Tritium diffusion in nonmetallic solids of interest for fusion reactors. Annual progress report, August 1, 1975--August 1, 1976

Tritium diffusion coefficients have been measured in a number of nonmetallic solids which have potential use as diffusion barriers or protective coatings in fusion reactors. Results have been obtained for various forms of alumina, beryllia, yttria, silicon carbide, boron carbide, glass, and pyrolytic carbon. The method of measurement involved tritium injection into solids followed by measurements of tritium release rates during heating. Measured diffusion values were significantly below the hydrogen diffusion coefficients determined for metals so nonmetallics would appear to have potential for being effective tritium barriers. Preliminary hydrogen solubility measurements were carried out for alumina and silicon carbide by measuring the amount of dissolved deuterium which was released from equilibrated specimens during heating. The technique appears to be a satisfactory means for determining temperature and pressure effects on solubility. Solubility information should be useful in determining both tritium inventories and permeation rates in CTR blanket components