Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
木村 駿; 武田 匡樹; 本島 貴之*
no journal, ,
Excavated damaged zone (EDZ) with changes in flow and transport properties induced by modification of hydraulic and mechanical properties could become short-circuit flow paths between a repository and the ground surface in the geological disposal of high-level radioactive waste. Hence, a sealing plug with slots that exceed the width of EDZ and filling the slots with clay material that has low hydraulic permeability is proposed as a countermeaure to prevent the flow of radionuclides through the tunnels and EDZ. Therefore, a small-scale experiment has been conducted to validate the performance in EDZ developing sedimentary rocks at the Horonobe Underground Research Laboratory. A circumference shape slot around a long borehole from the floor of the tunnel. Then, water-tight wall was constructed by filling with bentonite pellets. Results of hydraulic test in the long borehole show that the slot filling with bentonite pellet is effective to decrease hydraulic connectivity in EDZ for sedimentary rocks.
吉村 和也
no journal, ,
This study shows decreases in air dose rate and 
Cs activity on paved surface, which is a major radiation source in urban area, observed in urban areas 5-10 km far from the FDNPP. Air dose rate in Difficult-to-Return Zone, of which anthropogenic effects was ignorable, decreased faster in urban area than agricultural fields. The wash-off of radiocesium on paved surface was indicated to facilitate the decrease in air dose rate in urban area. The air dose rate in Specified Reconstruction and Revitalization Base Areas decreased faster than the other zones due to the decontamination, which reduced Cs activity on paved surface to less than about 20%. In areas where were not affected by decontamination, Residential Zone showed faster decreases in air dose rate and Cs activity on paved surface than the Difficult-to-Return Zone. This suggests that the anthropogenic effects other than the decontamination facilitate the decrease in air dose rate in urban areas.