Development of ceramic coatings for fission product retention in ceramic fuels.

A general discussion on glaze—type coatings for fission product retention within BeO spheres fuelled with PuO2 - ThO2 particles is presented. From these considerations, a glaze thickness of 0.004 inch was chosen as a basis for laboratory studies. Glaze development commenced with a conventional high temperature glaze; this was modified firstly by increasing the SiO2 content and then by progressively replacing some of the SiO2 by Ti02, Zr02. Ti02 - Zr02, BeO2 and BeO plus Ti02. Glaze structures varied from amorphous to predominantly crystalline. When applied to fuelled BeO cubes, some glazes failed to cover fuel particles and others tended to react with them, Two of the most promising glazes behaved poorly in fission product release experiments, probably because glaze—fuel interaction had allowed fuel migration to the glaze surface-It is concluded that glaze type coatings show little promise for the present applications