The study was conducted in order to determine the immobilization performance of low-level tritium waste in new cement mixtures. The grouts analyzed are fine mortars, fluid, self- compacting, with flowability, able to fill the smallest gaps in the solid waste container. The grouts curing showed compact and structural integrity without pores and cracks, so as to ensure radioactive tritium waste encapsulation.

Two types of solid/liquid tritium radioactive waste with known tritium activity have been prepared: one type containing a hydrophilic tritium compound and the other one a hydrophobic tritium compound.

The tritium waste was mixed with three different types of grout and poured in a cylindrical mould. The leaching of tritium from waste solidified/encapsulated in the cement mixtures immersed in an aqueous environment has been studied in order to select the most appropriate grout type as waste immobilization matrix.

Samples from the liquid surrounding the cements blocks were collected at predetermined time intervals and placed in the liquid scintillation cocktail and measured. The activity of the tritium released was then calculated.