DESTRUCTIVE EXAMINATION METHODS FOR THE INVESTIGATION OF NORTH ANNA HEAD PENETRATION #54

DESTRUCTIVE EXAMINATION METHODS FOR
THE INVESTIGATION OF NORTH ANNA
HEAD PENETRATION #54
Presentation to
NRC Research
Rockville, MD
January 18, 2006
Gutti Rao
Westinghouse Electric Company
Work Funded by Electric Power Research Institute (EPRI)
Slide 1
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Participants/Contributors
Westinghouse
EPRI
Gutti Rao (Tech Lead)
Joyce Conerman
Chris DeFlitch
Warren Junker
Al Vaia
Al Ahluwalia (Project Manager)
Francois Cattant (Consultant)
Noel Peat (Consultant)
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Slide 2
Objectives
z
z
z
z
z
Destructive Examination of Complete Alloy 600/82/182
Penetration/Weld from Service
Physical Characterization and Identification of Head Penetration
Weld Defects
Identify Interrelationship between Various Types (Axial,
Circ or Other) of Defects
Characterization of Annulus Environment & Wastage
Identify Mechanistic Aspects of Formation and Root Cause
of Cracking
(Leading to Correlation of Discovered Defects with Prior Reported
NDE Indications)
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Slide 3
Summary of Tasks
Preliminary NDE
Development of Sectioning Plan – Identification
Preliminary Sectioning
Additional NDE
Detailed Sectioning and Macroetch
Detailed NDE on Azimuthal Sections
Metallography
Chemistry
Hardness
Fractography
Fabrication History Review
Review of Results Assessments and Conclusions
Slide 4
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Project Status
z
Workscope 95% Completed
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Draft Report Initiated
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Final Report Scheduled for April 1, 2006
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Slide 5
Presentation Focus
The Current Presentation is Focused on Two Aspects of the
Destructive Examination
z
Effective Utilization of Additional NDE Technologies
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Development of Innovative Sectioning Plan and Sectioning
Methods
– To Maximize Defect Characterization Capabilities
– To Minimize Man-Rem Exposure
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Slide 6
As-Received Condition of CRDM Nozzle 54
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Slide 7
Vendor Inspection Data (Provided)
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Slide 8
Vendor Inspection Data (Provided)
EC Done
EC
EC Done
EC
EC
EC
Isolated ID Indications
10
machine
Possible
Wastage
8
machine
Indications 1,2
machine
machine
Weld Profile
machine
machine
6
Cut on either
side of this
defect
machine
4
Indication 7
Indication 5
machine
2
previously
machined
Piece A
Indications 3,4
Piece B
0
previously
Piece
machined
machine
C
Piece A
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
Distance From Bottom (in)
machine
Major Initial Cuts
Completed Cuts
Proposed Cuts
Replica Indications
Degrees
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Slide 9
3-D Model of Indications Developed by
Westinghouse To Guide Sectioning
90°
180°
0°
270°
• Developed a 3-D Model of Penetration Indications
• Compared Model to Physical Cut Out to Identify Best Sectioning Plan
Slide 10
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NDE Assessments – For Sub-Surface/Surface
Emergent Crack Identification
z
Microset (High Resolution) Replication
z
Eddy Current Testing
z
Florescent Dye Penetrant Testing
z
Ultrasonic Testing
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Slide 11
Replication to Preserve Data from Wetted ID Face Weld
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Slide 12
Wetted ID Weld Surface Replication
Allows Identification of Crack Emergence on J-Weld Wetted ID Face and Observation of
Weld Bead Interactions
Slide 13
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Specific J-Weld Indication via Replication
Replication Allowed Identification of Several Wetted Face Emergent Cracks – this one at 300° Location
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Slide 14
Penetration ID Surface Replication
ID Replica Across
J-weld Region
ID Scratch
Surface Scratch
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Slide 15
EC Pencil Probe Tracing of Weld Interface
To Confirm Profile of Weld Interface (Establishes
Removable Excess Carbon Steel)
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Slide 16
Sectioning Layout to Remove Excess Carbon
Steel (3 Inch Clearance from Weld)
3 in. minimum
clearance from
interface
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Slide 17
Rough Cutting of NA Penetration 54
z
Band Saw was Used with Appropriate Capacity (Modified Jet,
7x12” Horizontal/Vertical Band Saw). Recommend Use of
Larger Saw.
z
A 3/4 in Bimetal 5/8 in Variable Pitch Blade (Blade was
Changed Frequently, Especially when Cutting Through
Weldment). Speed, Feed and Pitch of Blade were Dependant
on Horsepower of Drive Motor and Rigidity of Fixturing.
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Slide 18
Removal of Excess Carbon Steel
z
Fixture Capable of Rotational,
Elevation and Lateral Adjustment
z
Sample Holding Fixture Clamped
to Saw Base to Assure Rigidity
Between Sample and Saw Blade
z
Top of CRDM Penetration
Clamped to Fixture and Aligned
with Blade
z
Ratchet Cargo Straps were used to
Maintain Position and Rigidity
During Cut
Piece in Fixture for Removal of Excess
Carbon Steel
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Slide 19
Initial Sectioning Plan
Possible Wastage in CS
Cut (150°)
Pc B
Cut (60°)
Indication Group 1,2
Pc A
0°
180°
68°
Penetration Tube
Indication Group 3,4
Pc C
Weld Area
Cut (270°)
270°
As-Sectioned Pieces A, B & C
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Slide 20
Further Rough Cutting of NA Penetration 54
z
z
z
Major Sectioning Conducted to Obtain “Pie” Sections:
– Multiple vises used to align sample with blade.
– Cargo straps and wooden spacers and/or machining “toe”
clamps were used if support was required.
Thinner Slices Were Cut off of the Major Pie Sections to
Isolate Areas of Interest
Additional Machining Done to Sliced Faces:
– Multiple tilt machine vises and/or “toe” clamps were used
to hold piece as it was being milled.
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Slide 21
Sectioning Through Weld and Penetration
z
Large Plywood Base Plate was
Used to Support Sample
z
Various Shape and Thickness
Wooden Spacers were Used to
Align Sample with Blade
z
Ratchet Cargo Straps were
Used to Maintain Position and
Rigidity During Cut
60° Cut
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Slide 22
Sectioning Through Weld and Penetration
270 Degree Cut
Slide 23
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Piece A
270° Face
60° Face
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Slide 24
Piece A
270°
Face
Cut is parallel to wet face
minimum 1 in above top of
weld + butter
60° Face
Cut is 1 inch minimum from
bottom of last j-weld pass
Slide 25
Cut is 1 inch minimum
from butter and carbon
steel interface
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Piece B
60° face
150° face
90° picture
(replica)
70° picture
(replica)
135° picture
(replica)
NDE Indications from NDE performed at W
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Slide 26
Cut is 1 inch
minimum from butter
and carbon steel
interface
Cut is 1 inch minimum
from bottom of last j-weld
pass
Ridge is an artifact of
the cutting process
View of cuts from top
Cut is 1 inch
minimum from end of
j-weld
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Slide 27
Piece C
150° Face
270°
Face
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Slide 28
Piece C
150° Face
Wet Face
Cut is 1 inch
minimum from
butter and
carbon steel
interface
Cut is parallel to
wet face minimum
1 in above top of
weld + butter
Cut is 1 inch
minimum from
bottom of last
j-weld pass
Wet Face
270° Face
Cut is 1 inch
minimum from
butter and
carbon steel
interface
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Slide 29
Subsequent Sectioning – Thinner Slices for
More Detailed Examination
z
Based on Eddy Current/Replication Results and Vendor
Inspection Results
z
Objective to Isolate Areas of Interest
z
Plan is To
– Section
– Additional NDE on Faces
– Prepare Locations for Examination
– Detailed Investigation of Defects
Same Slicing Process as “Rough Cutting”
z
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Slide 30
Detailed Sectioning Plan
EC Done
EC
EC Done
EC
EC
EC
Isolated ID Indications
10
machine
Possible
Wastage
8
machine
Indications 1,2
machine
machine
Weld Profile
machine
machine
6
Cut on either
side of this
defect
machine
4
Indication 7
Indication 5
machine
2
previously
machined
Piece A
Indications 3,4
Piece B
0
previously
Piece
machined
machine
C
Piece A
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
Distance From Bottom (in)
machine
Major Initial Cuts
Completed Cuts
Proposed Cuts
Replica Indications
Degrees
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Slide 31
Piece B1A
75°
130°
Already
machined
60° face
150°
face
machine
Already
machined
machine
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Slide 32
Piece A1A
270°
face
A1A5
60° face
280°
30°
A1A1
machine
330°
A1A4
0°
A1A2
machine
A1A3
machine
EC
Slide 33
machine
EC
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Piece C1A
EC
machine
machine
C1A2
C1A3
C1A1
190°
machine
C1A4
150° face
165°
250°
270° face
EC
machine
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Slide 34
Eddy Current Examination of Sectioned Faces
z
Use of + pt Eddy Current Tool to Examine Sectioned Faces
z
Attempt to Identify Defects/Indications Prior to Metallographic
Preparation
z
Allows Identification of New Indications Missed by Original Section NDE
z
Allows Metallographic Examination to Focus on Specific Areas
z
Provide Continuing Observation and Tracking of Original NDE
Indications through to Confirmatory Metallographic Observation
z
“Guides the Eye” to Abnormal Weld Microstructure Regions
– Butter/Weld Interfaces
– Internal Weld Defects
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Slide 35
Example of Eddy Current and Subsequent
Metallographic Examination of Sectioned Face
Abnormal weld microstructure
EC+ Butter/Weld
interface
Eddy Current Inspection Results for the 60 Deg. Face using the +Point Probe (Piece B1A5)
Abnormal Weld Microstructure and Weld Butter Interface
Slide 36
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Correlation of Features in Metallography and
NDE “Images”
z
z
z
z
z
z
All Faces Examined (12 Azimuthal Sections)
Allows Clarification of Defect Types from Different Views
– + pt probe
– Polished Section
– Fluorescent Dye Penetrant
– Etched Sections
Weld Butter Interface are Visible in Ground Sections
Weld Microstructure Visible in Several Sections
Cracking Visible in Ground Sections – Clarified in Dye Penetrant
Observations
See Observations on 0 Degree Section (Piece A1A3)
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Slide 37
Comparison of Optical Metallography and Dye
Penetrant Images
Defect looking like
cracks with tiny
voids along it
Defect looking like
cracks with tiny voids
along it
EC Indication
W/B interface +
cracks
Top of the annulus
ends here
EC Indication
W/B interface +
EC Indication
Top of the
annulus
ends here
EC Indication
cracks
Defect looking
like branched
cracks
Defect looking like
branched cracks
Butter/Weld interface
Butter/Weld Interface
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Slide 38
Comparison of Optical Metallography and Dye
Penetrant Images
Short lack of fusion at the end of
the annulus
Series of cavities at
the weld/base metal
interface
Major crack
between 2
weld passes
EC+ Butter/Weld
interface
Short lack of fusion at the end of
the annulus
Series of cavities at the
weld/base metal
interface
Major crack
between 2
weld passes
EC+ Butter/Weld
interface
Abnormal weld
microstructure
EC
Abnormal weld
microstructure
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Slide 39
Eddy Current Inspection Results for the 0 Deg.
Face Using the +Point Probe (Piece A1A3)
W/B interface + cracks
EC Indication
EC Indication
Annulus Gap
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Slide 40
Finding of NDE and Low Magnification
Metallographic Observations of Sectioned Faces
z
Demarcation of Weld Butter Interfaces
z
z
Regions of Abnormal Weld Microstructures
– Regions of Weld Repair/Overlay
Cracks in Welds, Branched Cracks, Crack Networks
z
Void Alignment on Cracking/Series of Cavities
z
Lack of Fusion Regions (Including at the End of Annulus)
– Pursue Detailed Examination of Key Factors
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Slide 41
Summary of Approach and Findings to Date
z
Removal of Excess Carbon Steel is Necessary and Time and
Resource Consuming
z
Vendor NDE is a Good Starting Point but must be
Supplimented by Lab. NDE and Replication
z
Replication was most Useful at Confirming Weld Defect
Locations and Help Minimize Personnel Radiation Exposure
z
Replication was Helpful in Identifying Surface Cracks
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Slide 42
Summary of Approach and Findings to Date
(cont.)
z
3-D Model Aids Visualization of Defect Locations Facilitates
Development of Sectioning Plan
z
Sectioning Procedures Employed Rigid Clamping and Simple
Tooling Developed by Westinghouse Hot Cell Technicians
z
Use of NDE Methods on Sectioned Slices Provides an
Innovative Way to Track Indications and to Properly Locate
(Old and New) Defects
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Slide 43