forschungszentrum karlsruhe in der helmholtz-gemeinschaft fusion iter tbm project meeting, february...
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Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Review of Tritium Permeation Barrier Development for Fusion Application in
the EU J. Konys
• Introduction• Experimental * Process parameters of HDA (FZK) and CVD (CEA) techniques
• Results * Permeation data of HDA and CVD barriers
• Conclusions
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Introduction (1)
Why do we need TPB’s (Tritium Permeation Barriers)?
To reduce the Tritium release into the cooling water significantly (this was part of the WCLL blanket concept) EU Fusion Technology program selected Fe-Al-based coatings with Al2O3 as a thin top layer
First phase in EU (up to ca. 1998): 3 coating processes have been selected
Chemical vapour deposition (CVD) CEA Grenoble (F) Vacuum plasma spraying (VPS) JRC Ispra (I) Hot-dip aluminizing (HDA) FZK Karlsruhe (D)
The preparation procedures and characterization of each coating were summarized in reports until about end of 1998
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Second phase in EU (up to ca. “2002”):
Several qualification tests were strongly required for the final
selection of a so-called “reference coating”!
Measurement of the hydrogen permeation rate in the gas
phase
Measurement of the hydrogen permeation rate in Pb-17Li ?
Self-healing tests in Pb-17Li
Irradiation experiments of the coatings
Compatibility studies of coatings in flowing Pb-17Li at relevant
temperatures
Introduction (2)
Nevertheless, this phase is not really finished!!
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Experimental (1)
Hot-dip aluminizing process at FZK (simplified scheme)
Steel sample
(sheet or tube) Grinding Cleaning in
acetoneCoating, aq. flux-solutionPre-drying : 100°C
Glove-box (Ar-5%H2)
Hot-dip-aluminizing, 700°C
Cleaning in water
Heat treatment
(standard process)
HIP-process
(advanced process)
Coated sample
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Experimental (2)
Al2O3 - crucible
Sample
Steel tube
Al-melt
Furnace
Coating conditions
Temperature: 700°CMelt: Al or Al-SiSample dimensions: up to 200 mm in length
up to 40 mm in diameter
Hot-Dipping Facility
Ar-5% H2Glove-box
Furnace
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Experimental (3)
Hot-Dip aluminizing process
Parameters for hot dipping are: temperature at 700°C and dipping time of 30 s
Microstructure of hot dipped surface
The alloyed surface layer consists of brittle Fe2Al5, covered by solidified Al
Microstructure after heat treatment
Heat treatment at 1040°C/0.5 h + 750°C/1 hincorporates the solidified Al and transforms the brittle Fe2Al5-phase into the more ductile
phases FeAl and -Fe(Al)
FeAl
-Fe(Al)
F82H-mod.
HV 320
270
240F82H-mod.
Fe2Al5
AlHV 1000
230Kirkendall pores
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
FeAl
-Fe(Al)
F82H-mod.
HV 320
270
240
Hot-Dip aluminizing process
Parameters for hot dipping are: temperature at 700°C and dipping time of 30 s
Microstructure of hot dipped surface
The alloyed surface layer consists of brittle Fe2Al5, covered by solidified Al
Microstructure after heat treatment
Heat treatment at 1040°C/0.5 h + 750°C/1 hand an applied pressure of >250 bar (HIPing)reduces porosity and transforms the brittleFe2Al5-phase into the more ductile phases FeAland -Fe(Al)
F82H-mod.
Fe2Al5
AlHV 1000
230
Experimental (3)
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Experimental (4)
The hot-dipping process is compatible with heat treatment of the steel, including HIP process (if required for densification of Kirkendall pores)
The oxidation process to form alumina is included in the heat treatment
The hot-dip coating is good adhering to the steel, is dense and ductile enough
A reduction of tritium permeation rate in H2 gas by more than 3 orders of
magnitude can be achieved
Corrosion attack by Pb-17Li ........ see presentation of tomorrow
Hot-dip aluminization is a well-established industrial technology (at least for low-alloyed carbon steels)
Main characteristics of the Hot-dip aluminizing coating
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Chemical vapour deposition (CVD) by CEA
Industrial established 2-step process
Fe-Al coating
• Powder mixture: Fe-Al, NH4Cl and Al2O3
• T = 650-750°C, p < 10 mbar Ar, t = 1-5 hours
Al2O3 deposition
• MOCVD process (metalorganic precursor)
• T = 400-500°C, t = 1-2 hours
Experimental (5)
Al2O3
Fe-Al
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Vacuum plasma spraying (VPS) by JRC Ispra
Industrial established process
Al coating
• Powder: Al 54 from Metco
• Sand blasting before coating, then final sputter cleaning in vacuum apparatus
• Tsubstrate = 230-250°C
• Pressure: < 10-4 Pa
• Spraying distance: 220 mm
• Heat treatment necessary to transform the sprayed Al-layer into iron-aluminide
Experimental (6)
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
T (°C) VPS HDA CVD
300 450 3100 3100
350 400 2800 2100
400 380 1500 1600
450 380 2400 1300
pH2= 1 bar, steel: F82H-mod.
Results of permeation testing in H2–gas in different facilities
at ENEA Brasimone, Italy (PERI, CORELLI)
Permeation Reduction Factors (PRF)
Results (1)
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
T (°C) VPS HDA CVD
300 450 3100 3100
350 400 2800 2100
400 380 1500 1600
450 380 2400 1300
Results of permeation testing in H2–gas in different facilities
at ENEA Brasimone, Italy (PERI, CORELLI), 1998-2000
Permeation Reduction Factors (PRF)
pH2= 1 bar, steel: F82H-mod.
cancelled
Results (1)
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Results (2)
Permeation data of HDA-coated FM-steels in H2 and Pb-17Li
Ispra
uncoated disk and tube
coated disk and tube
PRF 2000
PRF 100
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Results (3)
VIVALDI facility at ENEA, Brasimone, Italy, 2001-2003
Eurofer tube, one end closed
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Permeation tests in VIVALDI facility
The coated samples were tested in sequence and compared with the bare sample, both placed together in the permeation chamber.
Hydrogen gas at a known fixed pressure of 1 bar was released into the permeation chamber. The gas permeated through the samples and caused a pressure rise in the inner calibrated volumes.
This pressure rise could be converted into an amount of moles of gas permeating per unit area of the samples.
By comparing the steady state fluxes of the coated and bare samples, one could calculate the Permeation Reduction Factor PRF.
Results (4)
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Permeabilities of CVD-coated tubes in H2-gas
Results (5)
1,3 1,4 1,5 1,6 1,7 1,8
1E-12
1E-11
CVD 1 T increase CVD 2 T increase CVD 1 T decrease CVD 2 T decrease Reference specimen Disk shaped sample
(m
ol m
-1s-1
Pa-1
/2)
1000/T (1/K)
750 700 650 600 550
T (K)
PRF 6
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Results (6)
Permeabilities of HDA-coated tubes in H2-gas
1,3 1,4 1,5 1,6 1,7 1,8
1E-14
1E-13
1E-12
1E-11
1E-10
(
mol
m-1 s
-1 P
a-1/2)
HD T increase HD T decrease Reference Disk shaped sample
1000/T (1/K)
750 700 650 600 550
T (K)
PRF 140
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Results (7)
Comparison of permeabilities of CVD-coated tubes in H2-gas and Pb-17Li
1,35 1,40 1,45 1,50 1,55 1,60 1,65 1,70 1,75
1E-13
1E-12
1E-11
1E-10 CVD 2 gas phase CVD 2 liquid metal T increase CVD 2 liquid metal T decrease Reference in gas phase Reference in liquid metal phase Disk shaped sample in gas phase
(m
ol m
-1s-1
Pa-1
/2)
1000/T (K-1)
450 400 350 300
T (°C)
PRF 15
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Results (8)
Pb17Li
Comparison of permeabilities of HDA-coated tubes in H2-gas and Pb-17Li
1,3 1,4 1,5 1,6 1,7 1,81E-14
1E-13
1E-12
1E-11
1E-10
HD T increase HD T decrease HD T increase 2 Ref T increase Ref T decrease Disk shaped sample HD in gas phase
(m
ol m
-1s-1
Pa-1
/2)
1000/T(1/K)
700 650 600 550T (K)
PRF 15
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Results (9)
Reasons for too low PRF’s in Pb-17Li
HDA sample
CVD sample
cracks
bad coating quality
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Conclusions
Conclusions (1)
A large R&D activity regarding the development of coating techniques for TPB‘s was launched in the EU during the last 10 years.
Fe-Al-type coatings were identified as potential materials for TPB‘s and partly qualified in the gas phase. They fulfill the requirement of PRF 1000. CVD and HDA process were selected as possible candidates for being the “reference coating“ for TPB‘s. A final selection between both coatings has not yet been made.
The low PRF‘s in Pb-17Li (required was a PRF 75) obtained in the VIVALDI experiments, demonstrated a distinct sensitivity of PRF to the coating quality.
Nevertheless, the reason for the too low PRF‘s in the presence of Pb-17Li is not really known or understood. A reaction of Al2O3 to form LiAlO2 is discussed in literature, but not believed to explain the current results.
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Conclusions
Since 2001/2002, no further development regarding coating techniques was made, (either at CEA nor at FZK) because “design people“ decided to live without TPB‘s in the (at that time) existing WCLL blanket concept.
Therefore, no more funding from the EU was available. Only a small budget for the permeation measurements at ENEA Brasimone, Italy, was launched.
In 2003, a change from WCLL to HCLL blanket concept was made, due to budget restrictions in the EU.
In the new HCLL concept, temperatures up to 550°C (or maybe higher) are envisaged in the “Pb-17Li area“ of the blanket structure. This was or is the return of the necessity of coatings for the reduction of tritium permeation into the coolant (He) and also for so-called“ corrosion barriers“, because of the increasing dissolution corrosion of structural steels in high-temperature Pb-17Li.
Nevertheless, a new programme for the continuation of the TPB/corrosion barrier development is not decided for funding in the EU at the moment.
Conclusions (2)
Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftFUSION
ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys
Contributions to this work
FZK (Germany)J. Konys, H. Glasbrenner, K. Stein-Fechner, Z. Voss, O. Wedemeyer
CEA (France)C. Chabrol, A. Terlain ENEA (Italy)G. Benamati, A. Aiello, I. Ricapito
JRC Ispra (Italy)A. Perujo