I. Tiseanu , T. Craciunescu and teamEURATOM-MEdC, National Institute for Lasers, Plasma and Radiation Physics NILPRP, Bucharest, Romania

e-mail: tiseanu@infim.ro SEWG meeting on „Gas balance and fuel retention“, July 2010

WP10-PWI-01-02-01/MEdC/BS/PS

X-ray micro-tomography studies on CFC samples for porosity network characterization

X-RAY MICROTOMOGRAPHY for IFMIF

• IFMIF HFTM miniaturized specimens and irradiation capsule

X-RAY MICROTOMOGRAPHY for JET/ITER

• ITER- Compressed pebble bed• ITER- Welded Steel Pipe with Cu cables• ITER like Nb3Sn superconducting wires• MgB2 superconducting wires• JET reference CFC materials: DMS780 / NB31• NDT inspection of tungsten coating uniformity• NDT inspection of CFC / Cu/CuCrZr interfaces

INFLPR experience in X-ray microCT for NDT inspection of fusion materials

UPGRADED: INFLPR X-RAY nano-CT FACILITY

• X-ray source– 10 - 225 kV– Focus spot < 0.8 m

• Detector– a-Si flat panel – 1210 x 1216 pixels– 0.1 x 0.1 mm2

• Six-axis, high precisionmanipulator

• Magnification factor ≤ 2000

Resolution benchmark: JIMA Mask (< 0.4 µm)

Recently, the X-ray tube has been upgraded to state of the art nanofocus 225 kVp.

Gold foil spiral (foil thickness – 5 µm)Micro Resolution Chart for X-ray 0.4-15 µm

Cross-section through the X-ray microtomography reconstruction and corresponding picture of the

irradiation capsule, shown as a CAD model

Tomographic cross-section illustrating the gap (lack of thermal contact) between the heater coil and the groove channel.

Tungsten wire Heater clad Groove

Details are clearly visible as, for example, the heater tube (1 mm diameter) with interior tungsten wire (100 m diameter).

X-ray transmission micro-tomography inspection of non-

irradiated HFTM capsule(designed and manufactured at FZK)

The absolute error of geometrical measurements is sufficient for the assessment of the structural integrity of the irradiation capsule and for the geometry description of the thermal-hydraulic modeling.

I. Tiseanu, M. Simon, T. Craciunescu, B. N. Mandache, Volker Heinzel, E. Stratmanns, S. P. Simakov, D. Leichtle. Assessment of the structural integrity of a prototypical instrumented IFMIF high flux test module rig by fully 3D X-ray microtomography. Fusion Engineering and Design, 82, p. 2608–2614, 2007.

samples with similar composition and even larger dimensions than the HFTM rig

braze by nickel based filler metals used to high temperature base metals as in the HFTM rig.

ITHEX experimental facility (FZK)

dedicated to thermal-hydraulic investigations concerning mini-channel geometries as applied in IFMIF.

several mini-channel test sections are investigated in order to optimize the HFTM helium cooling technology.

the mini-channel test sections can be heated by electrical heaters and are instrumented with thermocouples to measure the temperature distribution.

Brazing quality assessment

30 mm

Brazing structure

Thermocouples and heater wires

WP10-PWI-01-02-01/MEdC/BS/PS X-ray micro-tomography studies CFC samples for porosity network characterization

• Participation at DITS project - post mortem analysis by providing high

resolution tomography measurements on CFC samples

• Qualification of the initial porosity of the new CFC ITER reference

material NB41

• Porosity characterization of tungsten coated CFC samples

Determination of Focus spot size by:Micro Resolution Chart for X-ray 0.4-15 µm

X-ray source target materialFour different types of transmission targets have been tested:

1. the standard W target on aluminum window2. thin W target on beryllium window3. thin Mo target on beryllium window 4. W target on diamond window.

X-ray source target materialFour different types of transmission targets have been tested:

1. the standard W target on aluminum window2. thin W target on beryllium window3. thin Mo target on beryllium window 4. W target on diamond window.

High resolution tomography on CFC materials

Optimization of competing CT parameters:-Focus size as small as possible;-X-ray intensity as large as possible;-Energy spectra optimized for best absorption contrast;-High magnification for macroscopic samples.

Optimization of competing CT parameters:-Focus size as small as possible;-X-ray intensity as large as possible;-Energy spectra optimized for best absorption contrast;-High magnification for macroscopic samples.

Sample size: 10x10 mm2

Sample size: 4x4 mm2

Space resolution: 2.5 µm

High resolution digital radiography

CFC-DMS780

CFC-NB31

Sample size: 2x2x6 mm3

CFC-NB11

CFC NB31: High resolution tomography

Sample size: ≥ 4x4x4 mm3

Voxel resolution

2.5 µm

5 µm

14 µm

Offset tomography

The main challenge is posed by the required micron range of the spatial resolution for rather macroscopic samples.

CFC: High resolution tomography Sample size: ≥ 4x4x4

mm3

Voxel resolution: 6 µm

CFC-NB31 CFC-DMS780

Morphology differences

The detailed 3D morphology representation of statistically relevant volumes of CFC (up to 5x5x5 mm3) materials was used in order to:

•evaluate the porosity factor;•detect possible materials defects like non-homogeneity or high Z dust inclusions.

Central panel: an axial cross section on a NB31 CFC sample (voxel resolution 6.6 µm); Left panel: a cut through the main fiber direction along dotted red line;Right panel: the longitudinal cross section along the green solid line.One notes a distinctive feature of NB31- the tiny fibers (needling) somewhat randomly distributed and going perpendicularly to the main fiber direction.

Central panel: an axial cross section on a NB31 CFC sample (voxel resolution 6.6 µm); Left panel: a cut through the main fiber direction along dotted red line;Right panel: the longitudinal cross section along the green solid line.One notes a distinctive feature of NB31- the tiny fibers (needling) somewhat randomly distributed and going perpendicularly to the main fiber direction.

Morphology of the CFC sample by High resolution tomography

CFC NB31: 6 µm/voxel; porosity factor 8.05% CFC DMS780: 6 µm/voxel; porosity factor 9.41%

Quantitative evaluation of the CFC porosity factor

A procedure for a quantitative evaluation of the sample porosity factor has been introduced and tested. For example for CFC NB31 and CFC DMS780 we obtained porosity factors of 8-10%; in good agreement with the manufacturer specifications

Q4-C and Q3-CQ4-C and Q3-C

Two sort of CFC: NB11-92 and NB11-98Two sort of CFC: NB11-92 and NB11-98

Deuterium Inventory in Tore Supra (DITS) post mortem analysis• sample cutting plan

finger no

tile no

quarter

part

weight in g

Deposit type Cfc type

Serial number

5 4 3 C 0.0367 erosion N11-92 S3325 4 4 C 0.0347 erosion N11-92 S3325 9 3 C 0.0315 thick N11-92 S3325 9 4 C 0.033 thick N11-92 S33210 9 3 C 0.0387 thin,

shadowedN11-92 S259

10 9 4 C 0.0359 thin, shadowed

N11-92 S259

10 20 3 C 0.0388 thin, shadowed

N11-92 S259

10 20 4 C 0.0341 thin, shadowed

N11-92 S259

26 16 3 C 0.0366 erosion N11-98 S52426 16 4 C 0.0403 erosion N11-98 S524

Cu & porosity

Only Cu porosity

Deuterium Inventory in Tore Supra (DITS) post mortem analysis• Overview experiment

Cu brazed CFC NB11: - pattern of Cu “filaments” along the fiber interspaces

Cu brazed CFC NB11: - pattern of Cu “filaments” along the fiber interspaces

Sample size: ≥ 2x2x6 mm3

Sample: CFC NB11F10 T20 Q3/4 P C

CT parametersU=60kV, I=175 µATarget: WFocus spot size: <2.0 µmVoxel resolution: 8.0 µm

OverviewexperimentOverviewexperiment

Deuterium Inventory in Tore Supra (DITS) post mortem analysis• Quantitative evaluation of the CFC porosity factor

porosity factor ~12.5%

Sample: CFC NB11F10 T20 Q3/4 P CSample: CFC NB11F10 T20 Q3/4 P C

CT parametersU=80 kV, I=150 µATarget: MoFocus spot size: <1.5 µmVoxel resolution: 2.75 µm

CT parametersU=80 kV, I=150 µATarget: MoFocus spot size: <1.5 µmVoxel resolution: 2.75 µm

Morphology:Bright regions: CuStrong connectivity of the pores along main fiber direction

Morphology:Bright regions: CuStrong connectivity of the pores along main fiber direction

Deuterium Inventory in Tore Supra (DITS) post mortem analysis• Investigation of the Cu heat sink region

Sample: CFC NB11F5 T9 Q3/4 P C

CT parametersU=90kV, I=200 µATarget: MoFocus spot size: <1.5 µmVoxel resolution: 2.75µm

Morphology:oStrong connectivity of the pores along main fiber directionoPores “coated” by TioTi penetrated up to 1.6 mm?role of Ti in D retention?

Morphology:oStrong connectivity of the pores along main fiber directionoPores “coated” by TioTi penetrated up to 1.6 mm?role of Ti in D retention?

Deuterium Inventory in Tore Supra (DITS) post mortem analysis• Quantitative evaluation of the CFC porosity factor

Sample: CFC NB11F5 T9 Q3/4 P CSample: CFC NB11F5 T9 Q3/4 P C

CT parametersU=75 kV, I=250 µATarget: MoFocus spot size: <1.5 µmVoxel resolution: 2.75 µm

CT parametersU=75 kV, I=250 µATarget: MoFocus spot size: <1.5 µmVoxel resolution: 2.75 µm

Morphology:Strong connectivity of the pores along main fiber direction

Morphology:Strong connectivity of the pores along main fiber direction

porosity factor ~10%

Sample: CFC NB11F26 T16 Q3/4 P CSample: CFC NB11F26 T16 Q3/4 P C

CT parametersU=95 kV, I=180 µATarget: MoFocus spot size: <1.5 µmVoxel resolution: 2.75 µm

CT parametersU=95 kV, I=180 µATarget: MoFocus spot size: <1.5 µmVoxel resolution: 2.75 µm

Morphology:Metallic structures present in the gaps between the main fibersBright regions: CuGray regions: Ti

Morphology:Metallic structures present in the gaps between the main fibersBright regions: CuGray regions: Ti

Deuterium Inventory in Tore Supra (DITS) post mortem analysis• Investigation of the Cu heat sink region

Sample: CFC NB11F26 T16 Q3/4 P C

Morphology:Metallic structures advance along main fiber direction interspaces up to 3 mm!Bright regions: CuGray regions: Ti

500 1000 1500 2000 2500

0

300

600

900

Scatteringgraphite

Mo target

Cu

PH

Achannel

Ti

Cu Ti

X-ray µbeam fluorescence

Computer tomography (µCT) systems are configured to take many views of the object in order to build a 3-D model of its internal structure. For the NDT inspection of miniaturised samples the microtomography analysis is guaranteed for feature recognition down to a few tens of microns. 3-D tomographic reconstructions are obtained by a proprietary highly optimized computer code based on a modified Feldkamp algorithm.

Computer tomography (µCT) systems are configured to take many views of the object in order to build a 3-D model of its internal structure. For the NDT inspection of miniaturised samples the microtomography analysis is guaranteed for feature recognition down to a few tens of microns. 3-D tomographic reconstructions are obtained by a proprietary highly optimized computer code based on a modified Feldkamp algorithm.

The microbeam fluorescence (µXRF) component is a configurable film thickness and composition measuring tool. Main components: optical X-ray beam collimation options, a PIN diode X-ray detector, motorized micrometric x-y-z stage for accurate sample positioning.

The microbeam fluorescence (µXRF) component is a configurable film thickness and composition measuring tool. Main components: optical X-ray beam collimation options, a PIN diode X-ray detector, motorized micrometric x-y-z stage for accurate sample positioning.

Tomo-Analytic

WP10-PWI-05-02-02/MEdC/PS - “X-ray microbeam absorption/fluorescence method as a non-invasive solution for investigation of the erosion of W coatings on graphite/CFC”

Conclusion and future work

• High resolution cone beam tomography has been optimized for CFC samples• High resolution cone beam tomography has been optimized for CFC samples

We would like to apply the method:• on the new NB41 ITER reference CFC samples;• on the tungsten coated CFC samples.

We would like to apply the method:• on the new NB41 ITER reference CFC samples;• on the tungsten coated CFC samples.

Current space resolution: ~ 2.5 µm

Target ~ 1 µm !

• A procedure for a quantitative evaluation of the sample porosity factor has been developed and applied on relevant CFC materials.• A procedure for a quantitative evaluation of the sample porosity factor has been developed and applied on relevant CFC materials.

The potential of multi-energy tomography techniques to improve the quality of the density resolution of the reconstructed images would be assessed.

• Activities on the microtomography characterization of the Tore Supra CFC samples have been initiated. Main focus: improve the accuracy of the porosity factor measurements!

SEWG meeting on „Gas balance and fuel retention“, July 2010