The fact that the radioactive cesium (* 1) released in the accident at the Fukushima Daiichi Nuclear Power Station is adsorbed by the biotite in the granite to the weathered biotite (* 2) that has been altered by many years of wind and rain, is the University of Tokyo Graduate School. It was confirmed by a research group of Hiroki Mukai, a specially appointed researcher at the Graduate School of Science, and Toshihiro Kogure, an associate professor.It is likely to attract attention with its epoch-making discovery that is expected to greatly contribute to the research and development of measures against radioactive contamination in the future.
According to the University of Tokyo, the research group finely placed various minerals with a size of several tens of microns, which are thought to be present in the soil of Fukushima, on the substrate in order to reproduce the adsorption of radioactive cesium soil after the accident.A solution containing very low concentration of radioactive cesium was dropped there, and the amount adsorbed on each mineral was measured by a radiation recording medium.
As a result, it was found that radioactive cesium is concentrated and adsorbed on weathered biotite.Moreover, it was clarified that the radioactive cesium adsorbed on the weathered biotite was not eluted unless the acid was strong enough to dissolve the mineral itself, whereas the radioactive cesium adsorbed on other minerals was easily eluted. I did.
The researchers believe that low concentrations of radioactive cesium will not easily elute into the environment if they are washed away by rainfall and strongly fixed to weathered biotite.The amount of weathered biotite contained in the soil is largely related to the outflow of radioactive materials.
Decontamination work is still underway in Fukushima, but the results of this study are likely to have a major impact on the long-term diffusion and migration prediction of radioactive materials.
* 1 Radioactive cesium A general term for the radioactive isotopes 137Cs and 134Cs of cesium formed by the nuclear fission reaction in a nuclear reactor.
* 2 Weathered biotite A black sesame-like biotite found in granite that has been altered by the weather.Also known as vermiculite.