Patent Number: 
Section: claims

1. A method for retaining ruthenium within a vitrified product obtained by a vitrification of a nitric acid aqueous solution stemming from a reprocessing of radioactive liquid effluents, the nitric acid aqueous solution comprising radionuclides including ruthenium, the vitrification comprising:a) calcining the nitric acid aqueous solution to form a calcine;b) mixing the calcine with a glass frit;c) heating the mixed calcine and glass frit until a molten mixture is obtained; andd) cooling the molten mixture to form the vitrified product in which the radionuclides including ruthenium are included;wherein the method comprises, before a), adding to the nitric acid aqueous solution a composition comprising a lignin, a lignocellulose, a salt thereof or a mixture thereof wherein the content of the lignin, the lignocellulose, the salt thereof or mixture thereof is more than 70% by mass based on the mass of the composition. 2. A method for manufacturing a vitrified product by vitrifying a nitric acid aqueous solution stemming from a reprocessing of radioactive liquid effluents, the nitric acid aqueous solution comprising radionuclides including ruthenium; the method successively comprising:a) adding to the nitric acid aqueous solution a composition comprising a lignin, a lignocellulose, a salt thereof or a mixture thereof wherein the content of the lignin, the lignocellulose, the salt thereof or mixture thereof is more than 70% by mass based on the mass of the composition;b) calcining the nitric acid aqueous solution, thereby obtaining a non-tacky calcine;c) mixing the non-tacky calcine with a glass frit;d) heating the mixed non-tacky calcine and glass frit until a molten mixture is obtained; ande) cooling the molten mixture to form a vitrified product in which the radionuclides including ruthenium are retained.