Abstract
This paper describes a required initial performance of the low diffusion layer in sub-surface radioactive waste disposal facility which will be constructed firstly in Japan after carry in out a full-size model test by a general method of construction with selected materials and mix proportion. Field demonstration tests conducted by using full-size models are described in order to confirm the actual constructoin peformance on site under 100m deep land level and the crack control effect of the low diffusion layer with the mix proportion selected from the laboratory tests. It was demonstrated that the design procedure for the materials and mix proportion was evaluated as being appropriate and the low diffusion layer could exhibit the required initial performance such as compressive strength, Young modulus of elasticity, void content, effective diffusion coefficient of tritium and the crack generating situation. A calculating method is also proposed for the effective diffusion coefficient of tritium.
