Methodology of safety evaluation about land disposal of low level radioactive wastes

Accompanying the progress of the construction project of low level radioactive waste storage facilities in Aomori Prefecture, the full scale land disposal of low level radioactive wastes shows its symptom also in Japan. In this report, the scientific methodology to explain the safety about the land disposal of low level radioactive wastes is discussed. The land disposal of general wastes by shallow burying has already had sufficient results. In the case of low level radioactive wastes, also the land disposal by shallow burying is considered. Low level radioactive wastes can be regarded as one form of industrial wastes, as there are many common parts in the scientific and theoretical base of the safety. Attention is paid most to the contamination of ground water. Low level radioactive wastes are solid wastes, accordingly the degree of contamination should be less. The space in which ground water existes, the phenomena of ground water movement, the phenomena of ground water dispersion and Fick's law, the adsorption effect of strata, and the evaluation of source term are explained. These are the method to analyze the degree of contamination from safety evaluation viewpoint. (Kako, I.)