1. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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

2. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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 Al 2 O 3 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

3. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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!!

4. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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) GrindingCleaning in acetoneCoating, aq. flux-solution Pre-drying : 100°C Glove-box (Ar-5%H 2 ) Hot-dip-aluminizing, 700°C Cleaning in water Heat treatment (standard process) HIP-process (advanced process) Coated sample

5. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys Experimental (2) Al 2 O 3 - crucible Sample Steel tube Al-melt Furnace Coating conditions Temperature:700°C Melt:Al or Al-Si Sample dimensions:up to 200 mm in length up to 40 mm in diameter Hot-Dipping Facility Ar-5% H 2 Glove-box Furnace

6. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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 Fe 2 Al 5, covered by solidified Al Microstructure after heat treatment Heat treatment at 1040°C/0.5 h + 750°C/1 h incorporates the solidified Al and transforms the brittle Fe 2 Al 5 -phase into the more ductile phases FeAl and  -Fe(Al) FeAl  -Fe(Al) F82H-mod. HV 320 270 240 F82H-mod. Fe 2 Al 5 Al HV 1000 230 Kirkendall pores

7. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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 Fe 2 Al 5, covered by solidified Al Microstructure after heat treatment Heat treatment at 1040°C/0.5 h + 750°C/1 h and an applied pressure of >250 bar (HIPing) reduces porosity and transforms the brittle Fe 2 Al 5 -phase into the more ductile phases FeAl and  -Fe(Al) F82H-mod. Fe 2 Al 5 Al HV 1000 230 Experimental (3)

8. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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 H 2 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

9. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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, NH 4 Cl and Al 2 O 3 T = 650-750°C, p < 10 mbar Ar, t = 1-5 hours Al 2 O 3 deposition MOCVD process (metalorganic precursor) T = 400-500°C, t = 1-2 hours Experimental (5) Al 2 O 3 Fe-Al

10. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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 T substrate = 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)

11. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys T (°C)VPSHDACVD 3004503100 35040028002100 40038015001600 45038024001300 pH 2 = 1 bar, steel: F82H-mod. Results of permeation testing in H 2 –gas in different facilities at ENEA Brasimone, Italy (PERI, CORELLI) Permeation Reduction Factors (PRF) Results (1)

12. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys T (°C)VPSHDACVD 3004503100 35040028002100 40038015001600 45038024001300 Results of permeation testing in H 2 –gas in different facilities at ENEA Brasimone, Italy (PERI, CORELLI), 1998-2000 Permeation Reduction Factors (PRF) pH 2 = 1 bar, steel: F82H-mod. cancelled Results (1)

13. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys Results (2) Permeation data of HDA-coated FM-steels in H 2 and Pb-17Li Ispra uncoated disk and tube coated disk and tube PRF  2000 PRF  100

14. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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

15. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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)

16. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys Permeabilities of CVD-coated tubes in H 2 -gas Results (5) PRF  6

17. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys Results (6) Permeabilities of HDA-coated tubes in H 2 -gas PRF  140

18. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys Results (7) Comparison of permeabilities of CVD-coated tubes in H 2 -gas and Pb-17Li PRF  15

19. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION ITER TBM Project Meeting, February 23-25, 2004, UCLA Jürgen Konys Results (8) Pb17Li Comparison of permeabilities of HDA-coated tubes in H 2 -gas and Pb-17Li T (K) PRF  15

20. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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

21. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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 Al 2 O 3 to form LiAlO 2 is discussed in literature, but not believed to explain the current results.

22. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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)

23. Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft FUSION 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