Structural refinement and dispersion of high level radioactive contaminated soil processing by chemical interface controlled and high-speed shearing washing technique

Chemical interface controlled dispersion and high-speed shearing water washing tests were implemented for the purpose of optimization of processing conditions with highly radioactive contaminated soils of over 570,000 Bq/kg in Fukushima and the following results were obtained. (1) Dispersion and miniaturization of the radioactive contaminated soil over 570,000 Bq/kg was enhanced in alkalized washing solution and optimization of pH control is required according to soil characteristic. >From these results, it is recommended that pH 10.5, 10.7 and 11 are optimized pH for soil B, C and A, respectively. (2) Refinement of contaminated soils was also promoted by collision of contaminated soil particles toward washing machine walls and inter-particle collision during soil washing process and remarkable washing performance was achieved under the combination of dispersion and high-speed shearing washing condition with 50% (maximum) solid density in wash solution and for 1 h operation at least. (3) Remarkable well-ordered structural refinement and accumulation of the contaminated soil particle group with strong FP confinement were observed at the particle size under 10 µm after crack/washing process. (author)