The Fukushima nuclear accident released radioactive cesium into the atmosphere, polluting the surrounding environment.Recent studies have revealed that some of the radioactive cesium released from the reactor was scattered while being contained in fine particles of several microns (μm) or less.Such fine particles are also called cesium balls, and since the concentration of radioactive cesium per particle is considerably higher than that of contaminated soil particles, there is a concern about local radiation effects on the vicinity of the particles.

　The research group focused on the fact that the silicate glass (ordinary glass) that composes these radioactive fine particles is a substance that can be dissolved in a liquid, although it is gentle, and using fine particle samples collected in the environment, the research group used them. The dissolution rate in pure water and seawater and its temperature dependence were determined.

　As a result, the dissolution rate in seawater is more than an order of magnitude faster than in pure water, and radioactive fine particles with a radius of about 10 μm at the seawater temperature in the coastal area of ​​Fukushima Prefecture are completely dissolved in about 1 years, and radioactive cesium is dissolved in the solution. It was confirmed that it would be released.However, the current concentration of radioactive cesium in seawater is less than the lower limit of detection (about XNUMX Bq / L), and it is considered that there is no effect on the environment due to dissolution.

　The results of this research will be important scientific findings for clarifying the radiation effects of radioactive cesium released by the Fukushima nuclear accident and the future transition of environmental pollution.

Paper information:[Scientific Reports] Dissolution behavior of radiocaesium-bearing microparticles released from the Fukushima nuclear plant