AN EXPERIMENTAL STUDY LIQUID RADIOACTIVE WASTE TREATMENT PROCESS USING INORGANIC ION EXCHANGER

摘要

Using commercial inorganic, organic sorbents and activated carbons, the treatment of low level liquid radwaste in nuclear power plant was studied. The batch, column and pilot test were performed using simulants and actual liquid radwaste. The tests were focused on the removal capacity of the sorbents under sodium ion concentration since the liquid radwaste commonly contains a large amount of sodium ion which may affect the removal capacity of ion exchangers. The target ions to remove with sorbents were radionuclides such as Co-58, Co-60, Cs-134, and Cs-137 which are the major species in the liquid radwaste. The fundamental experiments showed that the inorganic sorbents and activated carbons have a better efficiency under sodium ion concentration for a cesium removal than a cobalt removal, whereas the organic resin is better for the cobalt removal. A new process for liquid radioactive waste treatment was proposed here based upon the experimental results. That is composed of a filter, activated carbon, inorganic ion exchanger, organic cation exchanger and organic anion exchanger in series. The process showed that the activated carbon was not effective for the cobalt removal, but had the ability to reduce the COD of liquid waste. The organic anion exchanger was used to control pH and to remove radioactive iodine if present. This combined process of using the inorganic ion exchanger was 4～8 times more effective than that of the conventional organic ion exchnager.