Hitachi, Ltd.

Nisshin Steel Co., Ltd.

Hitachi Engineering Co., Ltd.

Akira Minato

Masahiko Itoh

Heihatiro Midorikawa

Katsumi Ohsumi

Takashi Honda

Yasumasa Furutani

Yasuo Hira

Kenya Ohashi

Takashi Hasegawa

Masakiyo Izumiya

Kenzi Machizawa

Katsumi Suzuki

Eizi Kashimura

Osao Sumita

Yuko Sasaki

Shiro Kobayashi

Takehiko Ito

Hisao Itow

Tomio Yoshida

Kiichiro Katayama

Yoshiyuki Hoshino

Saburo Shoji

Toshio Kawakami

Kenji Machizawa

Hisao Itou

Kazutoshi Itoh

Tsuyoshi Kambayashi

Tutomu Shimizu

Yosio Kanekiyo

Mamoru Suzuki

Mituru Kubo

Eiji Kashimura

Magnetic attracting means, especially a permanent magnet, is disposed in a high pressure feed water heater drain pipe line or air separator water tank of feed water and condensed water systems in a thermoelectric power plant. By adoption of this arrangement, iron oxides contained in water in the feed water and condensed water systems can effectively be attracted and removed by this magnetic attracting means.

Apparatus for removing iron oxides from water in feed water system of a

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.

Inhibition of deposition of radioactive substances on nuclear power

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.

Method of reducing radioactivity in nuclear plant

A silver electrode (4) on a lead frame (2) is bonded to an aluminum electrode (5) on a silicon chip (1) with a copper wire (3). The resulting semiconductor device was immersed in a solution of benzotriazole in ethyl alcohol. An Ag-benzotriazole film (6) was formed on the surface of the silver electrode (4) and a Cu-benzotriazole film (7) was formed on the surface of the copper wire (3), while an Al-benzotriazole film (8) was formed on the surface of the aluminum electrode (5). Even if water penetrates into the semiconductor device, the silver electrode (4), the aluminum electrode (5) and the copper wire (3) are effectively protected by the anti-corrosive Ag-benzotriazole film (6), Cu-benzotriazole film (7) and Al-benzotriazole film (8) to exhibit excellent damp-proof.

Resin packaged semiconductor device having a protective layer made of a

A nuclear power plant using a structural material consisting of metal which comes into contact with a liquid in which radioactive substances are dissolved has a function to suppress the deposition of the radioactive substances. In this function, metal elements constituting the surface layer of the structural material which comes into contact with the liquid are oxidized by injecting oxidizing agents from outside, thereby preliminarily producing an oxide film. The oxidizing agents comprise at least one kind selected from the group consisting of oxygen, hydrogen peroxide, chromate, nitrite, molybdate, tungstate and ferrate. Particularly, by suppressing the deposition of radioactive substances on a stainless steel, the dose rate of exposure of workers is effectively reduced.

Nuclear power plant providing a function of suppressing the deposition

The invention is to provide zirconium or its alloy used as a material for a chemical device and a nuclear reactor etc. is surface-treated with an oxidizing acid containing an oxidizing metal ion. The oxidizing acid is at least one member or a mixture of two or more selected from the group consisting of, for example, nitric acid (HNO.sub.3), hydrogen peroxide (H.sub.2 O.sub.2), hypochlorous acid (HClO) and potassium permanganate (K.sub.2 MnO.sub.4) solution, among which nitric acid is most preferred. The oxidizing metal ion is at least one member selected from the group consisting of, for example, ruthenium, rhodium, palladium, osmium, iridium, platinum, chromium, vanadium and cerium ions. Particularly preferred treatment conditions comprise a nitric acid concentration of 14 mol/l (65%) which is close to an azeotropic concentration, a ruthenium ion concentration of at least 1.times.10.sup.-3 mol/l and a treatment temperature of a boiling temperature (120.degree. C.). The surface of zirconium or its alloy to be treated may be washed previously with an aqueous acid solution containing hydrofluoric acid. The method of inhibiting corrosion of zirconium or its alloy by surface-treating it with an oxidizing acid containing an oxidizing metal ion can be formed easily a uniform protective film on the surface thereof.

Method of inhibiting corrosion of zirconium or its alloy

A method of inhibiting corrosion of carbon steel piping of condensate and feed water systems in a power generating plant, characterized by continuing the water in said piping to flow after also said plant has been shut down until it is restarted up and by keeping the specific electric conductivity of flowing water at 0.5 .mu.S/cm or less.

Method of inhibiting corrosion of carbon steel piping of condensate and

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.

Process for removing metal surface oxide

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.

Process for regenerating cleaning fluid

A process for the partial hot dipping of a long steel strip is disclosed which comprises forming an oxidation-inhibiting film, oxygen-impermeable and thermally stable in a hot-dipping bath, which film is produced by the chemical reaction of an iron content in the steel strip with an oxidation inhibiting film-forming agent, such as an inorganic phosphoric acid compound, on a predetermined area of the steel strip surface, forming, as required, an intermediate layer comprising an inorganic binder, such as water glass, on the resulting film, forming a carbon-containing, plateing-stopping film as a top coat on the intermediate layer, and hot dipping the steel strip.

Process for partial hot dipping of steel strips

In a hermetically circulating absorption type refrigerator including a regenerator, a condenser, an evaporator, an absorber and a heat exchanger, the regenerator has an absorbing solution heating tube flux provided between tube plates. The tube plates are encased within a shell of the regenerator. Non-soluble electrodes are arranged between each of the tube plates and the shell. Then, an anti-corrosive current is made to flow through at least one of an end portion of the heating tube, the tube plates and the shell to thereby enhance the anti-corrosion effect together with an anti-corrosive agent or inhibitor.

Hermetically circulating, absorption type refrigerator

In a hermetically circulating, absorption type refrigerator based on a closed circulation system of constituent members comprised of a successive communication of a regenerator, a condenser, an evaporator, an absorber and a heat exchanger, refrigeration being produced by repetitions of concentration, refrigerant dilution, and heat exchange of an aqueous concentrated lithium bromide solution sealed in the circulation system, the aqueous concentrated lithium bromide solution contains at least one each of (a) an inhibitor having a boiling point higher than the solution temperature in the regenerator and (b) an inhibitor having a boiling point lower than the solution temperature in the regenerator. Corrosion of metallic materials used in a refrigerant circulation loop of the refrigerator and those in the absorbing solution circulation loop can be effectively prevented.

In a hermetically circulating, absorption type refrigerator based on a closed circulation system of constituent members comprised of a successive communication of a regenerator, a condenser, an evaporator, an absorber and a heat exchanger, refrigeration being produced by repetitions of concentration, refrigerant dilution, and heat exchange of an aqueous concentrated lithium bromide solution sealed in the circulation system, a hydrogen gas generated in the refrigerator is continuously converted to water, condensed and removed or returned to the refrigerator as a refrigerant. The pressure increase in the refrigerator can be prevented, and a high refrigerating performance can be continuously maintained without any special maintenance.

A hermetically circulating, absorption type refrigerator based on a closed circulation system comprised of a successive communication of a regenerator, a condenser, an evaporator, an absorber and a heat exchanger, parts or the whole of said constituent members in contact with an absorbing solution being comprised of a copper material selected from copper and copper alloy, and refrigeration being produced by repetitions of concentration, refrigerant dilution and heat exchange of an aqueous lithium bromide solution sealed in the circulation system is characterized in that the absorbing solution is an aqueous lithium bromide solution containing (a) a nitrate and (b) at least one triazole compound selected from benzotriazole and tolyltriazole, and has a particularly distinguished corrosion resistance.

A martensitic stainless steel to be used for the impellers of turbo-blowers, compressors and the like consisting essentially, based on weight of 0.04 - 0.15% C, up to 2.0% Si, 0.2 - 2.0% Mn, 3.5 - 6.0% Ni, 10 - 16% Cr, and at least one element selected from the group consisting of 0.5 - 3.0% Mo, 0.01 - 0.8% Nb, and the balance being Fe. The amounts of .delta.-ferrite therein is not more than 10%. The steel may further contain up to 0.2% additional element or elements, i.e., N, Al, Ti, Ca, and/or a rare-earth element or elements. The steel of this composition offers high strength, great toughness, and good weldability and, when annealed after welding, it will display the same properties as after quenching and tempering. Impellers made of this steel are for heavy-duty, high-efficiency applications.

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Hitachi, Japan

Akira Minato