Abstract: An autonomous, decentralized fast breeder reactor includes a single reactor main vessel which houses a plurality of small-size reactor subsystems each having a small-scale fast breeder reactor core, and a plurality steam generator subsystems. These subsystems function in an autonomous manner and are caused to undergo a heat transfer with one another by a coolant circulating naturally through the interior of the main vessel, thereby constructing a cooperatively operating system. Steam generated by the steam generators is introduced to a turbine system and utilized in generating electricity. The condensate from the turbines is cooled by a heat accumulating pool, and the heat is utilized in a separate system. The entire system is installed underground and use is made of the difference in elevation. Use also is made of solid bedrock to construct a housing facility for the reactor.

Abstract: A low-water-pressure-controlled hydrologic test using a measurement pipe containing an inner packer which is equipped with a water pressure gage at its tip is disclosed. Some water is poured into the measurement pipe in advance so as to diminish the pressure head difference between the in-pipe pressure and the pore water pressure of the rock concerned. The permeability coefficient is obtained by measuring changes in the recovered water level in terms of pressure changes. In the case of an aquiclude, the inner pressure is raised by expanding the inner packer, the permeability coefficient being obtained by detecting the changes in inner pressure. Thus, the method allows a permeability test to be conducted continuously at various depths. In addition, it helps to shorten the measurement time to a remarkable extent and enables the rock condition to be investigated without departing from the natural condition.

Abstract: In a method for recovering plutonium and uranium from spent nuclear fuel by solvent extraction having solvent consisting of tri-n-butyl phosphate, dibutyl phosphate and n-dodecane, the improvement comprises separating the n-dodecane from the phosphate by freeze-drying and separating the phosphate from each other and residual impurities by fractional distillation.

Abstract: A high-level radioactive waste liquid, produced in a reprocessing plant, is treated by a freeze-drying step. A low-level radioactive waste liquid containing water, nitric acid and nuclides is obtained from the sublimate of the freeze-drying step. Fission products, actinides, corrosion products (iron, chromium, nickel, etc.), sodium nitrate and sodium hydroxide, not sublimated, are separated as a residue. An alkaline solution such as sodium hydroxide solution is added to the residue to dissolve sodium nitrate and sodium hydroxide. The dissolved nitrate and hydroxide are then separated from the residue containing fission products and the corrosion products.

Abstract: A nuclear excitation laser type intra-reactor neutron flux measuring system of this invention is comprised of a laser oscillator filled with a nuclear exciting gas such as .sup.3 He, KrF or XeF, mounted on the tip of a control rod. The nuclear exciting gas is made into a plasma by the neutrons or the fragments of fissioned nuclei when the tip is positioned in the reactor core by raising the control rod. Since the nuclear exciting gas made into a plasma itself generates a laser beam or amplifies a laser beam projected from the outside, the behavior of neutrons can be monitored in detail after guiding this light response to the light processing system located outside, distinguishing the energies of neutrons from the spectrum and calculating the density and the flux of the neutron in each energy. Furthermore, the detecting sensitivity can be enhanced by forming the responsive membrane made of U.sub.3 O.sub.8 and so on, on the laser oscillator.

Abstract: A dispersion strenghened ferritic steel having excellent ductility and toughness which has been heat treated to produce a matrix having a tempered martensitic structure composed of 0.05 to 0.25% by weight of carbon, 0.1% by weight or less of silicon , 0.1% by weight or less of manganese, 8 to 12% by weight of chromium, 0.1 to 4.0% by weight in total of molybdenum and tungsten, and 0.02% by weight or less of oxygen (exclusive of oxide particles) with the balance being iron and inevitable impurities and, homogeneously dispersed in the matrix, composite oxide particles comprising Y.sub.2 O.sub.3 and TiO.sub.2 in an amount of 0.1 to 1.0% by weight in total of Y.sub.2 O.sub.3 and TiO.sub.2 and a TiO.sub.2 to Y.sub.2 O.sub.3 molar ratio of 0.5 to 2.0.

Abstract: A dispersion strengthened ferritic steel cladding tube for use in a nuclear reactor and having a double-layer structure is provided. The cladding tube comprises a tube body made of a dispersion strengthened ferritic steel having a ceramic dispersed therein and containing 8 to 13% by weight of chromium. The inner surface of the tube body is lined with a ferritic steel containing 18 to 30% by weight of chromium. The cladding tube has not only excellent compatibility with a mixed oxide fuel but also excellent high temperature strength and swelling resistance.A method of producing the cladding tube using powder metallurgy is also provided.

Abstract: An improved process of vitrifying a radioactive liquid waste by absorbing a radioactive liquid waste into a glass frit cartridge made of molded glass fibers and heat-melting the cartridge to vitrify the liquid waste. The invention is characterized by absorbing a radioactive liquid waste containing ruthenium into the glass frit cartridge together with a reducing agent. By the process of the invention, the formation of gaseous ruthenium is effectively suppressed during the heat-melting.

Abstract: Disclosed are a method of making a connection in a liquid and an apparatus therefor wherein a first connector having a protrusion at its front end is housed in a protecting tube which is open at its lower end and into which a gas is introduced, the protecting tube is filled with the gas so as to form a gaseous space therein within the liquid, a second container which is normally held within the liquid and which has a destructible plate at its upper end is exposed to the gaseous space, and the destructible plate is destroyed by the front end of said one connector so as to connector both connectors, whereby the connection in the liquid can be made without being affected by an ambient liquid.

Abstract: A process for electrolytically treating a radioactive liquid waste includes electrolyzing a radioactive liquid waste containing sodium compounds using mercury as a cathode in an electrolytic cell, separating the liquid waste into an amalgam of metals, inclusive of sodium, and residue, separating the metals including the sodium from the amalgam, purifying and reutilizing the metals, and recycling the mercury in the electrolytic cell.

Abstract: A process for preparing uranium tetrafluoride by reacting a uranous solution with a hydrofluoric acid solution in a fluorination precipitation tank is provided. A cylindrical inner tube having upper and lower ends opened is disposed in the tank in the longitudinal direction thereof. An agitator is arranged within the inner tube to generate a descending or ascending stream inside the inner tube and a ascending or descending stream outside the inner tube, thereby producing a circulation of reaction liquor in the tank. The uranous solution and the hydrofluoric acid solution are introduced into the tank from the upper part thereof and the produced uranium tetrafluoride crystals are withdrawn from the lower part of the tank together with a part of the reaction mother liquor. The amount of the hydrofluoric acid solution added to the uranous solution is adjusted so that the fluorine concentration in the reaction mother liquor in the tank is maintained at 2 to 4 g/l.

Abstract: A process for compacting radioactive waste by precompressing the waste in each of capsules while filling the waste into the capsule to thereby compress the waste to the desired bulk/true density ratio under a small total pressing load and diminish damage to the inner surface of the die used, each of the capsules having a cross sectional form corresponding to a divided segment of the cross section of an HIP treatment container, then placing the capsules into the HIP treatment container, subsequently filling the HIP treatment container with a metal powder as a filler, thereafter degassing and sealing the HIP treatment container and subjecting the container to an HIP treatment in its entirety. The process precludes scattering of the radioactive substance from the waste and release of waste fragments to assure improved safety.

Abstract: In a two-arm type manipulator, it is very rare that two arms develop trouble simultaneously due to malfunction of motors and/or cables. In view of the above fact, motors for actuating manipulator joint mechanisms and cables connected between the motors and the manipulator frame are removably mounted on the shoulder section of the frame of the manipulator. Further, the first arm is so arranged as to be accessible to the second shoulder section or the second arm is so arranged as to be accessible to the first shoulder section. Therefore, it is possible to allow an access of one manipulator arm to the other disabled manipulator elements (motors and/or cables) for removal and replacement of the disabled elements with new elements without aid of another manipulator, in particular, where the manipulator is equipped in atomic facilities which refuse access, thus saving equipment investment.

Abstract: Disclosed are a method of making a connection in a liquid and an apparatus therefor wherein a first connector having a protrusion at its front end is housed in a protecting tube which is open at its lower end and into which a gas is introduced, the protecting tube is filled with the gas so as to form a gaseous space therein within the liquid, a second connector which is normally held within the liquid and which has a destructible plate at its upper end is exposed to the gaseous space, and the destructible plate is destroyed by the front end of said one connector so as to connect both connectors, whereby the connection in the liquid can be made without being affected by an ambient liquid.

Abstract: The improvement in a nuclear reactor having a calandria tank containing moderator and a plurality of coolant flow channels which penetrate through the calandria tank and are loaded with fuel assemblies, the moderator and the coolant being isolated from each other. The improvement is constituted by a pressure container surrounding the outside of the calandria tank, a gap between the calandria tank and the pressure container being charged with the coolant; a recirculation pump for recirculating the coolant through the coolant flow channels; and a steam separator which is positioned inside the pressure container and separates the coolant flowing through the coolant flow channels into steam and water; whereby an improved nuclear reactor having a unitary pressure container structure is constructed.

Abstract: Herein disclosed is a dual-tube heat pipe type heat exchanger comprising a heat pipe confined with a working fluid for transferring a heat as a latent heat by repeating evaporations and condensations. The heat pipe includes an outer tube which is disposed within a hot fluid such that its axis is generally horizontal. Further included is an inner tube which is inserted in the outer tube and radially offset upward to substantially contact with the top portion of the inner face of the outer tube and to confine a space between the inner circumference of the outer tube and the outer circumference of the inner tube, thus forming the heat pipe.

Abstract: An image-transmitting fiber includes at least one first fiber element for transmitting light power therethrough, and a plurality of second fiber elements disposed around and extending along the first fiber element. The second fiber elements cooperates with one another for transmitting an image of an object therethrough. The first fiber element is greater in diameter than each of the second fiber elements.

Abstract: A method for thermal decomposition treatment of a radioactive waste uses an apparatus comprising a container for holding molten matter of a radioactive waste containing a sodium compound, a pair of electrodes contacting the molten matter, and a power source for applying voltage between the electrodes while changing the polarity thereof every several tens of seconds. In this apparatus, the molten matter can be heated in the container by Joule heat, which is evolved by electric current directly flowed through the molten matter, so that the sodium compound contained in the radioactive waste can be decomposed, vaporized and removed to recover a stabilized radioactive solid as a residue in the container.

Abstract: A swinging-type apparatus for automatically examining pipes includes first and second clamping devices provided at the ends of an extendible body. The first clamping device is made to clamp a first pipe, the second clamping device is made to unclamp the first pipe, is lifted up away from the first pipe, swung to an adjacent second pipe to be examined, lowered down to the second pipe and made to clamp the same. Next, the first clamping device is made to unclamp the first pipe, is lifted up away from the first pipe, swung to the second pipe, lowered down to the second pipe and made to clamp the same. Sensors provided on at least one of the clamping devices then examine the second pipe. By repeating these operations, the apparatus can be made to travel from one pipe to another to examine a cluster of pipes. The apparatus can also be made to move along a pipe axially thereof by extending and shortening the length of the extendible body.

Abstract: This invention is drawn to a high-speed centrifugal extractor having improved weirs for selectively separating a heavy liquid and a light liquid. Each of the selection weirs has a double tube structure consisting of an outer cylinder extending from a rotor peripheral wall towards a rotor rotary shaft and an inner cylinder which is inserted into the outer cylinder through the rotor peripheral wall in such a manner that the insertion length of the inner cylinder can be varied. The heavy liquid selection weir has a heavy liquid withdraw port at the wall of the outer cylinder positioned inside the heavy liquid phase, while the light liquid selection weir has a light liquid withdraw port at the wall of the outer cylinder positioned inside the light liquid phase. By varying the insertion length of the inner cylinder into the outer cylinder, the position of an interface at which the heavy and light liquid phases are separated inside a rotor can be changed.