Medical, industrial and research laboratories using RI (RI waste)

Radioactive liquid and solid wastes from utilization of RI are exclusively collected and treated by the Japan Radioisotope Association. Organic liquid waste and flammable solid wastes are treated by incineration, and stored in suitable containers. Inflammable solid wastes are compressed with a compactor, and placed in 200 L drums.

Technological development

Development of treatment technology for liquid wastes is mainly aimed at solidification of the concentrated liquid waste to reduce the product volume ratio. Cementation technology was originally adopted while bituminization, plastic solidification with unsaturated polyester resin, and improved cemen­tation technologies were developed later. The latest solidification treatment adopts the dry-pelletizing method combining a film evaporator and a granu­lator. The resulting granules are mixed with Portland cement and solidified in 200 L drums. This method gives a high waste volume reduction compared to the early cementation method.

Technology development of solid waste treatment has largely focused on incineration technology and volume reduction technologies for miscellane­ous waste. Incineration for chlorine-containing materials including PVC using an incinerator with a water-cooled cylindrical chamber has been developed. This incinerator has an off-gas system as a countermeasure against dioxin. An incinerator with an ash melting system has also been developed with a high temperature chamber to burn and melt simultane­ously or an incinerator and a separate melting furnace. This type of incin­eration system can treat flammable and non-flammable materials producing slug granules with high volume reduction ratio.

For non-combustible wastes, super-compaction technology and melting technology have been developed. A super-compaction system with over 10 MN compressive force has been developed using a triaxial compressive or a uniaxial compressive machine with a drawing mould for direct encapsulation to 200 L storage drums. Both high-frequency induction or plasma heating furnaces are used in NPP for melting. The high-frequency induction furnaces use a disposable crucible, which can be placed directly in a 200 L drum. Some treatment technologies such as vitrification, steam reforming, etc., for iodine filters and ion-exchange resins are under development.

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