Patent Number: 045267120
Section: summary

BACKGROUND OF THE INVENTION This invention relates to a process for treating a radioactive waste, and more particularly to a process for treating a radioactive sludge waste suitable for reducing greatly in volume the waste such as radioactive sludge discharged from a nuclear power plant. In a nuclear power plant, granular ion-exchange resins mainly used for purifying a condensate, powder resins of filter aids mainly used for purifying a reactor water, filter sludge of filter aids comprising mainly cellulose used in a radioactive waste treatment system, etc. are wasted as so-called radioactive sludge waste. Since such a radioactive sludge waste has radioactivity, it is stored in a slurry state in storage tanks, or in a state caked with cement in drums. Storage of such a radioactive sludge waste in the slurry state causes serious problems such as corrosion of storage tank walls, etc., thereby making it difficult to store the radioactive sludge waste for a long time. Further, tanks of large capacity are required for storing the radioactive sludge waste. In storage of the radioactive sludge waste in the cemented state, a large number of drums are required for the storage because in order to obtain strength necessary to keep the cemented state or caked state an amount of the radioactive sludge waste to be mixed with cement is limited. For example, in a drum with capacity of 200 l, only 10.about.20 kg of the radioactive sludge waste which is about 30 l in volume can be filled, which means that the radioactive sludge waste of 30 l becomes a waste of 200 l. In order to reduce the volume of the radioactive sludge waste, various treatments therefor are tried, one of which is to burn up used granular resins and power resins, however these include a lot of water even after being subjected to centrifugal separation, so that complete combustion of the resins can not be effected. Another treatment for reducing the radioactive sludge waste is to make it powder and form the powder into pellets, which is described in Japanese Laying-open of Patent Application No. 52-94866 (1977). In this treatment, only about 150 kg of the radioactive waste can be filled in a drum of the capacity of 200 l. The reduction in volume is not enough. Therefore, a great reduction of the radioactive sludge waste in volume is desired strongly. SUMMARY OF THE INVENTION An object of the invention is to provide a process for treating a radioactive waste, wherein its volume is reduced greatly. Another object of the invention is to provide a process for treating a radioactive sludge waste, in which the radioactive sludge waste is reduced in volume effectively and greatly, and converted to a material which is easy in handling. Briefly stated, a feature of the invention comprises the steps of pulverizing a radioactive waste in a slurry state such as radioactive granular ion-exchange resins powder resins, filter sludge, etc. into dry powder which is combustible, burning the dry powder into ashes, and forming the ashes in blocklike articles which are easy to handle, such as pellets. By converting the radioactive waste in slurry into ashes through pulverizing and burning, the radioactive waste is reduced in volume greatly. Further, the ashes are converted into pellets which are easy to handle by pelletizing.