Solidification method for radioactive waste

The present invention concerns a solidification method for radioactive wastes generated from a nuclear power plant. Kneading water and a cement type solidification material are supplied to a kneading vessel to produce a solidification paste. In this case, the specific gravity of wastes previously filled into a solidification container is measured, and light weighted aggregates are supplied to the kneading vessel by such an amount as required for controlling the specific gravity of the solidification paste equal or approximate to that of the pellets. The sufficiently kneaded solidification pastes are charged to the solidification container and aged for a predetermined period of time to be a solidification product. With such procedures, since the difference of the specific gravity between the solidification materials and the wastes can be reduced, the wastes can be prevented from rising. Further, since the weight of the solidification materials is reduced, the handling load can be mitigated. (I.N.)