Doryokuro Kakunenryo Kaihatsu Jigyodan

Kawasaki Jukogyo Kabushiki Kaisha

Japan Nuclear Cycle Development Institute

Nippon Denki Garasu Kabushiki Kaisha

Doryoku Kaunenryo Kaihatsu Jigyodan

Hiroshi Igarashi

Hiroaki Kobayashi

Noriaki Sasaki

Tetsuya Shimizu

Michiru Fujita

Tomohito Iikubo

Hirotaka Uehara

Shin-ichiro Torata

Noboru Endo

Toshio Masaki

Toshio Nakamura

Yoshiyuki Yasuike

Katsumi Inada

Makoto Yamaguchi

Hirokazu Takeuchi

Yasuhisa Ikeda

Kazunari Noguchi

Shunji Yoshizawa

Shinichi Usui

Junichi Adachi

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

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

Nickel-base alloy for glass-contracting member used in unenergized state

A melting furnace for treating wastes is provided which has a container equipped with a feed port for a glass raw material and wastes to be treated at the top thereof and a discharge port for molten glass containing said wastes at the bottom thereof, the container having a wall made of a heat resistant alloy and the container wall being in contact with molten glass inside the container; a heating electrode disposed in the container, the container wall acting as a counter electrode for the heating electrode; and a cooling system disposed at the back side of the container wall. By directly supplying electric power to the glass means disposed at the back side of the container wall. By directly supplying electric power to the glass between the container wall and the heating electrode, the molten glass containing the wastes can be formed. By conducting cooling of the container wall by the cooling system, corrosion of the wall due to the atmosphere in the container can be restricted.

Melting furnace for treating wastes and a heating method of the same

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

An electric melting furnace for solidifying highly radioactive waste in glass has a melting cavity made of a non-conductive refractory and adapted to melt a raw material consisting of highly radioactive waste and a glass material by passing a current between horizontally opposing electrodes, and to extract the molten glass material through a plurality of outlet ports at a bottom portion of the furnace, the melting cavity being partitioned by a non-conductive partitioning refractory provided on the bottom portion of the furnace between outflow ports. Since the furnace is so structured that the melting cavity is partitioned by the non-electrically conductive refractory, all current lines connecting the pair of electrodes for melting the highly radioactive waste, which contains elements of the platinum group, detour around the partitioning refractory. According to the current line distribution produced, it is just as if the electrodes were located on the upper side of the refractory as seen from each section of the partitioned melting cavity. This makes it possible to prevent the current flowing between the electrodes from concentrating in deposits which collect at the furnace bottom and contain the platinum-group elements in high concentration. It is also possible to reduce melting cavity depth in comparison with the melt surface area and inter-electrode distance.

Electric melting furnace with partitioned melting cavity for solidifying

An electric melting furnace for glassifying high-radioactive waste characterized in that, in a furnace for melting glass containing platinum-group elements which has an outlet of glass at the bottom part of a melting tank, the bottom of the furnace surrounding the outlet has an inclination of more than 30.degree. and not more than 70.degree. with respect to the horizontal plane toward the cullet, and the distance l.sub.1 between a surface-inside opening part of the outlet and bottom ends of at least a pair of electrodes (3a, 3b) for supplying most of power required for glass melting is a half or more, but not exceeding, of the distance (l.sub.2) between the electrodes (3a, 3b).

Electric melting furnace for glassifying high-radioactive waste

Growing community of inventors

Hitachinaka, Japan

Hiroshi Igarashi