)
~
I 7 Westinghouse RSG 11/16 0.040 b,C, C Model F CE RSG 3/4 0.042 System 80 Westinghouse RSG Models 3/4 0.043 D&E All CE RSGs 3/4 0.048 (Except Sys 80)
Westinghouse RSG 7/8 0.050 [ j Models 33, 44, & 51 The allowable external pressure for the sleeve and tube was calculated per classical collapse pressure equations for each sleeve size. Based on these calculations, the sleeve has a greater external pressure capability than the tube. Thus, the sleeve exceeds the strength of the original tube for external pressure loadings.
The design primary stress intensities for each steam generator design were calculated assuming that the tube was completely removed from the sleeve. The maximum stress intensities (Table 8.1.2) meet the primary stress (P,n) limits.
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FTl Non-Proprietary TABLE 8.1.2 PRIMARY MEMBRANE STRESS INTENSITY RANGE MAXIMUM ASME CODE PARENT TUBE SLEEVE STRESS PRIMARY STRESS ALLOWABLE SIZE CRITERIA INTENSITY RANGE STRESS *
(ksi) (ksi) 11/16" OD x 0.040" wall P s S. P. = [. 30.0 s,c.
3/4" OD x 0.042"/0.043" wall P.s S. P = [. ] 30.0 bez 3/4" OD x 0.048" wall P s S. P.=[. J 30.0 7/8" OD x 0.050" wall P.s S. P. = [ 30.0 NOTES:
(1) Stress values are for design pressure at 650*F for the sleeve. The analysis conservatively assumes the tub is not present.
8.2 Fatigue Test Loads Section 111 of the ASME B&PV Code does not provide design rules for sleeves fabricated by electrochemical deposition of material. In such cases, the ASME B&PV Code, Section 111, Appendix 11 [13.2] allows the use of experimental stress analysis to substantiate the critical, or governing, stresses. The adequacy of the installed material and its bond to the tube to withstand operational pressure and thermal cyclic loading was demonstrated by means of fatigue testing per the ASME B&PV Code, Section Ill, Article ll-1500 [13.2].
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FTl Nen-Proprittery Three different f atigue test specimens were used to demonstrate the fatigue life of the Electrosleeve" for the steam generator design transients listed in Appendix A.
Specimen 1: The minimum bond specimen was f abricated by machining away the tube and sleeve such that a small sleeve-to-tube bond length exists w e.
(nominally ( 3 inch). These specimens were subjected to experimental fatigue tests consisting of axialload cycling, thermal cycling, and pressure cycling. Refer to Section 7.2 for a description of these tests.
Specimen 2: This specimen was used to evaluatgcircumferential cracks. The
]lekgth and a full circumferential tube was removed over a [
EDM notch was then machined in the exposed sleeve 30% through-wall. The radius at the bottom of the EDM notch was 0.003 inch or less. Refer to Section 7.2 for a description of these tests.
Specimen 3: This specimen was used to evaluate axial crackg. The tube was removed over a[ Neigth and a f. b c Jion's eau notch was then machined in the exposed sleeve {
]f'n"dh or less. Refer tothroujh at the bottom of the EDM notch was[
Section 7.2 for a description of these tests.
The Electrosleeve* is designed to accommodate allloads that the steam generator tube may experience due to normal plant conditions and all anticipated transients specified for the steam generator. The tables presented in Appendix A summarize the expected transient conditions used in the design of the sleeves for the different sizes of tubes.
Calculations were prepared for each sleeve design to determine a conservative maximum loadin0 for a sleeve in any steam generator tube based on the transients listed in Appendix A. These calculations include pressure, thermal gradient, thermal differential, and seismic loading.
The loads were evaluated for tubes either locked or unlocked at the tube support plates. The tube loading calculated for a locked tube enveloped the tube loads calculated for a tube in the unlocked condition. As a result, the fatigue loading evaluation considered the tubes to be locked at all tube support plates. The locked 4
tube axialloads increase near TSP vertical restraints similar to the TSP-to-wrapper FRAMATOME TECHNOLOGIES, INC.
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l FTl Non-Proprietary support in Figure 8.2.1. The tubes most affected are the first tubes in each row closest to the TSP support.
l FIGURE 8.2.1 PERIPHERAL TUBES AFFECTED BY TSP-TO-WRAPPER SUPPORTS i
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= AFrected Peripherot Tubes O@ ~-
h verticat support ayp)
OO@ --
OO@
OOO@ '#~'""'
0000@
000000 Loads due to thermal and pressure transients were calculated for[ s't eved tube cases using the transients listed in Appendix A. 'Nhere possible, transients were grouped together and the number of cycles adjusted accordingly. The structural model for each of these cases considered a tube with sleeves installed at the top of the tubesheet and at least three TSP locations. [ 6, c,e.
- 3. The sleeved tube conditions considered are:
- Sleeved periphery tube (severed and unsevered), and Sleeved interior tube (severed and unsevered).
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FTl N n-Pr:pri;t:ry The loading analysis model for the periphery tube case (Figure 8.2.1) considered the following boundary conditions:
. The tube is coupled to the tubesheet and to each of the TSPs,
The loading analysis model for the interior tube case considered the following boundarf conditions:
- Tha sleeved tube and its adjacent tubes are coupled to the tubesheet and to l each of the TSPs, and
- The tube is either severed or unsevered between the sleeve attachment bonds.
The specific combination of geometry and operating conditions, that resulted in the highest load for a given transient grouping, was used in the mechanical test program.
The load ranges were calculated based on the following conditions:
- A single peripheral tube is sleeved at 70 F after it initially locked to the support plate at 100% power conditions. Only this tube was assumed to interact with the wrapper and shell, i
- Interior sleeved tubes were iniluenced only by adjacent tubes and not by the shell and wrapper.
l The calculated axial tube loads for all transients were combined into a set of test load ranges. The required number of test cycles was determined per ASME Appendix 11 (13.2] and was based on the number of test assemblies and various factors relating the test conditions to the actual operating conditions.
The fatigue load testing sequence for Specimen 1 is shown in Table 8.2.1 (same as Table 7.2.2) for the recirculating steam generators. The load testing sequences were utilized in the tests described in Section '7.2.
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A FTl Non-Proprietary TABLE 8.2.1
SUMMARY
OF MINIMUM BOND FATIGUE TEST LOAD RANGESon2 4
5/8" OD x 0.037" TUBE SIZE LOADS (Ibs) LOAD RANGE (Ibs) TEST CYCLES C ~1
. h,c.d L- ._i l
1 t
3/4" OD x 0.042"/0.043"/0.048" TUBE SIZE LOADS (Ibs) LOAD RANGE (Ibs) TEST CYCLES l I !
r 7
- b,c.d i I
l L J 7/8" OD x 0.050" TUBE SIZE LOADS (Ibs) LOAD RANGE (Ibs) TEST CYCLES l' 7 e kr,/
j L a !
NOTES:
(1) The loading listed represents the worst case combination, (i.e., peripheral tube,40 i year service life, Transient + FIV + OBE Loads).
(2) The ASME Appendix 11, Testing Factors have been applied to these loads and cycles j based on the number of test specimens and test conditions.
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FTl N:n-Pr:pri;tary Fatigue testing was performed (Section 7.2) to determine the life of an Electrosteeve" with a part through wall defect in a degraded tube. This testing included tubes and sleeves with circumferential and axial crack-like defects (i.e., EDM machined defects).
These specimens were subjected to testing representative of the design life of the steam generator.
Fatigue test loads were calculated for the sleeve specimens to represent the operating pressure and thermal stress ranges for the steam generator life. To simulate the normal operating transient stresses, an equivalent load was calculated to account for the thermal stress gradient and the differential pressure versus stress present in the sleeve. Ws additionalload was determined based on the pressure versus thermal membrane and bending stress. The equivalent loading was combined with loads due to pressure and thermal expansion differences to give the test loading. This test load created an equivalent membrane and bending stress in the tube / sleeve at the defect location representative of normal fatigue transient loadings. Both 3/4" OD and 7/8" OD sleeved tube specimens were tested. The test loadings and total cycles required in the fatigue tests in Section 7.2 are listed in Tables 8.2.2 and 8.2.3 (Tables 8.2.2 and 8.2.3 are the same as Tables 7.3.2 and 7.3.3, respectively).
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FTl Non-Proprietary )
TABLE 8.2.2 I FATIGUE TEST LOADS 1
11/16" OD X 0.040" TUBE SIZE"'
INTERIOR LOCKED TUBE LOAD SET FOR 40 EFPY AXlAL LOAD SET (lbr) AXIAL LOAD RANGE (lbs) TOTAL TEST CYCLES E 6,s d _
PERIPHERAL LOCKED TUBE LOAD SET FOR 40 EF PY i AXIAL LOAD SET (Ibs) AXlAL LOAD RANGE (lbs) TOTAL TEST CYCLES
- I
, AXIAL LOAD SET (Ibs) AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES
[ 7 b e, g
L '
PERIPHERAL LOCKED TUBE LOAD SET TESTEDi2>
l
- AXIAL LOAD SET (Ibs) AXIAL LOAD RANGE (lbs) TOTAL TEST CYCLES '
C 7 hJi l
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FTl N:n Pr:pri;tIry TABLE 8.2.2 (Cont'd)
( ) FATIGUE TEST LOADS l
l 7/8" OD x 0.050" TUBE SIZE .__
l INTERIOR LOCKED TUBE LOAD SET FOR 40 EFPY AXIAL LOAD HANGE (Ibs) TOTAL TEST CYCLES AXIAL LOAD SET (Ibs)
~7 I 6,c,d L- .__)
1 PERIPHERAL LOCKED TUBE LOAD SET TESTED'23 AXlAL LOAD SET (Ibs) AXIAL LOAD RANGE (Ibs) TOTAL TEST CYCLES 7
I b>c4 L J
- NOTES
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(1) The fatigue qualification for an 11/16" tube was performed by comparison of these test loads and the testing performed using the 3/4" and 7/8" OD tubes.
(2) All test specimens were cycled to failure or 40 EFPY (whichever occurred first) using a load set representing an interior locked tube and were then conservatively cycled throu
[ ]ghthough-wall the load setin the defect representing sleeve. The total a testperipherallocked tube. Each cycles shown for the peripheral l
tube represent the minimum time to failure.
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FTl Non-Proprietary TABLE 8.2.3 3 FATIGUE TEST LOADS i
PARENT TUBE SIZE PRESSURE RANGE TOTAL TEST CYCLES (psi)
I ~~1 11/16" tube"' x 0.040" wall
)
3/4" tuber2" ' x 0.042", :
0.043", 0.048" wall 7/8" tubet2na' x 0.050" wall L y i
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i NOTES:
(1) The fatigue qualification for an 11/16" tube size was performed by comparison of the test loads and the testing performed using 3/4" and 7/8" OD tubes.
j (2) The total test cycles shown represent the minimum failure time for any specimen of this type tested.
('3 ) Each specimen had a 1 inch long TWaxial,[
defect in)Qthe sleeve.100% of the tube was removed. See Figure 7.3.2.
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8.3 Flow-Induced Vibration '
The flow-induced vibration (FIV) analyses evaluated fluid-elastic stability margins I
(FSM) and random vibration response for the nickel sleeve. For all of the steam generator designs analyzed, sleeves were assumed to be installed at all TSPs and TTS locations in both the hot and cold legs. The fluid-elastic stability margins and the responses to smLil-scale turbulence were examined. Possible vortex shedding was not considered to be a problem. No credit was taken for increased local damping due to sleeves. The FlV analyses were performed using Connor's constants, percent i damping, and added mass coefficient as listed in Table 8.3.1. The percent damping value used is based on FTl testing data.
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FTl Non-Propristzry c TABLE 8.3.1
[ ] FLOW INDUCED VlBRATION ANALYSES RESULTS
RANDOM VIRGIN FLOW STABILITY MARGIN VIBRATION PEAK (FSM)nar' FATIGUE STRESS SLEEVE TUBE (VT) or (psi, rms) FATIGUE USAGE SLEEVED COLD TUBE SLEEVE FACTOR SG DESIGN TUBE (ST) HOT LEG U BEND LEG 1
Westinghouse VT l Model D and E ST Westinghouse VT Model F ST f
CE Model 67, VT l CE ANO-2, and CE Model 3410 ST CE (Fort VT Calhoun)
ST Westinghouse VT Models 33,44 and 51 ST t J HQIlui:
(1) FIV Acceptance Criteria f* 1 b) d L J l (2) FIV Constants and Coefficients l~ ~l N N L J l (3) Worst case tube in RSGs analyzed.
FRAMATOME TECHNOLOGIES, INC. l
FTl Non Proprietary The FlV tube model included the hot leg, U-bend, and cold leg tubing between the tubesheets. This model allows cross flow loads to be applied to the U-bend tubing for evaluating the tube support plate sleeves. The cases considered are virgin and sleeved tubes. The results of all of the FIV analyses are presented in Table 8.3.1. The bounding cases for each similar design are presented in the Table. For the 7/8" OD 4
tube designs, the Westinghouse Model 51 RSG is bounding, and for the 3/4" OD tube Westinghouse designs, the D5 is bcunding. Specific analyses were performed for the Combustion Engineering (CE) System 80, ANO-2, and Fort Calhoun RSG designs to bound all CE RSG designs. The analyses indicate that the Electrosfeeve" is acceptable for ' installation in all RSGs with respect to FIV considerations.
8.4 Thermal / Hydraulic The effect of an Electrosfeeve" installation on steam generator performance was analyzed for heat transfer, flow restriction, and steam generation capacity. Several cases were considered in the evaluation, either a single sleeve in a tube or multiple sleeves in a single tube. All steam generators designs were considered in these analyses. In addition, cases in which the sleeved tubes were distributed asymmeto: ally among the RSGs were considered.
The analyses show that the thermal / hydraulic effects of electrosteeving are minimal.
l The effects of installed electrosleeves on primary flow are presented in Table 8.4.1 for j each of the steam generator designs. The results are presented as an equivalent number of sleeves installed havir.g the same impact as plugging one tube. ,
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FTl N:n-Pr:pritt2ry TABLE 8.4.1 THERMAL / HYDRAULIC EFFECTS OF i SLEEVES IN STEAM GENERATOR TUBES
% FLOW REDUCTION AND TUBE SLEEVE / PLUG RATIOS i LANT TYPES l c FOR (CASE E 3 WITH C RSG 3 [ TUBES PER RSG AFFECTED)
CASE CASE PLANT
% FLOW SLEEVE / PLUG % FLOW SLEEVE / PLUG REDUCTION RATIO REDUCTION RATIO F- -I !
Westinghouse Model D O/ g)
Westinghouse Madel E Westinghouse
- Model F CE System 80 l
CE Model 67 l
Westinghouse l
Model 33 Westinghouse Model 44 Westinghouse Model 51 L d l
NOTES:
(1) Case [ f Hot leg Tubesheet Sleeve (TSS) only (2) Case [h Hot leg iSS, and 1 TSP sleeve FRAMATOME TECHNOLOGIES, INC.
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. --- - _.- -._-. - - ~. .- - . --.- - - - . . .
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FTl Non-Proprietary in summary, the thermal / hydraulic analyses of the Electrosleeve" show:
- A smaller, unrecoverable pressure drop due to maintaining a larger sleeve ID, and j
+. A minimal effect on heat transfer since the sleeve is in direct contact with the 1 tube. ;
I 8.5 Sleeve Structural Limits t
NRC Draft Regulatory Guide 1.121 (RG 1.121) (13.61 provides guidance for I determining the degradation limits for PWR steam generator tubes. Since the sleeve replaces a portion of the original tube, the structurallimit: f ar a degraded sleeve were determined using this guideline. The required minimum sleeve wall thickness was calculated for the defined sleeve pressure boundary length only. The tapered sections of the sleeves are not included in the structural assessments.
Three criteria for normal operating conditions (level A) and four criteria for faulted r conditions (level D) were. evaluated in the sleeve / tube bonding joint and in the straight l sleeve section. The minimum ~ wall thickness required to accommodate three times the normal operating pressure differential or 1.43 times the limiting accident pressure differential was detern bed from the tests described in Section 6.7.
The analysis results in Tables 8.5.1 and 8.5.2 show that any sleeve exhibiting a uniform thinning flaw [ 3th'rIugh-wall at a location where the tube has a 100%
through-wall flaw meets the RG 1.121 criteria. However, the circumferential extent of
- the uniform thinning flaw for tube locations near vertical restraints, such as the TSP-to-wrapper support shown in Figure 8.2.1, is limited. The circumferential degradation limit for these tube locations varies based on the plant specific main steam line break (MSLB) loading and degradation depth. A plant may choose not to sleeve these tube locations or to remove an installed sleeve from service if circumferential through-wall '
tube cracking occurs.
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FTl Ncn-Pr:pri:mry TABLE 8.5.1 1 ELECTROSLEEVE" STRUCTURAL LIMITS LEVEL A CONDITIONS ALLOWABLE DEFECT IN THE NOMINAL TUBE SLEEVE THICKNESS"'
MAX AP OD THICKNESS CRITERIA (psi) (inch) (inch) % SLEEVE WALL (mils) 1600 11/16 0.040 I ,,, c]
p 3 2000 3/4 0.042 Interior Tubes 1600 3/4 0.043 2000 3/4 0.048 1600 7/8 0.050 1600 11/16 0.040 p 3 2000 3/4 0.042 Peripheral Tubes
- 1600 3/4 0.043 2000 3/4 0.048 1600 7/8 0.050 1600 11/16 0.040 3AP 5 P ,,,
2000 3/4 0.042 1600 3/4 0.043 2000 3/4 0.048 1600 7/8 0.050 L l NOTES:
(1) Assumes 100% uniform thinning of the tube wall at the same location as the sleeve uniform thinning flaw.
(2) Applies to tubes adjacent to TSP verticai supports (i.e. TSP-to-wrapper wedge locations).
(3) Circumferential degradation extent of tube locations (Note 2) is limited as discussed in Section 8.5.
(4) Revised limits for locked tubes.
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FTl Non-Proprietary TABLE 8.5.2 ELECTROSLEEVE" STRUCTURAL LIMITS LEVEL D CONDITIONS ALLOWABLE DEFECT IN THE NOMINAL TUBE SLEEVE THICKNESS"'
MAX AP OD THICKNESS CRITERIA (psi) (inch) (inch) % SLEEVE WALL (mils)
P 0.7 S, 2650 11/16 0.040 I h,d 2500 3/4 0.042 2650 3/4 0.043 2585 3/4 0.048 2650 7/8 0.050 3p p 2650 11/16 0.040 2500 3/4 0.042 2650 3/4 0.043 2585 3/4 0.048 2560 7/8 0.050 2650 11/16 0.040 AP5,0.9 P,%,,
2500 3/4 0.042 ,
2650 3/4 0.043 2585 3/4 0.048 l
2560 7/8 0.050 p_ , p, 2650 11/16 0.040
)*o*.bsf'8* 2500 3/4 0.042 2650 3/4 0.043 2585 3/4 0.048 2560 7/8 0.050 L. J ,
NOTES:
(1) Assumes there is 100% uniform thinning of the tube wall at the same location as the sleeve uniform thinning flaw.
(2) Revised limits for locked tubes.
FRAMATOME TECHNOLOGIES, INC.
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FTl Nrn-Preprixt:ry FTl developed a burst pressure correlation to determine the burst structural limits for part through-wall and 100% through wall flaws. The FTl burst pressure correlation was developed by using both FTl burst tests and industry test data. The FTl burst tests were performed with various lengths and depths of EDM notches as well as with and without electrosfeeves. Figure 8.5.1 shows the normalized burst pressure for l
Alloy 600 tubes versus the predicted normalized burst pressure using both the FTl and 1
EPRI (13.73] burst correlations. The burst test results for electrosleeves show close agreement to the FTl burst pressure correlation. Table 8.5.3 provides a summary of the allowable part through-wall flaw for each sleeve size listed in Table 5.1.1.
FIGURE 8.5.1 NORMALIZED BURST PRESSURE F 7 b,C,k L
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FTl Non-Proprietary TABLE 8.5.3 ELECTROSLEEVE" DRAFT REG. GUIDE 1.121 STRUCTURAL LIMITS BURST AND LEAKAGE LIMITS'*"5' 11/16" OD x 3/4" OD x 3/4" OD x Y!8" OD x 0.040" 0.042"/ 0.048" 0.05G"
-Tube 0.043" Tube Tube Tube
% , b,c. UA b 3 g, b C Indication Type Sleeve Sleeve Sleeve Sleeve Thickness Thickness Thickness Thickness
%TW'5 i2
% T W'8' %TW8 % T W'85 Uniform Thinning ian4: p q b, c.cl i
O D Pit *'
Axial Crack s 3/4 inch'5' Axial Crack > 3/4 inch""5' 360# Circumferential Crack 2xs> L -I NOTES:
(1) A slight reduction in the structural limit occurs for axial crack lengths [
).
(2) The circumferential degradation extent for tubes adjacent to the TSP periphery vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(3) The % through-wall in the above table is of the sleeve nominal thickness.
(4) The structural limit for OD pitting and uniform thinning were determined using the AP values as shown on Tables 8.5.1 and 8.5.2.
(5) The structural limit for crack-like defects was determined using the larger of either three times the normal operating pressure differential at 100% power or 1.43 times the limiting accident pressure differential as listed in Appendix A for each tube size.
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FTl Non Pr pristtry FTl also developed a burst pressure correlation to determine the burst structural limit j for a 100% through-wall pit. This burst pressure correlation was developed using FTl j burst test results of Alloy 600 tubes with part through-wall and 100% through-wall j pits of various diameters. Using the burst pressure correlation, an analysis was l I
performed to determine the acceptable diameter for a pit that was 100% through the sleeve wall and that did not have any structural sgpport from the parent tube. The ana!ysis determined that a [ ] pit in the Electrosfeeve" met all of the g structural requirements of RG 1.121. A remaining ligament for OD and ID pits of b 3 of the sleeve nominal thickness meets the structural requirements of RG 1.121.
In addition, a 100% through-wall sleeve pit with a diameter less than [ t coincident with a 100% through-wall tube crack will typically not exhibit leakage that exceeds the usual plant leakage limit (150 gpd) during either normal or faulted operating conditions. A[ 3 b'ond width between any through-wall tube ,
I degradation and a sleeve ID pit precludes the potential for any leakage.
Fatigue test results, presented in Section 7.3, indicate that any sleeve with a crack-like 4,c flaw,[, )through-wall of the sleeve exhibits a margin against fatigue failure that greatly exceeds the RG 1.121 fatigue requirements. The test results are applicable whether the tube wall is removed from the sleeve OD or if the tube has a 100%
through-wall flaw. Additionally, a conservative fracture mechanics evaluation for a 6, c thinned sleeve with a deep,[ 3 through-wall, infinite length axial flaw was q performed. The axial flaw propagation depth from this analysis is less than[ Jof the nominal thickness sleeve over eighteen (18) months of operation. This growth value is used in the plugging limit evaluations in Section 12.0.
l
.The structural limits for the three distinct regions of the tube affected by the installation of the Electrosleeve" are summarized in Table 8.5.4. The three distinct regions of the tube are illustrated in Figure 8.5.2 (same as Figure 5.1.1).
1 1
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FTl Non-Proprietary TABLE 8.5.4 ELEGIAQ31Egy1* SJEUCTURAL ACCEPTANCE STANDARD REGION'" COMPONENT ACCEPTABLE STRUCTURAL DEGRADATION A TUBE e Plant Technical Specification Requirements SLEEVE e Allindications are acceptable B TUBE e Plant Technical Specification Requirements SLEEVE"' e Minimum thickness (Table 5.1.1) e No leak path e Mir.imum bond length ( 3 e ID pit 100% through-wall C TUBE e All Indications are acceptable SLEEVE"'
- Minimum thickness (Table 8.7.1) l s
- Uniform thinning ( 3 e C.
Axial crack ( )ktb
- Axial crack C 3 , c.
360' Circumferential crack C ]
e OD & ID pit [ ]
(Special Evaluation or Contingency Resolutions)'ai e ID pit 100% through-wall with a tube bond C y b,c NOTES:
(1) The Electrosleeve" nominal thickness was used to calculate % through-wall.
(2) installation minimum thickness, disbond process violations, ID pits, and nodules require a Non-Conformance Report (NCR) resolution with the Owner's concurrence to justify acceptability for service.
(3) Note that the circumferential degradation extent for tubes adjacent to the TSP periphery vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
-(4) See Figure 11.1.1 for definition of Regions A, B, and C.
(5) Assumes 100% of the tube is removed.
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FTl Non-Propristary FIGURE 8.5.2 TYPICAL ELECTROSLEEVE" PRESSURE BOUNDARY Y
ALLOY 600 4 PARENT TUBE i b, C C 7 r .:
2 ELECTROSLEEVE
/
~~
li l lL N
., :p NOTE: Pressure Boundary region is denoted by the shaded areas.
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FRAM ATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary 8.6 Creep Analysis ASME Code Case N-47 [13.5] established design rules for Section lil, Class 1 components for the conditions when the metal temperature exceeds those established by Section Ill. The design rules in the code case [13.29] are designed to guard against:
Ductile rupture from short term loadings, e Gross distortion, Creep rupture from long term loadings, and
- Creep fatigue failure.
The analysis results presented in Section 8.1 and the mechanical testing in Section 7.0 demonstrate ductile rupture from short term loadings are not a concern. The other design aspects are discussed below.
8.6.1 Gross Distortion During creep, a specimen under load will undergo permanent deformation over time. The amount of deformation will vary based on stress, time, and temperature. The majo:ity of the creep tests descrioed in Section 6.6 were performed at[ fu'nder a number of different loads. Additional tests were
%c s, c.
performed at[. 3,a.nd[ 3to evaluate the influence of temperature.
The creep response of the Electrosleeve" material was modeled using an equation often referred to as the Garofalo equation [13.38]. The creep test results formula used is:
] b ,c, cl Where: I l L J p FRAMATOME TECHNOLOGIES, INC.
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. - . . - _ . . - _. .- _ . . - . - . _ - _ - - . . _ - . . - - . _ = - _ = . - . . .
FTl Ncn Pr prist:ry The material constants for the creep equation were determined by fitting the curve to the results from constant load tests (Figure 8.6.1). The temperature
- correction term was conservatively based on published data for Nickel 200.
FIGURE 8.6.1
[ STRAIN (%) VS. TIME"' 6 O)C)k e 3 l'
, J L
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FTl Non-Proprietary The computer program ANSYS was then used to create a finite element model using various tube / defect geometries to calculate the total creep strain. The following cases were considered and are illustrated in Figure 8.6.2:
c kc e [. 3 axial, uniformly spaced defects,[ ], wide, infinite length; Ac e 360* circumferential defect;[ ] , wide; in the free span, at the secondary tubesheet face, at the secondary tubesheet face within a sludge pile; and c
Parent tube removed for 360' over a[ 3 length.
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FTl Non-Proprl:ttry FIGURE 8.6.2 TUBE DEFECTS MODELED_ [ 3 TUBE CASE 1
]c [ SLEEVE MANWhNN%A[ MAM\%\\N/
I x
/ x h h NN h M W %%MNMh1 c CASE 2
[ 3 INFINITELY LONG AXIAL DEFECTS 100%1Winto TUBE 1 ' TUBE
\
4N +
l
' SLEEVE ~q
' CASE 3 360 deg. CIRCUMFERENTIAL DEFECT,100% TW into TUBE TUBE SLEEVE mmsm, -msm,f i
~
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FTl Non-Proprietary With the exception of a sleeve at the secondary tubesheet face, each case was assumed to be a freespan tube defect to maximize the thermal gradient stress across the tube / sleeve interface, in each case, the tubing defect was modeled to extend 100% through-wall to the tube / sleeve interface.
The finite element analysis imposed the steady state loads generated during 100% power and transient fatigue loads. The transient loads included the loads generated under the worst case locked tube scenario.
The analysis results for various times are summarized in Tables 8.6.1 and 8.6.2, and the results are displayed graphically in Figure 8.6.3. Converting the calculated creep strains into expected deformations in the steam generator demonstrates the Electrosleeve" is not subject to any gross distortions, FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprist:ry TABLE 8.6.1
[ ] ELECTROSLEEVE" INSTALLED IN THE TUBE FREE SPAg8)
FREE SPAN DEFECT TYPE: TUBE REMOVED'28 MEMBRANE + LOCAL TUBE SIZE TOTAL TIME MEMBRANE
(%) BENDING (%) (%)
(inches) (hours)"'
I 7 b,CA 11/16 l
3/4 7/8 l-t2 FREE SPAN DEFECT TYPE: 360' CIRCUMFERENTIAL CRACK >
MEMBRANE + LOCAL TUBE SIZE TOTAL TIME MEMBRANE
(%) BENDING (%) (%)
(inches) (hours) b,Cd 11/16 3/4 7/8 L
J (See notes on next page)
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FTl Non-Proprietary TABLE 8.6.1 (Cont'd) b 3 ELECTROSLEEVE" INSTALLED Inl THE TUBE FREE SPAN (8' FREE SPAN DEFECT TYPE: 8 INFINITE LENGTH AXIALStai TUBE SIZE TOTAL TIME MEMBRANE MEMBRANE + LOCAL (inch) (hours)"' (%) BENDING (%)
(%)
l I b'qC' d 11/16
, 3/4 7/8 L J NOTES:
(1) C 36,8 (2) Defects are 100% through the tube wall. Refer to Figure 8.6.2.
(3) Results include locked tube transient loading.
6 (4) { g. , C l
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FTl N:n-Pr:pri;ttry TABLE 8.6.2 c.
3ELECTROSLEEVE"
{
INSTALLED AT TOP OF TUBESHEET
I 360',100% THROUGH-WALL CIRCUMFEREN11AL CRACK'2' TOP OF TUBESHEET DEFECT TYPE:
(OUTSIDE SLUDGE PILE)
MEMBRANE MEMBRANE + LOCAL TUBE SIZE TOTAL TIME I
(%)
(inches) (hours)'
r 6Ad 9
7/8
,j L
TOP OF TUBESHEET DEFECT TYPE: 360',100% THROUGH-WALL CIRCUMFERENTIAL CRACK'23 (WITHIN THE SLUDGE PILE)
MEMBRANE MEMBRANE + LOCAL TUBE SIZE TOTAL TIME (inches) (hours)"8 (%)
l hefM 7/8 L- J NOTES (1) { g, bed (2) Defects are 100% through the tube wall. Refer to Figure 8.6.2.
(3) Results include locked tube transient loading.
b, C (4) [
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FTl Non-Proprietary FIGURE 8.6.3 ANSYS VS. [. ] fEST DATA Cs k b ]
l l
1
- s 8.6.2 Creep Rupture Over the last half century, considerable research and effort has been spent developing methods to predict creep rupture. Many of these techniques involve l time-temperature parameters whereby short-term tests at high temperature are used to predict long term exposure to lower temperatures. Analysis of data for a variety of aluminum , iron , nickel , titanium , cobalt , and copper-based alloys led Monkman and Grant to the following empirical relationship [13.35]:
log t, + m log (m ,) = C Where:
t, '= time to rupture m,e = minimum creep rate m and C = material constants that differ among alloy groups, but are nearly fixed values for different lots within the same alloy group FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propristtry in a comparison between various extrapolative techniques, the Monkman-Grant relationship was more accurate than that provided by any of five different time-temperature parameters [13.36). The Monkman-Grant relationship for the Electrosleeve" is illustrated in Figure 8.6.4.
FIGURE 8.6.4 7
F b,c,d
_J L
Using the relationship illustrated in Figure 8.6.4, the ANSYS constants discussed earlier, normal operating temperature, and differential pressure, a conservative time-to-rupture analysis for a sleeve with the tube removec can be performed. Table 8.6.3 shows the time-to-rupture for the sleeve sizes in this vpical: l t
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FTl Non-Proprietary TABLE 8.6.3 b b ],C l
STEAM T-HOT HOOP PRESSURE MINIMUM TIME TO GENERATOR (*F) STRESS CREEP RATE RUPTURE DESIGN (KSI) (%/1000 HR) (HRS)
CE SYS 80
, W-E b,c>d W-D W-F CE (0.048 wall)
W-51 L )
- The analyses summarized in the above table are conservative for the following reasons
- Operating T-hot is higher than the average metal temperature of the Electrosleeve*,
e Radial thermal expansion imparts a compressive stress on the sleeve ID that limits creep deformation, e The temperature correction used for the ANSYS material constants is conservative, and e The calculation does not assume any support from the parent tube, tube support plate, or tubesheet.
i With these conservatisms, the simplified estimate of creep rupture time agrees with the more rigorous ANSYS analysis to demonstrate that creep rupture is not a concern at operational temperatures and pressures.
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FTl N:n-Pr prist ry 8.6.3 Creep Fatigue Failure Evaluation The ASME Section lll Appendices [13.21 contain rules fer experimental stress analysis to determine whether or not a component can withstand the cyclic loading required for its intended application. A specific requirement is for the test sample to have the same composition and to be subjected to identical mechanical working and heat treatment as the actual component. The purpose of identical processing is to produce mechanical properties equivalent to those of the materialin question.
This experimental design philosophy has been expanded to address creep-fatigue. Test samp!es were creep tested to strains equal to and exceeding that expected in actual steam generator service (Section 7.4). The samples were then subjected to cyclic testing in accordance with the ASME Code. The tests dernonstrated that the Electrosleeve" has substantial fatigue life after creep deformations equal to and greater than that expected in service.
The testing summarized in Section 7.4 included the following safety margins:
- The ASME methodology includes a safety factor based on the number of samples being tested. With onl/ one sample being tested, the required safety margins were maximino. Testing additional samples would have reduced the required fatigue loads and/or cycles.
- One of the samples went through fatigue testing before and after the creep exposure.
For the expected creep deformations and transient loading in steam generator tubing, the Electrosleeve* is not subject to failure by the combined effects of creep and fatigue.
8.6.4 Creep Summary The creep deformations in the Electrosleeve" are extremely small at operational temperatures and loads. Testing and analysis demonstrate no failures from gross distortion, creep rupture, or creep fatigue will occur under the steam generator operating conditions.
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FTl Non-Proprieta.y 8.7 Design Summary The Electrosleeve" has been qualified for installation in the following steam generator designs:
The Electrosteeve" is qualified for installation over all tube defect types including IGA, circumferential cracks, axial cracks, pitting, and other similar defects. The Electrosleeve" is qualified for installation in tube freespan regions, at tube expansion transitions, and at tube support plate regions. The sheve is a structural repair of the parent tube. Installation in tube locations adjacent to the TSP vertical supports is !
limited as discussed in Section 8.5. The installed , minimum and nominal sleeve wall !
thicknesses are shown in Table 8.7.1. I I
TABLE 8.7.1 ACCEPTABLE WALL THICKNESSES FOR AN INSTALLED SLEEVE j INSTALLED SLEEVE INSTALLED MINIMUM WALL SLEEVE NOMINAL THICKNESS WALL THICKNESS TUBE SIZE (INCH) (INCH) c 11/16" OD x 0.040" wall b, c, e 3/4" OD x 0.042/0.043/0.048" wall 7/8" OD x 0.050" wall L d i The field process is designed and operated to install the nominal sleeve wall thickness.
Testing indicates that a [ ]4c.
nominal bond length between the sleeve and tube will carry all structural loads. For conservatism, the bond length for field acceptance will i be set at a minimum ( ) Ifgure 8.5.2 ill s{ rates the bond length and pressure I 1
boundary. The minimum bond length of[ ] t both sleeve ends provides )
adequate structural attachment to a parent tube. Bonding of the Electrosleeve* to the l
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FRAMATOME TECHNOLOGIES, INC. I 8-35
FTl Non-Prrprl;ttry degraded tube region (i.e., tube between the two minimum bond attachments) is not required to meet the structural design requirements (Figure 8.5.2).
Testing has demonstrated that a sleeve repair with a 30% through-wall defect in the sleeve wall and a tube 100% t(rough-wall defect occurring at the same location may be expected to last at least [)EFhY. Thus, an inspection interval of 5 years was established.
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I FTl Non-Proprietary I l
9.0 DESIGN VERIFICATION - CORROSION '
The objectives of the corrosion evaluation are to determine the susceptibility of the j Electrosleeve" material to known Alloy 600 degradation mechanisms such as stress l
corrosion cracking (SCC) and to evaluate the corrosion potential of the Electrosleeve*
material in environments that may exist in an operating steam generator.
The corrosion evaluation was performed by first addressing general corrosion characteristics and then evaluating primary and secondary side environments.
Operating experience is presented in Section 3.0.
9.1 General Corrosion Properties Nickel and nickel alloy materials are used in many corrosion applications, ospecially in caustic environments. In fact, "most tough corrosion problems involving caustic and caustic solutions are handled with nickel" [13.57, pg. 243]. Because of the widespread use of nickel, the corrosion resistance of high purity nickel has been thoroughly investigated and documented. This research is directly applicable to the Electrosteeve" since the electroformed sleeve consists of high purity (>99.5%),
nanocrystalline nickel material.
9.1.1 Literature Survey of Nickel Corrosion A generalliterature review was performed comparing the corrosion behavior of Alloy 600 and pure nickel [13.40] in various environments. Corrosion rates are summarized in Table 9.1.1.
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r-FTl N:n-Pr:pri;tIry TABLE 9.1.1
SUMMARY
OF LITERATURE SURVEY NICKEL AND ALLOY 600 GENERAL CORROSION RATES IN VARIOUS ENVIRONMENTS CORROSION RATE (mils per year)
ENVIRONMENT Nickel /Ni-200 Alloy 600 WATER, D; stilled, High Purity 200'F 0.001 0.001 No data ,
160'F CO 2/ air l 0.02-0.2 No data Fresh Water Sea Water <1.0 Minor Pitting ACIDS, I Boiling Sulfuric ,
5 %,214*F 34 249 10%,216'F 120 390 19%,219'F 110 640 50%,253 F >1000 >1000
-75%,360 F 910 >1000 96%,560 F >1000 860 Hydrochloric 10%-30%, Aerated,86 F ~80 No data 10%-30%,Deaerated,86 F ~10 ~10 30%,Deaerated,86 F ~70 ~100 Phosphoric
<40% Room Temp <1 <0.1
>40% Room Temp <1 <2 Elevated Temp 150 - 220 High Organic Acids Deaerated Low Low Aerated High Low ALKAllS Caustic Soda Low Low Other Alkalis Low Low Ammonia (400*C - 600 C) High Low Ammonium Hydroxide (>1 %) Low No Data SALTS Reducing Varied, Low Varied, Low Neutral / Alkaline Low, <5 Varied, Low Oxidizing Mostly High Varied, Low - High FRAMATOME TECHNOLOGIES, INC.
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FTl Non Proprietary Chemical environments, including liquid metals, are presented in Reference 13.57 relative to the cracking tendencies, in general, both nickel and its alloys effectively resist attack in acid, neutral, and alkaline conditions. The presence of highly c,.a 'ing species has been found to decrease this resistance in some chemical environments. For example, both nickel and nickel alloy corrosion has been observed in an acidic and highly oxidizing environment containing sulfur species. A galvanic attack between pure nickel and Alloy 600 or Monel 400 material will not occur in steam generator environments due to the low potential difference generated by the formation of a coupling of these two materials.
9.1.2 Comparison of Nickel Plating and Electrosleeve" Nickel plating has been successfully used to repair steam generator tubes since 1985[13.39]. This experience is summarized in Section 3.0 (Table 3.1). The nickel plating utilized has typically been thin walled (5-8 mils) compared to the thicker walled (> 25 mils) Electrosleeve" repair method. The nickel plating is intended to be a corrosion resistant " patch" rather than a structural repair. ,
l Both electrosleeves and nickel plating are >99.5% pure nickel. Phosphorus is micro-alloyed in the Electrosteeve" to add thermal stability. Nickel plating has a conventional polycrystalline grain structure whereas the electrosleeving process produces a nanocrystalline microstructure. The relative grain boundary volume l
is smaller in polycrystalline materials than in nanostructures. Therefore, alloy )
elements, such as phosphorus that migrates to the grain boundaries, tend to be l present at much higher concentrations at the grain boundaries of polycrystalline i structures. As a consequence, the small phosphorus content in the Electrosleeve" material would be more evenly distributed in its microstructure than in its corresponding coarser grained counterpart. Because of this difference in microchemistry, nanostructures are more resistant to intergranular corrosion phenomena (IGA, SCC) than their microcrystalline counterparts.
l l
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FTl Nrn-Pr:prl;t:ry The corrosion properties of nanostructures were evaluated in a literature survey.
Most of the corrosion evaluations conducted to date have been laboratory studies involving potentiodynamic polarization techniques. The studies typically show comparable general corrosion resistance in nanostructured materiels relative to their conventional counterparts.
The effect of phosphorus on the corrosion resistance of nickelis complex since it depends on the environmental conditions. However, at phosphorus concentrations of less than 0.9%, the corrosion behavior of the alloy is similar to that of pure nickel [13.50]. Thermodynamic computations have been performed to assess the stability of nickel (Ni) and nickel-phosphorus (Ni-P) alloys in high temperature aqueous media [13.44]. Potential-pH diagrams constructed for Ni and Ni-P alloys (with P concentrations s 25% by weight) at temperatures up to 200*C show that the presence of P does not noticeably alter the normal thermodynamic stability domains (i.e., potential-pH) for Ni.
Since numerous soluble (and insoluble) P-bearing species (usually PO4 type) can be formed, high P concentrations may affect corrosion kinetics; however, the presence of P is not expected to compromise the excellent thermodynamic stability of Ni and its oxides in high temperature water.
The general conclusion from this comparison is that the Electrosleeve" material will perform the same as steam generator nickel plating in regards to corrosion I behavior. Specific tests to evaluate the corrosion characteristics of the Electrosteeve" material were performed as discussed below.
9.1.3 General Corrosion Tests of Electrosleeve" Corrosion tests were performed on Electrosleeve" samples to confirm general corrosion properties for the material. The environments used were severe and were not representative of normal or faulted steam generator chemistry.
However, the environments will attack Alloy 600. Thus, these tests are meant to characterize Electrosteeve" material, not to predict the life in a steam generator.
The corrosion mechanisms tested included IGA, SCC, pitting, and crevice corrosion. Standard ASTM test procedures were followed.
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1 I
FTl Non-Proprietary 9.1.3.1 Boiling Sulfuric Acid IGA Test The boiling sulfuric acid-ferric sulfate test [13.24] is a standard ASTM method to detect the susceptibility of wrought, nickel-rich, chromium-bearing alloys to IGA. This method uses ferric chloride in 50% boiling sulfuric acid. The test is aggressive to nickel based materials with little or no chromium due to the oxidizing nature of the ferric ion.
For this test, five Electrosleeve" specimens, one-inch long, were exposed to 50% boiling sulfuric acid containing ferric chloride for 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.
The Electrosfeeve" specirnens were removed from the test solution and examined by transverse cross-section for evidence of IGA. No IGA was found. This was expected since the Electrosteeve" material is intrinsically resistant to IGA due to its nanocrystalline grain size which minimizes variations between grain boundary chemistry and grain interiors.
9.1.3.2 Polythionic Acid SCC Test o
i The polythionic acid test [13.25] is a standard ASTM method used to !
evaluate the relative resistance of stainless steels and related I materials to SCC. The test is applied to wrought products, castings, and weld metals by immersion in a solution containing polythionic l acid at room temperature. Cracking of austenitic stainless steels (Type 302 and 304) would be expected in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or less in this solution. The Electrosleeve" test period was 46 hours5.324074e-4 days <br />0.0128 hours <br />7.60582e-5 weeks <br />1.7503e-5 months <br />. The environment may also produce areas of intergranular attack; however, the test was not used for intergranular attack. l Five Electrosleeve" specimens, one-half inch long, were tested. Five additional electrosleeved tube samples were tested as C-rings. These C-ring specimens had the Electrosfeeve" in tension on the inside surface to evaluate the effect of applied stress. All C-ring samples were stressed to produce sleeve yielding.
FRAMATOME TECHNOLOGIES, INC.
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i l
FTl Non-Pr priettry j After exposure to the corrosion environment, transverse cross-sections were examined metallographically. There was no evidence l of SCC in the Electrosleeve" material.
9.1.3.3 Magnesium Chloride SCC Test The boi!ing magnesium chloride test [13.261 is a standard ASTM method employed to evaluate the relative resistance of wrought, cast, and welded stainless steels and related alloys to SCC. The test can detect the effects of composition, heat treatment, surface finish, microstructure, and stress on the susceptibility of these materials to chloride SCC. The test is carried out in a solution of magnesium chloride (about 45%) which boils at 311*F (155'C) for a duration of 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
Five Electrosleeve" specimens, one-half inch long, were tested. Five additional electrosfeeved tube samples were tested as C-rings. These C-ring specimens had the Electrosteeve" in tension on the inside surface to evaluate the effect of applied stress. All C-ring samples were stressed to produce sleeve yielding.
After exposure to the corrosion environment, transverse cross-sections were examined metallographically. There was no evidence of SCC in the Electrosteeve" material.
9.1.3.4 Sodium Chloride SCC Test The sodium chloride SCC test [13.27] is a standard ASTM method used to characterize the SCC resistance of aluminum, ferric, and other alloys exposed to alternating immersion or wetting and drying conditions. The typical cycle time is 10 minutes immersion in the solution and 50 minutes drying in air. This test is an accelerated test to evaluate the resistance to SCC and is not intended to predict performance in specialized chemical environments.
Five Electrosleeve" specimens, one-half inch long, were tested. Five additional electrosleeved tube samples were tested as C-rings. These C-ring specimens had the Electrosleeve" in tension on the inside FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary surface to evaluate the effect of applied stress. All C-ring samples a were stressed to produce sleeve yielding.
The test specimens were exposed for 21 days to a 3.5% sodium chloride (Nacl) solution at room temperature with alternate wetting and drying.
Metallographic examination of the specimen cross-sections revealed
' no SCC.
9.1.3.5 Ferric Chloride Pitting and Crevice Corrosion Test The ferric chloride test [13.28] is a standard ASTM method used to evaluate the resistance of stainless steels, nickel-base, chromium-bearing, and related alloys to pitting and crevice corrosion. This test is an accelerated test designed to cause the breakdown of type 304 stainless steel at room temperature. The test evaluates pitting and crevice corrosion.
Pittina Corrosion Five Electrosleeve" specimens, one-half inch long, were exposed to !
~t he test solution of 6% ferric chloride in water at room temperature.
The ferric chloride used in this test provides an aggressive, strongly oxidizing, acidic environment to accelerate the test process. The specimens were exposed to the solution for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Examination of cross sections of the samples showed no evidence of pitting on the Electrosleeve". As observed in other test results, the effect of the ultra-fine-grained size of the Electrosleeve" materialis a resistance to pitting corrosion.
4 FRAMATOME TECHNOLOGIES, INC.
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___.m..___.-.___ _ _ _ _ _ _ . _ _ . . _ . . . _
FTl Non-Prepristory Crevice Corrosion The same solution used in the pitting step is used in the crevice corrosion test. Sandwiching a Teflon rod between two electrosleeved tube halves created crevice specimens. A total of five crevice specimens were exposed to the test solution for a period of I
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> at room temperature.
Some crevice corrosion was observed in four of the ten half-tube samples (two per crevice specimen). The remaining six half-tube samples showed ao evidence of crevice corrosion. Some attack of the Electrosleeve" material was expected in this highly oxidizing acidic environment. With six of the ten specimen surfaces showing I
no crevice corrosion, it is concluded that even in this severe test environment, the Electrosleeve" material shows good resistance to i crevice corrosion.
9.1.3.6 Summary of Characterization Tests Standard ASTM tests were used to characterize performance of the material relative to corrosion mechanisms. The results of these tests revealed no susceptibility to IGA in the boiling sulfuric acid test. No cracks were found in the samples exposed to the polythionic acid, boiling magnesium chloride, or alternate immersion tests. The ferric chloride test showed that the samples had no susceptibility to pitting corrosion and only slight susceptibility to crevice corrosion.
The performance of nanocrystalline micro-alloyed Electrosleeve" material was found to be acceptable in these tests and similar to that expected of high purity polycrystalline nickel.
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i FTl Non-Proprietary l
9.2 Primary Side Corrosion Evaluation in general, corrosion in the primary system of a PWR is minimized by careful control of the environmental characteristics. The reactor coolant system (RCS) is a closed system that does not come in contact with outside contaminant sources. The environment is further controlled by limiting the presence of contaminants to low levels as required by plant technical specifications. The RCS chemistry control parameters and expected limiting values for the various modes of operation are given in Table 9.2.1. The corrosion of nickel and nickel based alloys is minimal during power operation due to:
The addition of dissolved hydrogen which acts as a reducing agent, e Controlling the dissolved oxygen content to 100 ppb, e The pH at temperature is maintained slightly alkaline, and
- Nickel solubility is low at operating temperatures I (approximately 550-650'F (288-343'C)). ;
TABLE 9.2.1 PRIMARY SIDE MATRIX CHEMISTRY PARAMETERS Plant Boron Lithium Oxygen Temperature Hydrogen Hydrogen Chloride Fluoride Mode (ppm) (ppm) (ppm) ( F) Peroxide (cc/kg) (ppm) (ppm)
(ppm) 1 0-2000 2.2-3.5 <0.1 Tw-T. 0 25-35 <0.15 <0.15 2 2000-3000 0-3.5 <0.1 Tw-T , 0 0-35 <0.15 <0.15 3 To 4 (>250 F) 200 (>250 F) (>250 F) 5 3000 0 0-3 <200 <10 0 <1 <1 6 3000 0 8 Ambient 0-6 0 <1 <1 FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary To evaluate corrosion performance of the Electrosfeeve" materialin the primary side environment, the following conditions were addressed:
1 I
e Full Power Operating Conditions
- Borated Primary Water
- Pure Water.with Hydrogen 1
- Shutdown Conditions Boric Acid
- Crud Burst
- Parent Tube PWSCC Residual Stresses in Parent Tube
- Ability of Sleeve to Stop PWSCC i
l Table 9.2.2 contains a summary of the primary side principal chemistry parameters in !
a typical PWR and their values during testing.
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)
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I FRAMATOME TECHNO!.OGIES, INC. 1 9-10 1-
FTl Non-Proprietary TABLE 9.2.2 PRIMARY SIDE CHEMISTRY COMPARISON PARAMETERS Plant Mode Boron Lithium Oxygen Temperature Hydrogen Hydrogen (ppm) - (ppm) (ppm) (*F) Peroxide (ppm) (cc/kg) -
Plant Test Plant Test Plant Test Plant Test Mant Test Plant Test 1 (>5%) 0-2000 650 - 2.2-3.5 0-2 <0.1 <0.01 Thot - 662 O O 25-35 40-45 2500 Tcold 2 2500 0 <0.1 <O.01 176 3 (0-5%) 2000- 0-3.5 200 - 610 302 O O-35 4 3000 482 5 (<2OO*F) 3000 2500 0 0 0-8 NA <200 194 <10 10- 0 0 ,
100 '
6 (Refueling)) 3000 1200 O O 8 8 Ambient 75 0-6 0 1
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-PropriItary Framatome (Europe) has performed numerous corrosion tests on steam generator tube nickel plating to demonstrate performance in this environment [13.391. As previously discussed, the corrosion behavior of high purity standard nickel plating and high purity Electrosleeve" nickel forming is comparable. Thus, the data on steam generator tube nickel plating is directly applicable.
9.2.1 Full Power Operating Conditions Corrosion testing was performed on nickel plating in environments that included pure water and primary water chemistry conditions [13.391. Highly stressed hard rolled transition zones or highly stressed reverse U-bend (RUBS) specimens were used in the testing. Also, samples were subjected to temperature and pressure cycling in pure water to induce deformations in the nickel layer.
9.2.1.1 Pure Water Testing The objective of this test was to determine the cracking resistance of highly stressed nickel plating in pure water and to compare it to Alloy 600.
RUB specimens were tested in an autoclave at the following conditions:
- Environment: pure water [
6,c E
].
- Temperature: [ ],
- Pressure: {
1
- Test Period: (
3 h,c.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary The RUB specimens used in this test were as follows:
- Two specimens without nickel plating, y
- Three specimens with[. 7of nickel plating,
- Three specimens with [. Yo'f nickel plating, and
- Three specimens with [. Yo'Inickel plating.
NOTE: The heat of Alloy 600 material used in this test has been shown to crack in less than 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> in deaerated pure water environments.
After 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, the test specimens were examined and, as expected, the unplated specimens contained numerous cracks.
Following 4,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, a second examination of the specimens was performed. Cracking was not observed on any of the nickel plated specimens regardless of the plating thickness at either the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> or 4000 hour0.0463 days <br />1.111 hours <br />0.00661 weeks <br />0.00152 months <br /> examinations.
The conclusion of this test is that a nickel sleeve will not crack in pure water and will protect Alloy 600 against cracking. The thicker Electrosleeve" (>25 mils) offers greater protection to the Alloy 600.
9.2.1.2 Primary Water Testing The objective of this test was to determine the cracking resistance of highly stressed nickel plating in primary water and to compare it to Alloy 600. j i
Two Alloy 600 RUB test specimens with 4 mils (100 m) of nickel plating, along with unplated Alloy 600 RUB control specimens, were a
placed in an autoclave at the following test conditions [13.39]:
- Environment: ( t 1
I 6 i
) ,c l.
FRAMATOME TECHNOLOGIES, INC. I 9-13 !
FTl Non-Pr:prl:ttry l b \
e Temperature: [ 3, ,c e Pressure: [
e Test Period: [
J.g NOTE: The heat of Alloy 600 material used in this test has been shown to crack in less than 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> in deaerated pure water environments.
After 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, the autoclave was opened for a specimen inspection. No cracking of the nickel plated specimens was observed; however, the unplated Alloy 600 control specimens were severely cracked.
At the end of the test period (15,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />), the specimens were again examined. No SCC, general corrosion, or pitting of the nickel plate was observed.
The conclusion of this test is that a nickel sleeve will not crack in primary water and will protect the Alloy 600 tube ID from cracking.
The thicker Electrosteeve" (>25 mils) offers greater protection to the Alloy 600.
i 9.2.2 Shutdown Conditions l
l The main corrosion concern during primary side shutdown conditions is the i presence of boric acid. The effect of boric acid, at various temperatures and l concentrations, was evaluated on nickel plating. In addition, electrosleeves l
were tested at conditions that simulate oxidizing shutdown crud burst i
conditions.
9.2.2.1 Boric Acid - Cold Shutdown l
l Both aerated and deaerated solutions were tested to evaluate nickel plating.
FRAMATOME TECHNOLOGIES, INC.
l 9-14
._. . -.-. =. .. . . . - . . .- . - . .. . - . . _ .
I I
l FTl Non-Proprietary l
l Two nickel plated Alloy 600 test strips were tested in an open beaker at the following conditions:
b e Environment:[., },c
[ 3,b,C e Temperature: [
f'#
e Test Period: [ ] b,C l
l At the end of the test period, the specimens were examined and weighed. The measured weight loss was negligible [
- 3. his minimal measured l weight loss is equivalent to a corrosion rate Then, two nickel plated Alloy 600 test strips were tested in an open beaker at the following conditions:
e Environment: {
l )'b,c
'C l e Temperature: [
e Test Period: [ ~j .
f C A
3' At the end of the test period, the specimens were examined and l weighed. There was no measurable weight loss.
I i
4 FRAMATOME TECHNOLOGIES, INC.
l
! 9-15 l
l.
FTl N:n-Pr:prl:ttry 9.2.2.2 Boric Acid - Elevated Temperatures A group of tests were performed on nickel plated Alloy 600 tubes in a boric acid environment at elevated temperatures. These tests address the potential for corio an of nickel plating from boric acid trapped within Alloy 600 cracks. The tests also partially address Mode 5 conditions.
i Nickel plated tuHng specimens were placed in Alloy 600 capsules, )
welded shut, placed in a furnace at room temperature, and tested at the following conditions:
- Environment:[
b'b,C
- Temperatures: C ]'
- Test Period: [ ].
kC solution. The oxygen level for Mode 5 is 0-8 ppm, and temperature is less than 200 F. Thus, the test did not address worst case oxygen levels for Mode 5 but did encompass the temperature and typical boron concentration.
The specimens were removed from the oven and examined at the end of the test period. No corrosion of the nickel plating was ,
observed for the three test temperatures.
FRAMATOME TECHNOLOGIES, INC.
9-16
FTl Non-Proprietary 9.2.2.3 Shutdown Crud Burst / Cleanup During a typical plant shutdown for a maintenance or refueling outage, an RCS crud burst is induced through an adjustment to the coolant pH and oxidant level. For this, the plant is borated to the refueling concentration, the lithium and dissolved hydrogen removed, and hydrogen peroxide (up to 10 ppm) may be added when the temperature has decreased to less than 200* F. This condition is typically maintained for a period of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to reduce the crud inventory in the RCS prior to continuing the refueling activities. This condition was evaluated by testing Electrosleeve" specimens at the following conditions:
- Environment: [
h,C 3
- Temperatures:[
- Test Period: [ ]'
- Test Specimens: ( ).b,C Specimens ~were tested at each concentration. At the end of the test period, the specimens were examined and weighed. [,
b
].,c,d No localized attack was observed on the Electrosleeve" surface. There was no significant difference in the hydrogen peroxide concentrations.
E
] ,b C, d FRAMATOME TECHNOLOGIES, INC.
9-17
FTl N:n-Propri;ttry 9.2.2.4 Low pH and Shutdown Chemistry Conditions The use of the Electrosleeve" as a repair requires the corrosion test to envelop the expected chemical conditions during shutdown as well as during operation.
l l
Mode 5 Corrosion Testina Electrosleeve" specimens were tested in the following environment:
e Boron: ( ),b,C
- Oxygen: ( 2
e pH: [ Y'
. Temperature: [ ).b,c These conditions were selected to envelop expected plant conditions during shutdown with the controlling elements being the boron and the dissolved oxygen.
l The samples were first exposed to a [ 3 environment [
]with examinations mPde at intermediate times. The examinations revealed that the samples had passivated [ ] $$h the weight loss had essentially stopped (within the precision of the weight loss measurement).
The temperature was lower d to ambient b
). i e test was maintained [
]b,c,e(and no additional weight loss was observed. The conclusion from this test is that no detectable degradation is expected in the Electrosleeve" due to shutdown chemistry conditions.
l l
l l
l l
FRAMATOME TECHNOLOGIES, INC.
! 9-18 l
FTl Non-Proprietary Electrosleeve" in Low oH Conditions To simulate a low pH excursion during shutdown, a test using sulfuric acid to lower the pH to 4.0 was performed. The samples from the Mode 5 test were used in the following environment:
6
- Boron: 3 , , c.
[
- Oxygen: [ 3, '
b
- pH: [ 3,c
- Temperature: [. ]s,c Intermediate examinations were made revealing that, after a short period of time, the samples passivated and no further weight loss was detected. This test supports earlier test results that demonstrate little or no corrosion of the electrosleeves is expected due to normal shutdown chemistry conditions.
The conclusion from this test is that even with an artificially lowered pH, virtually no additional degradation occurred in the Electrosleeve" samples.
FRAMATOME TECHNOLOGIES, INC.
9 19
FTl Non-Prcpri;t:ry 9.2.3 Parent Tube SCC Two tests have been performed to evaluate SCC in the parent tube. The &st test verified that a nickel plated layer would prevent SCC in the parent tube at highly stressed regions by providing a protective layer.
A test was also performed with electrosteeves to verify that high residual tensile stresses are not induced into the parent tube at the ends of the sleeve.
9.2.3.1 Stress Corrosion Cracking Protection PWSCC susceptible Alloy 600 specimens containing stresses greater than 30 to 35 ksi tested in 10% NaOH (caustic) solution were shown to rapidly induce stress corrosion cracking. Steam generator roll transition mockups were used to evaluate the effect of nickel plating on SCC [13.39). -The Alloy 600 tubes were rolled using a five-step l
rolling process, which resulted in two roll transition regions in each 1
mockup. The specimens were tested at the following conditions:
a
- Environment: [ )b c.
- Temperature: [ ]I., c.
- Pressure:
)b,c
[
- Test Period: [ 3.
The test solution was injected in the mockups which were then I
internally pressurized.
b
{ ] m,c.
ockups were tested:
l b> C;k
- I ,
l *L J Mockups were pre-cracked 100% through-wallin a sodium tetrathionate solution (at room temperature) prior to being plated. b These mockups were plated [ 3. M FRAMATOME TECHNOLOGIES, INC.
9-20 l
. -_ - . . = .- -. _ . _ - . _
4 I
FTl Non-Proprietary l Unplated Alloy 600 tubing produced 50% through-wall cracks after 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> and 100% through-wall after 240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br />.
b 6,c,cl 3.The ;
mockups plated with 100 or 150 m (4.0 or 5.9 mits) of nickel l
showed no attack or damage to the nickel plating.
Thus, a nickel plating thickness of 4.0 mils or greater provides protection of the parent tube from PWSCC. An Electrosleeve" will offer improved protection because nanostructured materials provide greater resistance to SCC. The design thickness for the Electrosleeve" is greater than 25 mils which provides a greater level of corrosion resistance.
9.2.3.2 Stress Corrosion Cracking (Effect of Stress)
A primary concern with standard steam generator sleeving has been the introduction of residual tensile stresses into the Alloy 600 parent tube due to the sleeving process. Such tensile stresses lead to PWSCC in the parent tube while the sleeve typically does not experience SCC. Electrosleeving has the advantage of not introducing these high residual tensile stresses to the tube.
The objective of this corrosion test is to demonstrate the absence of significant residual stresses imparted on the Alloy 600 tube after electrosfeeving. A second objective is to demonstrate the resistance of the Electrosleeve" to SCC.
The corrosion test environment was as follows:
b,c e Environment: [ 3, e Temperature: ( ) ,b,C e Pressure: ( 3 e Test Period: [ ].b,C FRAMATOME TECHNOLOGIES, INC.
9-21
1 FTl N n Pr:prist;ry These corrosion specimens are from the locked tube tests described in Section 7.1. The 3/4" OD tubing, EPRI heat 96834, was known to be susceptible to SCC in caustic environments. C bceii 1
The measured installation stress due to locked tubes was nominally 3.0 ksi tensile. Alloy 600 will not produce PWSCC in the steam generator environment or SCC in a caustic environment for these stress levels.
The sleeved tubes were cut from the locked tube mockup and placed in the autoclave. [
b,c, d
], the test was intended to evaluate residual stress.
b,C
[ ]C-rings, fabricated from the same heat of Alloy 600 without an installed Electrosleeve", were included in the test as control specimens. The C-rings were electropolished to remove approximately 0.5 mil from each surface and loaded to a nominal O.5% strain.
The specimens were removed from the autoclav,e c nd c examined.
Stress corrosion cracking was observed in allL J -rings ranging in
[ ). Yhe susceptibility of the Alloy 600 to SCC was confirmed in the test condition.
+
los c No SCC was observed along the length of the[ 3electrosfeeved specimens. Thus, high residual tensile stresses were not induced into the parent tube at the ends of the sleeve. In addition, there was no degradation of the Electrosleeve" material. ,
FRAMATOME TECHNOLOGIES, INC.
9-22
FTl Non-Proprietary 9.2.4 Summary of Primary Side Tests Corrosion testing of high purity nickelin pure water and primary water environments at accelerated temperatures indicate that the Electrosfeeve"is not I expected to experience corrosion degradation at steam generator operating conditions.
l Shutdown crud burst testing determined that the general corrosion of the Electrosteeve" over a 40 year life [
{
3C !
If boric acid is trapped in the crevice of an existing tube crack and the j Electrosleeve" is installed, tests indicate that no corrosion attack of the sleeve is expected. ;
The wall thickness of an Electrosfeeve" (>25 mils) exceeds the minimum required thickness to protect the tube from initiating or propagating SCC in highly stressed regions. In addition, SCC is not expected to occur in the Alloy 600 parent tube at the ends of the Electrosleeve". l l
9.3 Secondary Side Corrosion Evaluation l
Evaluating the corrosion performance of a material for secondary side environments is more difficult than evaluating the primary side performance due to the wide range of chemistry conditions that may be encountered. Steam generator upset chemistry '
conditions may result from condenser in-leakage, ion exchange resin regenerant chemicals (caustic and acid) from condensate polishing and makeup demineralizer systems, acidic sulfur species from resin ingress, chlorides, and corrosion product iron and copper.
l The effect of these contaminants is further compounded by the concentrating mechanisms associated with heat transfer and boiling in the steam generators. The generally accepted steam generator and secondary system chemistry program is All Volatile Treatment (AVT). In this program, there are no solids intentionally added to the steam generators for chemistry control. Only volatile chemicals such as ammonia and hydrazine are used for corrosion control. !
1 1
FRAMATOME TECHNOLOGIES, INC.
9-23
FTl Nrn-Pr:pri tiry Corrosion of the Electrosleeve" in the secondary side environment of a PWR is l minimized by the following environmental characteristics:
e Hydrazine is added to scavenge oxygen, e Feedwater dissolved oxygen is < 5 ppb, e The feedwater pH is maintained in the alkaline range (> 8.8) by adding ammonia or other amines, e Nickel solubility is low at operating temperatures (approximately 550-650 F (288-343*C)),
o Plant operating procedures call for operator action in the event of severe chemistry excursions to minimize time at the event, and
. Exposure of the sleeve to the secondary side is minimal. This is due to the Alloy 600 degradation being tight SCC or IGA. In addition, no crevice is created between the sleeve OD and tube ID.
If exposed to the secondary side bulk water, there are no corrosion concerns for the Electrosleeve" provided that the water chemistry is within the recommended specifications. Table 9.3.1 provides secondary side chemistry values and Table 9.3.2 provides a summary of the secondary side principal chemistry parameters in a typical PWR. However, considering that the main reason to utilize electrosleeves is to arrest Alloy 600 cracking, the Electrosleeve" must withstand the environment that locally forms at the crack tip.
i l
l FRAMATOME TECHNOLOGIES, INC.
9-24
FTl Non-Proprietary l l
TABLE 9.3.1 l SECONDARY SIDE MATRIX CHEMISTRYm l
l
, PARAMETERS Plant Sulfate Sodium Chloride Copper Oxygen Temperature Boron Iron l
Mode (ppb) (ppb) (ppb) (ppb) (ppb) ( F) (ppm) (ppb) 1 <20 <20 <20 <1 (FW) <5 (FW) T %, - T,o,o <10 <5 (FW) 2 T%,- Teow i 3 <100 <100 <100 N/A <100 to <10 N/A 1
.i 4 200 l 5 <1000 <1000 <1000 N/A <100 <200 <1 N/A (FW) )
6 <1000 <1000 <1000 N/A <100 Ambient <1 N/A l 4 (Refuel) (Source) l l
l NOTES: l
?
(1) Lead (Pb) limits not established. l l
1
.I i
l i
l l
FRAMATOME TECHNOLOGIES, INC.
9-25
- FTl Non-Proprietary TABLE 9.3.2 -
SECONDARY SIDE CHEMISTRY COMPARISON"8 PARAMETERS Mont Mode SuHeen Sedum CModde Copper Oxygen . Temperstwo Boros tron -
(ppbt typhi topbi typbl topb) g=p3 topni typbi Plant Test P:ent Test Plant Test Plant Test Plant Test Plant - Test Plant Test Plant Test 1(>5%P <20 0-3E5 <20 0- 3E7 <20 0-2E7 <1 (FW) 6E6 . c5(FW) <5- T hot-Tooid 265- <10 0 <5 (FW) sludge
+ sludge 3E9 305 2
3 (0-5%) <100 <100 <100 MA <100 <10 MA 4
5 (<200T) <1300 <1000 <1000 NA <100 (FW) <200 <1 MA 6(RF) <1000 <1000 <1000 MA <100(Sourm) Amtnent <1 MA NOTES:
(1) Lead (Pb) limits not established, (2) Test used 1 gram of lead (Pb).
FRAMATOME TECHNOLOGIES, INC.
9-26
FTl Non-Proprietary i
j The performance of the Electrosleeve"in severe secondary side environments was
, evaluated by exposing the sleeve to extreme environments at elevated temperatures.
j This was addressed by exposing highly stressed tube /Electrosteeve" samples in an environment known to cause SCC in Alloy 600. Arrest of cracking at the Alloy
{ 600/Electrosleeve" interface demonstrates the corrosion resistance. The environments
- included high concentrations of active species.
4 e Chloride in acidic and alkaline media, e Sulfate in acidic and alkaline media, and e High/ low redox conditions.
- The chemistry of these extreme environments may be approached in a localized region ;
of the secondary side. However, the acidity and redox potential values for these tests I
- were chosen to accelerate the material degradation and are not present in an operating
[ unit. ;
- Evaluation of worst case conditions under sludge piles was also tested. These tests
- were performed in refreshed autoclaves which incorporate steady state heat transfer i conditions. These tests simulate the steam generator operation. As in an operating !
- unit, the heat transfer process concentrates chemical solutions. The tests were f'
accelerated by increasing the bulk water concentrations of the contaminants by factors
, greater (typically 1000x) than those expected in an operating unit excursion event. !
1 The objective of these tests was to conservatively evaluate the degradation of the '
Electrosleeve" material when exposed to extreme environments (e.g., caustic, acidic, fresh water in-leakcae, etc.) under simulated operating conditions that involve heat i transfer in a confined geometry (e.g., sludge pile). While several postulated chemistry
- t
[ environments have been presented in the literature, Reference 13.55, the testing
{
[ performed using the Electrosleeve" material with the heat transfer effects envelops most chemical conditions, i
- i t
i- !
i FRAMATOME TECHNOLOGIES, INC. ,
9-27
FTl Non-Pr:prietIry 9.3.1 SCC Propagation Tests To evaluate the crack arrest capability of electrodeposited nickel, two test 5 were conducted. The first test demonstrated the ability of nickel-plated steam generator tubes containing through-wall cracks to maintain their integrity in a secondary side environment (chemistry and pressure conditions). The second test demonstrated the ability of highly strained electrosfeeves to arrest ODSCC in Alloy 600 tubing.
A summary of the test conditions and results for these crack property tests is contained in Table 9.3.3.
TABLE 9.3.3
SUMMARY
OF CRACK PROPAGATION TESTS TEST PURPOSE TEST ENVIRONMENT RESULTS SCC Propagation Tests F ~~7 (Pre-cracked S/G Tubing) 'J SCC Propagation Tests (Stressed C-rings)
L J r
FRAMATOME TECHNOLOGIES, INC.
9-28
l FTl Non-Proprietary 9.3.1.1 Precracked Steam Generator Tubing Test Steam generator tubing, containing OD initiated cracks (including through wall cracks), was nickel plated and tested in a mockup (see Figure 9.3.1). The purpose of the test was to determine whether through-wall cracks in nickel plated steam generator tubes will continue to propagate through the nickel plating when exposed to secondary side conditions [13.39].
FRAMATOME TECHNOLOGIES, INC.
9-29
I FTl Non-Proprietary FIGURE 9.3.1 SECONDARY SIDE CAPSULE TESTS MANOMETER AUTOCLAVE HEAD a
i SECONDARY _
ARGON PRESSURE ENVIRONMENT 285 BAR NH 3
= NICKEL PLATING P = 185 BAR T = 360C b
l 'N
/ THROUGH WALL CRACK hh t; aylh!
i l E Nd@j$Mk2 FRAMATOME TECHNOLOGIES, INC.
9-30
i j
FTl Non Proprietary j The test conditions were as follows:
- Environment: [ !
t h >C 3
i e Temperature: ( 2, e Differential Pressure: (
i ] k,c
- Test Period:[ .
e
.Three nickel plated pre-cracked tubes were exposed to these t
conditions for the test duration. Ultjasonic examinations conducted
(
1 3 '
] indicated no increase in the depth of the cracks when compared to pre-test examination data. Thus, with the pre-cracked tubes, the electroplate provided tube integrity.
f 1
1 9.3.1.2 Crack Arresting C-Ring Test j I j
Alloy 600 steam generator tubing with and without an installed i i
Electrosleeve", in the form of highly stressed C-rings, was used to l evaluate the ability of the Electrosleeve" to arrest a crack propagating from the tube OD. Testing was performed in a 10%
i NaOH (caustic)' environment that is known to cause SCC in susceptible Alloy 600 material.
The test conditions were as follows:
e Environment: C h i ], , C !
i j b I
! e Temperature: ( ], ,c 4
- FRAMATOME TECHNOLOGIES, INC.
- _ 9-31 jy7u y y .-- w - ,-o n. c - . .m -
l FTl Non-Proprinttry
- Pressure: [
e Test Period: b
~l.b, c b
Testing was performed using ( ) ,C.
C-ring specimens; rom each of the following four tube types:
[
- Bare Alloy 600 tubes, e Electrosleeved Alloy 600 tubes,
- Bare electrosleeves, and e Nickel 200 tubes (3/4" OD x 0.049" wall)
The specimens were prepared from 3/4" OD Alloy 600 tubing (EPRI heat number 96834) that has been shown to be susceptible to SCC in this environment.
All C-rings were electropolished to remove approximately 0.5 mil from each surf ace. To place the Electrosfeeve" in tension in the final C-ring configuration, the electrosteeved tube specimens were machined to an Alloy 600 nominal tube wall of 10 mils. C-ring specimens were then stressed to 1.0%,1.5%, and 2.0% strain.
Dimensional analysis of the test specimens (bare Electrasleeve",
Nickel 200, Alloy 600, and electrosteeved Alloy 600) following the 3,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> test confirmed all C rings maintained tensile stresses throughout the test period.
The bare Electrosfeeve" material and Nickel 200 showed no evidence of SCC under the conditions tested.
The Alloy 600 displayed severe intergranular SCC following the 3,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> exposure. Table 9.3.4 presents crack depth and strain levels.
FRAMATOME TECHNOl.OGIES, INC.
9-32
FTl Non-Proprietary TABLE 9.3.4 MAXIMUM SCC PENETRATIONS IN ALLOY 600 CONTROL SPECIMENS AVERAGE OF MAXIMUM STANDARD APPLIED STRAIN CRACK DEPTHS DEVIATION
(%) (mils) (mils) 1.0 0 ],j 1.5 2.0 L .]
bc.
[ 3, the lowest applied strain yields considerable variability in the maximum extent of SCC. However, all applied strains produced maximum crack lengths in excess of the nominal 10 mil thickness of the Alloy 600 tubing used with the electrosfeeved specimens.
All of the testp electrosfeeved C-ring specimens C ge e 3 displayed the SCC penetrations through[ 3 wa,ll Alloy 600 tubing. The SCC growth stopped at the Electrosleeve" material.
Based upon exposure time, the cracks were likely to have remained
" blunted" at the Electrosteeve* interface. C 6,c,d I 3 No evidence of either sleeve disbonding or crack ,
propagation along the interface was noted in any of the test l specimens.
l In summary, the conclusions from this test are:
e Bare Electrosleeve" material behaves in a manner consistent with Nickel 200 and displays complete immunity to caustic SCC, e Propagating SCC in Alloy 600 is " blunted" by the Electrosleeve",
and FRAMATOME TECHNOLOGIES, INC.
9-33 ;
FTl Non-Prsprictary l
- The high stress conditions at the " blunted" Alloy 600 cracks do not result in Electrosleeve* disbonding or interfacial cracking. ;
1 l
l 9.3.2 Capsule Tests 1
The objective of this test was to characterize the corrosion performance of the Electrosleeve" materialin confined conditions of extreme bulk water chemistry.
Test conditions were as follows:
. Environment: Demineralized water; 2,000 psi oxygen overpressure or deaerated (by bubbling nitrogen through the solution prior to the test),
o Temperature: 508*, 536*, 580*, & 608'F (265*, 280*, 305', & 320'C),
o Test Period: 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> (approximately 31 days).
Five-inch long sections of Monel 400 tubing containing three-inch long electrosteeves were used to manufacture the capsules.
The electrosleeved tubing capsules were sealed with Monel 400 nut / cap assemblies on both ends. One end of the capsule contained a pressure transducer to identify any through-wallleakage. The capsules were then placed into a furnace and heated to the respective test temperatures (see Figures 9.3.2 and 9.3.3). A total of twenty-four (24) different temperature and environmental combinations were tested. Table 9.3.5 presents the tests and the results.
FRAMATOME TECHNOLOGIES, INC.
9-34
FTl l'Jon-Proprietary FIGURE 9.3.2 CAPSULE FURNACE SETUP 200 PSI 200 PSI OXYCEN PRESSURE NITROCEN PRESSURE 1/16" OD X 18" LONC
- CAPILLARY LINE ,
L RESERVOIR I
CAPSULE FURNACE OXYCEN NITROCEN l
l l
FRAMATOME TECHNOLOGIES, INC. :
9-35 i
^ ^ - - _. . . . - .
FTl Nsn-Prcpriittry FIGURE 9.3.3 CAPSULE TESTING FOR FAULTED SECONDARY SIDE ENVIRONMENTS _
PRESSURE TRANSDUCER l
l W W l
FURNACE B! ele 1
~ = LIQUID LEVEL AT TEST CONDITIONS
.
ELECTROSLEEVE "
I TEST CAPSULES < s,
@jfl 7[ CLAMPING (CAPSULES 11-16)R!NG
=
y- CARBON STEEL M
{ g (CAPSULES 15,16)
FRAMATOME TECHNOLOGIES, INC.
9-36
llllIlIl 4l y
e, r
a b,
t C i
e b, r _
p o
r P-n N
o J I
T F
5 3
9 E
L B
A T
7 3-9 C
N I
S E
I G
O L
O N
H C
E T
E M
O T
A
[ S E
M A
T O
N L R F
. l l1
l l
1 1
FTl Non-Propri;t::ry i The tests performed with 2,000 psi oxygen (~3,000 ppm) are extremely conservative and are not intended to be representative of the oxygen content of the secondary side chemistry.
Destructive examination of the capsule specimens (see Table 9.3.5) provided the following correlations between the chemical environments and the extent of Electrosfeeve" degradation.
C b c,d i
Under severely oxidizing conditions,( b 3, which contained sulfuric acid, experienced sleeve degradation. Capsules [ 3, which had added sodium hydroxide, exhibited none to minimal attack.
C b,C3 d
]. In general, caustic environments were not aggressive to the sleeve material, b
Neutral chemistries,{ ], had no measurable sleeve degradation.
No evidence of cracking f the Electrosteeve" was found in the regions of capsules [ ],6which were externally stressed. [
b
} c,c, d ombination of Pb and high caustic was aggressive to the carbon steel but not aggressive to the Electrosleeve".
The conclusion from these tests is that the Electrosfeeve" material will be attacked under highly acidic with highly oxidizing environments. The sleeve is resistant to caustic environments and to attack without oxygen. The highly FRAMATOME TECHNOLOGIES, INC.
9-38
\ .-. _ _ _ _ _
l l
FTl Non-Proprietary !
oxidizing condition (2,000 psi oxygen) is not present on the secondary side of the steam generator or within the Alloy 600 cracks. '
9.3.3 Heat Transfer Sludge Corrosion Tests The objective of these corrosion tests was to assess the corrosion performance of an Electrosleeve" when a large area is exposed to extreme chemistry conditions under a sludge pile.
These tests address the formation of dynamic crevice environments that form in operating steam generators and yield information on the performance of the ;
Electrosleeve" material under these environments. However, in the steam generator, the sleeve is not exposed to these environments over large areas.
Typically, the only portion of the sleeve exposed would be the tips of the cracks in the Alloy 600 tube.
1 Heat transfer corrosion tests allow the direct comparison of bulk water environments between the operating unit and the laboratory test. The test ]
design involved heat transfer simulation similar to the hot leg of a steam 1
generator and simulation of a sludge pile around the tube, i i
2 Accelerated conditions were chosen to assess the chemistry limits of the
! material performance. The three bulk water environments selected addressed three different operating scenarios of feedwater contamination: condenser cooling water, sodium hydroxide, and sulfuric acid. The latter species are used I as ion exchange resin regenerants that may be accidentally produced in the event of operational malfunctions in the water treatment or condensate l
j polishing systems. Normally these events are short, lasting on the order of a few hours. The present water chemistry specifications call for remedial action in such events which may even necessitate immediate unit shutdown. A summa y of heat transfer corrosion tests is contained in Table 9.3.6.
i l
l l
1 4
4 4
J FRAMATOME TECHNOLOGIES, INC.
9-39 l \
FTl Non-Pr:prietary TABLE 9.3.6
SUMMARY
OF HEAT TRANSFER SLUDGE CORROSION TESTS b) C)k J
L l
FRAMATOME TECHNOLOGIES, INC. l 9-40
FTl Non-Proprietary Exoerimental Figure 9.3.4 is a schematic of the refreshed autoclave loop that was used ir.
these tests. The tests were conducted in[ [AYloy 600 autoclaves. Three internally heated tube mockups were fastened to the autoclave cover. Each mockup had a cartridge heater and the tube was internally pressurized with helium [ 3. 'khe pressure simulates operating hoop stresses and enhances heat transfer with minimal occurrence of tube hot spots.
The heat flux was controlled to simulate operating conditions.
1 FIGURE 9.3.4 I REFRESHED AUTOCLAVE LOOP 1
r- ;;
ll FEEDTANK
" A::=
ELECTRIC HEATERS
_ _ PRESSURE CONTR0llER i
l I
l y S%PLE H,io -*-
x y PRESSURE CONTROL 63 VALVE
' " y =
X~
@ m 3SuRE REllEF y
ruer VALVE PROCESS CONDENSER FRAMATOME TECHNOLOGIES, INC.
9-41
FTl Non-Prrpriit:ry bC The tube was hard rolled into[ 3 carbon steel holders. Figure 9.3.5 presents the mockup arrangement.
FIGURE 9.3.5 STEAM GENERATOR ELECTROSLEEVED TUBE MOCKUP FOR SLUDGE AND FAULTED CHEMISTRY TESTS b>Ci d
(
l I
L ._J FRAMATOME TECHNOLOGIES, INC.
9-42
FTl Non-Proprietary Each holder was filled with a mixture of fossil boiler sludge consisting of ~70%
magnetite and ~30% metallic copper with additional added species. The composition of the sludge mixtures are listed below:
TABLE 9.3.7 COMPOSITION % WElGHT OF SLUDGE MIXTURE AND OTHER CHEMICAL SPECIES USED TO FILL THE SLUDGE SIMULANT HOLDERS I 7 b,c,d l
L $
Each tube was electroslee
- 3. The tube in the sludge holder contained a circumferential groove, nominally 1/8-inch wide, and four drilled holes,1/16-inch diameter. One drilled hole,1/16-inch diameter, was placed in the freespan i of the tube between the holders. This arrangement ensures maximum heat flux l through the sleeve. Figure 9.3.5 details the groove and drilled hole that exposed the Electrosteeve* to the secondary side chemistry.
Electrochemical Environments The feedwater chemistry for these tests simulated three different types of in-leakage. The in-leakage types were:
- Fresh Water (condenser cooling water),
- Caustic (sodium hydroxide), and
- Acid (sulfuric).
1 FRAMATOME TECHNOLOGIES, INC.
9-43
FTl Nen-Propri;ttry The under-deposit chemistries produced by these solutions generically included the scenarios of high pH, low pH, and condenser cooling water ingress. The tests were accelerated by using concentrations approximately 1000X greater than in an anticipated event. Moreover, the redox potential of the solution was raised by increasing the concentration of dissolved oxygen (by a factor of 1000X). This increase caused the region under the sludge to be aggressive to the tubing. Additional acceleration was obtained by the presence of aggressive species in the simulated sludge [13.51,13.52,13.53].
Feedwater solutions were prepared by mixing the targeted species with deionized water. Lake Ontario Water (LOW) was used as fresh water. For l I
LOW, MULTEQ [13.42] predicts an alkaline pH concentration. The dissolved oxygen concentration was prepared by sparging the feedwater with the appropriate nitrogen / oxygen mixture.
9.3.3.1 Fresh Water ingress Test l
This test addressed the condition in which a chronic and massive condenser cooling water intrusion occurs during operation. The test parameters were as follows:
- Feedwater: I i
L J b
epH: [ ] >C.
l FRAMATOME TECHNOLOGIES, INC.
9-44
I FTl Non-Proprietary
- Temperature:
1 l
L J
- Pressure: [ ,
boc. ,
3
- Test Periods: [
g 6, c. j Results Tube assemblies were removed for examination C 3I'ho attack of the Electrosleeve" material or the Monel 400 parent tube material was observed [-
],b,c d3 Test Sianificance Under extreme accelerated conditions which simulate the under deposit environment in an operating unit, the Electrosteeve" performance is excellent. (
b,C, el The test severity was greatly increased by the high dissolved oxygen concentration, which imposes high redox potential particularly under the sludge pile where local anodic regions may be prevalent due to FRAMATOME TECHNOLOGIES, INC, 9-45
FTl N:n-Propri;tiry (
the possibility of forming differential oxygen cells as a result of Ic::alized steaming. The concentration capability of the sludge piles has been demonstrated (hideout return phenomena in operating units) and measured in lab experiments. The tube surface and the Electrosleeve" were exposed to solutions with high impurity concentrations under the sludge pile. The solution concentration increased with time to several orders of magnitude greater than the bulk water [13.54].
Behavior predicted from thermodynamic considerations and assessed by the capsule tests was consistent with the Electrosleeve" material.
MULTEQ predicts alkaline environments based upon the concentration of the bulk chemistry (LOW)*used in the test. Even for high values of redox, the Electrosleeve" nickel was passive.
9.3.3.2 Acid Ingress This test addressed the condition of a massive continuous acid ingress in a steam generator during operation. Test parameters were as follows:
- Feedwater: [
L, c.
- Temperature: [
h J,C
- Pressure: [ ]s,e
] b,C o ]5,c
\
- Test Period:
{
l i
l l- FRAMATOME TECHNOLOGIES, INC.
9-46
FTl Non-Proprietary Results E
b,c) 3 5
Destructive examination of the regions under the sludge showed corrosion attack on the Electrosleeve" material and the tube substrate. The extent of attack [ Nxamined was approximately the same which indicates that the degradation occurred during the initial, high oxygen period. The observed degradation was general corrosion with some regions of localized attack.
Test Sianificance l
The test addressed an unbuffered, continuous, large acid ingress in a steam generator. The severity of the test was increased due to the
)
acid concentration being a factor of 1,000X over any credible l realistic scenario (typically less than 300 ppb free acid). [
bcd
) ,Such a scenario is not realistic if l
an operator were to follow the EPRI Se:ondary Chemistry Guidelines l
[13.41]. An acid intrusion would immediately trigger corrective actions, including plant shutdown, which would essentially eliminate ,
i the heat flux induced concentrating mechanisms generated during l the tests described above. l FRAMATOME TECHNOLOGIES, INC.
9-47
FTl Non-Pr:prietiry The severity of the test was augmented by increasing the dissolved oxygen concentration, thus increasing the redox potential, especially under the sludge pile.
The results confirmed that a combination of highly acidic and highly oxidizing conditions are aggressive to the Electrosteeve".[
b 3, w,C)hen the redox was lowered by decreasing the dissolved oxygen concentration, the Electrosleeve" performed satisfactorily. This effect confirmed the trend observed in the capsule testing, l The heat transfer test was more severe than the corresponding capsule test because there is a continuous addition of acid to the heat transfer surfaces and the concentration of contaminants under the sludge pile. MULTEQ calculations determined low (less than 1.0) solution pH values at concentration factors of 1,000X which was rapidly reached under the sludge pile. The material potential impressed by the solution redox was transpassive as in the capsule test.
In credible acidic excursions ex,tscted in operating steam generators, the Electrosleeve" material demonstrates resistance to corrosion.
9.3.3.3 Caustic Ingress This test addresses the condition of a massive continuous caustic ingress in a steam generator during operation. The test parameters were as follows:
- Feedwater: [
l b, C i
FRAMATOME TECHNOLOGIES, INC.
9 48
.. . _. - . . - . - .= .. . - . - -- .. .- -
FTl Non-Proprietary o' Temperature:[ - ,
]6jc \
- Pressure: [
3 b,C I
I
- Test Period: b l b>C \
Results l Examination of the tube in the areas under the sludgg piles revealed 1 no attack of the Electrosleeve" or the' tube after[3exposureb
- b 3 J eC d Test Sianificance Under extreme caustic conditions, the test confirmed acceptable performance of the Electrosleeve". The excursion scenario was highly accelerated in terms of the total caustic concentration and the solution redox potential. The degradation observed [
)has' consistent with the data obtained in the capsule testing and in agreement with the thermodynamic data.
9.3.4 Secondary Side Corrosion Rate E
h,C,d
)
FRAMATOME TECHNOLOGIES, INC.
9 FTl Non-Proprietary C
si J.,c d 1 As previously discussed, the main objective of the corrosion testing was to demonstrate the effectiveness of the Electrosleeve" repair at remedying the SCC degradation problem. The heat transfer tests j demonstrated that the Electrosleeve" can also perform under j anticipated, realistic operating scenarios if exposed to such )
chemistries. l 9.4 Exposure to Mercury at Room Temperature 9.4.1 Environment Assisted Cracking A literature search was conducted on environment assisted cracking of pure nickel materials. A number of environments, highly unlikely to exist in a PWR, were identified that might produce stress corrosion type flaws in the Electrosteeve". A number of sources, captured in Reference 13.57, indicate that pure nickel is not resistant to liquid mercury. Reference 13.58 states that the nickel weight loss in the presence of 600'F heated mercury is 900 mg/ inch 2 in 30 days of exposure. The expected depth of penetration of the stress
- corrosion cracks in the normal crystalline nickel is reported to be, in the same l
conditions as above, between 10 and 90 mil.
9.4.2 Experimental Procedure A liquid mercury attack experiment of Electrosleeve" was defined similar to an ASTM G-38 test [13.59]. Stressed areas of C-Rings were submerged in liquid mercury at room temperature.
E p e,e i.
FRAMATOME TECHNOLOGIES, INC.
9-50
FTl Non-Proprietary 9.4.3 Results b
[ ),icthe C-Rings presented the following results:
l C s 3 ,c,e i
e No recordable indications were found using liquid penetrant l' examination, and b e Using an analytical scaleC gg
),,cM no weight loss [ 3w,as observed.
( b 3.,c,d 1 i
9.5 Corrosion Evaluation Summary i
Qualification of the corrosion properties of the Electrosleeve" was performed using a j three phased program. The first phase involved a literature review and selection of tests, including ASTM standard tests, to determine the susceptibility of the Electrosleeve* to known forms of Alloy 600 damage such as IGA and SCC. The second phase focused on corrosion testing in specific primary side environments that !
are known to be detrimental to Alloy 600 tubing. The third phase focused on i secondary side environments including alkaline, neutral, and acidic in the presence of oxidizing and reducing species and, in many cases, at extreme conditions to accelerate the corrosion processes.
A comparative review of the general corrosion characteristics of nickel and Alloy 600 demonstrates that Alloy 600 is typically more resistant to general attack in highly oxidizing acidic solutions but is more susceptible to IGA and SCC. This agrees with experience in the steam generator environment where IGA and SCC are the
. predominant modes of degradation for Alloy 600 tubes.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propriet:ry Testing performed on electrosteeves included caustic and ASTM standard tests to determine the susceptibility of the material to IGA and SCC. These tests demonstrated resistance of the Electrosleeve" material to IGA or SCC. The sleeve was shown to protect the Alloy 600 tube from SCC on the primary side and to stop SCC from propagating into the Electrosleeve" from the secondary side of the tube (see Table 9.5.1).
l l
l 1
1 1
1 FRAMATOME TECHNOLOGIES, INC. ;
- 9-52
FTI h@ary -
TABLE 9.5.1 ,
P
SUMMARY
OF MATERIAL SUSCEPTIBILITY (ACCELERATED) TESTS ,
TEST PURPOSE - TEST ENVIRONMENT SPECIMEN DESCRPTION RESULT 5 Susceptdnirty to Boihng 50% Suttunc Acid-Femc -
No evidence of IGA.
IGA Sulfate et RT; Standard ASTM Method: E 3 %C b,C,cl Stros= Corrosion % Solution of Polytheorwc Acid at No endence of SCC of Electroeiseve" metenal Cracking (SCC) RT; Standard ASTM Method;[
Test - ] 4.c.
ASTM G 35 Stress Corrosson Boehng 45% MgCl2 at 311*F for 3 No evidence of SCC in the Electronieeve" metenal; Cracking (SCC) tws: Standard ASTM Method; { No endence of pstting or cracking on plated surface Test ]b,c ASTM G 36 Stress Carrosen 3.5 % Solutum of Nacl at RT with No evidence of SCC Cracking (SCC) attemete werting & drying of Test ASTM G 44 speamens; ( c Standard ASTM Method;[
L Stress Corrosum 10% Solut of NaOH at 662*F; The unplated Anoy 600 mockups cracked 50% through-wan Cracking (SCC)
Test
{ }C after 120 hrs exposure; and 100% after 240 hrs. No evidence of stress corrose cracking in the mockups with C Joect,osioeve . -
k.C, f Stress Carrosson 10% Solution of NaOH at 662*F; No evidence of SCC was found on any of the electrosleeved Cracking (SCC)
Test (Effect of
{ ] b. C speamens. (
, Cf Pttting O Crevice 6% Fame Chionde Solution at RT '
Some slight general corrosion on Electrosaeeve" material, but no Co-rosion Test Pittmg Test- G 348 evidence of pitting. [
ASTM G 48 Crevice Test -L f*C
//
NOTES:
(1) These mockups were prea: recked through-war with a room temperature sodium tetrathionate solution pnor to being pisted.
FRAMATOME TECHNOLOGIES, INC.
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4 9
FTI Prcprist:ry Both circumferential and axial SCC conditions have been repaired with nickel plating.
The nickel plating has also been installed over Alloy 600 tube cracks that are 100%
through-wall. Thus, the nickel plating has been exposed to primary side environments as well as secondary side environments (via the tube cracks) [13.56]. This is exactly the same manner that the Electrosleeve" will be exposed to the two environments.
The performance of the nickel plating in foreign plants has been excellent in 10 years of service.
Corrosion testing was conducted on both nickel plating and electrosleeves to evaluate I
the Electrosleeve" material performance in primary and secondary environments.
Primary side tests included pure water, primary water, and boric acid. A summary of i these tests is contained in Table 9.5.2. Secondary side tests included heat transfer conditions, sludge, and confined geometry (crevices) with the associated concentrating mechanisms evaluated. A summary of these tests is contained in Table 9.5.3.
1 I
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FRAMATOME TECHNOLOGIES, INC.
l l-9-54
FTl Proprietary TABLE 9.5.2
SUMMARY
OF PRIMARY WATER CORROSION TESTING TEST PURPOSE TEST ENVIRONMENT RESULTS Primary Water during Norraal Operation No corrosion or degradation of Nickei plating b,C Primary Water during Shutdown Negligible Corrosion of Nickel Plating, (Aeratid) f fsJCd L J Primary Water during Shutdown Negligible Corrosion of Nickel Plat ## {'g (Deserated)
C no;ntrated Boric Acid No corrosion or degradation of Nickel (To simulate boric acid trapped within plating cracks) g S;tur!.ted Boric Acid (Aer ted without Oxygen replenishment)
( i some pitting observed. Nicket Hydroxide formation on the surf ace of specimens b
ke,d S;turated Boric Acid Very deep through-wall pitting (Aerat:d with Oxygen replenishment) observsd b,c,el i
k Primary Water SCC Unplated control specimens heavily cracked after [ JbC Nickel plated specimens did not exhibit SCC, no corrosion or pitting observed Pura Water SCC Unplated control specimens heavily cracked Nickel plated specimens did not exhibit SCC, regardless of plating thickness Caustic SCC in Roll Transitions Areas Unplated tubes cracked C boc ,d 3
No cracking ga served with(
)of Nickel plating Caustic Residual Stress Test in Locked No cracking was observed, especially Tube Arrangement in the transition regions, on the l specimens Temperature and Pressure Cycling in No leakage observed I Purs Water No loss of adhesion observed ,
[ Cracks well bridged by Nickel plating l FRAMATOME TECHNOLOGIES, INC. j 9-55 j
FTl Proprietary TABLE 9.5.3
SUMMARY
OF SECONDARY SIDE CORROSION TESTS RESULTS TEST PURPOSE , TEST ENVIRONMENT No corrosion of Electrosleeve" C, Sludge and Faulted Chemistry Tests
" )g (Caustic Excursions) 3 bo
,c d 4
Sludge and Faulted { l j
Chemistry Tests (Acid I Excursion) l J
Negligible Corrosion of Electrosleeve" Sludge and Faulted Chemistry Tests [
(Condenser in-feakage) b,Cj {
Ultrasonic examination before and SCC Propagation Tests after testing showed no increase in (Precracked S/G crack depths Tubing) 6,c SCC Propagation Tests [ ): No crackin observed in Electrosleeve*;
(Stressed C-rings) 3 '
Electrosleeved Capsule { ,e j s
Tests Electrosleeved Capsule l p,c,g i
{ J Tests Electrosleeved Capsule {
Tests b, Cod 3 high caustic tests showed relatively high corrosion rates, but much lower than acidic / oxidizing tests Electrosleeved Capsule {
Tests ]k #sf FRAMATOME TECHNOLOGIES, INC.
9-56
FTl Proprietary The following conclusions were reached based on the results of these tests and on comparison to expected conditions:
. Nickel plating is effective in protecting Alloy 600 steam generator tubing from PWSCC. High purity electrodeposited nickel materialis not susceptible to SCC or IGA in either the primary water environment or the secondary water environment.
. Electrosleeve" general corrosion is negligible in primary water environments under expected operating and shutdown conditions.
. Electrosleeve" corrosion is negligible in secondary environments. Additionally, the nature of tight cracks in Alloy 600 tubing limits exposure of the sleeve to the secondary side.
. Installation of electrosleeves does not introduce high residual stresses in the parent tube at the leading and trailing edges of the sleeve.
In conclusion, general corrosion, crevice corrosion, pitting, SCC, or IGA of the Electrosteeve" material is not a concern in PWR environments. The in-service experience of electrodeposited nickel materials supports this conclusion.
FRAMATOME TECHNOLOGIES, INC.
9-57
FTl Non Proprietary 10.0 SLEEVE INSTALLATION 10.1 Installation Procedure The sleeve procedure specification (SPS) defines the generic requirements for field installation of the Electrosleeve". The SPS was prepared following the guidelines of the ASME Code,Section XI, Code Case N-569 for steam generator tube sleeving and identifies the essential and non-essential variables for the process. The following is a summary of the installation procedure. Installation tooling, ALARA practices, and chemical procurement are also discussed.
10.1.1 Pre-installation Tube Eddy Current inspection An ECT inspection of the tubes is performed to identif'i which tubes are to be repaired and to verify that no pluggable defects exist outside the area to be sleeved. This step is a standard part of a steam generator ECT inspection outage.
10.1.2 Surface Cleaning / Preparation (Woods)
Mechanical cleaning of the tube ID is performed in the sleeving region to remove loose oxides and reduce contamination levels. Cleaning removes a g
substantial amount of radioactive contaminants prior to[ 7 activation process. Mechanical cleaning is accomplished by rotating and translating a hone or scraper on the tube ID in the sleeving region.
After removing the cleaning tip from the tube, the electroforming probe is inserted into the tube to the sleeving elevation. This step may involve installing multiple probes in different tubes, enabling several sleeves to be installed at the same time. The probe has integral seals to keep the solutions confined to the desired electroforming region, called the " plating cavity".
Final cleaning and preparation of the tube is accomplished by using the
[
3 electrolyte solution. [I The surface is activated by
[ Nolution through the plating cavity. C l
JP FRAMATOME TECHNOLOGIES, INC.
10-1
FTl Non-Propristtry l
The activation step is aggressive on edges such as ID crack surfaces, producing chamfered edges at the crack. The removal of a small amount of material permits the electroforming step to deposit material into the crack and produce a bridge across the ID of the crack.
10.1.3 Pre-Filming f The pure nickel [ hs an electroplated ( }to the surface of the tube [
c,e.
10.1.4 Electroforming [ [
The Electrosleeve" is deposited on the tube during this step of the process.
C C
~3 , C.
The probes and plating cavity are then purged with nitrogen and given a final rinse with deionized water. This completes the sleeve installation process and the electroforming probes are removed from the tubes.
10.1.5 Post-Installation NDE A post-installation UT inspection is conducted to examine the bond between the sleeve and the parent tube and to verify sleeve thickness and length.
Section 11.0 of this report presents additional information on NDE as it pertains to electrosteeving.
FRAMATOME TECHNOLOGIES, INC.
10-2
FTl Non-Proprietary 1 10.2 Process Verification 10.2.1 Process Qualification Requirements ASME Section XI Division 1, Code Case N-569, provides accepted rules for process qualification. Essential and non-essential process variables are defined (FTl imposes an expanded list of essential variables) and consecutive qualification samples are produced. The samples are then subjected to non-destructive and destructive examinations to prove that the target material properties have been met. Non-destructive examinations consist of ECT prior to installation and UT examination after sleeves are installed.
Destructive examinations include bend tests, hardness, and material composition analysis.
Process operating limits are defined in the qualification documents. Process controls and on-line monitoring during the electrodeposition process allow operators and quality control personnel to confirm the process variables.
System operator qualification requirements are well defined by the Code Case. [ 6,C;d 10.2.2 Field Installation Typical system operation in a power plant will generate witness tube / sleeve samples prior to installation of sleeves in the steam generator. This system is capable of producing witness sleeves simultaneous with installed Electrosleeve" specimens and thus provides significant assurance that material properties are being met. The witness tube can be sleeved with one of the electroforming probes used for sleeve installation in the steam generator, [
)e The witness tube sleeve is examined for bonding, surface finish, and thickness. [
J.e.
FRAMATOME TECHNOLOGIES, INC.
10-3
FTl N:n-Pr::prittIry Hardness, chemistry, or mechanical testing may be used to obtain information related to sleeve strength.
The following are typical variables monitored during the installation of the Electrosleeve":
c
. Flow rate e Pressure .
1 e Temperature
. Solution pH e . Voltage e Current 2
e Process Time All essential process variables, as listed in the SPS, are monitored and recorded as specified.
10.3 Electrosteeving Chemical Procurement and Quality Assurance Process The electrosteeving chemical procurement procedure specifies the steps to be taken for the procurement and inventory control of chemicals to be used in this process.[
b, C4.
FRAMATOME TECHNOLOGIES, INO.
10-4
FTl Non-Proprietary E
1 C
J. ,6 !
The documentation for the chemicals used is provided to the customer in the form of a data package to support transportation, receipt, and control at the plant site.
E l
. l 1
l c
).,e c
se 3.
10.4 Electrosleeving Process Detrimental Materials Control Detrimental materials are maintained by control and independent analysis of all process chemicals. [
l i
. l C,f 8 3.
I FRAMATOME TECHNOLOGIES, INC.
10-5
1 1
FTl Non-Pr:pri;ttry I i
An allowable level of detrimental materials in procured chemicals was defined and integrated into the chemical procurement procedure.[
].
E 3 0 C
J*
10.5 Installation System / Tooting l
The installation of the electroformed sleeve is accomplished remotely by tooling attachments mounted on a manipulator. Typical manipulators that may be used for sleeving include: ROGER", COBRA", and FLEXIVERA* manipulators. The sleeve installation tooling minimizes the personnel radiation exposures in accordance with l ALARA principles.
l l
FRAMATOW.2 TECHNOLOGIES, INC.
10-6 1
l FTl Non-Proprietary The sleeving system utilizes a series of skidt and trailers. Each skid contains a j . different portion of the fluids and chemicals required to successfully perform the sleeving process. The system contains a supply manifold to deliver the solutions from the skids to the probes. The probes are connected to a return manifold that collects the solution as it returns from the probes and directs it back to the appropriate skid.
The sequential steps of the electroforming process are computer controlled. Figure 10.5.1 depicts a schematic of the system.
The electroforming probe consists of a tubular anode b 3.eThe integral probe seats hold the probe in position. C
- C 3 . g.
t I
l l FRAMATOME TECHNOLOGIES, lHC.
l 10-7 I
4 .
FTl N:n-Pr:pri;t:ry FIGURE 10.5.1 ELECTROSLEEVE" INSTALLATION SYSTEM SCHEMATIC m
promwso SG A MINESSM 1
b,c,e l
1 L 1 FRAMATOME TECHNOLOGIES, INC.
10-8
_. . _ ~ . - .. . . _. - .. - . - . . . . . . - . - - - .... .
FTl Non-Proprietary FIGURE 10.5.1 (Cont'd)
ELECTROSLEEVE" INSTALLATION SYSTEM SCHEMATIC 1
i L
Cp i
I l d FRAMATOME TECHNOLOGIES, INC.
10-9
FTl Non-Pr:pri;t ry 10.6 ALARA The ALARA evaluation has been prepared using the process steps for electrosleeving in conjunction with radiation dose fielde representative of Westinghouse Model D steam generators. The exposure estimate is based on sleeving [ ] in a single steam generator channel head. This quantity is representative of a typical sleeving campaign and provides a useful standard for comparison. Table 10.6.1 provides detailed information regarding the assumed radiation fields as well as estimated exposures for the various sleeving activities and the total estimated process exposure.
I
{
l l
l l
1 l
FRAMATOME TECHNOLOGIES, INC.
10-10
E FTl Non Proprietary TABLE 10.6.1 SLEEVE ALARA EVALUATION (100 SLEEVES)
AVERAGE AREA DOSE RATES SURVEYED AREA DOSE RATES (R/Hr) l General Containment F c inside Biowall Area Near SG Playpen Playpen General Area Tooling Tent l 1
Manway Plane l 4
Manway @ 12" Manway @ 18" SG Bowl General Area Steam Generator Bowl Tubesheet Contact Low Dose Waiting Area L J ELECTROFORMED SLEEVE EXPOSURE SLEEVING PROCESS ACTIVITY EXPOSURE 1
(Man-Rem)
F Equipment Setup c}
System Hydro Test Sample Remote Tube Marking Install Sleeves Eddy Current and UT Post-installation Equipment Removal TOTAL MAN-REM PER ELECTROSLEEVE" L .1 FRAMATi ME TECHNOLOGIES, INC.
10-11
FTl N:n-Pr:pri;t:ry Remote manipulators will be used for the electrosleeving process. Since the manipulator is typically installed at an earlier time to support inspection or repair, the estimate provided does not include exposure associated with manipulator installation or removal.[
3 cg.
C
. C,e_ l 10.7 Sleeving Experience l As part of the qualification process, a number of tube conditions were evaluated to demonstrate the process capabilities. Sleeves were successfully installed into tubes l with the following conditions:
l e Contaminated 5/8" tubes, cleaning process evaluation, e Contaminated, sensitized, in-service tubes (Oconee Unit 1; 9 tubes),
e Shot peened tubes, e Dented tubes (see Figure 10.7.1),
e Cracked tubes (see Figure 10.7.1),
e Top of tubesheet roll transitions with 100% through-wall PWSCC cracks (laboratory induced), and e Tube support plate sections from a retired steam generator.
FRAMATOME TECHNOLOGIES, INC.
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i j FTl Non-Proprietary FIGURE 10.7.1 ELECTROSLEEVE" INSTALLATION EXPERIENCE i
l i
i l
j' .
t Sleeving in a cracked tube 10.8 Waste Processing The Electrosleeve" waste processing system utilizes two parallel processes. One treats the rinse water generated during the Electrosleeve" process application, and the other treats the spent process solutions [ ] The rinse water generated during the Electrosleeve" process is treated using a combination of ultra-filtration (UF) and reverse osmosis (RO). The spent process solutions are treated using a concentrate / dryer (CD) unit. The two parallel processes provide for volume reduction, maximum water recovery and purification, and stabilization of the solvent mixed waste stream to render it non-hazardous.
FRAMATOME TECHNOLOGIES, INC.
10-13
FTl Non-Proprietary 11.0 NONDESTRUCTIVE EXAMINATION The nondestructive examination (NDE) technologies evaluated to perform the examinations of an Electrosfeeve" are presented in this section. NDE inspection is required to provide specific dimensional information of an installed sleeve as well as in-service monitoring. The NDE inspection technique must provide a means to determine the sleeva thickness, the position of the sleeve relative to the intended repair location, and the presence of the sleeve-to-tube bond. Taking into account the above requirements, an evaluation was performed to select and qualify an inspection technique.
While eddy current (ECT) is an established NDE method for steam generator tube inspection, ultrasonic testing (UT) has been selected as the NDE inspection method for the Electrosleeve". UT has advantages relative to eddy current. The fundamental method of using sound propagation and reflection provides the advantages of thickness measurement and superior flaw detection.[
3.
11.1 NDE Requirements Three regions of a sleeved tube (Figure 11.1.1) were defined to clearly describe NDE requirements, capabilities, and qualification. In these regions, the primary pressure boundary transfers from the parent tube to the sleeve and back to the tube. The three regions and the inspection requirements fcr each region are discussed below.
FRAMATOME TECHNOLOGIES, INC.
11-1
FTl Non-Propri:tiry FIGURE 11.1.1 ELECTROSLEEVE" NDE REGIONS Parent Tube Electrosleeve Region A If
.g- '
Region B =E 3 Defect Region C
/
/
/
3r /
Region B =C _r.c J' /
n__ ,
Region A 3r /
Ct EleWosleeve Parent Tube 4
(Inside diameter) , ,, ,, ,,
b4 6,<.,
Po To Fo (Fo E 3') Fe (F + [ J') Fe Te P 1
FRAMATOME TECHNOLOGIES, INC.
11-2
FTl Non-Proprietary 11.1.1 Sample Regions The tube is the pressure boundary in the taper region (Region A). Thickness measurements in Region A are required at the locations marked P and P,,
where the P represents parent tube and "o" and "i" represent the outlet and inlet of the sleeve installation probe flow, respectively. The zero thickness transitions (To or T)i occur at the first presence of nickel plating.
The bond length which transfers the pressure boundary from the parent tube to the sleeve is Region B. This region extends from the start of a taper transition (F or Fli for a full thickness length [ ].6, c.
The full sleeve thickness transition occurs at the first measurable decrease in thickness from the average sleeve wall thickness. The combined parent tube / sleeve wallis the pressure boundary for this region.
The full thickness portion of the sleeve between the full thickness taper reinforcement regions is the mid-span or Region C. This section of the sleeve spans the parent tube flaw and is normally bonded over the entire region. However, the sleeve is the pressure boundary. Thickness measurements in the mid-span region are required at the locations marked Fi +[ 3f'FI, and F,-( 3 where F represents the full thickness, "c" represents the center, and "o" and "i" represent the outlet and intet, respectively.
11.1.2 Basic Electrosfeeve" NDE Requirements The NDE examination must be capable of characterizing the Electrosfeeve*
repair " tith respect to the following criteria:
11-3
FTl Nrn-Preprl:ttry e in-Service
- Sleeve OD Pitting - associated with 100% through-wall flaw in parent tube
- Parent Tube Cracking - flaw growth, depth, or extent
- Parent Tube Volumetric 'Nall Reduction - flaw growth, depth, or extent 11.2 NDE Methodology Evaluation A number of NDE companies, laboratories, and academic institutions have participated in a project to develop and evaluate new techniques for examination of the Electrosteeve". This section presents a discussion for each technology considered.
11.2.1 Eddy Current Some form of eddy current examination will be used to identify tube candidates for installation of an Electrosteeve". However, eddy current testing has not been widely used in the examination of nickel plated tube repairs due to the lack of penetration in the highly permeable nickel. There are significant problems with the use of eddy current techniques for examination of the Electrosfeeve" repair. The main difficulties are the discrimination of' sleeve geometry from degradation, the accurate depth sizing of crack-like flaws, and the detection of less significant degradation.
Saturation Probes l
Non-rotating saturation probes were evaluated early in the testing and l demonstrated difficulty in detection of flaws in the sleeve end transitions. The saturation field may have improved the detection of parent tube flaws within Region C; however, these flaws are of less concern within this region.
A magnetic-bias, rotating plus point probe was found to produce more noise and a lower signal-to-noise response than a nonmagnetic-bias probe. Thus, l the magnetic-blas plus point probe was eliminated as a viable examination I
technology for the Electrosleeve".
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l FTl Non-Proprietary Pulsed Eddy Current The use of pulsed eddy current was evaluated, Pulsed eddy current demonstrated a significant improvement in the technology, but the improved system still did not possess sufficient resolution to separate parent tube flaws from flaws that broached the Electrosleeve".
Rotatina Coil Methods Several rotating coil probe designs, including pancake coils, MICA coils, plus point coils, and differential pancake coils, were evaluated. Each of these probe types has demonstrated detection of significant parent tube or sleeve flaws at some level of sensitivity. One of these rotating coil designs could
, possibly perform the extent sizing of certain degradation types. As part of the rotating coil test program, multiple frequencies and mixing capabilities were also evaluated. Despite the extensive testing, the rotating coil technique.s have not demonstrated the ability to verify the structural integrity of the Electrosleeve" separate from the parent tube.
Swoot Freauencv Methods The use of an eddy current swept frequency algorithm has been proposed.
However, the technique is not commonly available and has not been evaluated.
11.2.2 Magnetic Methods One alternate approach for the validation of the Electrosleeve" repair was to examine the nickel layer by itself. This would require an examination method that is insensitive to the Alloy 600 parent tube, which is nonmagnetic.
Several magnetic examination methods were evaluated.
Remote Field Probes Remote field eddy current methods have been used for the examination of magnetic materials. An excitation coilis used to induce a field into the magnetic rr.aterial. The permeable tube material will conduct the induced field FRAMATOME TECHNOLOGIES, INC.
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FTl Nrn-Pr:prl:t:ry to a location remote from the excitation coil. A second receiver coil responds to the remotely induced field. Material variations between the two coils produce changes in the received signal.
Significant artifact signals were noted with a remote field technique. The technique has significant difficulty due to the presence of the carbon steel tubesheet or support plates.
Flux Leakaae i
Flux leakage techniques have also been used for the examination of magnetic material. A field is induced into a magnetic material and any changes in the permeability of the rnaterial will cause a local flux distortion.
Flux leakage examination was attempted on the Electrosleeve" repair. While there is some promise for this technique in freespan regions, flux leakage is also affected by the presence of carbon steelin the tubesheet and support plates.
11.2.3 Electromagnetic Acoustic Transducers (EMAT)
A magnetic field combined with an eddy current coil can be used to induce an acoustic pulse in a material. The eddy currents react with the magnetic field to produce a shock wave. As with any UT system, this acoustic energy is used to inspect the subject material. The primary difference with the EMAT system is that no liquid couplant is required to transmit the acoustic energy into the material. This technique is not currently being evaluated because there are no commercially available transducers that will fit into steam generator tubing.
11.2.4 UT Examination
- UT is conducted by transmitting sound into the tube wall and acquiring the returning echo from a reflective surface (i.e., tube OD surface, sleeve to parent tube interface (disbond), crack corner reflector, etc.). Ultrasonic ,
examination is excellent for detecting flaws and measuring thickness in seamless and longitudinally welded pipe and tubing [13.70). The time of FRAMATOME TECHNOLOGIES, INC.
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. - . _ - - - .. - .- ... .- - ~ . - - - . . - -. - -.- __. - . .- - .. - - -. _ ,
4 FTl Non-Proprietary flight (TOF), speed of sound in the material, and amplitude of the returning echo yield information about the reflecting surface and the distance of the i
, reflector from the transducer. The examination modes used during the I sleeve examinations are longitudinal wave normal beam (i.e., zero degree) and shear wave angle beam testing. I 11.2.5 NDE Technology Summary :
An NDE technique is required to discriminate sleeve geometry from degradation, to depth size crack-like flaws, and to detect less significant degradation. As the qualified NDE method, UT techniques will be presented in detail in the following sections. Installation and in-service inspection will be performed using UT methods and equipment as presented in Sections 11.3 through 11.7.
11.3 Ultrasonic Testing Background UT is the NDE technique selected to examine the Electrosleeve" repair. The probe is fabricated to define specific orientation angles for each transducer. The transducer orientations produce a normal beam as well as axial and circumferential shear waves.
11.3.1 Normal Beam Testing i Normal beam, or zero degree, testing directs sound energy at an incident angle normal to the tube ID wall. The ultrasonic sound wave travels through the couplant, impinges on the water / nickel interface, and a percentage of the energy propagates into the nickel. If the sleeve is bonded, the sound wave continues through the nickel / Alloy 600 interface and into the tube until it is reflected back to the transducer from the OD surface. If the sleeve is not bonded to the tube ID surface, the wave is reflected by the sleeve / tube interface. The TOF measurement is the time required for the sound to travel to a reflector and return to the transducer. The reflection may be from a discontinuity or from a surface of the material. If there are no material discontinuities (reflectors) within the combined sleeve / tube wall, the tube OD surface will reflect the sound energy. Material discontinuities such as disbond or pitting will produce a shorter TOF due to the reflection of the sound energy from a point closer than the tube OD.
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FTl Non-PrepriItary The TOF and the speed of sound in the material are used to determine the distance traveled. Thus, the material thickness may be calculated. The difference between the non-degraded material thickness TOF and a defect reflection TOF is used to define defect depth or size. In addition to bond 1
determination, applications for zero degree examination include detection of '
volumetric wall thinning, pits, and IGA.
11.3.2 Angle Beam Testing l
A transducer placed at an angle (Figure 11.3.1) produces a signal that enters the material along an incident angle. The resultant sound propagation is termed a shear wave.
Angle beam, or shear wave, testing differs from zero degree testing because the transmitted ultrasonic pulse is propagated at an angle (i.e.,45 degrees).
As shown in Figure 11.3.1, the ultrasonic wave propagates within the wall in a path that resembles a "V". In this figure, the TOF is the time difference between the ir' er surface reflection and the corner reflector formed by the l intersection of the crack and the tube OD.
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i FRAMATOME TECHNOl.OGIES, INC. l l
11-8 I
FTl Non-Proprietary FIGURE 11.3.1 UT WAVE "V" PATH TRANSDUCER
' " V" ID PATH i d 5' CRACK iE TUBE WALL i 4 /
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OD i SI 2 v- : 1 ti2 v-l PATH Y PATH j Time of Flight l V
INNER ,
DIAMETER /
SURFACE :
RESPONSE TOF (1 & 1/2 SKIP)
The detection of axial or circumferential crack-like indications is performed using shear wave testing. The shear wave detects cracks as well as volumetric type indications with sharp edges. Two separate transducers are required for the shear wave examination. One transducer is mounted to produce an axial propagation (along the length of the tube) of ultrasonic energy for the detection of circumferential flaws. A second transducer is mounted to propagate the ultrasonic energy in a circumferential direction for the detection of axially oriented flaws.
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1 FTl N:n-Pr:priItiry 11.3.3 Summary of Inspection Transducers and Functions i
Table 11.3.1 presents the required transducer for a given flaw type.
TABLE 11.3.1 TRANSDUCER AND FLAW TYPE COMPARISON TRANSDUCER FLAW TYPE Axial Shearwave, 45' Circumferential Cracks Circumferential Shearwave, 45* Axial Cracks Normal Longitudinal Wave, O Thickness, Volumetric Defects, Disbond With each primary beam direction (axial or circumferential), it is possible to propagate the shear wave in two directions. For example, the axial shear wave could propagate either up or down a vertical tube segment. Similarly, the circumferential shear wave could propagate either clockwise or
! counterclockwise around the tube wall. Due to the typical morphology of thin wall tube crack-like flaws, there is little difference in response between the two beam directions (for the purpose of this document, thin wall is defined as wall thickness less than 0.125 in:9. Flaws generally propagate normal to the originating tube surface and into the wall thickness. From the experimental data, it was concluded that the examination with two opposing beam directions for either the axial or circumferential direction is redundant and therefore unnecessary. On this basis, singio axial and single circumferential shear wave beams provide sufficient examination of the Electrosfeeve" repair.
A 45 degree shear wave angle in the material was shown to be optimum for the detection of crack-like flaws in the Electrosleeve" repair region. Angles less than 45 degrees reduce the reflected energy from crack-like flaws which propagate normal to the tube wall. This principle is illustrated by the normal beam (or zero degree) testing which is blind to tight, crack-like flaws. Angles greater than 45 degrees provide a longer transmission and attenuation path, a smaller reflected signal amplitude, and a reduced ability to separate closely spaced flaws.
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FTl Non-Proprietary Changes in tubing ID geometry affect the propagation of the sound energy.
The tapered region causes some beam redirection and minor reduction in reflected signal amplitude. Testing with EDM notches and pulled tube samples that have been sleeved has shown that the UT system is capable of defect detection within the tapered region. The effect of beam redirection on the indicated axial defect location is minimal.
i l
l 11.4 Ultrasonic System Description The UT-360 system used to perform ultrasonic testing consists of both hardware and )
a computer system. The system is used to ultrasonically examine both the steam l
generator tube and the Electrosleeve". The UT data acquisition equipment includes a UT probe head, probe motor unit, probe driver, water system, NDE Integrated Control (NIC) box, and the Hewlett-Packard (HP) computer station. The basic system diagram for a typical data acquisition station is shown in Figure 11.4.1.
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FTl Non Proprietary I
FIGURE 11.4.1 UT-360 SYSTEM DIAGRAM - DATA STATION Gjd.
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FTl Non-Proprietary A typical UT-360 containment setup is shown in Figure 11.4.2.
The NIC box controller performs all acquisition functions, with the exception of the UT signal processing.
FIGURE 11.4.2 UT-360 SYSTEM DIAGRAM - CONTAINMENT F N my
~ b, C I
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FTl Ncn-Prrprist::ry 11.4.1 Controller and Data Acquisition Communication cables connect the containment equipment to the control station. Fiber optic lines are used to transmit the UT waveforms, transmit the control signal used by the UT signal multiplex (MUX) system, and communicate with the NIC box. The computer processes, displays, and archives the data.
11.4.2 Probe Head and Motor Unit The probe head has three ultrasonic transducers as shown in Figure 11.4.3.
The motor unit contains a water seal, eddy current coils, the rotational l mcoder, and the motor to rotate the probe head. The UT probe is inserted
- o the tube by a probe driver. An axial position encoder is used to monitor tne elevation (or motion) of the motor unit within the tube. The probe rotation, combined with the controlled pull of the motor unit, results in a helical scan path for the transducer (s). The probe driver is used to position the probe to the target elevation prior to scanning. ECT coils are used to locate support structures (TS and TSP). The axial position encoder is set to an elevation relative to the support structure.
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FTl Non-Proprietary FIGURE 11.4.3 UT-360 SYSTEM DIAGRAM - PROBE HEAD
- Rotating 3 Transducer Probe Head 0 Degree (thickness / profilometry) 45 Degree axlal beam (cire cracks) 45 Degree circ beam (axial cracks) f '- - ~~-
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l The outside diameters of the UT probe and the plating probe prevent their i 1
use in severely dented tubes. To test the ability of the UT system to detect 6c flaws in a dented tube,f., 3,,a.xial EDM notch was installed in a tube with[ ]%c,4 inch deep dent. The UT system detected the EDM notch with both clockwise and counterclockwise shear wave beam directions.
The probe is centered in the tube / sleeve by devices that operate over the entire range of inside diameters. The UT transducers require couplant to efficiently transmit the sound energy to and from the tube wall. The couplant is stored in the water system and is introduced through the motor unit by a small positive displacement pump. The couplant is retained in the tube by a water seal.
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. _-~ _-_.
FTl Non-Pr:pri t::ry l
I The motor unit connects to the signal multiplex (MUX) box. Signals to and from the three probe transducers are handled via the motor unit. The MUX box communicates signal information to the control system.
11.5 UT Acquisition Parameters The UT system used to inspect an Electrosleeve" is summarized by the following parameters and specifications:
C., e Transducers: The transducers are[ 3, immersion transducers.
C Transducer Frequency: [ ],6 Axial Pitch: { ce C
Circumferential Pitch: [ 3. f, Digitizer Frequency: Shear Wave [ ,
c,e Longitudinal [ , cy,,
Target motion time of flight (TOF)is measured in digitizer counts. Target motion TOF in digitizer counts is converted to microseconds by dividing the TOF (counts) by the digitization frequency.
The microseconds are converted to distance (depth) in the material by multiplying by the speed of sound for the specific propagation mode (shear or longitudinal).
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FTl Non-Proprietary Coverage: 100 %
F j,d, e 11.6 UT Data Presentation The UT data is processed and displayed in several different modes for interpretation.
These data displays assist the analyst in selecting waveform data to be evaluated in detail. Flaw detection, characterization, and sizing are performed using C-scans, D-scans, A-scans, and profilometry displays. The following discussion will define each presentation mode used for the analysis of the UT data.
11.6.1 C-Scan Maps C-scan maps provide information pertaining to the strength (amplitude) and
]
TOF of the returning signal. All acquired waveform peak values are j displayed in a C-scan map. The C-scan maps provide three, two-dimensional l views of the scanned region. The first, and largest, view is a plan view image with axial and circumferential scan dimensions. This view represents the surface of the tube cut axially and rolled flat. Each data point or pixelin this map represents a returning signal amplitude. Each data point in the display is assigned a color based on the signal response amplitude. The color range is displayed in the legend of the C-scan map. Figure 11.6.1 shows a typical C-scan map, presented in gray-scale for ease of document reproduction. i FRAMATOME TECHNOLOGIES, INC.
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FTl Non-ProprietIry j in addition to the first view described in the previous paragraph, the C-scan map contains two additional views. The view to the right of the first view presents the returning signal strength information on a plot of axial scan length versus material depth. The axial scan length axis corresponds to the same axial scan length axis on the first view. The material depth axis corresponds to the TOF of the returning signal. The returning signal strength is plotted using the same color range as is used in the first view.
The third view in the C-scan map is below the first view. This view presents
(
the returning signal strength information on a plot of circumferential scan dimension versus material depth. The circumferential scan axis corresponds to the same circumferential scan axis on the first view. The material depth
! axis corresponds to the TOF of the returning signal. The returning signal strength is plotted using the same color range as is used in the first view.
The two views described above are useful when the strength of the signal at a particular depth is important. The C-scan display allows the analyst to l
identify areas of amplitude fluctuations that may indicate the presence of ID l
' pits, OD pits, nodules, and/or parent tube cracking.
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L FRAMATOME TF.CHNOLOGIES, INC. I 11-18
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FTl Non Proprietary FIGURE 11.6.1
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L J 11.6.2 D Scan Maps Another type of display used in the presentation of the data is the D-scan map. This display is interpreted in the same manner as the C-scan display; however, the pixel color represents the signal TOF converted to a thickness.
Thus, this information is a direct measurement. The analyst can verify combined sleeve / wall thickness and thus verify bond.
11.6.3 A-Scan Presentation The A-scan data format provides a means to analyze the collected radio frequency (RF) waveforms. The A-scan data represents the entire returned RF waveform as acquired by a transducer. The full waveform allows the analyst to investigate low amplitude signal responses that might otherwise go undetected in the peak data presentation. The A-scan display plots the returning signal amplitude as a function of time. The colors presented in the FRAMATOME TECHNOLOGIES, INC.
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)
FTl Non Prrpriet:ry main display of the A-scan presentation indicate signal response amplitude.
The A-scan presentation is the primary tool used to analyze signals for ,
l disbond, detect tube OD deposits, detect cracks, and evaluate volumetric-Indications. Using the A-scan display, the analyst determines thickness and measures detected flaw dimensions such as length, width and depth. Figure 11.6.2 is a typical A-scan presentation presented in gray-scale.
i l
FIGURE 11.6.2 C
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L J 11.6.4 Profilometry Displays The profilometry display is interpreted in the same manner as the C-scan display except that the pixel color represents the water path TOF. Using this display, the ID profile of the Electrosleeve" surface can be presented. The analyst can use profilometry to determine the sleeve length and the internal diameter. Profilometry can display inner diameter contours of the sleeve and parent tube including denting and sleeve taper profiles. The format of the
. profilometry display is similar to the C-Scan shown in Figure 11.6.1.
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- - . . .-- . - - . _ ~..-..- .. . - . . - - - . . . _ . . _ - .
l FTl Non-Proprietary l- .11.7 UT Analysis Techniques . ;
4 11.7.1 UT Probe Axial Location Data from the eddy current (ECT) coils and an axial encoder are combined to obtain probe axial location. The UT motor unit is inserted into the tube until the ECT coils detect the top of tubesheet (TTS). The axial encoder is set to reflect the axial position of the TTS. As the UT motor unit is inserted into the tube, each TSP is observed from the ECT readout on the UT-360 system.
i- When the UT signal detects the Electrosleeve", the motor unit is stopped L and retracted until the nearest TSP is detected with ECT. This location
- provides a reference for the axial encoder. The probe is then moved into the d
scan start position. After the scan is completed, the UT motor unit is moved
[ until the nearest TSP is detected, again by ECT, and the axial position is )
confirmed.
11.7.2 UT Analysis Techniques for Normal (Zero Degree) Beam Testing The normal (zero degree) beam TOF measurement is used to determine pit depth, disbond, and thickness. The transit time is measured from the time the ultrasonic wave is emitted to the time it returns to the transducer. By knowing the speed of sound through a given material (e.g., water, Alloy 600, or nickel), the depth can be determined.
The most common condition which can affect a UT-360 examination is the presence of tightly adhering deposits on the tube OD. These deposits occur at the sludge pile location, in packed TSP crevices, or in freespan regions.
These tightly adhering materials can attenuate ultrasonic signals. However, detection of volumetric flaws such as pits is not affected. As indicated before, volumetric flaw detection is accomplished by TOF measurements.
Volumetric indications, by definition, reduce the amount of wall material whereas deposits increase the amount of apparent wall material. By observing the TOF values as compared to the known wall thickness, classification of deposits can be accomplished.
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l FTl Non Pr:priit:ry i
J 11.7.3 UT Analysis Techniques for Shear Wave Testing The shear wave examination is used to detect and size defects such as SCC.
The primary signal chracteristics used to size SCC are amplitude and TOF.
As the probe shear wave transducer moves closer to a detected indication, the signal reflections will occur earlier in time and will change in amplitude.
The technique initially locates the maximum amplitude of the signal with respect to the tube wall thickness in order to determine the origination surface in addition, the presence of multiple reflectors from the same indication is noted. The flaw response signal characteristics will determine the appropriate method of sizing analysis.
The analysis of shear wave data uses three basic methods to estimate the depth of a crack. The methods are tip sizing, multiple skip method, and target motion TOF. Two additional techniques, Full Skip Normalization (FSN) and shear wave Mode Converted Signal (MCS), were developed to supplement and improve the accuracy of the above methods. Full Skip Normalization and shear wave Mode Converted Signal will be presented in this section.
Tio Sizino Method Obtaining a reflection from the crack tip is the most accurate method for crack depth sizing. Detection of a crack tip signal is rare in a steam generator tube examination unless the crack is deep and has significant volume (i.e., a large gap between crack faces).
Detection of a crack tip signalis indicated by a return signal that has a waveform reflection from the crack tip in addition to a waveform reflection from the corner reflector of the crack. This crack tip signal is rarely observed for two reasons. The first reason is that the reflection from the tip requires a minimum crack width (gap) of one tenth of a wavelength. The second reason is that a tip reflection signal cannot be distinguished from the corner reflector signal until the crack depth of penetration exceeds one wavelength.
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FTl Non-Proprietary The waveform for the crack tip and the corner trap will overlap for small depth cracks. For a 10 MHz transducer, the depth of penetration equivalent to one wavelength is 0.012 inch. Therefore, to detect the crack tip, the penetration depth must be greater than 0.012 inch and there must be a l
sufficient gap between the crack faces. As previously discussed, SCC in I steam generator tubes is extremely tight; thus, even deep cracks are '
prevented from being accurately sized using a tip signal, j
If the presence of a crack tip signalis determined, geometric calculations using the difference in the TOF of the two reflection signals can be used to 1
accurately calculate the depth of the crack. l 1
l Multiole Skio Method l The multiple skip method considers multiple reflections of the sound energy )
along the path of propagation. When the shear wave encounters a reflector, !
a return signalis obtained, if no reflection is encountered, the signal continues to propagate in the material with reflection from the OD to the ID and ID to the OD. Segments of the pattern are termed half skip (ID - OD), I full skip (ID - OD - 10), and 1 1/2 skip (ID - OD - ID - OD). l l
As the transducer moves along the axis of the tube, there are multiple geometric locations whare the ultrasonic signal reflects from a flaw. The j same is true for the rotation path of the transducer. Each wall reflection of the signal may be defined as a skip.
In the case of an outside diameter crack, as the depth of penetration increases, the amplitude of the inner diameter full skip response increases relative to the outer diameter signal response amplitudes at the half and 1 1/2 skip locations. When a crack produces significant reflection signals at the half, full, and 1 1/2 skip positions, the depth is considered to be near through-wall.
Based on the theory that a flaw of sufficient depth to reflect a wavelength will produce a significantly large amplitude return, significant return signals would be expected when the remaining wall is less than 0.012 inch. This response is demonstrated during each calibration acquisition. Deep OD l
. FRAMATOME TECHNOLOGIES, INC.
l 11-23 l
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l FTl N:n-Pr:pri;tiry calibration notches, where the remaining ID wall is less than 0.012 inch (one wavelength), produce a full skip response signal amplitude that is more than 50% of the average of the OD signal responses (from half and 1 1/2 skip). j I
Figures 11.7.1 and 11.7.2 illustrate the half and full skip signal reflection !
positions.
l FIGURE 11.7.1 HALF SKIP SJGNAL REFLECTION POSITION DIRECTION OF TRANSDUCER DISPLACEMENT
+----TRANSDUCER SOUND ENERGY PATH 10 l ! CRACK 0.050' WALL #
j 1 OD I INNER DIAMETER SURFACE RESPONCE '
CORNERi'EFLECTOR i
PEAK-TO-PEAK A/D COUNTS
\y (154 COUNTS)
FIGURE 11.7.2 FULL SKIP SIGNAL REFLECTION POSITION DIRECTION OF TRANSDUCER DISPLACEMENT
+--1RANSDUCER SOUND ENERGY CORNER PATH REFLECTOR INNER DIAMETER i CRACK TUBEWALL j , ,p i
OUTER DIAMETER i y
INNER DIAMETER E SURFACE RESPONSE !'b _.{
TOF (FULL OR1 SKIP)
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I FTI Non-Proprietary Figure 11.7.3 shows the loss of the full skip corner reflector after sleeve installation. The addition of ID sleeve material has eliminated the ID corner reflector. The presence and subsequent loss of the full-skip signal )
associated with laboratory-produced flaws were noted by comparing pre-sleeve and post-sleeve UT data. Thus, after sleeve installation, the multiple skip method is not used to size cracks in the parent tubing. ;
FIGURE 11.7.3 LOSS OF FULL SKIP SIGNAL WITH ELECTROSLEEVE'" i BEFORE ELECTROSLEEVE" l
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l FTl Non-Pr:pri:ttry Taraet Motion TOF This method uses the half skip target motion TOF information to determine the penetration depth of the crack, in the absence of reflections at the expected full skip, the analyst determines depth from the earliest or latest detected reflections along the target motion for the OD half skip signal. This method assumes that the reflections are 45 degree shear wave returns from the crack face. It also assumes that the earliest and latest detected reflections are coincident with the crack tip. Target motion TOF is the most accurate method for determining the location of the corner reflector.
When the depth associated with each skip is a multiple of the wall thickness, the estimated crack depths should be equal to the transducer displacement along the inspection axis. Figure 11.7.4 shows the target motion TOF for a 45 degree shear wave propagation to the crack tip and the corner reflector.
4 i
FRAMATOME TECHNOLOGIES, INC. j 11-26
FTl Non-Proprietary FIGURE 11.7.4 TARGET MOTION TOF DIRECTXMd OF TRANSOUCER DISPLACEIAENT EARUEST DETECTION I
e SuRrACE CigACx
_o 00 SURFACE DIRECTION OF TRANSD'JCER DISPLACEMENT CORNER REFLECTOR DETECTION ID SURFACE CpCK OD SURFACE The following example illustrates the method used to determine the depth of a reflection from a crack intersection with the tube OD surface. The same method is used to calculate the depth of the reflection from a crack tip.
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FTl Non-Prrpriitzry FIGURE 11.7.5 TOF CALCULATION FOR OD CORNER REFLECTION TOF = 114 counts atANSDUCER H SOUND ENEROY PATH INNER SURFACE INNER DIAMETER SURFACE REFLECTION 45 deg.
TUBE WALL = 0.048 inch l CRACK OUTER DIAMETER SURFACE CORNER REFLECTOR AND RESPONSE 1
l From Figure 11.7.5, the starting crack depth is determined by the equation
- l Starting Crack Depth at OD = [(TOF)
- sin 45 * (Vel.s.. Il /2 where:
TOF = the time difference in microseconds (us) between the inner surface reflection and the corner reflection formed by the intersection of the outer diameter surface and the crack, sin 45 = the sine of the angle of propagation = 0.7071, and Vel.3.... = the shear-wave speed in Alloy 600 (0.1217 inch per microsecond).
The product of the three factors is divided by two since the sound energy must travel to the corner reflector and return. TOF is measured in digitizer counts. Digitizer counts must be converted to microseconds by dividing by the digitization rate of the A/D converter,[ [For example, digitizer counts are converted to microseconds by the following:
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FTl Non-Proprietary TOF(ps) = (counts)/ Digitization Rate (counts / s) ,
TOF( s) =[ ]
={ ]d Solving for starting OD crack depth:
Starting Crack Depth at OD =[ )
= 0.049 inch = Tube Wall Thickness The above procedure is repeated for the crack tip. The difference between these two calculations is the crack depth.
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FTl Non-Propristtry c,C
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FRAMATOME TECHNOLOGIES, INC.
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c, c c, c Testing has demonstrated [ ] sizing method is independent of system gain, probe acquisition pitch, and signal saturation. Additional study
[ ll1 s developed a regression equation to correlate
( j'to a crack depth.
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FTl Non-Proprietary 11.8 Qualification Program for Longitudinal Wave UT As presented earlier, longitudinal wave UT is used for detection and sizing of volumetric flaws, disbond, and for combined wall thickness. The ASME Code Case
[13.7) was used ats a reference in developing the qualification of UT as a method of Electrosleeve" inspection. Samples with manufactured flaws were used to study the capabilities of UT. The electro-deposition was performed to the nominal thicknes values with tapers that were approximately [ 3Nength.
11.8.1 Parent Tube OD Pits l Definition An OD pit is a localized wall loss on the OD of the parent tube. This defect mechanism may occur in the parent tube material behind a sleeve.
~
Insoection Reouirement Parent tube OD pitting must be detected and sized within Region C where the sleeve is the pessure boundary (Figure 11.1.1). The ultrasonic technique must der.onstrate a high probability of detection (POD) of 40%
r through-wall parent tube OD pitting in Regions A and B (Figure 11.1.1) where the parent tube is all or part of the pressure boundary, i
i Samole Set Descriotion The sample set consisted of seven tube samples. The 3/4" version of the three-channel probe was used to acquire the data. The reported actual depths were determined using a pin micrometer to a measurement uncertainty of[ N'O c,, e The remaining wall resolution (RWR) of the UT system for a [ 3 transducer is[ Nfremaining wall thickness. At this RWR, the returning echo signal cannot be distinguished from the inner diameter surface reflection (interface signal). Therefore, no thickness less than the RWR can be measured by UT. Although pits with [ Y fess of remaining wall cannot be accurately depth sized, detection is not affected. As the OD pit FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Pr:prietary depth increases, the returning pit echo signal approaches the interface signal.
For deep pits, the pit signal merges with the interface signal preventing an accurate measurement of the depth.
When the signals merge, the UT analyst makes a call which indicates that the pit is deep but that an accurate measurement of the pit depth is beyond the capability of the system. For a nominal 0.043 inch parent tube wall thickness, this would cur at a pit depth [
c 3., e,erefore, this limitation does not affect the ability to detect or size a 40% through-wall pit in the parent tube OD. l l
Data Set The data set is presented in Table 11.8.1.
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TABLE 11.8.1 PARENT TUBE OD PIT SAMPLE SET C,d, &
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FTl Non-Pr:pri:tiry Results Table 11.8.2 summarizes the parent tube OD pit sizing analysis results for the thirty-one (31) indications presented in Table 11.8.1. The maximum undercalls from the analysis are reported under " Max Error".
TABLE 11.8.2 PARENT TUBE OD PIT SIZING RESULT c,f e I 1 l
L -I All OD pits were detected, which demonstrated a high POD for this defect mechanism. The NDE uncertainty is used in Section 12.0 to produce a conservative flaw disposition.
(
11.8.2 Sleeve OD Pits pefinition An OD pit is a localized wall loss on the OD of the Electrosleeve".
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FTl Non-Proprietary Insoection Reouirement c,E Sleeve OD pits with a depth greater than[ 3 of the sleeve wall thickness exceed the plugging limit. In the Electrosleeve" region where the sleeve is the pressure boundary, sleeve OD pitting must be detected and depth sized.
Samole Set Descriotion The OD pit sizing evaluation was performed with samples containing chemically induced pitting in the OD of the sleeve material. A method was devised to chemically generate pits on the OD surface of the Electrosteeve".
6, c.
[ 3EDM notches,[ ]b, c., were made at each target location to form a cross. Each cross was to terminate at the interface of the Electrosteeve" and the Alloy 600. Th9 pits were produced by injecting a chemical solution, consisting of various acids that attack only the nickel, into the center of each EDM cross. The process involved a series of chemical injections, holds, rinses, and differential focus optical (DFO) depth measurements to experimentally process each pit to a desired depth into the nickel. [
3.c,d, e h,c h> C The sleeve OD pit sample set consists of[ 33/4" OD tubes an( 37/8"
] dt flaws in the 3/4" OD samples OD and[.
tubes. There p(ere[
)l the 7/8" OD samples. The( 3 pit depths, as a percent through-wall based on DFO depth measurement technique, were achieved:
6,C
- [ 30% to 20% through-wall of the Electrosteeve" C
]'b, c ha C
- [ 321 % to 60% through-wall of the Electrosleeve"
(. 6, c
]'and
- [. 361% to 90% through-wall of the Electrosleeve" C 3.b'O kC
[ 3s,amples with( )b,c pits were destructively examined to provide information about the pitting evolution, diameter versus depth, and to validate the DFO technique.
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- . .. . =. . _ - -
1 FTl Non Proprictary
( q >6 jb6 b
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Data Set The data set is presented in Table 11.8.3.
In Table 11.8.3, "UT combined thickness at pit center line" is the thickness.
of the sleeve and the parent tube measured { -
a'bove the centerline of each pit. "UT parent tube thickness" is the thickness of the parent tube measured above the centerline of each pit. The " actual measured pit depth" is the depth of the pit measured by an optical differential focus from the outer diameter of the parent tube. This depth includes the parent tube thickness in addition to the depth of penetration of the pit into the sleeve material. The " calculated sleeve pit depth" is the difference between the
" measured pit depth" and the "UT parent tube thickness". This is the depth of penetration of the pit into the sleeve material.
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FTl Non-Proprietary i
- l TABLE 11.8.3 I
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FTl N:n-Prsprittrry 8!!fjJll!!
Tables 11.8.4 and 11.8.5 summarize the sleeve OD pit sizing analysis results for the data set as presented in Table 11.8.3.
4 TABLE 11.8.4 SLEEVE OD PITTING RESULTS - 3/4" TUBE C,d, C I~ 7 l
L J l The maximum errors reported in Table 11.8.4 are the maximum under-call errors for the sample set.
TABLE 11.8.5 SLEEVE OD PITTING RESULTS - 7/8" TUBE C,d> 6 7
L J The maximum errors reported in Table 11.8.5 are the maximum under-call errors for the sample set. All sleeve OD pits were detected, which
. demonstrated a high POD for this damage mechanism. The NDE uncertainty is used in Section 12.0 to produce a conservative flaw disposition.
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T 1 FTI Non-Proprietary ,
i .11.8.3 - Disbond .
l Definition
, A disbond region is an area where the nickel sleeve is not bonded to the ID e of t' a carent tube. Disbond regions are considered to have neither volume nor mas; 4! loss.
q Insoection Reauirement t The examination requirements specified in Section 6.A.2 of Reference 13.4 ;
.were used to select simulated disbond diameters. These requirements l specifically state: " Testing shall demonstrate that there are no nonbonded areas greater than 0.125 in. In width or length within the minimum required
. reinforcement length. Nonbonded areas greater than 0.125 in. and less than
. 0.250 in, may be evaluated by the Owner for acceptability. Nonbonded areas greater than 0.250 in. in any dimension are unacceptable. "' To meet these requirements, the population of simulated disbond samples ranged 1
.-from diameters less than 0.125 inch to diameters greater than 0.-250 inch.
.Samole Set Descriotion To simulate a disbond location between the Electrosleeve" and Alloy 600, contoured-bottom EDM burns were used to install disbond patches'of various diameters in the OD of Electrosleeve" samples. Each sample contained three contoured-bottom holes in the OD of the parent tube with the target depth terminating at the interface of the Electrosleeve" and Alloy 600. As a part of the disbond qualification, it was demonstrated that simulated disbond produces ultrasonic signal responses equivalent to actual process-induced I disbond.
C, C.
UT data was acquired at axial pitch values b 3 Pitch is the axial spacing between subsequent probe rotations. These three pitch values were required to demonstrate acceptable detection and extent
,c e sizing for the nominal [ .J a,c.quisition pitch.
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~ __ -. . _ . _ _ _ . - _. _ _ _ . _ _ _ _ ._-
FTl Ncn-Propristary It is necessary to measure two disbond edges when determining either axial or radial extent. A two times-pitch error bound allowed for an error equal to one pitch at each edge. If an analyst chose the edge signals such that each ;
edge determination contained an associated error of one pitch, the total error contained in the extent measurement would equal twice the pitch. As a result, for both axial anti circumferential disbond extent measurements, an I
error not to exceed two times the relative pitch was considered an acceptable performance bound for the analysis. This error bound would result in a maximum error for any extent measurement of [ .3Nhich i falls well within the [ r'i$h requirement.
Data Set
[ 3 mg'les were used [or the disbond qualification. The samples consisted of[ 3,3/4" and[ 3,i/8" samples for[ Nisbond regions (each contoured-bottom EDM represented the site of a single disbond region). Table 11.8.6 lists the disbond flaws that were fabricated to simulate process-induced disbond.
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l FTl Non-Proprietary TABLE 11.8.6 DISBOND SAMPLE SET c,d,e I 7 L -/
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FTl Non-Propriettry l To ensure detection and adequate extent sizing, FTl acquires data with an average axial pitch of [ 3dnYan average circumferential pitch of two degrees. The average circumferential pitch of two degrees can be converted to inch by the following equation:
Cire. pitch (in.) = (Circ. pitch (")]*[(3.14159'lD(in.))/360( )]
Three axial pitches were acquired to demonstrate that variances of an average pitch of E J YdSid not produce an unacceptabie extent determination.
Table 11.8.7 provides the extent sizing bounds as a function of pitch.
TABLE 11.8.7
- TWO PITCH EXTENT SIZING ERROR BOUNDS AXIAL AND CIRC. EXTENT TOLERANCES CIRC. AXlAL SAMPLE INSIDE CIRC. EXTENT AXIAL EXTENT SIZE DIAMETER PITCH BOUND PITCH BOUND (inch) (inch) (inch) (inch) (inch) (inch) 3/4" 7/8" L a Results Tables 11.8.8 and 11.8.9 summarize the sleeve disbond sizing analysis results for the data set presented in Table 11.8.6.
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i FTl Non-Preprietary Table 11.8.8 displays the results from comparing the UT circumferential extent measurements to the actual measured circumferential disbond extents. The maximum expected circumferential error bound for 3/4" and 7/8" samples was noted in Table 11.8.7 [ ), '
respectively. All of the UT measured circumferential extents were within the expected bounds. The maximum errors reported in Table 11.8.8 are the maximum under-call errors for the sample set. The data includes two separate analyst results of three different axial pitch values.
TABLE 11.8.8 DISBOND CIRCUMFERENTIAL EXTENT SIZlP' RESULT CIRCUMFERENTIAL EXTENT RESULTS
[3-CHANNEL CENTERED PROBE]
SAMPLE SIZE: 3/4" AXIAL AVERAGE STANDARD MAX PITCH FTlUT ERROR DEVIATION RMSE ERROR (inch) ANALYST (inch) (inch) (inch) (inch)
C:
L _l SAMPLE SIZE: 7/8" cdd 1
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FTl Non-Propristtry Table 11.8.9 displays the results from comparing UT axial extent measurements to the actual measured axial disbond extents. The expected maximum exter.1 bounds for axial pitch values (
3, #
N'ere noted in Table 11.8.7 f.
respectively. All UT measured axial extents were within the expected bounds.
The maximum errors reported in Table 11.8.9 are the maximum under-call errors for the sample set.
3 TABLE 11.8.9 DISBOND AXIAL EXTENT SIZING RESULTS AXIAL EXTENT RESULTS
[3-CHANNEL CENTERED PROBE]
SAMPLE SIZE: 3/4" AVERAGE STANDARD MAX AXlAL FTlUT ERROR DEVIATION RMSE ERROR PITCH ANALYST (inch) (inch) (inch) (inch)
(inch) r~ cd)
L J SAMPLE SIZE: 7/8" C c,d1 I- 4 FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary Both analysts detected all eighteen (18)' disbond regions. The comparison of the UT measurements to the actual axial and circumferential disbond extent measurements demonstrates that the UT method is within the expected l bound of two times the relative pitch. This indicates that distinct edge signals exist at disbond boundaries and contribute to the repeatability of sizing disbond extent within the expected bounds. The worst case root mean squared error (RMSE) and maximum error reported meet the 0.125 and 0.250 inch diametric disbond sizing sequirements [13.7].
11.8.4 ID Pits Definition 1
ID pits may be formed on the inner diameter surface of the sleeve during the plating process. Sleeve ID pits are typically less than 0.050 inch in diameter ;
at the sleeve ID surface. t insoection Reauirement 6, C UT is required to detect ID pits with diametegin excess of [ . To ensure a high probability of detecting [ 3 diameter pits, the qualification testing must demonstrate the ability to detect ID pits of diameters greater j
[ ] ,% C> t ,
UT is required to ' determine'the location of the pit relative to the tube flaw.
ID pits that are within one-half inch of a detected parent tube flaw are unacceptable. The reason for this criterion is that the propagation of the P
parent tube flaw could result in coincidence with the ID pit and produce a
- potential leak path, i
'lD pits are conservatively assumed to be 100% through the sleeve materiah
^
therefore, no depth sizing is required. ID pits with a depth greater than one
- wavelength (' bc 3c,an,ebe detected because at depths greater than[_
3,'there should be at least two distinct surface reflections. j i
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FTl N::n-Prepristiry Samole Set Descriotion A set of tubes with ID pits was selected from the p ess pre-qualification c
and training runs. This sample set consists of[ 3 e.eved 3/4" OD tubes b
[ The tubes were examined with axial pitch values. The tubes were split axially to characterize each pit location and diameter at the inner diameter surface.
Data Sel The qualification samples are presented in Table 11.8.10. Axiallocation is expressed in inches relative to the marked tube end. The circumferential location is expressed in degrees of rotation from an established zero degree l
reference mark located fourteen inches from the marked tube end. The circumferentiallocations were estimated and were used to correlate the data I I
reported for pits in close proximity.
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FTl Non-Proprietary TABLE 11.8.10 ID PIT SAMPLE SET j C,fe 4
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FTl Nrn-Pr:priitzry Results J
The UT data was analyzed by a single analyst to determine a probability of detection for ID pits in the range of diameters represented by the sample set.
Table 11.8.11 presents the detection results for the three axial pitch values.
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FTl Non-Proprietary TABLE 11.8.11 ID PIT SAMPLE SET DETECTION RESULTS c,d,e I .
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FTl N:n-Prcpriit:ry The analyst detected all ID pits [ .
c,d>C 11.8.5- Combined Wall Thickness Definition The combined wall thickness is the combination of the parent tube wall
- thickness and the sleeve wall thickness.
Insoection Reauirement The UT must be able to measure the combined wall thickness to sufficient securacy to assure the sleeve wall meets the required minimum thickness.
r- n C E.
The thickness measurement must be accurate to L J to support the minimum thickness requirements for sleeve installation.
Samole Set Descriotion l
The sample cet consists of thickness measurements performed during the destructive evaluation of the laboratory SCC sample set. Thickness t
measurements from the ultrasonic data analysis were compared to the thickness values determined by the destructive evaluation at each of the flaw locations. ,
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FTl Non-Proprietary l Data Set The destructive examination (DE) results are presented in Table 11.8.12.
TABLE 11.8.12
_ COMBINED WALL THICKNESS DATA SET C
C,d,D 9
m Results The time of flight between successive back wall reflections of the longitudinal (thickness) waveform were used to analyze the data.
The results listed in Table 8.11.13 show that the maximum error and the RMSE are sufficient to meet the requirements for sleeve thickness examination.
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FTl Non-Propristtry TABLE 11.8.13 COMBINED WALL THICKNESS RESULTS C sd)
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FTl Non-Proprietary 11.8.6 . Sleeve Nodules Nodules are a localized build up of plating material on the ID of the sleeve.
The UT system can detect and measure the nodule height. Typically, nodules are less than [ [In diameter and do not impact probe operation if the probe operation is impacted, the nodule height will be reduced by a suitable method.
11.9 Qualification Program for Shear Wave UT Shear wave UT is used for detection and sizing of crack-like flaws in the parent tube.
Samples with EDM flaws, laboratory induced stress corrosion cracking, and actual in-service generated defects were used to study the capabilities of UT. At present, there is no technique available to induce cracking in the Electrosleeve". Thus, the SCC was only in the parent tubing while the EDM notches were machined into both the parent tube and sleeve.
11.9.1 Definition Parent tube cracking occurs in the form of either outer diameter stress corrosion cracking (ODSCC), primary water stress corrosion cracking (PWSCC), intergranular stress corrosion cracking (IGSCC) associated with intergranular attack (IGA), or fatigue cracking. Cracks in thin wall tubing are planar in nature since a depth of penetration and an extent (length) are exhibited. These cracks propagate nearly perpendicular to their surface of origin, 11.9.2 Inspection Requirement -
Regions A and B (Figure 11.1.1) must be free of defects (based on ECT) at the time of sleeve installation. If parent tube cracking occurs in either of these regions, the tube will be plugged. In these regions, UT must
' demonstrate a high probability of detection of service induced cracks that have depths of penetration exceeding 40% through-wall of the parent tube, i
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FTl Ncn-Prepritt"ry Region C (Figure 11.1.1) contains one or more parent tube defects that have been covered by the Electrosleeve". For those defects that are cracks, the ultrasonic technique must detect the crack and also determine the depth of penetration. The accuracy at which UT can measure crack depth directly affects the sleeve plugging criteria presented in Section 12.0.
11.9.3 Sample Set Description This sample set included EDM notches, laboratory induced ODSCC and PWSCC, and service induced ODSCC, PWSCC, and IGA. Most of the samples were analyzed before and after sleeving. The following sections provide additional information on the crack sizing sample set.
EDM Samole An EDM method was used to fabricate flaws in a sleeved 3/4" x 0.043" wall Alloy 600 tube samO'le[. .
An AX EDM is oriented along the length of the parent tube or sleeve. Axial and cirenatferential EDM notches were placed in each region (Figure 11.1.1) of the tudrosleevr repair.
The EDM notches were placed in selected regions and originated from the parent tube OD, the parent tube ID, or the sleeve ID. Flaws at various depths and locations were made to demonstrate UT detection and sizing capability throughout the sleeved regions. The depths of the flaws are referenced as percent through-wall (%TW) of the mean wall thickness (MWT) of the parent tube. [
- kC 3%
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FTl Non Proprietary j
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).1These parent tube flaws are used to calibrate the equipment. The flaws demonstrate the capability of the UT examination to detect and size crack-like indications in the parent tube.
E c
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These FOM notches originated in the parent tube OD and are used to demonstrate the detection of crack-like indications in Regions A and B (Figure 11.1.1). The flaws in Regions A and B were used to determine the influence of UT Leam redirection resulting from the tapers.
E c C.
). ,These EDM notches originated in the parent tube OD and were used to demonstrate the detection and sizing of crack-like indications in Region C.
Laboratorv induced SCC Samoles hc o
[. ] tube samples with laboratory induced ODSCC were obtained for use in the NDE qualification. Each sample was a 3/4" x 0.048" Alloy 600 tube,
[ ]b,c, and had two[ ] b,Cjt transitions. The area of interest was at the upper transition, two inches from the tube end. The samples were sleeved and were then destructively examined. [
s -
3,e b, C.
( ), 3/4" x 0.043" Alloy 600 tube with laboratory induced b, c PWSCC, were obtained for use in the NDE qualification. These[, ] samples had roll expansions. Based on the destructive evaluation, the samples had multiple, ID initiated, axial SCC located at the roll transitions. The ID cracks FRAMATOME TECHNOLOGIES, INC.
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FTl N:n-ProprlItcry that had propagated to the OD surface were the only cracks evaluated for 4 the qualification since PWSCC that has been sleeved is no longer exposed to the environment.[ .
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( ] samples were examined before and after the sleeving process.
The examination was performed to determine the ability of the UT technique to detect and size stress corrosion cracks at expansion transitions after sleeve installation.
In-Service Induced SCC Samoles (Not Sleeved)
[ ] samples from tubes (3/4" x 0.043" Alloy 600) pulled from steam generators were analyzed to demonstrate the ability of the UT techniques to detect and size ODSCC. The[ 3I'amples included
)frhe span axial defects and[ 3 axial defect at a support plate [ ]f'reespan axial defects; and
{ ]b,c circumferential defect at the tube sheet expansion transition. These samples demonstrated the ultrasonic detection and sizing of ODSCC in the parent tube material.
The purpose of the destructive evaluation of these samples was to determine the crack depth. [
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FTl Non-Proprietary in-Service Induced SCC Samoles (Sleeved) b,C hsC This sample set consisted of f_ 3 TSP sections from[ 3 tubes (7/8" x 0.050" Alloy 600) pulled from steam generators. Each section contained PWSCC, ODSCC, IGA, or dents. These regions were examined by the UT technique before and after the sleeving process. The samples were examined from both ends to demonstrate consistent crack detection capability.
The sleeves were oriented to place the defects in Regions A, B, and C. This was performed to demonstrate the ability of the UT technique to detect cracks of 40% through-wall beneath the tapers as well as beneath the full thickness portion of the sleeve. The purpose of the destructive examination of these samples was to determine the crack depth for POD versus depth calculations. C
] b,c,e Table 11.9.1 summarizes the location of dents and flaws with respect to sleeve placement. In some samples, the sleeve was intentionally placed such that the flaws were located in Regions A and/or B to demonstrate detection of cracks in all repair regions. The dents were sized as part of the pre-sleeve inspection.
TABLE 11.9.1
SUMMARY
OF DENT DEPTHS C, d> 6
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FTl N:n-Pr:pri:tIry 11.9.4 Data Set The data sets are presented in Tables 11.9.2 through 11.9.5. The EDM data set consists of axial (A) and circumferential (C) EDM notches greater than or equal to 10% through-wall of the parent tube thickness.
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FTl Non-Proprietary TABLE 11.9.2 EDM SAMPLE DATA SET c,g,g, 7
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FTl N:n-Pr:prist ry Laboratory Induced SCC Samoles TABLE 11.9.3 LABORATORY INDUCED SCC SAMPLE SET c.,d,e I l t
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d FTl Non Proprietary TABLE 11.9.4 IN-SERVICE SCC SAMPLE SET- NOT SLEEVED c,d,g
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f FTl Non Prepritt ry TABLE 11.9.5 l lN-SERVICE SCC SAMPLE SET - SLEEVED l r 7 l
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i-FTl Non-Proprietary l 11.9.5 Results EDM Samole The depths of the EDM notches were determined using either the tip
( detection method or the target motion time of flight method.
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FTl N n-Propristiry TABLE 11.9.6 AXIAL EDM SAMPLE RESULTS C,d,e F- 1 I
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FTl Non Proprietary TABLE 11.9.7 CIRCUMFERENTIAl, EDM SAMPLE RESULTS c, d,e I ~l l
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FTl Nrn-Pr:prist:ry Laboratorv induced SCC Samoles in general, the laboratory induced SCC samples were evaluated using the multiple skip method for the pre-sleeve analysis and the tip detection or target motion time of flight methods for the post-sleeve analysis.
Table 11.9.8 contains the analysis of the pre-sleeving data. The pre-sleeving data for sample 1B were not analyzed prior to the destructive evaluation of the sample set. Table 11.9.9 contains the analysis results of the post-sleeving data. l l
TABLE 11.9.8 LABORATORY SCC SAMPLE RESULTS - PRE-SLEEVE Ci d> 6 I 7 l
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i FTl Non Proprietary TABLE 11.9.9 LABORATORY SCC SAMPLE RESULTS - POST-SLEEVE C,ds e 1 l l
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1 FTl Non-Proprietary In-Service Induced SCC Samoles (Not Sleeved) 4 In general, the target motion time of flight method was used to analyze the in-service induced SCC samples. Table 11.9.10 contains the results of the
- unsleeved in-service SCC samples.
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FTl Non-Proprietary TABLE 11.9.10 IN-SERVICE SCC SAMPLE RESULTS - NOT SLEEVED C.j cly C.
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FTl Nrn-Preprl:t ry in-Service Induced SCC Samoles (Sleeved) in general, the target motion time of flight method was used to analyze these in-service induced SCC samples before and after sleeving.
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FTl Non-Proprietary TABLE 11.9.11 IN-SERVICE SCC SAMPLE RESULTS - SLEEVED ANALYSIS COMPARISON c,d, e
]
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FTl N:n Prepristzry C
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TABLE 11.9.12 IN-SERVICE SCC SAMPLE RESULTS PRE- VS. POST SLEEVING -
c ,d> e.
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FTl Non-Proprietary 11.10 UT Qualification Results i This section summarizes the flaw detection and defect sizing capabilities of the UT system and the UT peer review.
Detection Table 11.10.1 presents a summary of flaw detection performance for the mechanisms covered in Sections 11.8 and 11.9. The " Lower Flaw Size" is the smallest dimension of interest detected. The " Upper Flaw Size" gives the largest flaw dimension in the sample set. The " Detection Ratio" represents the ratio of flaws detected to the total l number of flaws in the samples. The " POD 95% LCL" (Lower Confidence Limit) is the
" Detection Ratio" corrected for the statistical strength of the supporting data set. For each defect type, the POD value is computed for the sample range.
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FTl N:n Prrprittiry TABLE 11.10.1
SUMMARY
OF FLAW DETECTION b,c, d,e
,-- 7 t
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The POD curve as a function of depth 'vas created from the crack data set. The curve was generated through the use of a logistic regression as described in Reference 13.71.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary FIGURE 11.10.1 CRACK DETECTION POD c,dj e
- F, q t
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l Figure 11.10.1 shows a high probability of detection of defects within the range of the ,
combined wall thicknesses for tube sizes covered in this topical. In Regions A and B, the parent tube represents part or all of the primary pressure boundary. Therefore, any future defects that might develop in Regions A and B must be detected with a high POD and dispositioned per the plant technical specifications, i
FRAMATOME TECHNOLOGIES, INC.
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FTl N:n-Pr:pristiry Sizina Performance i
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Table 11.10.2 presents a summary of the sizing results for the flaw mechanisms in Sections 11.8 and 11.9. " Max Error" is the maximum under-call.
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TABLE 11.10.2
SUMMARY
OF SIZING PE;'
f 0RMANCE by C,d,e.
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FRAMATOME TECHNOLOGIES, INC. i 11-81 1
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FTl N:n-Pr pri;t:ry l Ultrasonic Examination Peer Review Summary A peer review of the UT examination technique for the Electrosleeve'"was conducted on September 17-18,1997 in Lynchburg, Virginia. A total of ten people participated in the review.
The peer group recommended that larger sample set sizes be used for detection and sizing performance demonstration. Additionally, the technique essential variables and acceptth $ ranges should be clearly and completely defined in the procedure. Finally, the inspection and analysis procedures should address specific flaw data acquisition and analysis.
FTl has completed flaw specific qualification on statistically significant sample sets.
Procedures have been revised to define essential variables and to address flaw specific analysis techniques.
11.11 Advanced UT Analysis Evaluation The application of UT sizing of thin wall cracks was studied to better understand and improve the crack depth sizing accuracy. The study identified two techniques that can be used to improve the UT crackgth sizing accuracy:[
). These techniques are based on confirmed physical principles and improve the accuracy and confidence of the UT depth sizing methodology.
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The value of the[ ] ' hnique e is its ability to accurately size deep cracks.
C b>Cjd 4e 3b 3 technique provides " defense in depth" to support other sizing techniques in verifying sleeve structural integrity.
FRAMATOME TECHNOLOGIES, INC.
11 88
FTl Ncn Proprinttry 11.12 Technique Application One of the key challenges for in-service inspection is to demonstrate that OD initiated defects have not propagated into the sleeve. For normal beam UT, the analysis technique is a straight forward TOF analysis. However, a number of different analysis techniques are available to detect and size cracks. The integration of the various analysis techniques into a coherent inspection plan for cracks is discussed below (Figure 11.12.1).
r FIGURE 11.12.1 UT OD INITIATED CRACK SIZING LOGIC C j C, C6 3
CRACK TIP ANALYSIS
[
ANALYSIS
] [ANALYSIS3 l
l Crack with gap > 0.001" and Parent Tube Cracks Postulated depth > 0.012' w/o Full Skip Sleeve Crack ;
Sleeve i l
Parent Tube i
FRAMATOME TECHNOLOGIES, INC.
11-89
FTl N:n-Pr:priitzry
. If there is a tip signalin the shear wave response, it will be used to determine
' the crack depth.[.
ip signals are typically present for cracks that have significant volume (gap) and depth. .
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j.4e analysis ill be used to track flaw growth in the parent tube and e
sleeve material.- If a ]R st. signal response is detected, the[ 3 analysis method will be applied providing an additicnal verification of sleeve integrity. The more 4 conservative analysis result will be used to determine the flaw depth. The use of( ),e, ,
methods provides a defense iri depth for the verification of structuralintegrity of the sleeve as discussed in Section 12.0.
11.13 NDE Qualification Conclusions The examination requirements were defined for the three sleeve regions of an installed Electrosfeeve". The sleeve structural pressure boundary is the primary NDE region of interest due to the need to determine if tube defacts have propagated into the sleeve material.
Multiple NDE techniques were evaluated. While eddy current is a preferred technique for inspection of steam generator tubes, all available probe designs have encountered difficulties with sleeve examination. The primary eddy current problems are poor accuracy in depth sizing and poor detection of small SCC cracks in the parent tube.
The SCC detection capability and principles of UT provided the basis for UT as the selected NDE technology for examination. UT is the only technology with the proven FRAMATOME TECHNOLOGIES, INC.
'11-90
, FTl Non-Proprietary
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capability to satisfy the sleeve installation examination requirements of thickness, l positioning, and bond. In addition, UT inspection provides in-service monitoring of l bond and flaw growth. l 1
The crack depth sizing accuracy based on conventional time of flight measurements j provides satisfactory results when RMSE is considered as the error standard.
- improvements in UT crack depth sizing were researched during the qualification process.[ $1 proved techniques have been evaluated,[ i
] ].c,eThese techniques were evaluated using EDM bC notches and[ 3 p,reviously acquired UT data and DE information.C j
, ].CBased e on information
- provided in this topical report, UT has been qualified as the inspection method of the
, Electrosteeve". The accuracy and detection capability of the UT technique enables it
} to verify acceptable sleeve installation and to monitor the in-service integrity of the repaired pressure boundary of a steam generator tube.
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FRAMATOME TECHNOLOGIES, INC. i 11-91 I l
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12.0 PLUGGING LIMIT DEFINITION '
To successfully disposition steam generator tube degradation and any potential accompanying sleeve degradation in accordance with Appendix B of 10 CFR Part 50, j an in-service inspection process capable of performing the following tasks must be implemented:
- Detect indications of tube degradation, e Characterize the indications by type, e.g., crack-like, wear, and pitting, e Determine the orientation of crack-like degradation, and
- Accurately size the depth of degradation.
To meet these requirements, FTl implemented the Degradation-Specific Management (DSM) concept to establish inspection and repair criteria [13.75]. Section 11.0 presented the associated nondestructive examination methods that will be used, along with the qualification results. Section 12.0 combines the examination concepts described in Section 11.0 with the structurallimits listed in Section 8.0 to define the Electrosleeve" plugging limit. Thus, the Electrosleeve" plugging limit was determined using a defect-specific structural limit with a reduction to account for combined flaw growth (during an inspection interval) and NDE sizing uncertainty. The postulated defects considered in the plugging limit evaluation included uniform thinning, OD and ID pitting, cracking, and disbond.
The following terms are used in Section 12.0:
Structural Limit: The maximum allowed reduction in the structural material by a
-specific degradation mechanism that meets the RG 1.121 requirements.[
},C oe-Reoair Limit: A defect limit below the structural limit that takes into account the NDE measurement uncertainty and the potential growth of a defect during the planned inspection interval. f.
c, e.
FRAMATOME TECHNOLOGIES, INC.
12-1
)
FTl N:n-Pr:pri;t:ry Electrosleeve" Pluaaina Limit: The amount of measured degradation that initiates an action to plug or repair an Electrosleeve". This value encompasses all of the defects analyzed and currently encompasses all of the RSG tube sizes.(
C,6 Growth: Flaw-specific expected degradation per inspection interval based on corrosion and/or fatigue properties. [
c,e 95% Lower Confidence Limit (LCL): For a normal distribution of errors,[.
c, e RMSE: Root mean squared error.
Inspection Interval: The inspection interval used for the calculations [
], b,c 12.1 Repair Limit for Uniform Thinning Degradation The uniform thinning degradation mechanism can occur in the Electrosleeve" material due to material wear or general corrosion. The st{uctural limit calculations defined#a maximum allowed structural degradation of[ 3 of't$e sleeve wall (Table 8.5.3). [
C, C
]. The repair limit is determined by decreasing the allowed structural degradation to account for degradation growth and NDE uncertainty.
c The assumed growth rate for wear degradation per cycle is[
until3,s detected. Per the definition in Section 9.3.4, a conservative upper limit of( ]o1 he sleeve wall for general corrosion growth is used for a sleeve OD thinning degradation mechanism r bac during a typicall 3 inspection interval. Actual growth will be considerably lower due to the quality and corrosion resistance of the sleeve material and the expected operating environment, which is less harsh than the environment used in the corrosion testing.
FRAMATOME TECHNOLOGIES, INC.
- 12-2
FTl Non Proprietary The 95% LCL and UT sizing RMSE for wall thickness measurement associated with a normal beam examination (Table 11.10.2) are [, ], N respectively. (Table 12.1.1 summarizes the repair limits for all sleeve nominal thicknesses based on the UT sizing RMSE.)
TABLE 12.1.1 REPAlR LIMITS FOR UNIFORM THINNING C C J ,6-BASED ON UT SIZING Allowed Growth During Structural UT RMSE Inspection Repair Limit Tube OD x Degradation"'
Thickness (Sleeve Wall) Interval <2 ggg,,y, w,g;3 ggg,,y, w,gg3 (gg,,y, w,gg3 (inch)
(%) (mils) (%) (mils) (%) (mils) (%) (mils) 11/16 x 0.040 r c,d3 e 1 3/4 x 0.042/0.043 3/4 x 0.048 7/8 x 0.050 L-.
._)
NOTES:
(1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(2) The inspection interval [
].
12.2 Repair Limit for Sleeve Pitting and Disbond 12.2.1 Sleeve OD Pitting The Electrosleeve" nickel material is subject to pitting degradation in improbable environments for an operating steam generator. The structural limit calculations defined a maximum allowed structural degradation [
b ,ca d,e. y
]. This calculation assumed [ 3of thedtube wall was removed due to any form of degradation and that[ fof'the sleeve wall was removed due to sleeve OD pitting.
l FRAMATOME TECHNOLOGIES, INC.
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FTl Ncn-Propri;ttry )
G The conservative upper limit of [ ] (je see Section 9.3.4) of the sleeve wall for general corrosion growth is used for a sleeve OD pitting degradation mechanism during a typicaI{ ]4 cycle. Actual growth will be considerably lower due to the quality and corrosion resistance of the sleeve material and the expected operating environment, which is less harsh than the environment used in the pitting corrosion tests.
The 95% LCL and the upper limit UT sizing RMSE (Table 11.10.2) for pit sizing associated with a nogmal beam examination are[.
). (fable 12.2.1 summarizes the repair limits for all sleeve nominal thicknesses based on the UT sizing RMSE.)
TABLE 12.2.1 REPAIR LIMITS FC R OD PITTING cC j
BASED ON UT SIZING Adowed Growth During l
Structural UT RMSE Inspection Repair Limit Tube OD x Degradation"' (Sleeve Wall) Intervale2 ggg,,y, w,ij)
Thickness (Sleeve Wall) (Sleeve Wall) j (inch) (%) (mils) (%) (mils) (%) (mils) (%) (mils) 11/16 x 0.040 (- e,d, e 1 3/4 x 0.042/0.043 3/4 x 0.048 7/8 x 0.050 L J NOTES:
(1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(2) The inspection interval [ }.
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1 FTl Non-Proprietary
,12.2.2 ~ Sleeve ID Pitting The electroforming process may produce an ID pit during Electrosfeeve" installation (Section 11.8.4). An ID pit is assumed to be[. NNkgh the sleeve thickness. The inspection requirements for a sleeve ID pit specify a high probability of detection for pit diameters greater than[- .
b,c, d, c C -
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12.2.3 Sleeve-to-Tube' Disbond Reference 13.4 specifies the installa ion NDE requirements for disbond. All .
- t disbond areas greater thane Jin any direction in Region B require an evaluation and concurrence from the plant owner for acceptability. Disbond areas greater than[ ]In any direction in Region B are unacceptable.
Table 12.5.2 lists the requirements for disbond.
'12.3 Repair Limit for Cracking Degradation Using Conventional UT Methods The results of the Electrosleeve" corrosion testing program and the use of nickel as a repair in Europe and Canada indicate the likelihood of a true crack-like flaw propagating into the sleeve material by corrosive attack is extremely low. However, plant safety requires validation of this low probability characteristic through in-service inspection.
E c
- 3. ,e.
6,c,C The assumed growth rate for postulated cracking degradation is[ ) per cycle until detected, which is the same as the s wth rates for other currently non-demonstrated 7 :(postulated) degradation modes. Ho, aver, crack growth may occur due to fatigue. A conservative upper limit for fatigue crsck growth, based on fracture mechanics
- analysis (Section 8.5), is( ['f the sleeve nominal thickness during an[ ]p l FRAMATOME TECHNOLOGIES, INC.
12-5
FTl Nsn-Prrprintiry '
le c inspection interval. The[ l
, ] howth rate is used for all sleeve nominal thickness values.
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t 54AMATOME TECHNOLOGIES, INC.
12-6
FTl Non-Proprietary TABLE 12.3.1 REPAIR LIMITS Cd j
Allowed Growth During Structural UT RMSE Inspection Repair Limit Tube OD x Degradation (Sleeve Wall) Interval (') (Sleeve Wall)
Thickness (Sleeve Wall) (Sleeve Wall)
(inch)
(%) (mils) (%) (mils) (%) (mils) (%) (mils) 11/16 x 0.040 F e,fE7 3/4 x 0.042/0.043 3/4 x 0.048 7/8 x 0.050 L j L40TES:
(1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(2) [
3.e,g (3) The inspection interval ( ]b,e .
TABLE 12.3.2 REPAIR LIMITS #> 0 I
Allowed Growth During Structural UT Error inspection Repair Limit Tube OD x Degradation 95% LCL Interval (Sleeve Wall)
Thickness (Sleeve Wall) (Sleeve Wall) (Sleeve Wall)
(inch)
(%) (mils) (%) (mils) (%) (mils) (%) (mils) 11/16 x 0.040 l' ejp 3/4 x 0.042/0.043 3/4 x 0.048 7/8 x 0.050 L J NOTES:
(1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(2) C 3.e,e j (3) The inspection interval [ ].(,'c.
FRAMATOME TECHNOLOGIES, INC.
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1 FTl Non-Proprintzry
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i 12.4 Repair Limit for Cracking Degradation Using Advanced UT Methods The advanced techniques presented in Section 11.11 provide a basis for re-evaluation of the NDE uncertainty values. These techniques are being developed to provide 4
better depth characterization of crack-like flaws. This sectiop describes how the{
2 ,]Iechniques will be used to improve (reduce) the UT NDE uncertainty.
c,e 12.4.1 Deterministic [ 3 Description c,e An evaluation of the[ ]versus the UT shearwave TOF method conventional flaw sizing techniques was performed using a small number of EDM notches. The results from both techniques were compared to actual notch depths. [
c,d,e J-C c,d, e.
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l FRAMATOME TECHNOLOGIES, INC.
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l FTl Non-Proprietary TABLE 12.4.1 l
REPAIR LIMITS b c,e l Allowed Growth During
! Structural UT Error Inspection Repair Limit Tube OD x Degradation Interval'*
l (Sleeve Wall) (Sleeve Wall) l Thickness ggi,,y, w,ii) (3g ,y, w,ii)
(inch)
(%) (mils) (%) (mils) (%) (mils) (%) (mils) 11/16 x 0.040 i' c,d,e1 3/4 x 0.042/0.043 3/4 x 0.048 7/8 x 0.050 L J NOTES:
(1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(2) C c 3 ,e 6, C (3) ' The inspection interval ( ].
C,6 12.4.2 Deterministic [ 3 Description Cta FTl evaluated the( ) technique as another method to obtain more accurate flaw measurements. [
j c,d, e J
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Preprittiry C
f>e The more conservative of the two analyses, , will be used to i establish crack depth. The effect of combining both techniques provides a
" defense in depth" approach ensuring that cracks are removed from service l before the structural limits are reached. [_
C J. ,e.
TABLE 12.4.2 REPAIR LIMITS b c, C, Allowed Growth During Structural UT Error inspection Repair Limit Tube OD x Degradation (Sleeve Wall) Interval'8' (Sleeve Wall)
Thickness (Sleeve Wall) (Sleeve Wall)
(inch) (%) (mils) (%) (mils) (%) (mils) (%) (mils) 11/16 x 0.040 F c,ggl 3/4 x 0.042/0.043 3/4 x 0.048 7/8 x 0.050 L _]
NOTES:
j (1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(2) [ c
),e b
(3) The inspection interval ( ]. , C.
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l FRAMATOME TECHNOLOGIES, INC.
12-10
FTl Non-Proprietary 12.5 Electrosfeeve" Plugging Limits C,6 The Electrosleeve" plugging limit is[ )through-wall of the sleeve nominal thickness.
The minimum repair limits for all sleeve nominal thickness values based on the UT uncertainty from the conventional crack sizing techniques are listed in Table 12.5.1.
bc TABLE 12.5.1 c
[ ], REPAIR LIMITS ( ),e, CONVENTIONAL MINIMUM REPAIR LIMIT REFERENCED TABLE SIZING ERROR (% THROUGH WALL SLEEVE)
CALCULATION RMSE F c,4g7 95% LCL L J c),e The minimum repair limit isl lthrough-wall of the sleeve nominal thickness.
E e,d,e- c,d e 3
3The[ ]through-wall Electrosleeve" plugging limit also applies to the tubes adjacent to the TSP vertical supports (Figure 8.2.1); however, the circumferential extent for any degradation is limited as discussed in Secticn 8.5.
c The[ 3 p,d,e.lugging limit includes margin for the errors associated with conventional sizing techniques. However, many of these sizing errors, especially undercalls, are minimized with( .
c e, d, e
)., d, CThus, the[ ] plugging limit provides adequate margin to all s
- limits imposed by RG 1.121.
C c, dj e FRAMATOME TECHNOLOGIES, INC.
12-11
i FTl Ncn-Pr:pristcry TABLE 12.5.2 ELECTROSLEEVE" PLUGGING LIMITS ELECTROSLEEVE" and TUBE REGION COMPONENT PLUGGING LIMIT (Based on UT Measurement)
A TUBE e Plant technical specification requirements SLEEVE"' e All indications are acceptable ianai B TUBE e Plant technical specification requirements SLEEVE"' e Indication [ 3
. Minimum bond [ 3 e,e e Disbond C e Thickness [
)c,e C TUBE e None SLEEVE"' Indication [.
3 c,d,e e Thickness [ ) 4c NOTES:
(1) b (2) 'C c,e 3-1 (3) [ c,e.
l l
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FRAMATOME TECHNOLOGIES, INC.
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L-_.-________________
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FTl Non-Proprietary I
l TABLE 12.5.3 C,C-REPAIR LIMIT BASED ON UT SIZ!NGb 3 11/16" OD X 0.040" TUBE b,C, C-Electrosleeve" Allowed Growth During Degradation Type Structural UT RMSE Inspection Repair Limit Degradation (Sleeve Wall) Interval'8' (Sleeve Wall)
(includes 100% (Sleeve Wall) (Sleeve Wall)
Through Wall (%) (mils) (%) (mils) (%) (mils) (%) (mils)
Degradation in Tube)
Uniform Thinning"' F c,$
OD Pitting -
Axial Crack s 3/4" Axial Crack > 3/4"i2 360' Circumferential Crack"'
3/4" OD X 0.042"/0.043" TUBE b, c, C.
b Electrosleeve" Allowed Growth During Degradation Type Structural UT RMSE inspection Repair Limit Degradation (Sleeve Wall) Interval'8' (Sleeve Wall)
(includes 100% (Sleeve Wall) (Sleeve Wall)
Through-Wall (%) (mils) (%) (mils) (%) (mils) (%) (mils)
Degradation in Tube)
Un! form Thinning"' T~ e,d,9
~
OD Pitting
~
'Axlal Crack s 3/4" Axial Crack > 3/4"i2:
360* Circumferential Crack"' L NOTES:
(1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
I2) ( c J ,6 b
(3) The inspection interval ( ). , C.
FRAMATOME TECHNOLOGIES, INC.
12-13
FTl Non-Prepristtry TABLE 12.5.3 (Cont'd)
REPAIR LIMIT BASED ON UT SIZING [ ]e,e 3/4" OD X 0.048" TUBE h,c,0.
Electrosleeve" Allowed Growth During Degradation Type Structural UT RMSE Inspection Repair Limit Degradation (Sleeve Wall) Interval (Sleeve Wall)
(includes 100% (Sleeve Wall) (Sleeve Wall)
Through-Wall (%) (mils) (%) (mils) (%) (mils) (%) (mils)
Degradation in Tube)
Uniform Thinning"' F c,d,e1 OD Pitting Axial Crack 5 3/4" Axial Crack > 3/4"<2:
360' Circumferential Crack"' b J 7/8" OD X 0.050" TUBE h, c,#
Electrosleeve" Allowed Growth During Degradation Type Structural UT RMSE Inspection Repair Limit Degradation (Sleeve Wall) Interval'8' (Sleeve Wall)
(Includes 100% (Sleeve Wall) (Sleeve Wall)
Through-Wall (%) (mils) (%) (mils) (%) (mils) (%) (mils)
Degradation in Tube)
Uniform Thinning"' I c,d[
OD Pitting Axial Crack s 3/4" Axial Crack > 3/4-i2>
360* Circumferential Crack"' k- d NOTES:
(1) Note that the circumferential extent for degradation at tubes adjacent to the TSP vertical supports (Figure 8.2.1) is limited as discussed in Section 8.5.
(2). ( 3c,e b
(3) The ins,eection interval ( }. , c.
FRAMATOME TECHNOLOGIES, INC.
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d FTl Non-Proprietary
13.0 REFERENCES
13.1 ASME Boiler and Pressure Vessel Code, Section 11,1989 Edition with 1989 Addenda.
13.2 ASME Boiler and Pressure Vessel Code, Section 111 and Section 111 Appendices,1989 Edition with No Addenda.
13.3 ASME Boiler and Pressure Vessel Code,Section V,1992 Edition with 1993 Addenda.
13.4 ASME Boiler and Pressure V-- of Code,Section XI,1989 Edition with 1989 Addenda and Code Case N-569, " Alternative Rules for Repair by Electrochemical Deposition of Class 1 and 2 Steam Generator Tubing,"Section XI, Division 1.
13.5 ASME Boiler and Pressure Vassel Code, Code Case N-47-33, " Class 1 Components in Elevated Temperature Service."
13.6 USNRC Draft Regulatory Guide 1.121, " Bases for Plugging Degraded PWR Steam Generator Tubes."
- 13.7 ASME Code Case N-504-1, " Alternative Rules for Repair of Class 1,2, and 3 Austenitic l Stainless Steel Piping."
l 13.8 F.P. Vacaro, et al, " Remedial Measures for Stress Corrosion Cracking of Alloy 600 j Steam Generator Tubing," presented at Traverse City Third International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, l l
September 1987.
13.9 J.E. Gutzwiller, S.W. Glass, "New Options for improved Steam Generator U-Bend Integrity," presented at the SMIRT 9, post-conference seminar on Assuring Structural Integrity of Steel Reactor Pressure Boundary Components, Davos, Switzerland, August 1987.
13.10 EPRI Utility Experience Report, Electronucleaire Utility, Plants: Tihanga 1, 2, 3, and Doel 1, 2, 3, 4, June 1987.
13.11 EPRI Steam Generator Tube Sleeving: Design, Specification and Procurement Checklist, Research Project S408-5, Topical Report December 1989.
1 FRAMATOME TECHNOLOGIES, INC.
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FTl Ncn-Prcpriittry J
13.12 EPRI TR-103824, Project 2859, Steam Generator Reference Book, Revision 1, December ;
1994.
i 13.13 ASTM E 8 93, " Standard Test Methods for Tension Testing of Metallic Materials."
l
- 13.14 ASTM E 21-92, " Standard Test Methods for Elevated Temperature Tension Testing of Metallic Materials."
13.15 ASTM E 111-82, " Standard Test Method for Young's Modulus, Tangent Modulus, and Chord Modulus."
13.16 ASTM E 606-92,'" Standard Practice for Strain-Controlled Fatigue Testing."
13.17 ASTM E 466-82, " Standard Practice for Conducting Constant Amplitude Axial Fatigue .
Tests of Metallic Materials."
l 13.18 ASTM E 467-90, " Standard Practice for Verification of Constant Amplitude Dynande ;
l Loads on Displacements in an ' Axial Load Fatigue Testing System." .
4 13.19 ASTM E 468-90, " Standard Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic Materials." ,
l~
13.20 ASTM E 290-92, " Standard Test Method for Semi-Guided Bend Test for Ductility of i Metallic Materials."
(
13.21 ASTM B 489-85, " Standard Practice for Bend Test for Ductility of Electrodeposited and ,
Autocatalytically Deposited Metal Coatings on Metals." ,
13.22 ASTM E 139-83, " Standard Practice for Conducting Creep, Creep Rupture, and Stress-Rupture Tests of Metallic Materials."
13.23 ASTM E 92 82, " Standard Test Method for Vickers Hardness of Metallic Materials."
l 13.24 ASTM G 28-85, " Standard Test Methods of Detecting Susceptibility to Intergranular
- Corrosion in Wrought, Nickel-Rich, Chromium-Bearing Alloys."
l l FRAMATOME TECHNOLOGIES, INC. ,.
13-2
FTl Non-Proprietary 13.25 ASTM G 35-88, " Standard Practice for Determining the Susceptibility of Stainless Steels and Related Nickel-Chromium-Iron Alloys to Stress-Corrosion Cracking in Polythionic Acids."
l 13.26 ASTM G 36-87, " Standard Practice for Evaluating Stress Corrosion Cracking Resistance l of Metals and Alloye L a Boiling Magnesium Chloride Solution." l 13.27 ASTM G 44-88, " Standard Practice for Evaluating Stress Corrosion Cracking Resistance ,
of Metals and Alloys by Alcernate immersion in 3.5% Sodium Chloride Solution."
l 13.28 ASTM G 48-93, " Standard Test Methods for Pitting and Crevice Corrosion Resistance of j Stainless Steels and Related Alloys by Use of Ferric Chloride Solution."
13.29 ASME TJ290.A716,1976, " Criteria for Design of Elevated Temperature Class 1 Components in Section Ill, Division 1, of the ASME Boiler and Pressure Vessel Code."
13.30 L.N. Bystrov and A.B. Tsepelev, " Thermal Activation Analysis of Nickel Creep in the Temperature Range 200-500*C," Izvestiya Akademii Nauk SSSR, Metally, Allerton Press, Inc, No. 4, pp.171-178,1984.
13.31 Paul Shaninian and M.R. Achter, " Temperature and Stress Dependence of the Atmosphere Effect on Nickel-Chromium Alloy," pp. 244-250, Transacticns of AmerictA Society of Metals, Vol Li,1959. Ray T. Bayless, Editor, American Society of Metals, Cleveland, Ohio.
13.32 ANSYS Finite Element Code, Version 5.2. !
13.33 Tibor Turi and Uwe Erb, " Thermal Expansion and Heat Capacity of Porosity-Free Nanocrystalline Materials," Material Science & Engineering, Volume A204, p. 34,1995. I l
13.34 DELETED 13.35 F.C. Monkman and N.J. Grant, "An Empirical Relationship Between Rupture Life and ;
- Minimum Creep Rate in Creep-Rupture Tests," Proc. ASTM. Volume 56, pp. 593-605, l
1956.
13.36 H.R. Voohees, " Assessment and Use of Creep-Rupture Properties," Metals Handbook -
Ninth Edition. Volume 8, Mechanical Testing, American Society for Metals,1985.
FRAMATOME TECHNOLOGIES, INC.
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1
FTl N:n-Prrpriittry 13.37 D.B. Darling and J.A. Richards, Ill, " Nickel Plating of Pressurizer Heater Nozzles to Prevent PWSCC," Nuclear Plant Journal. November-December 1994.
13.38 R.K. Penny and D.L. Marriott, Desion for Creeo 2nd Edition. Chapman & Hall,1995.
13.39 B. Michaut, F. Steltzlen, B. Sala, Ch. Laire, J. Stubbe, " Nickel Electroplating as a Remedy to Steam Generator Tubing PWSCC," Sixth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, The !
Minerals, Metals, & Materials Society,1993.
13.40 U. Erb, " Corrosion Behaviour of Nanocrystalline Materials - A Literature Review," 1906, Department of Materials & Metallurgical Engineering, Queens University, Kingston, Ontario, Canada.
13.41 PWR Secondary Water Chemistry Guideline - Revision 3, EPRI TR-102134 Revision 3,
' May 1993.
13.42 MULTEO: Equilibrium of an Electrolytic Solution with Vapor-Liquid Partitioning and Precipitation, EPRI NP-5561-CCML, July 1992.
13.43 E. Pierson, J. Stubbe, " SCC Testing of Steam Generator Tubes Repaired by Welding Sleeves," Sixth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, The Minerals, Metals & Materials Society, 1993.
13.44 M.H. Kaye, W.T. Thompson, " Nickel-Phosphorus Redox Potential-pH Diagrams," Centre for Computational Thermochemistry, Kingston, ON, Canada,1996.
13.45 Z. Yang, T.H. Yip, R. Zhang and D.D. Perovic, "Effect of Grain Size on the Initiation and Growth of Fatigue Cracks in Nickel and Nickel-based Alloys."
13.46 Ning Wang, Zhirui Wang, K.T. Audt and U. Erb, Aust, Acta Metall, "Effect of Grain Size on Mechanical Properties of Nanocrystalline Materials," Vol. 43, No. 2,1995.
13.47 G. Palumbo, F. Gonzalez, V. Krstic and U. Erb, Scripta Metall, " Geometric Considerations for the Creep Failure of Nanostructured Materials." !
13.48 V. Sugimura, P.G. Lim, C.F. Shih and S. Suresh, Acta Metallurgica,1995.
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Proprietary 13.49 DELETED 13.50 P. Marcus and O. Oda, " Influence du phosphore sur la dissolution et la passivation du nickel en milieu acide," Mem. Sci. Rev. Metall. 715,(1979).
4 13.51 F. Gonzalez and P. Spekkens, " Localized concentration processes and corrosion in nuclear steam generators," 9th International Congress on Metallic Corrosion v.3, p. 235 (1984),
13.52 F. Gonzalez and P. Spekkens. " Corrosion of Alloy 600 under Steam Generator Sludge Piles," 4th Symp. on Environ. Degr. of Mater. in Nucl. Power Systems Water Reactors, Jekyll Island 1989.
13.53 F. Gonzalez and P. King, " Corrosion Performance of Alloy 800 Tubing under CANDU Steam Generator Conditions," International Symposium Contribution of Materials Investigation to the Resolution of Problems Encountered in PWR Plants, Fontevraud, France, Sept 10-14,1990.
13.54 F. Gonzalez and P. Spekkens, " Concentration processes under tubesheet sludge pile in nuclear steam generators," Proceedings of the Water Chemistry and Materials Performance Conference, Oct 21,1986 Toronto, Canada, also published in Nuclear Journal of Canada 1, 129-140 (1987).
13.55 J.B. Lumsden, S.L. Jeanjaquet, A. McIlree, " Insights on Local Chemistry from
. Examination of Tubes," Imp. The Unstanding and Control of Corrosion on the Secondary Side of SG, October 9-13,1995, Airlie, VA.
13.56 F. Larue, A. Gelpi, B. Michaut, " Nickel Plating S.G. Tubing Repair," Proceedings of the 1991 JAIF International Conference on Water Chemistry in Nuclear Power Plants, Japan Atomic Industrial Forum, Inc., April 1991, pp.163-167.
13.57 M.G. Fontana, " Corrosion Engineering," McGraw Hill, Third Edition,1986, pp.134135.
13.58 G.F. Nejedlik and E.G. Vargo, " Material Resistance to Mercury Corrosion,"
Electrochemical Technology, 3:250(1965).
13.59 ASTM G 38 73 " Standard Practice for Making and Using C-Ring Stress Corrosion Test Specimens."
FRAMATOME TECHNOLOGIES, INC.
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FTl N:n-Pr:pri;ttry 13.60 E.O. Hall,"The Deformation and Aging of Mild Steel: lli Discussion of Results," Proc. Phys.
Soc. London B64, pp. 747-753, (1951).
13.61 N.J. Petch,"The Cleavage Strength of Polycrystals," Journal of the fron ano Steel Institute, 174, pp. 25-28, (1953).
13.62 D. Osmola, P. Nolan, U. Erb, G. Palumbo, and K.T. Aust, " Microstructural Evolution at Large Driving Forces during Grain Growth of Ultrafine-Grained Ni-1.2wt%P," Phys. Stat.
Sol. (a) 131, pp. 569-574, (1992).
13.63 K. Boylan, D. Ostrander, U. Erb, G. Palumbo, and K.T. Aust,"An in-Situ Tem Study of the Thermal Stability of Nanocrystalline Ni-P," Scripta Metallurgica, et Materialia, Vol. 25, pp.
2711-2716,(1991).
13.64 I". Kissinger, " Reaction Kinetics in Differential Thermal Analysis," Analytical Chemistry, Vol. 29, pp.1702-1706, (1957).
13.65 S.C. Mehta, D.A. Smith, and U. Erb, " Study of grain growth in electrodeposited nanocrystalline nickel-1.2wt% phosphorus alloy," Materials Science and Engineering, A204, pp. 227-232, (1995).
13.66 M. Ratzker, D.S. Lashmore, and K.W. Pratt, " Electrodeposition and Corrosion Performance of Nickel-Phosphorus Amorphous Alloys," Plating and Surface Finishing, September 1986 pp.74-82.
13.67 G.W. Dini," Electrodeposition, The Materials Science of Coatings and Substrates," Noyes Publications, Park Ridge New Jersey,1993.
13.63 R.F. Keating, P. Hernalsteen, and J.A. Begley, "EPRI Guidelines for Laboratory Measurements of the Burst Strength of Degraded Steam Generator Tubing."
13.69 Ch. Claire, E. Pierson, G. Strubbe "Begium Experience on Repair of Steam Generator Tubes," EUROCORR '96, Nice, September 23,1996.
13.70 C.F. Andreone, S. Yokell, Tubular Heat Exchanger Inspection, Maintenance and Repair, McGraw Hill,1998, p. 311.
13.71 NUREG/CR-6227, PNNL-9433 " Performance Demonstration Tests for Eddy Current inspection of Steam Generator Tubing," Pacific Northwest Laboratory, May 1996.
FRAMATOME TECHNOLOGIES, INC.
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- . . . _. .. . . . . - . _ = . .-. . -_. . _ . . - . . - . .
FTl Non-Proprietary 13.72 F.Krautkramer and H. Krautkramer, Ultrasonic Testing of Materials,4th Edition, Springer-Verlag,1990.
I 13.73 Draft EPRI Report TR-105505, " Burst Pressure Correlation for Steam Generator Tubes with Through-Wall Axial Cracks," February 1995.
l 13.74 C.S. Smith," Grains, Phases, and Interfaces: An Interpretation of Microstructure," p. 47, Trans. AIME, 175.15(1948).
13.75 USNRC Draft Regulatory Guide DG-1074, " Steam Generator Tube Integrity." i l
l I
l l
I l
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9 APPENDIX A PWR DESIGN INFORMATION m
his . . i i. i i i
. i
FTl N:n-Pr:prittrry TABLE A.1 W-D DESIGN INFORMATION b,c,e r 7 i
L- J FRAMATOME TECHNOLOGIES, INC.
FTl Non-Proprietary TABLE A.1 (Cont'd)
W-D DESIGN INFORMATION N)C E 1
1' l
m I
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FTl N:n-Pr:priettry TABLE A.1 (Cont'd)
W-D DESIGN INFORMATION b, C,C.
.b ]
L _]
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A-4
FTl Non Proprietary TABLE A.1 (Cont'd)
W D DESIGN INFORMATION
~
b, C; 6.
l D g j -
FRAMATOME TECHNOLOGIES, INC.
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1 FTl N:n-Pr:prittary TABLE A.2 W-E DESIGN INFORMATION b> Cp C.
l I
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L g FRAMATOME TECHNOLOGIES, INC.
A3
-~ . ~ ~ - - - . . . . . . ~ . - . . . . . . . _ . . ~ . . . . - - . _ . _ . - -
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jFTl Non-Proprietary TABLE A.2 (Cont'd)
W-E DESIGN INFORMATION lo, C,e-f- 7 9
d 1
L. J FRAMATOME TECHNOLOGIES, INC.
A7
FTl Non-Proprietary TABLE A.2 (Cont'd)
W-E DESIGN INFORMATION b, C, 6 FRAMATOME TECHNOLOGIES, INC.
A-8
FTl Non-Proprietary TABLE A.2 (Cont'd)
W-E DESIGN INFORMATION
. b, C,c,
] ,
FRAMATOME TECHNOLOGIES, INC.
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I FTl Ncn-Preprl:ttry TABLE A.3 CE SYS 80 DESIGN INFORMATION g
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- FRAMATOME TECHNOLOGIES, INC.
A-10
FTl Non-Proprietary TABLE A.3 (Cont'd)
CE SYS 80 DESIGN INFORMATION
_ b,C, e L J FRAMATOME TECHNOLOGIES, INC.
A-11
FTl Non Proprietary TABLE A.3 (Cont'd)
CE SYS 80 DESIGN INFORMATION
- ]
L J l FRAMATOME TECHNOLOGIES, INC.
A 12
FTl Non-Proprietary TABLE A.4 M/ESTINGHOUSE 7/8" TUBING S/G DES!GN INFORMATION 6, c, e L _J i
FRAMATOME TECHNOLOGIES, INC.
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FTl Non-Propristery TABLE A.4 (Cont'd)
WESTINGHOUSE 7/8" TUBING SIG DESIGN INFORMATION b, c,e
_j L l FRAMATOME TECHNOLOGIES, INC.
A-14
FTl Non-Proprietary TABLE A.4 (Cont'd)
WESTINGHOUSE 7/8" TUBING S/G DESIGN INFORMATION
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A 15
FTl Nrn-Pr:prist:ry TABLE A.4 (Cont'd)
WESTINGHOUSE 7/8" TUBING S/G DESIGN INFORMATION .
O, C; 6.
I i
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I L ._J i FRAMATOME TECHNOLOGIES, INC.
A-16
. . . .-. ._ =. . - . . . . . . - -- .- .. . - .. -.-. -
FTl Non-Proprietary TABLE A.4 (Cont'd)
WESTINGHOUSE 7/8" S/G TUBING DESIGN INFORMATION b,C,e.
r 1 1
1 L. J FRAMATOME TECHNOLOGIES, INC.
A-17
FTl N:n-Prtpriitzry TABLE A.5 COMBUSTION ENGINEERING 3/4" x 0.048" TUBING S/G DESIGN INFORMATION b>CA
[ l L J i
FRAMATOME TECHNOLOGIES, INC.
A 18
l FTl N:n-Propri:ttry TABLE A,5 (Cont'd)
SOMBUSTION ENGINEERING 3/4" x 0.048" TUBING S/G DESIGN INFORMATION
~ b,co e l
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A 19 o
FTl N:n-Preprl2ttry TABLE A.5 (Cont'd)
SOMBUSTION ENGINEERING 3/4" x 0.048" TUBING S/G DESIGN INFORMATION b (30 i
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. FRAMATOME TECHNOLOGIES, INC. I A-20
l FTl Non-Proprietary TABLE A.5 (Cont'd)
COMBUSTION ENGINEERING 3/4" x 0.048" TUBING S/G DESIGN INFORMATION I:),Cj 6.
l l
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l l A-21
FTl N:n-Pr:priitary TABLE A 5 (Cont'd)
COMBUSTION ENGINEERING 3/4" x 0.048" TUBING S/G DESIGN INFORMATION l],C A.
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TABLE A 5 (Cont'd) J COMBUSTION ENGINEERING 3/4" x 0.048" TUBING S/G DESIGN INFORMATION i
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TABLE A.5 (Cont'd)
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A-24
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FTl Non-Proprietary TABLE A.6 W-F DESIGN INFORMATION
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FTl Non-Prcpriltary TABLE A.6 (Cont'd)
W-F DESIGN INFORMATION I b, c, e. 1 1
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l FTl Non-Proprietary TABLE A.6 (Cont'd)
W-F DESIGN INFORMATION i f
bA] I I
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- A 27 ,
FTl Non-Prepri;ttry TABLE A.6 (Cont'd)
W-F DESIGN INFORMATION JC,2, l
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