Hitachi, Ltd.

Nippon Engelhard Ltd.

Hitachi Kyowa Kogyo, Ltd.

Masaki Takeshima

Hideo Yusa

Mikio Hirano

Toru Saito

Yoshikazu Sugimoto

Kiyotaka Shirosaki

Susumu Horiuchi

Kunio Kamiya

Masao Kitamura

Ryozo Kikkawa

Atou Shimozato

Toshio Ishidate

Takashi Taniguchi

Masashi Kawaguchi

Liquid wastes from atomic power plants are treated in an apparatus comprising a low electroconductivity liquid waste concentrator for evaporating a low electroconductivity liquid waste with outside steam as a heat source, and another liquid waste concentrator for evaporating another liquid waste with steam generated by evaporation of the low electroconductivity liquid waste in the low electroconductivity liquid waste concentrator as a heat source.

Apparatus for treating radioactive liquid wastes

Backwash water containing radioactive cruds of a non-filter aid type filter of the primary cooling water system of an atomic power plant is treated by leading the backwash water directly, or supernatant obtained by removing coarse cruds by settling in advance, to a waste resin settling tank for backwash water containing waste ion exchange resin powder from filter-demineralizer of the condensation-purification system of the atomic power plant, mixing the backwash water or the supernatant with the backwash water from the filter-demineralizer in the tank, thereby allowing the cruds contained in the backwash water or the supernatant onto the waste ion exchange resin powder, and settling the crud-adsorbed waste ion exchange resin powder, thereby separating and removing the cruds from the backwash water from the non-filter aid type filter. Recycle of fine cruds can be eliminated with enhanced percent crud removal, and recycle time of backwash water can be shortened. Load on a concentrator can be reduced with reduced number of drums filled with radioactive waste.

Process for treating liquid waste containing solid fine particles

A method of and a system for removing miniuscule solid particles from liquid wherein the liquid to be processed is supplied to one end of at least one filter element which may be a porous tube filter open at opposite ends and formed with a multiplicity of tiny openings in its wall having a first surface and a second surface. The liquid flows along the first surface and a portion thereof is passed through the tiny openings from the first surface side to the second surface side because of the latter being under lower pressure than the former, to be drawn off as filtrate. The rest of the liquid or a concentrated liquid portion flows out of the other end of the filter element. The flow velocity F of the liquid flowing along the first surface and/or the flow velocity f of the filtrate through the tiny openings is controlled such that the ratio F/f can be kept at a predetermined value.

Method of removing minuscule solid particles from liquid and system

A method and system for continuously regenerating dehumidifiers of a charcoal adsorber system are provided. Off-gas, including radioactive noble gases, such as xenon and krypton, is physically adsorbed in charcoal adsorbers and discharged to the atmosphere after its radioactivity has decayed. Before passing to the charcoal adsorbers, the off-gas is subjected to dehumidifiers consisting of a molecular sieve or some other desiccant. A couple of dehumidifiers is alternately used because periodic regeneration for the dehumidifier is necessary to recover moisture adsorption ability of the desiccant. The regeneration for the dehumidifier is completed by the steps of purging the dehumidifier with fresh air, and thereafter circulating the fresh air within a closed loop including a heater, dehumidifier, cooler condenser, and blower. Moisture absorbed in the dehumidifier is carried away by circulating heated fresh air and separated from the fresh air by cooling condensers. After completion of the regeneration, the fresh air is returned to the charcoal adsorber system for further treatment. By employing fresh air as regeneration gas, the regeneration for dehumidifiers can be completed faster and with less contamination as compared with a conventional method of employing off-gas for regeneration.

Method and system for regenerating dehumidifier for use in charcoal

A radioactive waste discharged from a radioactive substance handling equipment is dried and powdered, and the powder is pelletized. The resulting pellets are stored in an inner vessel of a store vessel having a double structure for a predetermined period to attenuate the radioactivity of the pellets. Then, the pellets are taken out from the store vessel and packed into a sealing vessel. A binder is injected into the sealing vessel to effect solidification.

Method and apparatus for treatment of radioactive wastes

An iodine adsorbent comprises an alumina carrier having a large number of pores having a mean pore size of 200 to 2,000 A and silver supported on the alumina carrier. The alumina carrier has a pore volume of at least about 0.1 cc/g. High percent iodine removal is obtained in a highly humid atmosphere, and an amount of silver supported on the carrier is much reduced.

Iodine adsorbent

A vent gas containing radioactive iodine and methyliodide is effectively decontaminated by chemically adsorbing the iodine contained in the vent gas onto an activated carbon layer at first, then physically adsorbing the methyl iodide contained in the vent gas onto another activated carbon layer separately disposed from the former activated carbon layer, and retaining the radioactive iodine and radioactive methyl iodide on the respective activated carbon layers for a definite period of radioactive decay.

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Hitachi, Japan

Masaki Takeshima