Abstract
A lot of contaminated wastes have been produced by decontamination works at contaminated areas around Fukushima prefecture, Japan, and piled up at temporary storage sites. At some temporary sites, it was found that leaching water was accumulated under stacks of contaminated “plant” wastes and contained radioactive cesium. To handle the wastes and the solution properly, decontamination tests of the leaching water were examined with molybdophosphate type cesium adsorbents synthesized by radiation-induced graft polymerization method. At batch adsorption tests, 75% of radioactive cesium was successfully removed with radiation graft cesium adsorbents. At column adsorption tests, radioactivity concentration of the leaching water could be reduced under 75 Bq/L as an indication of the provisional limit value up to around 500 times volume as large as an adsorbent volume. Moreover, brownish-red color of leaching water was succeeded to be decolored by amine type radiation graft adsorbents for water discharge. For development of volume reduction method of contaminated plant wastes, radioactive cesium extraction tests from the wastes and removal tests from the extracts were executed using contaminated oil cakes of sunflower seeds as a model of contaminated plant wastes. As a result, 65% of radioactive cesium was successfully extracted from the oil cakes to liquid phase, and more than 65% of radioactive cesium could be collected from the extract by radiation graft cesium adsorbents. These results showed a possibility of an application of these processes to volume reduction method for contaminated plant wastes.
