Treatment of spent ion exchange resin

Ion exchange resins are generally used for treating radioactive water in atomic power facilities. Such resins are mainly composed of copolymers of styrene and divinylbenzene. In the form of granule or powder, these resins are chemically stable and difficult to treat or disposed of. Investigation and testing have been carried out in an effort to utilize microwaves for volume-reduction treatment of spent ion exchange resins discharged in great amounts from radioactive water processing facilities. An apparatus is developed which can effectively perform heating, combustion and volume reduction of resins. Granules of silicon carbide is used as the material for the moving b-d since it has good microwave-absorbing properties as well as high temperature resistance and thermal conductivity. The granules are mechanically stirred during operation to increase the heating efficiency. A required volume of granular or powdered ion exchange resin is fed after the furnace temperature reaches about 600 ∼ 700 deg C. This process is found to be very efficient compared to direct application of microwaves to waste resins. Exhaust gas generated in the furnace is processed subsequently in the secondary furnace. The inner wall of the secondary furnace also consists of silicon carbide to promote absorption of microwaves. It has been shown that the furnace temperature can be increased over 100 deg C. It is also found possible to perform quick control of the temperature and combustion process and to carry out combustion of fire resisting waste materials. (Nogami, K.)