Hitachi, Ltd.

Hitachi Engineering Services Co., Ltd.

Hitachi Nuclear Engineering Co., Ltd.

Hitachi Engineering Co., Ltd.

Yoshimasa Kiuchi

Tatsuo Izumida

Makoto Kikuchi

Shin Tamata

Takashi Nishi

Masami Matsuda

Hiroyuki Tsuchiya

Kenji Noshita

Ryozo Kikkawa

Takahiro Sanada

Yasuo Hattori

Shoichi Ouchi

The present invention relates to a method for treating radioactive laundry waste water generated from a nuclear power plant, nuclear fuel reprocessing plant, or radioactive nuclides handling facilities, and provides a method for treating the waste water safely and for reducing the volume of generated radioactive waste to a minimum. Radioactive laundry waste water containing a detergent of which major contents are a nonionic surface active agent and inorganic builders is concentrated by an evaporating concentrator, the concentrated waste water is dried and pulverized to dry powder by a rotary centrifugal thin film dryer, and the dry powder is incinerated. By using the above detergent, foaming at the concentration can be reduced, and the concentrated waste water can be easily dried and pulverized. Further, the dried powder can be incinerated stably and safely without influencing undesirable effect on the body of the incinerator. In accordance with the present invention, laundry waste water can be treated simply and safely, and the final volume of radioactive waste can be reduced to minimum.

Method for treating radioactive laundry waste water

An object of the present invention is to improve retainability (distribution coefficient) for C-14 of a radioactive waste solidified body. The waste is solidified with a solidification agent containing a soluble substance which yields an insoluble substance by a reaction with carbonic ions, insoluble carbonates, or a mixture of the above substances. And, as for a pre-treatment, the soluble substance which yields an insoluble substance by a reaction with carbonic ions is previously reacted with liquid waste, and subsequently the solidification is performed. The retainability (distribution coefficient) for C-14 of the solidified body of the waste increases about one order.

Solidification agents for radioactive waste and a method for processing

Objective of the present invention is to provide a preferable solidified body ensuring performance of artificial barrier in a solidifying process for incombustible miscellaneous solid waste and other wastes such as calcined ashes by preventing generation of hydrogen gas by a reaction of amphoteric metal included in the waste with solidifying materials. In order to suppress the reaction of the amphoteric metal with the solidifying materials, any one or arbitrary plurality of the following three means are provided in the solidifying materials; (1) A means for forming protection film on surface of the amphoteric metal, (2) A means for enhancing hydration reaction of cement, (3) A means for reducing basicity of the solidifying materials. In accordance with the present invention, a preferable solidified body can be obtained by a simple and easy method which does not necessitate separation and pre-treatment of the waste.

Method for solidification of waste, and apparatus, waste form, and

A vessel for solidifying radioactive waste pellets includes a vessel body, an inner lid mounted within the vessel body and fixedly secured to an upper portion of the vessel body, and a device for preventing the pellets from floating fixedly secured one end thereof to the inner lid. The inner lid has an opening formed at a generally central portion thereof, and the pellet float prevention device is extended into the opening of the inner lid to define gaps therebetween allowing the passage of a solidifying material in the state of a liquid or a slurry therethrough but preventing the passage of the radioctive waste pellets therethrough. The pellet prevention device, when receiving a downward urging force, is bent downward to enlarge the gaps therebetween for allowing the radioactive waste pellets to pass therethrough. The pellet float prevention device is returned by a resilient restoring force to its initial position when the downward urging force is released. The pellet float prevention device comprises a plurality of coil springs fixedly secured to the inner lid in a radial manner, and some of the plurality of coil springs extend to an area close to the center of the opening in the inner lid. The coil springs are extended in such a manner that the axis of each of the coil springs is displaced a predetermined angle from the center of the opening in the inner lid.

Vessel for solidification treatment of radioactive waste pellets

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Katsuta, Japan

Yoshimasa Kiuchi