ML040500598

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SCE Responses to NRC RAI Regarding Relaxation Requests 1 and 2 for Reactor Pressure Vessel Head Penetration Inspection Requirements in NRC Order EA-03-009. Attachment 3, WCAP 15819-NP, Rev 1 Through Figure 5-10
ML040500598
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 02/09/2004
From:
Southern California Edison Co
To:
Office of Nuclear Reactor Regulation
References
EA-03-009, WCAP 15819-NP Rev 1
Download: ML040500598 (47)
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Attachment 3 SCE Responses to NRC Request for Additional Information Summary Information Regarding Relaxation Requests 1 and 2 WCAP 15819-NP, Revision 1: "Structural Integrity Evaluation of Reactor Vessel Upper Head Penetrations to Support Continued Operation: San Onofre Units 2 and 3" Non-Proprietary version

Westinghouse Non-Proprietary Class 3 WCAP-15819-NP January 2004 Revision 1 (Revision 0 was never published)

Structural Integrity Evaluation of Reactor Vessel Upper Head Penetrations to Support Continued Operation:

San Onofre Units 2 and 3 Westinghouse

WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-15819-NP Revision 1 Structural Integrity Evaluation of Reactor Vessel Upper Head Penetrations to Support Continued Operation: San Onofre Units 2 and 3 S. Jirawongkraisorn January 2004 Verifier:

.Alvare2 Piping Analysis & Fracture Mechanics Approved:

PpnAaly F M

  • ~~~Piping Analysis & Fracture Mechanics Westinghouse Electric Company LLC P.O. Box 355 Pittsburgh, PA 15230-0355 3 2004 Westinghouse Electric Company LLC All Rights Reserved

iii TABLE OF CONTENTS LIST OFTABLES . v....

LIST OF FIGURES ............ vi I INTRODUCTION .. 1-1 1.1 RECORD OF REVISIONS .1-2 2 HISTORY OF CRACKING IN HEAD PENETRATIONS .2-1 3 OVERALLTECHNICALAPPROACH .3-1 3.1 PENETRATION STRESS ANALYSIS .3-1 3.2 FLAW TOLERANCE APPROACH .3-1 4 MATERIAL PROPERTIES, FABRICATION HISTORY AND CRACK GROWTH PREDICTION .4-1 4.1 MATERIALS AND FABRICATION .4-1 4.2 CRACK GROWTH PREDICTION .4-1 5 STRESS ANALYSIS .. 5-1 5.1 OBJECTIVES OF THE ANALYSIS .5-1 5.2 MODEL. 5-1 5.3 STRESS ANALYSIS RESULTS - OUTERMOST CEDM PENETRATION (49.7°)5-1 5.4 STRESS ANALYSIS RESULTS - INTERMEDIATE CEDM AND ICI PENETRATIONS .5-2 5.5 STRESS ANALYSIS RESULTS - CENTER CEDM PENETRATION .5-2 5.6 STRESS ANALYSIS RESULTS - HEAD VENT .5-2 6 FLAW TOLERANCE CHARTS .6-1

6.1 INTRODUCTION

.6-1 6.2 OVERALL APPROACH .6-1 6.3 AXIAL FLAW PROPAGATION .6-3 6.4 CIRCUMFERENTIAL FLAW PROPAGATION. 64 6.5 FLAW ACCEPTANCE CRITERIA .6-6 January 2004 Revision I

iv 7

SUMMARY

AND EXAMPLE PROBLEMS ............. .. ................. 7-1 7.1 SAFETYASSESSMENT ................................ 7-1 7.2 EXAMPLE PROBLEMS ................................ 7-2 8 REFERENCES ................................ 8-1 APPENDIX A CEDM HOOP STRESS Vs DISTANCE FROM BOTTOM OF WELD PLOTS . A-APPENDIX B COMPARISON OF THE HOOP STRESS DISTRIBUTION BELOW THE WELD BETWEEN THE AS-BUILT AND AS-DESIGNED J-WELD GEOMETRY [161 . B-I APPENDIX C THROUGH-WALL FLAW GROWTH BELOW THE WELD CHARTS (LIMITING CASE) . C-1 January 2004 Revision I

v LIST OF TABLES Table 1-1 San Onofre Units 2 & 3 Head Penetration Nozzles with the Intersection Angles Identified [11] ................................................. 1-3 Table 4-1 San Onofre Units 2 & 3 RIV Head Adapter Material Information [11] .............................. 4-7 Table 6-1 Summary of R.V. Head Penetration Flaw Acceptance Criteria ........................................... 6-8 Table 6-2 San Onofre Units 2 & 3 Penetration Geometries ....................... .......................... 6-8 Table 7-1 Example Problem Inputs: Initial Flaw Sizes and Locations ............................................... 7-5 January 2004 Revision I

vi LIST OF FIGURES Figure 1-1 Reactor Vessel Control Element Drive Mechanism (CEDM) Penetration ............ .............. 1-4 Figure 1-2 Location of Head Penetrations for San Onofre Units 2 & 3 [ 11 ......................................... 1-5 Figure 2-1 EDF Plant R/V Closure Head CRDM Penetrations - Penetrations with Cracking ............. 2-4 Figure 2-2 Inspection Results for U.S. CRDM/CEDM Penetration Nozzle (Spring 2003) .................. 2-5 Figure 3-1 Schematic of a Head Penetration Flaw Growth Chart for Part-Through Flaws .................. 3-3 Figure 4-1 Yield Strength of the Various Heats of Alloy 600 Used in Fabricating the San Onofre Units 2 & 3 and French Head Penetrations ........................ ........................................ 4-8 Figure 4-2 Carbon Content of the Various Heats of Alloy 600 Used in Fabricating the San Onofre Units 2 & 3 and French Head Penetration ............................................. ................... 4-9 Figure 4-3 Screened Laboratory Data for Alloy 600 with the MRP Recommended Curve (Note that the Modified Scott Model is also Shown) ................................................................ 4-10 Figure 4-4 Model for PWSCC Growth Rates in Alloy 600 in Primary Water Environments (325CC),

With Supporting Data from Standard Steel, Huntington, and Sandvik Materials ............. 4-11 Figure 4-5 Summary of Temperature Effects on PWSCC Growth Rates for Alloy 600 in Primary Water...................................................................................................................... 4-12 Figure 5-1 Finite Element Model of CEDM Penetration ................................................................ 5-3 Figure 5-2 Finite Element Model of ICI Penetration ....................................... ......................... 54 Figure 5-3 Vent Pipe Finite Element Model ................................................................ 5-5 Figure 5-4 Stress Distribution at Steady State Conditions: Outermost CEDM Penetration Nozzle (49.7 Degrees) (Hoop Stress is the Top Figure, Axial Stress is the Bottom Figure) ..................... 5-6 Figure 5-5 Stress Distribution at Steady State Conditions for the 29.1 Degrees CEDM Penetration (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure) ................ .................... 5-7 Figure 5-6 Stress Distribution at Steady State Conditions for the 7.8 Degrees CEDM Penetration (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure) . 5-8 Figure 5-7 Stress Distribution at Steady State Conditions for the Center CEDM Penetration (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure) . 5-9 Figure 5-8 Stress Distribution at Steady State Conditions for the ICI Penetration Nozzle (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure) . 5-10 Figure 5-9 Stress Contours in the Head Vent Nozzle as a Result of Residual Stresses and Operating Pressure (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure) . 5-11 Figure 5-10 Axial Stress Distribution at Steady State Conditions for the Outermost CEDM Penetration (49.7 Degrees), Along a Plane Oriented Parallel to, and Just Above, the Attachment Weld . 5-12 Figure 6-1 Stress Intensity Factor for a Through-Wall Circumferential Flaw in a Head Penetration .. 6-9 January 2004 Revision I

vii Figure 6-2 Inside, Axial Surface Flaws, .5" Below the Attachment Weld, Nozzle Uphill Side - Crack Growth Predictions for San Onofre Units 2 & 3.............................................................. 6-10 Figure 6-3 Inside, Axial Surface Flaws, .5" Below the Attachment Weld, Nozzle Downhill Side -

Crack Growth Predictions for San Onofre Units 2 & 3 ..................................................... 6-11 Figure 6-4 Inside, Axial Surface Flaws, At the Attachment Weld, Nozzle Uphill Side - Crack Growth Predictions for San Onofre Units 2 & 3.............................................................. 6-12 Figure 6-5 Inside, Axial Surface Flaws, At the Attachment Weld, Nozzle Downhill Side - Crack Growth Predictions for San Onofre Units 2 & 3.............................................................. 6-13 Figure 6-6 Inside, Axial Surface Flaws, .5" Above the Attachment Weld, Nozzle Uphill Side - Crack Growth Predictions for San Onofre Units 2 & 3.............................................................. 6-14 Figure 6-7 Inside, Axial Surface Flaws, .5" Above the Attachment Weld, Nozzle Downhill Side -

Crack Growth Predictions for San Onofre Units 2 & 3 ..................................................... 6-15 Figure 6-8 Inside, Axial Surface Flaws, At the Attachment Weld, Head Vent- Crack Growth Predictions for San Onofre Units 2 & 3.............................................................. 6-16 Figure 6-9 Outside, Axial Surface Flaws, Below the Attachment Weld, Nozzle Uphill Side - Crack Growth Predictions for San Onofre Units 2 & 3.............................................................. 6-17 Figure 6-10 Outside, Axial Surface Flaws, Below the Attachment Weld, Nozzle Downhill Side - Crack Growth Predictions for San Onofre Units 2 & 3.............................................................. 6-18 Figure 6-11 Outside, Circumferential Surface Flaws, Along the Top of the Attachment Weld - Crack Growth Predictions for San Onofre Units 2 & 3 (MRP Factor of 2.0 Included) ............... 6-19 Figure 6-12 Through-Wall Axial Flaws Located in the Center CEDM (0.0 Degrees) Penetration - Crack Growth Predictions for San Onofre Units 2 & 3................................................................ 6-20 Figure 6-13 Through-Wall Axial Flaws Located in the 7.8 Degrees CEDM Row of Penetrations, Downhill Side - Crack Growth Predictions for San Onofre Units 2 & 3 .......................... 6-21 Figure 6-14 Through-Wall Axial Flaws Located in the 29.1 Degrees (CEDM) Row of Penetrations, Downhill Side - Crack Growth Predictions for San Onofre Units 2 & 3 .......................... 6-22 Figure 6-15 Through-Wall Axial Flaws Located in the 49.7 Degrees (CEDM) Row of Penetrations, Downhill Side - Crack Growth Predictions for San Onofre Units 2 & 3 .......................... 6-23 Figure 6-16 Through-Wall Axial Flaws Located in the 55.3 Degrees (ICI) Row of Penetrations, Downhill Side - Crack Growth Predictions for San Onofre Units 2 & 3 .......................... 6-24 Figure 6-17 Through-Wall Axial Flaws Located in the 55.3 Degrees (ICI) Row of Penetrations, Uphill Side - Crack Growth Predictions for San Onofre Units 2 & 3........................................... 6-25 Figure 6-18 Through-Wall Circumferential Flaws Near the Top of the Attachment Weld for CEDM and ICI Nozzles - Crack Growth Predictions for San Onofre Units 2 & 3 (MRP Factor of 2.0 Included) ........................................................................ 6-26 Figure 6-19 Section XI Flaw Proximity Rules for Surface Flaws (Figure IA-3400-1) ..................... 6-28 Figure 6-20 Definition of "Circumferential" ........................................................................ 6-29 January 2004 Revision 1

viii Figure 6-21 Schematic of Head Penetration Geometry ........................................ 6-30 Figure 7-1 Example Problem I .7-6 Figure 7-2 Example Problem 2 .7-7 Figure 7-3 Example Problem 3 .7-8 Figure 7-4a Example Problem 4 (See also Figure 7-4b) .7-9 Figure 7-4b Example Problem 4 (See also Figure 7-4a) . 7-10 Figure 7-5 Example Problem 5 .7-11 Figure A- I Hoop Stress Distribution Below the Weld Downhill and Uphill Side (° CEDM Penetration Nozzle).................................................................................................................................. A-2 Figure A-2 Hoop Stress Distribution Below the Weld Downhill Side (7.80 CEDM Penetration Nozzle).................................................................................................................................. A-3 Figure A-3 Hoop Stress Distribution Below the Weld Uphill Side (7.80 CEDM Penetration Nozzle).................................................................................................................................. A-4 Figure A-4 Hoop Stress Distribution Below the Weld Downhill Side (29.1 0 CEDM Penetration Nozzle).................................................................................................................................. A-5 Figure A-5 Hoop Stress Distribution Below the Weld Uphill Side (29.10 CEDM Penetration Nozzle).................................................................................................................................. A-6 Figure A-6 Hoop Stress Distribution Below the Weld Downhill Side (49.7° CEDM Penetration Nozzle).................................................................................................................................. A-7 Figure A-7 Hoop Stress Distribution Below the 'eld Uphill Side (49.7° CEDM Penetration Nozzle).................................................................................................................................. A-8 Figure A-8 Hoop Stress Distribution Below the Weld Downhill Side (55.3° ICI Penetration Nozzle) A-9 Figure A-9 Hoop Stress Distribution Below the Weld Uphill Side (55.3° ICI Penetration Nozzle).. A-10 Figure B-l Nozzle ID and OD Hoop Stress (° CEDM Nozzle Downhill and Uphill Case).B-2 Figure B-2 Nozzle ID and OD Hoop Stress (7.8 CEDM Nozzle Downhill Case) .B-3 Figure B-3 Nozzle ID and OD Hoop Stress (7.8 CEDM Nozzle Uphill Case) .B-4 Figure B-4 Nozzle ID and OD Hoop Stress (29.1 0 CEDNI Nozzle Downhill Case) . B-5 Figure B-5 Nozzle ID and OD Hoop Stress (29.1 CEDMI Nozzle Uphill Case) . B-6 Figure B-6 Nozzle ID and OD Hoop Stress (49.7°CEDMI Nozzle Downhill Case) .B-7 Figure B-7 Nozzle ID and OD Hoop Stress (49.7' CEDMI Nozzle Uphill Case) .B-8 Figure B-8 Nozzle ID and OD Hoop Stress (55.30 ICI Nozzle Downhill Case) .B-9 Figure B-9 Nozzle ID and OD Hoop Stress (55.3°ICI Nozzle Uphill Case) .B-10 Figure C-I Through-Wall Axial Flaws Located in the Center CEDM (0.0 Degrees) Penetration . C-2 January 2004 Revision I

ix Figure C-2 Through-Wall Axial Flaws Located in the 7.8 Degrees Row of CEDM Penetrations Downhill Side ............................................................... C-3 Figure C-3 Through-Wall Axial Flaws Located in the 29.1 Degrees Row of CEDM Penetrations Downhill Side ............................................................... C-4 Figure C-4 Through-Wall Axial Flaws Located in the 49.7 Degrees Row of CEDM Penetrations Downhill Side ............................................................... C-5 Figure C-5 Through-Wall Axial Flaws Located in the 55.3 Degrees Row of ICI Penetrations Downhill Side ................................................................ C-6 Figure C-6 Through-Wall Axial Flaws Located in the 55.3 Degrees Row of ICI Penetrations Uphill Side ................................................................ C-7 January 2004 Revision I

1-1 INTRODUCTION In September of 1991, a leak was discovered in the Reactor Vessel Control Rod Drive Mechanism (CRDM) head penetration region of an operating plant. This has led to the question of whether such a leak could occur at the San Onofre Units 2 & 3 Control Element Drive Mechanism (CEDM), In-Core Instrumentation (ICI) or head vent nozzle penetrations. Note that the designation CRDM (Westinghouse and French designs) and CEDM (Combustion Engineering Design) are synonymous. The geometry of interest is shown in Figure 1-1. Throughout this report, the penetration rows have been identified by their angle of intersection with the head. The locations of the head penetrations for San Onofre Units 2 & 3 are shown in Figure 1-2 [11] and the angles for each penetration are identified in Table 1-1 [11].

The CEDM leak resulted from cracking in Alloy 600 base metal, which occurred in the outermost penetrations of a number of operating plants as discussed in Section 2. This outermost CEDM location, as well as a number of intermediate CEDM locations, the ICI nozzles, and the head vent were chosen for fracture mechanics analyses to support continued safe operation of San Onofre Units 2 & 3 if such cracking were to be found. The dimensions of all the CEDM penetrations are identical, with a 4.05 inch Outside Diameter (OD) and a wall thickness of 0.661 inches [11]. The ICI penetrations have an OD of 5.563 inches and wall thickness of 0.469 inch; however, they all have a counterbore of 0.407 inch which extend to more than 12 inches from the bottom of the tube [11]. For this reason, the counterbore thickness shall be used when evaluating all ICI nozzle flaws. For the head vent, the OD is 1.05 inches and the wall thickness is 0.154 inches. All of these dimensions are summarized in Table 6-2.

The basis of the analysis was a detailed three-dimensional elastic-plastic finite element stress analysis of several penetration locations, as described in detail in Section 5 and a fracture analysis as described in Section 6. The fracture analysis was carried out using crack growth rates recommended by the EPRI Materials Reliability Program (MRP). These rates are consistent with service experience. The results are presented in the form of flaw tolerance charts for both surface and through wall flaws. If indications are found, the charts will determine the allowable service life of safe operation. The service life calculated in the flaw tolerance charts are all in Effective Full Power Years (EFPY).

Note that there are several locations in this report where proprietary information has been bracketed and deleted. For each of the bracketed locations, reasons for proprietary classifications are given using a standardized system. The proprietary brackets are labeled with three different letters to provide this information. The explanation for each letter is given below:

a. The information reveals the distinguishing aspects of a process or component, structure, tool, method, etc., and the prevention of its use by Westinghouse's competitors, without license from Westinghouse, gives Westinghouse a competitive economic advantage.
c. The information, if used by a competitor, would reduce the competitor's expenditure of resources or improve the competitor's advantage in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product.

Introduction January 2004 Revision I

1-2

e. The information reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse.

This report has been revised to reflect the latest technical information available. The reasons for this revision and the improvements made are summarized in the following table.

1.1 RECORD OF REVISIONS Record of Revisions Revision Date Description 0 May Original Issue 2002 January This revision was prepared to include the latest technology on dealing with the 2004 cracking issue in the RPV head penetration nozzles. Some major changes made are as follows:

1) New flaw tolerance charts were generated based on the PWSCC crack growth data per NIRP-55 revision I [4HI.
2) Hoop stress distribution below the weld plots (Appendix A), comparison between hoop stress distribution below the weld with as-built and as-design weld sizes (Appendix B), and through-wall crack growth below the weld charts supporting inspection coverage (Appendix C) are included in this report.

Introduction January 2004 Revision I

1-3 Table 1-1 San Onofre Units 2 & 3 Head Penetration Nozzles with the Intersection Angles Identiried [11]

Nozzle Angle Nozzle Angle Nozzle Angle No. Type (Degrees) No. Type (Degrees) No. Type (Degrees) 1 CEDM 0.0 35 CEDM 25.2 69 CEDM 42.4 2 CEDM 7.8 36 CEDM 29.1 70 CEDM 42.4 3 CEDM 7.8 37 CEDM 29.1 71 CEDM 42.4 4 CEDM 11.0 38 CEDM 29.1 72 CEDM 42.4 5 CEDM 11.0 39 CEDM 29.1 73 CEDM 42.4 6 CEDM 11.0 40 CEDM 29.1 74 CEDM 42.4 7 CEDM 11.0 41 CEDM 29.1 75 CEDM 42.4 8 CEDM 15.6 42 CEDM 29.1 76 CEDM 42.4 9 CEDM 15.6 43 CEDM 29.1 77 CEDM 42.4 10 CEDM 15.6 44 CEDM 32.6 78 CEDM 42.4 11 CEDM 15.6 45 CEDM 32.6 79 CEDM 42.4 12 CEDM 17.6 46 CEDM 32.6 80 CEDM 43.4 13 CEDM 17.6 47 CEDM 32.6 81 CEDM 43.4 14 CEDM 17.6 48 CEDM 33.8 82 CEDM 43.4 15 CEDM 17.6 49 CEDM 33.8 83 CEDM 43.4 16 CEDM 17.6 50 CEDM 33.8 84 CEDM 43.4 17 CEDM 17.6 51 CEDM 33.8 85 CEDM 43.4 18 CEDM 17.6 52 CEDM 33.8 86 CEDM 43.4 19 CEDM 17.6 53 CEDM 33.8 87 CEDM 43.4 20 CEDM 22.4 54 CEDM 33.8 88 CEDM 49.7 21 CEDM 22.4 55 CEDM 33.8 89 CEDM 49.7 22 CEDM 22.4 56 CEDM 34.9 90 CEDM 49.7 23 CEDM 22.4 57 CEDM 34.9 91 CEDM 49.7 24 CEDM 23.9 58 CEDM 34.9 92 ICI 55.3 25 CEDM 23.9 59 CEDM 34.9 93 ICI 55.3 26 CEDM 23.9 60 CEDM 37.1 94 ICI 55.3 27 CEDM 23.9 61 CEDM 37.1 95 ICI 55.3 28 CEDM 25.2 62 CEDM 37.1 96 ICI 55.3 29 CEDM 25.2 63 CEDM 37.1 97 ICI 55.3 30 CEDM 25.2 64 CEDM 37.1 98 ICI 55.3 31 CEDM 25.2 65 CEDM 37.1 99 ICI 55.3 32 CEDM 25.2 66 CEDM 37.1 100 ICI 55.3 33 CEDM 25.2 67 CEDM 37.1 101 ICI 55.3 34 CEDM 25.2 68 CEDM 42.4 January 2004 Introduction Introduction January 2004 Revision I

1-4 Uphill Side (1800)

I/D hill \ Cladding Downhill Side J ld__

(00) J Weld Head Penetration Nozzle Figure 1-1 Reactor Vessel Control Element Drive Mechanism (CEDNI) Penetration ianuary 2004 Introduction Introduction January 2004 Revision I

1-5 L

Figure 1-2 Location of Head Penetrations for San Onofre Units 2 & 3 [11]

Introduction January 2004 Revision I

2-1 2 HISTORY OF CRACKING IN HEAD PENETRATIONS In September of 1991, leakage was reported from the reactor vessel CRDM head penetration region of a French plant, Bugey Unit 3. Bugey 3 is a 920 megawatt three-loop Pressurized Water Reactor (PWR) plant which had just completed its tenth fuel cycle. The leak occurred during a post ten year hydrotest conducted at a pressure of approximately 3000 psi (204 bar) and a temperature of 194 0 F (90 0 C). The leak rate was estimated to be approximately 0.7 liter/hour.

The location of the leak was subsequently established on a peripheral penetration with an active control rod (H-14), as seen in Figure 2-1.

The control rod drive mechanism and thermal sleeve were removed from this location to allow further examination. A study of the head penetration revealed the presence of longitudinal cracks near the head penetration attachment weld. Penetrant and ultrasonic testing confirmed the cracks.

The cracked penetration was fabricated from Alloy 600 bar stock (SB-166), and has an outside diameter of 4 inches (10.16 cm) and an inside diameter of 2.75 inches (7.0 cm).

As a result of this finding, all of the control rod drive mechanisms and thermal sleeves at Bugey 3 were removed for inspection of the head penetrations. Only two penetrations were found to have cracks, as shown in Figure 2-1.

An inspection of a sample of penetrations at three additional plants were planned and conducted during the winter of 1991-92. These plants were Bugey 4, Fessenheim 1, and Paluel 3. The three outermost rows of penetrations at each of these plants were examined, and further cracking was found in two of the three plants.

At Bugey 4, eight of the 64 penetrations examined were found to contain axial cracks, while only one of the 26 penetrations examined at Fessenheim 1 was cracked. The locations of all the cracked penetrations are shown in Figure 2-1. At the time, none of the 17 CRDM penetrations inspected at Paluel 3 showed indications of cracking, however subsequent inspections of the French plants have confirmed at least one crack in each operating plant.

Thus far, the cracking in reactor vessel heads not designed by Babcock and Wilcox (B&W) has been consistent in both its location and extent. All cracks discovered by nondestructive examination have been oriented axially, and have been located in the bottom portion of the penetration in the vicinity of the partial penetration attachment weld to the vessel head as shown schematically in Figure 1-1.

[~~~~~~~~~~~~~

History of Cracking in Head Penetrations January 2004 Revision I

2-2 Non-destructive examinations of the leaking CRDMI nozzles showed that most of the cracks were axially oriented, originating on the outside surface of the nozzles below the J-groove weld and propagating primarily in the nozzle base material to an elevation above the top of the J-groove weld. Leakage could then pass through the annulus to the top of the head where it was detected by visual inspection. In some cases the cracks initiated in the weld metal or propagated into the weld metal, and in a few cases the cracks propagated through the nozzle wall thickness to the inside surface.

[

scee History of Cracking in lead Penetrations January 2004 Revision I

2-3 The cracking has now been confirmed to be primary water stress corrosion cracking. Relatively high residual stresses are produced in the outermost CEDM penetrations due to the welding process. Other important factors which affect this process are temperature and time, with higher temperatures and longer times being more detrimental. The inspection findings for U.S. plants are shown in Figure 2-2. From this figure, as of Spring 2003, it is interesting to note that a low percentage of CE-fabricated vessels have been found to be cracked (only 9 of 1332 penetrations UT and/or ET inspected in CE-fabricated vessels have shown cracking whereas 117 of 628 penetrations in non-CE-fabricated vessels experienced cracking or leakage). In addition, no cracks in the head vent have been found.

History of Cracking in Head Penetrations January 2004 Revision 1

2-4 270' 270' 0.

r 0 Lakino Pnetrtlon 90

  • Crocked Penetrot;on 90'
  • Crocked Pentrot on BUGEY 3 BUGEY 4 270 0.

90

  • Crocked Penetration FESSENHEIM I Figure 2-1 EDF Plant RIV Closure Head CRDNI Penetrations - Penetrations with Cracking January 2004 in Head History of Cracking in Penetrations lead Penetrations January 2004 Revision I

2-5 CRDMWCEDM Penetrations Inspected CRDM/CEDM Inspection Results 3500- 1400-3000- 1200-2500- 1000-0a 0l 9 2000-1 800-C 0

a o

0

' 1500- 0 600-l, .2 E

Z z 1000- 400-500- 200-CE Vessels Non-CE Vessels CE Vessels Non-CE Vessels I *UT and/or ET 0 BMV Only U Not Yet Inspected l l UT/ET wtih No Cracks U Cracked (not leaker) U Leaker Figure 2-2 Inspection Results for U.S. CRDM/CEDM Penetration Nozzle (Spring 2003)

(f( I History of Cracking in Head Penetrations January 2004 Revision 1

3-1 3 OVERALL TECHNICAL APPROACH The primary goal of this work is to provide technical justification for the continued safe operation of San Onofre Units 2 & 3 in the event that cracking is discovered during in-service inspections of the Alloy 600 reactor vessel upper head penetrations.

3.1 PENETRATION STRESS ANALYSIS Three-dimensional elastic-plastic finite element stress analyses was performed to determine the stresses in the head penetration region [6]. These analyses have considered the pressure loads associated with steady state operation, as well as the residual stresses that are produced by the fabrication process.

3.ac.c 3.2 FLAW TOLERANCE APPROACH A flaw tolerance approach has been developed to allow continued safe operation until an appropriate time for repair, or the end of plant life. The approach is based on the prediction of future growth of detected flaws, to ensure that such flaws would remain stable.

If an indication is discovered during in-service inspection, its size can be compared with the flaw size considered as allowable for continued service. This "allowable" flaw size is determined from the actual loading (including mechanical and residual loads) on the head penetration for San Onofre Units 2 & 3. Acceptance criteria are discussed in Section 6.5.

The time for the observed crack to reach the allowable crack size determines the length of time the plant can remain online before repair, if required. For the crack growth calculation, a best estimate is needed and no additional margins are necessary.

The results of the evaluation are presented in terms of simple flaw tolerance charts. The charts graphically show the time required to reach the allowable length or depth, which represents additional service life before repair. This result is a function of the loading on the particular head penetration as well as the circumferential location of the crack in the penetration nozzle.

Overall Technical Approach January 2004 Revision I

3-2 Schematic drawings of the head penetration flaw tolerance charts are presented as Figure 3-1.

This type of chart can be used to provide estimates of the remaining service life before a leak would develop from an observed crack. For example, if a part-through flaw was discovered, the user would refer to Figure 3-1, to determine the time (t,) which would be remaining before the crack would penetrate the wall or reach the allowable depth (ta) (e.g. alt = 0.75).

Overall Technical Approach January 2004 Revision I

3-3 Flaw Becomes Through - Wall 1.0 C-C, Time ( Months )

Figure 3-1 Schematic of a Head Penetration Flaw Growth Chart for Part-Through Flaws Overall Technical Approach January 2004 Revision I

4-1 4 MATERIAL PROPERTIES, FABRICATION HISTORY AND CRACK GROWTH PREDICTION 4.1 MATERIALS AND FABRICATION The reactor vessels for San Onofre Units 2 and 3 were manufactured by Combustion Engineering with head penetration nozzles from material produced by Huntington Alloys and Standard Steel in the USA. The carbon content and mechanical properties of the Alloy 600 material used to fabricate the San Onofre Units 2 and 3 vessels are provided in Table 4-1. The material CMTRs were used to obtain the chemistry and mechanical properties for the vessel head penetrations.

The CMTRs for the material do not indicate the heat treatment of the material. However, Westinghouse records indicate that the Huntington materials were annealed for one hour at a temperature of 1700'F - 1800'F, followed by a water quench. The Standard Steel materials were annealed for six hours at 16250 F, and air cooled. Figures 4-1 illustrates the yield strengths and carbon content, based on percent of heats, of the head adapter penetrations in the San Onofre Units 2 and 3 vessels relative to a sample of the French head penetrations which have experienced cracking. The general trend for the head adapter penetrations in San Onofre Units 2 and 3 are of a higher carbon content, higher mill annealing temperature and lower yield strength relative to those on the French vessels. These factors should all have a beneficial effect on the material resistance to PNVSCC in the head penetrations.

4.2 CRACK GROWTH PREDICTION The cracks in the penetration region have been determined to result from primary water stress corrosion cracking in the Alloy 600 base metal and, in some cases, the Alloy 182 weld metal.

There are a number of available measurements of static load crack growth rates in primary water environment, and in this section the available results will be compared and a representative growth rate established.

Direct measurements of Stress Corrosion Cracking (SCC) growth rates in Alloy 600 are relatively rare. Also, care should be used when interpreting the results because the materials may be excessively cold worked, or the loading applied may be near or exceeding the limit load of the penetration nozzle, meaning there will be an interaction between tearing and crack growth. In these cases the crack growth rates may not be representative of service conditions.

The effort to develop a reliable crack growth rate model for Alloy 600 began in the spring of 1992, when the Westinghouse Owners Group began to develop a safety case to support continued operation of plants. At the time, there was no available crack growth rate data for head penetration materials, and only a few publications existed on growth rates of Alloy 600 in any product form.

The best available publication at that time was that of Peter Scott of Framatome, who had developed a growth rate model for PWVR steam generator materials [1]. His model was based on a study of results obtained by McIlree, Rebak and Smialowska [2] who had tested short steam generator tubes which had been flattened into thin compact specimens.

Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-2 An equation was fitted to the data of reference [2] for the results obtained in water chemistries that fell within the standard specification for PWR primary water. Results for chemistries outside the specification were not used. The following equation was fitted to the data at 330'C (6260 F):

da-9 8 xO-1 1 (K-9)1 16 m/sec (4-1) dt where:

K is in MPa VIm The next step was to correct these results for the effects of cold work. Based on work by Cassagne and Gelpi [3], Scott concluded that dividing the above equation by a factor of 10 would be appropriate to account for the effects of cold work. The crack growth law for 330'C (6260 F) then becomes:

da-2 .8x 10-12 (K_ 9 )1.16 M/SeC (4-2) dt Scott further corrected this law for the effects of temperature. This forms the basis for the PWR Materials Reliability Program (MRP) recommended crack growth rate (CGR) curve for the evaluation of SCC where a power-law dependence on stress intensity factor was assumed [4HJ.

The MRP recommended CGR curve was used in this report for determining the primary water stress corrosion crack growth rate and a brief discussion on this recommended curve is as follows:

jaxcxc Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-3 I

I a.c'e There is a general agreement that crack growth in Alloy 600 materials in the primary water environment can be modeled using a power-law dependence on stress intensity factor with differences in temperature accounted for by an activation energy (Arrhenius) model for thermally controlled processes. Figure 4-3 shows the recommended CGR curve along with the laboratory data from Huntington materials used to develop the curve.

I Iafc'e Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-4

[

The applicability of the MRP recommended model to head penetrations was recently confirmed by two independent approaches. The first was a collection of all available data from Standard Steel and Huntington Alloys materials tested over the past ten years [4H]. The results are shown in Figure 4-3, along with the Scott model for the test temperature.

The IRP crack growth curve was structured to bound 75 percent of the 26 heats for which test results were available. Fits were done on the results for each heat, and the constant term was determined for each heat. This was done to eliminate the concern that the curve might be biased from a large number of results from a single heat. The 75'1' percentile was then determined from these results. The MRP expert panel on crack growth endorsed the resulting curve unanimously in a meeting on March 6 and 7th 2002. This approach is consistent with the Section Xl flaw evaluation philosophy, which is to make a best estimate prediction of future growth of a flaw.

Margins are incorporated in the allowable flaw sizes. The entire data set is shown in Figure 4-3, where the data have been adjusted to a single temperature of 3250 C.

A second independent set of data were used to validate the model, and these data were obtained from the two inspections carried out on penetration no. 75 of D. C. Cook Unit 2. which was first found to be cracked in 1994 [4G]. The plant operated for one fuel cycle before the penetration was repaired in 1996 and the flaw was measured again before being repaired. These results were used to estimate the PWSCC growth rate for both the length of the flaw and its depth. These two points are also shown in Figure 4-4, and are consistent with the laboratory data for Huntington materials. In fact, Figure 4-4 demonstrates that the MRP model is nearly an upper bound for these materials. The D. C. Cook Unit 2 penetrations were made from Huntington materials.

Since San Onofre Units 2 & 3 operates at a temperature of 310.50 C (591'F) in the head region

[9], and the crack growth rate is strongly affected by temperature, a temperature adjustment is necessary. This temperature correction was obtained from study of both laboratory and field data for stress corrosion crack growth rates for Alloy 600 in primary water environments. The available data showing the effect of temperature are summarized in Figure 4-5. Most of the results shown here are from steam generator tube materials, with several sets of data from operating plants, and results from two heats of materials tested in a laboratory [4A].

Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-5 Study of the data shown in Figure 4-5 results in an activation energy of 31-33 Kcal/mole, which can then be used to adjust for the lower operating temperature. This value is slightly lower than the generally accepted activation energy of 44-50 Kcallmole used to characterize the effect of temperature on crack initiation, but the trend of the actual data for many different sources is unmistakable.

a~c,e Therefore the following crack growth rate model was used for the San Onofre Units 2 & 3 head penetrations for crack growth in all the cases analyzed.

d =1.40 x 10-12 (K - 9)116 ni/sec dt January 2004 Fabrication History Material Properties, Fabrication and Crack History and Growth Prediction Crack Growth Prediction January 2004 Revision I

4-6 where:

K = applied stress intensity factor, in lPa1m`

This equation implies a threshold for cracking susceptibility, Ks((' = 9 Nhali . The crack growth rate is applicable to propagation in both axial and circumferential directions.

January 2004 Fabrication II tistory Material Properties, Fabrication anal Crack istory and Growth Prediction Crack Growth Prediction January 200 Revision I

4-7 Table 4-1 San Onofre Units 2 & 3 RN Head Adapter Material Information [11]

lI f I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I I I

+ *4- I

+ + I I I I~~~~~~~~~~~

4- 4-

+ + I I I-4 4 4 4 4 4 4 4 1 I- I- 1 1 I- I. 4 4 I- I- 4

_ _ _ ~I _ _ I _ _ _ _ _ I _ __ I __

I * *1- 1-4 4 +

  • 4 + 1-I I l 4 -4 4 4 4 4 4 4 1 1 -1 I_ _ _ _ I _ _ _ _ _ _ _ _ _ _ _ _ _

Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-8 50

  • EdF (11 Heats) 45 ------ ----- ----- ----- ------ ----- ----- - - San Onofre 2 (19 Heats) 40 E San Onofre 3 (12 Heats)

U, 0

4)

I 2 e20 4) 10 CL~~~~~~~ ~ ~ ~O Yield Strength (ksi)

Figure 4-1 Yield Strength of the Various Heats of Alloy 600 Used in Fabricating the San Onofre Units 2 & 3 and French Head Penetrations Material Properies, Fabrication History and Crack Growth Prediction January 2004 Revision 1

4-9 80 70 Z 60 5

0 r 40 0

-W r- 30

)

I-o¶ 20 10 0

Ilb 0)

(4-,9 e N:9 t4%

01, zll Carbon Content (Weight %)

Figure 4-2 Carbon Content of the Various Heats of Alloy 600 Used in Fabricating the San Onofre Units 2 & 3 and French Head Penetration C()  ::7 Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-10 Figure 4-3 Screened Laboratory Data for Alloy 600 with the NIRP Recommended Curve (Note that the Modified Scott Model is also Shovn)

Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-11 ac.e Figure 4-4 Model for PWSCC Growth Rates in Alloy 600 in Primary Water Environments (325 0 C), With Supporting Data from Standard Steel, Huntington, and Sandvik Materials I Note that the data have been normalized to a temperature of 3250C. The actual test temperatures are listed in parenthesis after the caption. For example, the Huntington data were obtained at temperature ranging from 315'C to 331 0 C.

Material Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

4-12 TEMPERATURE, DEG. C 372 352 333 315 298 282 1E-08 .9- 1 4- * =1 1,000 1- 4---9 * -

+ -4 4 -

-t-----4 4 -

1E-09 .100 I z

Uc 0 C)

-J Uj 6 w G

2 I lE-10 10 CC H

0 0

C-)

1E-11 1 U.

FCGSUU.DRW 1E-12 0.1 0.00155 0.0016 0.00165 0.0017 0.00175 0.0018 RECIPROCAL TEMPERATURE, 1/DEG. K Note: All symbols are for steam generator materials, except the solid circles, which are head penetration laboratory data.

Figure 4-5 Summary of Temperature Effects on l'WSCC Growth Rates for Alloy 600 in Primary Vater IMaterial Properties, Fabrication History and Crack Growth Prediction January 2004 Revision I

5-1 5 STRESS ANALYSIS 5.1 OBJECTIVES OF THE ANALYSIS The objective of this analysis was to obtain accurate stresses in each CEDM or head vent and its immediate vicinity. To do so requires a three dimensional analysis which considers all the pertinent loadings on the penetration [6]. An investigation of deformations at the lower end of the housing was also performed using the same model. Four CEDM locations were considered: the outermost row (at 49.7 degrees angular position from the RV centerline), rows at 29.1 degrees, 7.8 degrees, and the center location (0 degree). In addition, the ICI penetrations (55.3 degrees) and head vent were analyzed.

The analyses were used to provide information for the flaw tolerance evaluation, which follows in Section 6. Also, the results of the stress analysis were compared to the findings from service experience, to help assess the causes of the cracking which has been observed.

5.2 MODEL A three-dimensional finite element model comprised of isoparametric brick and wedge elements was used to obtain the stresses and deflections. Views of CEDM, ICI, and head vent models are shown in Figures 5-1, 5-2, and 5-3 respectively. Taking advantage of the symmetry of the vessel head, only half of the CEDM penetrations were modeled. Similarly, only half of the center penetration was modeled.

In the models, the lower portion of the Control Element Drive Mechanism (CEDM) penetration nozzle, In-Core Instrumentation (ICI) nozzle, the head vent, the adjacent section of the vessel closure head, and the joining weld were modeled. The vessel to penetration nozzle weld was simulated with two weld passes, while four weld passes were used for the head vent nozzle. The penetration nozzle, weld metal, cladding and the vessel head shell were modeled in accordance with the relevant materials.

The only loads used in the analysis are the steady state operating loads. External loads, such as seismic loads, have been studied and have no impact since the penetration nozzles are captured by the full thickness of the reactor vessel head into which the penetrations are shrunk fit during construction. In addition, the duration of the seismic loading is very short and will not have any significant impact on the overall primary stress corrosion crack (PWSCC) growth. The area of interest is in the penetration near the attachment weld, which is unaffected by these external loads.

5.3 STRESS ANALYSIS RESULTS - OUTERMOST CEDM PENETRATION (49.7")

[~~~~~~~~~~~~~~~~~~~~~~~~~~~

Stress Analysis January 200 Resision I

5-2

[

I aDc, 5.4 STRESS ANALYSIS RESULTS - INTERMEI)IATE CEI)M AND ICI PENETRATIONS

[

5.5 STRESS ANALYSIS RESULTS - CENTER CEDNI PENETRAT-ION

] a.c.c 5.6 STRESS ANALYSIS RESULTS - HEAD VENT

[

Stress Analysis January 2004 Revision I

5-3 Figure 5-1 Finite Element Model of CEDM Penetration Stress Analysis January 2004 Revision I

5-4 Figure 5-2 Finite Element Model of ICI Penetration January 2004 Stress Analysis Stress Analysis January 2004 Revision I

5-5 Figure 5-3 Vent Pipe Finite Element Model Stress Analysis January 2004 Revision I

5-6 ANSYS 5.7 JAN 10 2002 232: 20 05 PLOT NO. 3 ELEMENTS PowerGraphics EFACET=1 f '4 / / \>t , AVES-Mat

-10000 0

40000

-5000 0 10000 0 l / /XN \ ~~~~~~~SMN

-40791 Na-~I3CEDN(49.7dCYC .05/2.728,2.SE-03,A) - Operating ANSYS 5.7 JAN 10 2002 2 3 2 0 09 PLOT NO. 4 ELEMENTS MAT NUN NODAL SOLUTION TIME=4004 SZ (AVG)

RSYS=11 PowerGraphics EFAcET=1 AVRES=Mat DM1 = 437118 smN =-40791 sMX1 =72667

-40791

-1 0000

~0 20000 30000 40000 100000 WaI3CEDN(49.7dCYC SS,.05/2.728,2.5E-03,A) -Operatig Figure 5-4 Stress Distribution at Steady State Conditions: Outermost CEDM Penetration Nozzle (49.7 Degrees) (Hoop Stress is the Top Figure, Axial Stress is the Bottom Figure)

Stress Analysis January 2004 Revision

5-7 ANSYS 5.7 JAN 11 2002 11:13:07 PLOT NO. 3 ELEMENTS PowerGraphics EFACET=1 MAT NUM NODAL SOLUTION TIME=4004 SY (AVG)

RSYS=11 PowerGraphics EFACET=1 AVRES=Mat DMX =.436108 SMN =-17871 SMX =89230

_ -17871

-10000

~0

- 10000 220000 30000 40000 50000 100000 Wat3CEDM(29.1d,CYC SS,4.05/2.728,2.5E-03,A) - Operating ANSYS 5.7 JAN 11 2002 11:13:09 PLOT NO. 4 ELEMENTS MAT NUM NODAL SOLUTION TIME=4004 SZ (AVG)

RSYS=11 PowerGraphics EFACET=1 AVRES=Mat DMX =.436108 SMN =-42808 SMX =56453

_ -42808

-10000

- 0 10000 20000 3 0 000 40000 0000 100000 Figure 5-5 Stress Distribution at Steady State Conditions for the 29.1 Degrees CEDM Penetration (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure)

Stress Analysis January 2004 Revision I

5-8 l ~ ~~~~/ ~ ~~~~~~~~~~~

088 7 46

\ \ \ l \ / ~~~~~~~~~~~~ELEMENTS Power~raphics NODAL SOLUTION PowerGraphic5 AVRES=Mat

-12 04 9

-10000 0

10000 Wat3CEDM(7.8d,CYC SS,4.05/2.728,2.5E-03,A) - Operating ANSYS 5.7 JAN 11 2002 05 37:49 PLOT NO. 4 ELEMENTS MAT NUN NODAL SOLUTION TIME=4004 SZ (AVG)

RSYS=11 Power~raphics EFACET=1 AVRES-Mat DMX =.432624 SMN =-41176 31000 0

=330000 2

40000

-500 00 100000 Wat3CEDM(7.8d,CYC SS,4.05/2.728,2.5E-03,A) - Operating Figure 5-6 Stress Distribution at Steady State Conditions for the 7.8 Degrees CEDM Penetration (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure)

Stress Analysis cob January 2004 Revision 1

5-9

, ' \ l 1 1 l / / 0 ~~~~~~~~~~~~03:

15 15 PowerGraphics NODAL SOLUTION PowerGraphics 4i E : Z ! r E Il l trx / / -  :::; s AVRES-Nat ADMRE==43a~~~~~~~~~~~~~~~~

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-4335979 SM _-39791 f= p _ \ X f _ =83 ol~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

10000 3 0000 50000 1 0000 0 Wat3CEDM(Od,CYC S.4.05/2.728,0,A) - Operating Figure 5-7 Stress Distribution at Steady State Conditions for the Center CEDM Penetration (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure)

Stress Analysis COl January 2004 Revision I

5-10 jANSYS 5.7 JAN 11 2002 13: 45 36 K I /~~~~~~~~~~~~~~~~~EEENTSh PLOT NO. 3 EFACET=1 MAT NUM

.)\ ; \ E/NODAL l

  • 09 SOLUTION i CA

\ il l \kE 0\\g / Power~raphics(AiVG)

TPT~~~~~~~~~~~~~~~~~~SY5T4 EFACET=1 AVRES=Mat

\ _ [ /\ I / \ / ~~~~~~~~~~~~~~~~~~~~~~~DMX

=.451882

X s -

/ /

_ l l 9 / X ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

=-36480 E \ s s Xl / / \t / \ E ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

m=77025 36480

- 10000

~0 10000

\ _ 4 8 / \ / \ _ ~~~~~~~~~20 000

- 50000 1000 00 Wat3 ICI(55.3d,CYC SS,5.563/4.625,2.5E-0A - p t9 X ~~~~~~~~~~~~~~~~~ANSYS 57 PLOT NO. 4 ELEMENTS MAT NUM NODAL SOLUTION TIME=4004 SI (AVG)

RSYS=11 PowerGraphics EFACET=1 AVRES=Mat0 DMX -. 451882 SN =-38783 SMX =66313

-38783

-10000

~0 000 20000 30000 4000

- 50000 100000 563

)Wat3 ICI(55.3dcyc SS,. /4.625,2.E-03A) O Figure 5-8 Stress Distribution at Steady State Conditions for the ICI Penetration Nozzle (Hoop Stress is the Top Figure; Axial Stress is the Bottom Figure)

Stress Analysis January 2004 Revision 1

klPE 6 2002

- ~~~ELEMENTS c

/ / / ~ower~raphic NOD)AL S!LJTION PowerGraphlcs 200FT~

/~~~~~~~~~~~~~~~~~~~ i1000 00 St4X0 590 6 2 0000 I'__ _ _-___

- _ I I-f-A"IjD.A Result

- ~L,_ ufnmll iue Figure 5-9 Stress Conto of Residual Stresses and Figre Cont _nreus-in te(Hoop Stress Head Vein isj~U,~"'

the Top Figure;

-~operatingl

-1 r l Whyq i

stress Analysis Ja~~~~~~~~~~~~~~~nary 2004

5-12 ANSYS 5.7 JAN 15 2002 16:31:44 PLOT NO. 2 DISPLACEMENT TIME=4004 RSYS=SOLU DMX =.437118 DSCA=10 XV =-1 ZV =2 DIST=8.772 XF =-.168385 YF =64.552 ZF =63.403 VUP =Z PRECISE HIDDEN NODAL SOLUTION TIME=4004 SZ (AVG)

RSYS=SOLU DMX =.426592 SMN =-52505 SMX =72723

-52505 10000 30000 50000 3

400000 4 0000 100000 Wat3CEDM(49.7d,CYC SS,4.05/2.728,2.5E-03,A) - Operating Figure 5-10 Axial Stress Distribution at Steady State Conditions for the Outermost CEDM Penetration (49.7 Degrees), Along a Plane Oriented Parallel to, and Just Above, the Attachment Weld CaQ Stress Analysis January 2004 Revision I

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