2021 Volume 2021 Issue 8 Pages 55-65
The levels of radioactive cesium contamination in stored water and bottom sediment of irrigation ponds have been surveyed by governmental offices. They report radioactive cesium to have been detected in the water from a small number of ponds, and that,in some cases, radioactive cesium in the sediment significantly exceeded 8 kBq/kg. Experimental decontamination of the sediments and various research studies have revealed that radioactive cesium is mainly adsorbed on the surface layer of sediments and tends to bind strongly to clay particles and organic matter. In March 2014, the Ministry of the Environment announced the policy of carrying out decontamination of irrigation ponds. This was followed by rapid decontamination of ponds. In situ measurement technologies, such as the use of plastic scintillation fiber (PSF) and a pole sensors, have been developed that can find hot spots and count the vertical radioactivity distribution in sediment. The radioactive cesium concentration in sediments has been reliably decreased as a result of this decontamination project.
