Fusion Science and Technology / Volume 47 / Number 4 / May 2005 / Pages 844-850
Technical Paper / Fusion Energy - Fusion Materials
Tritium permeation can be significantly reduced by a suitable barrier on the structural materials of a future fusion power plant. Since alumina has the capability of tritium permeation reduction, the development of such coatings on ferritic martensitic steels by different techniques like hot-dip aluminizing (HDA) by Forschungszentrum Karlsruhe, Germany (FZK) and chemical vapor deposition (CVD) by Commissariat a l'Energie Atomique, France (CEA) was funded by the European Commission (EC) during the last 10 years. The final objective was to identify a so-called reference coating for structural components of a lithium-lead cooled blanket.
This paper describes the process specifications and the results of the corresponding hydrogen permeation measurements, performed at ENEA, Brasimone, Italy. The results for CVD and HDA coating showed clearly, that Permeation Reduction Factor's (PRF) of >1000 were sufficiently exceeded in H2 gas, but much lower values were obtained in the Pb-17Li melt. The post mortem analysis revealed that surface imperfections and spallation of parts of the coatings were responsible for the too low PRF's. Because of shifting of priorities and changes in the blanket design from WCLL to HCLL, the EU funding of all major R&D activities was postponed in 2002 until the redesign of the European Blanket Concepts was finished.