Doryokuro Kakunenryo Kaihatsu Jigyodan

Japan Nuclear Cycle Development Institute

Kawasaki Jukogyo Kabushiki Kaisha

Hiroaki Kobayashi

Hiroshi Igarashi

Michiru Fujita

Jin Ohuchi

Hirotaka Uehara

Satoshi Ikeda

Shinichi Nemoto

Makoto Yamaguchi

Kazunari Noguchi

Shunji Yoshizawa

Shinichi Usui

Yasuhisa Ikeda

Junichi Adachi

Yoshiyuki Yasuike

Naomi Tsunoda

A method of melting treatment of radioactive miscellaneous solid wastes wherein, even when the wastes contain various kinds of substances in a mixed state, each of the substances is efficiently induction-heated and the whole of the wastes can be melted quickly. The radioactive miscellaneous solid wastes are charged into a water-cooling type cold crucible induction melting furnace disposed within a high-frequency coil. A plurality of high-frequency currents each having a frequency suitable for induction-heating each of the various kinds of substances contained in the radioactive miscellaneous solid wastes are supplied to the high-frequency coil to melt the solid wastes by being induction-heated. The high-frequency currents of different frequencies may be simultaneously supplied to a single high-frequency coil or may be supplied to a plurality of high-frequency coils, respectively.

Method of melting treatment of radioactive miscellaneous solid wastes

Molten matter is discharged from a cold crucible induction melting furnace provided with a furnace body disposed within a high-frequency coil for heating the furnace body. A metallic discharging nozzle extends downwardly from an inner bottom portion of the furnace body and can be electrically insulated from the furnace body. A high-frequency coil for heating the discharging nozzle is disposed around the nozzle. An electric circuit for removing high-frequency noise generated from the high-frequency coil for heating the furnace body is disposed in the high-frequency coil for heating the nozzle. High reliability and high controllability can be achieved without electric short-circuits between the furnace body and the nozzle and noise interference between the high-frequency coils.

Apparatus for discharging molten matter from cold crucible induction

A flux for effectively melt-decontaminating a zircaloy contaminated with a radioactive contaminant Pu.sub.2 O.sub.3 is provided. The flux comprises a mixture of a metal flux of a metal (e.g. Ca or Mg) having a higher chemical activity than plutonium at a temperature above the melting point of the zircaloy with a halide flux of metallic compound (e.g. SnF.sub.2, PbF.sub.2, CoF.sub.2, CsF.sub.2) of a halogen element having a higher atomic number than fluorine and has a smaller absolute value of the standard free energy of formation than a fluorination product of plutonium (i.e. PuOF). The addition of the flux to a molten zircaloy causes plutonium contained in the melt to be converted, through a two-step reaction, to PuOF which can be then separated as slag.

Method for melt-decontaminating metal contaminated with radioactive

A machine for inspecting the surface conditions of structural members within a furnace, particularly within a furnace operating at a high temperature or with a highly radioactive environment, such as a melting furnace for processing radioactive wastes. The machine comprises a laser-transmission optical fiber incorporated with a laser projector at one end thereof inserted into the furnace and being connected to a laser beam source outside the furnace; a fiberscope incorporated with the objective portion at one end thereof inserted into the furnace and being connected to an image sensor located outside the furnace; means for calculating the distance to a structural wall surface on which the laser beam from a tip portion of the inspection machine has fallen, by subjecting an image from the image sensor to image processing; a double-walled tube of a structure such that the laser-transmission optical fiber is incorporated through an inner tube thereof, and a coolant introduced into a passageway within the inner tube returns in the vicinity of the laser projector at the tip portion; and a double-walled tube of a structure such that the fiberscope is incorporated through an inner tube thereof, and a coolant introduced into a passageway within the inner tube returns in the vicinity of the objective portion at the tip portion.

In-furnace inspection machine utilizing a double-walled structure

Glass melting treatment method

A method of melting treatment of radioactive miscellaneous solid wastes containing therein an electrically conductive substance and other waste components. This method comprises charging the radioactive miscellaneous solid wastes into a cold crucible induction melting furnace provided with a high-frequency coil; supplying a high-frequency current to the high-frequency coil of the melting furnace to thereby heat and melt the electrically conductive substance, e.g. a metal, in the miscellaneous solid wastes; indirectly heating the other components in the miscellaneous solid wasted by utilizing the electrically conductive substance as a starting source of heating and melting; and placing the whole of the radioactive miscellaneous solid wastes into a molten state.

A salt waste composed mainly of chlorides, which is generated from the step of a molten salt electrolytic purification in dry reprocessing of a spent metallic nuclear fuel, is reacted with boric acid at high temperature to convert the chlorides in the salt waste into oxides. The resulting oxides of the salt waste are easily vitrifiable, and a vitrification product is obtained by adding a vitrifying additive to the oxides, heat-melting the mixture to form a molten mixture and cooling the molten mixture.

Process for treating salt waste generated in dry reprocessing of spent

A process for reducing plutonium is provided in which hydrazine is added as a reducing agent to a nitric acid solution of tetravalent plutonium in the presence of active carbon catalyst to thereby reduce tetravalent plutonium into trivalent plutonium.

Growing community of inventors

Hitachinaka, Japan

Hiroaki Kobayashi