2022 Volume 78 Issue 2 Pages 128-139
The 2011 off the Pacific coast of Tohoku Earthquake affected severe damage to nuclear power plant in Fukushima. In the decommissioning of Fukushima Daiichi Nuclear Power Plant, fuel debris retrieval is a hard project because of scattering of radioactive materials, leakage contaminated water, and radiation exposure. To tackle those problems from the point of view of soil mechanics, super heavy bentonite slurry has been researched and studied. In the process of decommissioning, super heavy bentonite slurry may contact radioactive materials, and therefore, used slurry must be disposed as radioactive waste. However, disposal system of used super heavy bentonite slurry has not been established. Considering present radioactive waste disposal in Japan, it is desired that used slurry volume can be reduced and disposed according to the radiation level. The authors are attempting to built a disposal system with focusing on centrifugation in this study. This study measures the vertical distribution of constituent materials in centrifuged super heavy bentonite slurry by using methylene blue adsorption test. Results show following conclusions: i) The products of relative centrifugal acceleration and separation time may be essential element govering the amount of separating and collecting constituent materials from super heavy bentonite slurry by centrifugation. ii) Centrifugation is effective on separating and collecting of barite from super heavy bentonite slurry.
