Candidate wasteforms for the immobilization of chloride-containing radioactive waste

Immobilization of special categories of radioactive wastes containing both actinide and chloride species is of increasing interest. In the present contribution we report the results of investigations into the feasibility of immobilizing these wastes by vitrification and solid state reaction between zeolite and calcium phosphate and the waste. We also report on the reactions between the ceramic wasteforms and various glass binders used to convert the powder wasteforms into a monolithic form as these can adversely effect the properties of the monolith, e.g. leach resistance. These reactions can result in a loss of chloride from the product due to the formation of a volatile chloride or the formation of the soluble phase halite. Methods for overcoming these undesirable reactions are discussed. It was shown that vitrification was not a suitable process for these wastes but that they could be incorporated into either zeolite 4A or calcium phosphate to produce powder wasteforms with chloride leach rates below 0.2 mg m−2 day−1.