Transcript 幻灯片 1

ASIPP
Application of Infrared Thermography in NDT of
Plasma-Facing Components for Tokamaks
Pan QI, Qiang LI, Guang-Nan LUO
Institute of Plasma Physics
Chinese Academy of Sciences
P.O.Box 1126, Hefei, 230031 China
17th World Congress of Non-Destructive Testing
Exhibition Center, Shanghai, China, October 25 – 28, 2008
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Outline
• Background
• Infrared thermography applied in PFCs testing
• R & D at ASIPP for NDT of PFCs
• Summary and future work
ASIPP
Outline
• Background
• Infrared thermography applied in PFCs testing
• R & D at ASIPP for NDT of PFCs
• Summary and future work
ASIPP
Background
International Thermonuclear
Experimental Reactor (ITER)
Experimental Advanced Superconducting
Tokamak (EAST)
The background of my work is magnetic confinement fusion tokamak
ITER being constructed in France
The mini tokamak EAST constructed in our institute
By the end of september 2006, the engineering missions were completed
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The inner vacuum vessel with stainlesssteel PFCs (initial phase)
The inner vacuum vessel with graphite
tiles PFCs (first phase)
The cross-section of EAST in-vessel components
Passive plate
The vacuum vessel is the important part of tokamak. It
contains divertors, passive plate, high field plate and low
High field plate field plate. These parts make up of plasma facing
components (PFCs). The components consist of plasma
Low field plate
facing materials (PFMs) and Cu alloy heat sink. In the
initial phase, stainless steel was used as PFM. Doped
graphite tile is the main choice in the first phase (now) and
tungsten will be chosen as candidate in the future phase.
the purpose of PFCs is to protect the vacuum vessel,
Divertors
injection power system and diagnostic components.
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Problems of PFCs
•Engineering constraints
•Industrial constraints
bonding/joint
Ensure and control the quality of
manufacturing
(the keypoint for successful delivery of
PFCs)
(1)
When tokamak is working, PFCs are the first wall facing plasma, subjected to high heat flux,
bombardment of different particles and high magnetic filed. In this working conditions, PFCs
will meet the problems, which contain engineering constraints and industrial constraints. But
the transition (bonding/joint) between PFMs and heat sink is the most critical issue. How do we
ensure and control the quality of this part during manufacturing is the key point for successful
delivery of PFCs.
(1) M. Missirlian et al. Qualification of high heat flux components: application to target elements of W7-X divertor, in: 11th PFMC, Greifswald, Germany,october11th, 2006.
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Examination on quality of bonding/joint of PFCs
Destructive method
High heat flux(HHF) testing(very important)
Purpose
qualification of HHF PFCs design & modeling
qualification of advanced nondestructive tests
Method
screening test-heat load limit
fatigue test-fatigue limit
critical heat flux test-safety margin for heat transfer
Nondestructive method
X-ray tomography - a sample X-ray
examination allowed assessment of the different
copper infiltration rates inside CFC tiles, which
can change the global thermal conductivity of the
HHF element
Ultrasonic inspection– applied to test the
defect existing in PFMs/heat sink interface
Metallography
qualify the quality of the braze joint
Transient thermography – applied at the final
stage of the fabrication and provide a global
information about the thermal performance
Systematic fracture shear stress measurements
qualify the quality of the braze joint
Lock-in thermogaphy – applied to test PFCs
throughout manufacturing process
Pulsed thermography – this approach is under
development
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Comparison of the methods
Methods
HHF test
Nondestructive
No
Quantitative
Test cost
Portable
X-ray test
IR test
Yes
Yes
Yes
Yes
Yes
Yes
conditional
High
Low
High
Low
No
decision by
method
No
Ultrasonic
Yes
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Outline
• Background
• Infrared thermography applied in PFCs testing
• R & D at ASIPP for NDT of PFCs
• Summary and future work
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Transient thermography - SATIR
(SATIR : French acronym for Infra Red Acquisition and Data Processing Device)
In 1994,an infrared nondestructive testbed SATIR was developed for the
Tank: hot water
PFCs quality control by CEA (France
fusion institute). The principle is based
on the comparison of the surface
Pump
temperature
evolution
between
reference elements and tested elements
during a transient heat load, which is
Reference element
generated by hot and cold water
flowing successively in the cooling
(1)
Control system (loop)
channel drilled in heat sink. Interface
defects are detected
by a slower
temperature surface response. The
Tested element
surface temperature transition due to
the heating and cooling cycle is
measured by means of an infrared
The test-bed of SATIR
camera.
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(2)
This is the process of transient monitoring. The temporal evolution of the
Presence of defect surface temperature difference at each corresponding pixel of both elements
is calculated and the areal maxima (so-called DTref_max) distribution can be
obtained. A bonding flaw between PFMs and heat sink can be judged from
the distribution on the areas with the values of DTref_max higher than a
critical value verified by high heat flux (HHF)testing.
The disadvantage of the method is the necessity of a reference component.
An innovative data processing based on spatial autocorrelation and on energy
distribution at PFMs and heat sink bonding are being developed allowing
inspection of a component without the necessity to get a reference component.
(2)
No necessity of a reference component
(2) A.Durocher et.al. Qualification and Nondestructive examination methods of high heat flux plasma facing components, in: the 24th SOFT, Warsaw, Poland, Sept,12th, 2006
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Transient validation
Manufacturing of calibrated flaws at the
doped graphite tile/copper interface
Trans.IR calibration and validation
HHF test
(1)
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Lock-in thermography
(1)
•Investigations on possibility to detect
damage during Tokamak shutdowns
•Features
– Portable
– In-field
– Health check
– Annual check
– Global check
– Suspicious tiles monitoring
The Lock-in is a method based on propagation in the solids of
modulated thermal waves imposed at the surface of element. It
is used for evaluating the heat transfer capabilities of tiles,
mainly the PFM/heat sink bonding
Magnitude and phase-shift of surface temperature vary
according to thermal properties underneath. Phase-shift is
less sensitive to flux homogeneity and surface emissivity
Properties: easy to operate, no cooling, less emissivity
dependence
(3)
Lock-in thermography device (movable)
applied in TS Tokamak
(3) X. Courtois et al, In-situ monitoring of actively cooled plasma facing components using acoustic and thermal methods, Phys. Scr. T128(2007)189-194
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Pulsed thermography – ARGUS (Advanced infRared
thermoGraphy Unit for inSpection)
Principle: For each pixel, a frequency analysis based on
(4)
the fast Fourier transform algorithm(FFT) is calculated on
the cool down behavior after the flash. The defect detection
is not based on the power spectrum of the FFT, but on the
phase-shift of the basic frequency of the FFT(f1)and its
higher harmonics(f2,f3,…). The basic frequency(f1) is
adjusted to obtain a penetration depth reaching the foil/heat
sink interface, whereas the penetration of the first harmonic
frequency(f2) is limited to the PFM/foil interface. The means
that the phase image of each frequency addressed by the
FFT carries information about depth of the defect detected
The ARGUS setup
Application to AMC tiles inspection
(4) X. Courtois et al, In-situ monitoring of actively cooled plasma facing components using acoustic and thermal methods, Phys. Scr. T128(2007)189-194
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Comparison of three thermography methods
Methods
Trans.IR
Lock-in IR
Pulsed IR
Aim
Quality control and the
final acceptance test
Quality control and the
final acceptance test
Quality control and
the final acceptance
test
Technology maturity
Mature
Immature
Immature
No
No
Reference element
Yes
Data processing
Simple and less data
Complex and large
amount of data
Complex and large
amount of data
Equipment costs
Moderate
Cheap
Cheap
Test costs
Cheap
Cheap
Cheap
Mass testing
Ok
Ok
Ok
Quality criteria
Quantitative
Quantitative
Quantitative
Determination of
criteria
Comparison of HHF
calibration and complex
Portable
No
Comparison of HHF
calibration and complex
Yes
Comparison of HHF
calibration and
complex
Yes
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Outline
• Background
• Infrared thermography applied in PFCs testing
• R & D at ASIPP for NDT of PFCs
• Summary and future work
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Construction of test-bed
Technical indicator
Infrared camera
Pump
Hot water tank
Cold water tank
Hot water flow rate: 3.9m/s
Cold water flow rate:3.4m/s
Hot water temperature:98℃
Cold water temperature:25℃
Volume of hot water tank:100L
Volume of cold water tank:150L
Infrared camera:
ThermaCAM®PM595PAL,
320×240 pixels, 50 Hz
Tested sample
The experimental set-up at our institute
Benefiting from the experience of SATIR, we have constructed the test-bed based on
the method of transient thermography.
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HHF facility
Technical indicator
Max power: 10kW;
accelerate voltage: 10kV; cooling
water: 0.4MPa,2 m3/h;
Max scanning area:>30×30mm
The results of NDE performed on
the PFCs with calibrated defects
must be compared with the high
heat flux (HHF) test. So the facility
is important and necessary for
infrared thermography
The test equipment in ASIPP
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Our works
The IR image is used to
visualize the heat transfer
between the PFMs and heat
sink, which enables to
identify the calibrated defects
in thermal contact. Three
dimensional thermal finite
element analyses have been
performed to simulate the
defect. The experimental
observations obtained from
IR
thermography
have
confirmed the FE simulation.
Infrared image with defect in
flexible graphite layer
Simulation by ANSYS
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Edge detection for defect by canny operator
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Outline
• Background
• Infrared thermography applied in PFCs testing
• R & D at ASIPP for NDT of PFCs
• Summary and future work
ASIPP
Summary
Plasma-facing component is one of the most important in-vessel components in a
tokamak. High reliability and stability are necessary for high performance plasma
operations.
Good bonding/joint quality between the plasma-facing material and the heat sink is a
keypoint to realize the high reliability and stability, which requires reliable examinations
during manufacturing and at final batch reception.
Infrared thermography has proved to be a reliable and effective method in the
examination and been chosen as a candidate method in the manufacturing of the ITER PFCs.
R & D work is underway to establish reliable NDTs in future manufacturing of the nextstep EAST PFCs, mainly including IR thermography and ultrasonic inspections.
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Future work
Continuous efforts in developing IR transient thermography NDT, i.e., completion and
improvement of the system, esp. calibration with comparison to HHF testing
More NDT methods, e.g., ultrasonic inspection, will be examined for their use in the
manufacturing of the future EAST PFCs
The acceptance criteria for the NDTs must be determined via dedicated and reliable testings,
usually destructive ones
Portable Lock-in or Pulsed IR thermography test-bed will be useful for in-field examination,
may be used as an effective tool for routine health check and service life prediction of the
PFCs
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