METHOD FOR SOLIDIFYING RADIOACTIVE WASTE INCLUDING ACTIVE CARBON

PROBLEM TO BE SOLVED: To provide a method for producing an aggregated solid relating to radioactive wastes, in particular powdery active carbon, which can be efficiently and stably incinerated at a low cost, and to provide the aggregated solid.SOLUTION: The method for producing an aggregated solid includes: a water absorbing step of blending a radioactive waste slurry including powdery active carbon after the use in atomic energy-relevant equipment and a water absorber selected from a polyacrylic acid, a polyacrylic acid alkali metal salt, a polyacrylic acid alkaline earth metal salt, and cellulose-based fibers, at a ratio of 5 parts by mass of the water absorber to 100 parts by mass of a water content of the radioactive waste slurry to make the water absorber absorb remaining water in radioactive wastes; a combustible binder adding step of adding a powdery or granular combustible binder selected from petroleum wax, vegetable wax, Japanese wax, and white wax, which has a softening point equal to or lower than the boiling point of water and is solid at a room temperature, to a mixture of the radioactive wastes and the water absorber after water absorption at a ratio of 100 to 200 parts by mass of the combustible binder to 100 parts by mass of the radioactive wastes and blending them; a step of forming a mixture of the radioactive wastes, the water absorber, and the combustible binder after water absorption into a compact while keeping a temperature equal to or higher than the softening point of the combustible binder; and a cooling and solidifying step of cooling the compact to solidify it.