Experimental study of microbial transport on bentonite sand mixture

Mine, Tatsuya; Mihara, Morihiro  ; Oi, Takao 

On the geological disposal system of the radioactive wastes, the activities of the microorganisms that could penetrate through the buffer material might be significant for the assessment of this system. In this system, it is expected that the bentonite sand mixture, which is a candidate material of the buffer material, has a function to prevent the penetration of the microorganism into the buffer material. The microbial activity that arises in the buffer material inside seems to affect transport behavior of nuclides. But the effect of the microbial activity may not be significant in the case that the number of the microorganism that exists in the buffer material inside is limited and that the microorganism can not penetrate through the buffer material. In this study, it was confirmed whether the microorganisms would penetrate through the bentonite sand mixture. The results show that the microbial transport would not occur easily under the condition which is more than 1200kg/m of dry density and less than 50wt% of silica sand contents of the bentonite sand mixture.