Monolith matrix of calcium aluminate and gypsum—promising material for incorporating NaNO 3 -containing liquid radioactive waste

Possible applications of a new matrix were studied for incorporating radioactive aqueous NaNO 3 solutions arising at the nuclear fuel cycle enterprises. The matrix is formed by solidifying the solutions under study with cement consisting of a mixture of industrial calcium aluminate with gypsum. The compressive strength of the matrix was investigated as a function of the cement composition. The positive effect of sodium nitrate on the matrix strength was discussed and explained. As a result of the study, a matrix containing up to 24 wt.% NaNO 3 was obtained, meeting all the requirements imposed on the cemented radioactive waste.