Abstract: In a nuclear fuel reprocessing plant for processing a used nuclear fuel by a nitric acid solution, the present invention provides a nuclear fuel reprocessing plant characterized by including electrolytic reduction means for reducing the valence of oxidizing metal ions consisting of the nuclear fuel and dissolved in the nitric acid solution while they are kept under the ionic state. In a processing method of a nuclear fuel reprocessing plant for processing a used nuclear fuel by a nitric acid solution, the present invention provides also a corrosion-proofing method of a nuclear fuel reprocessing plant characterized in that electrolytic reduction is carried out so that the valence of oxidizing metal ions consisting of the nuclear fuel and dissolved in the nitric acid solution is reduced while the metal ions are kept under the ionic state and NOx gas is also generated.

Abstract: A hermetically closed circulation type, vapor absorption refrigerator which comprises a high temperature regenerator, a low temperature regenerator a condenser, an evaporator, an absorber and heat exchangers in a hermetically closed circulation system as essential constituent members composed of iron-based materials, where refrigeration is produced by repetitions of concentration of an absorbing solution sealed into the circulation system, dilution with a cooling medium and heat exchange, the inside wall of the high temperature regenerator being provided with a composite film of molybdenum oxides and iron oxide can be operated stably with a high reliability or corrosion resistance.

Abstract: An absorption type refrigerator has an aqueous absorbing solution. The absorbing solution comprises lithium bromide solution, 5-150 ppm by weight of NO.sub.3.sup.- and 0.1-0.4% by weight of LiOH, and is free from any triazole compounds. The absorbing solution further includes octyl alcohol.

Abstract: A nuclear power plant wherein surfaces of components contacting with nuclear reactor cooling water containing radioactive substances are coated with an oxide film, preferably being charged positively and/or containing chromium in an amount of 12% by weight or more, is prevented effectively from the deposition of radioactive substances thereon.

Abstract: The present invention is concerned with a method of reducing radioactivity in a nuclear plant by preliminarily forming oxide films on the surfaces of metallic structural members to be in contact with high-temperature and high-pressure reactor water containing radioactive substances before said metallic members are exposed to said reactor water. The method is characterized by the steps of subjecting said structural members to a first-step oxidation treatment of heating said structural members in an environment of a high temperature, and further subjecting the thus treated structural members to a second step oxidation treatment of heating said treated structural members in an environment having a higher oxidizing capacity than that of said environment in said first-step oxidation treatment to form a denser oxide film than an oxide film obtained in said first step oxidation treatment. According to the present invention, radioactivity in the nuclear plant can be reduced remarkably.

Abstract: An object to-be-washed bearing an oxide on the surface of a parent material metal is immersed in a liquid containing a complexing agent, electrons having energy levels on the base side with respect to the Fermi level of the oxide are generated outside the parent material metal by supplying external energy, and the electrons are injected into the oxide of the object to-be-washed immersed in the liquid.

Abstract: The present invention provides a process for removing a metal surface oxide from a metallic substance by contacting the metal surface oxide layer with a deterging liquid to introduce electrons into the metal surface oxide in contact with the deterging liquid to dissolve the metal surface oxide, which process is characterized in that a metal piece or carbon piece is immersed in the deterging liquid into which gaseous hydrogen has been introduced and the metal piece or carbon piece is electrically connected to the metal surface oxide on the metallic substance. The metal piece is preferably platinum or vanadium. A preferred deterging liquid is one having a pH of about 5 to 7 and containing a complexing agent.

Abstract: A cleaning fluid such as a chemical decontamination solution originally containing one or more cleaning or decontamination reagents in low concentrations and deteriorated after a cleaning or decontamination treatment step by containing metal oxides therein can be regenerated by introducing such a deteriorated cleaning fluid into an electrolytic cell, passing a direct current through said cleaning fluid between two electrodes, and removing said metal oxides by depositing dissolved metal ions on the cathode as metals from the cleaning fluid.

Abstract: A hydrogen generating apparatus comprising a cell having a plurality of chambers defined in the cell by cation exchange membranes and anion exchange membranes arranged alternately, a high concentration electrolyte and a low concentration electrolyte being filled alternately in said plurality of chambers, and a pair of electrodes guided into the chambers disposed on both the ends of said cell, respectively, and the open circuit voltage between said electrodes being higher than the decomposition voltage of water.