Hitachi, Ltd.

Other

Babcock-hitachi Kabushiki Kaisha

Hitachi Nuclear Engineering Co., Ltd.

Hitachi Kiso Co., Ltd.

Kunio Enomoto

Ren Morinaka

Eisaku Hayashi

Masahiro Otaka

Sadato Shimizu

Katsuhiko Hirano

Koichi Kurosawa

Shigeru Tanaka

Makoto Hayashi

Tasuku Shimizu

Noboru Chiba

Tetsuya Ishikawa

Satoshi Kanno

Kunio Hasegawa

Kazunori Sato

Kazuo Takaku

Shinji Sakata

Fujio Yoshikubo

Hideyo Saito

Minoru Ootaka

Kazuo Amano

Masayuki Nishino

Makoto Kitano

Yuichi Ishikawa

Motoya Ito

Shigeo Hattori

Yasumasa Tamai

Takashi Saito

Nobuo Shimizu

Kazumi Anazawa

Keiichi Uraki

Takashi Matsunobu

Hirotsugu Fujimoto

Yoshinori Karatsu

Hiroshi Tsujimura

Tsukasa Ikegami

Toshihiko Yoshimura

Yoshio Fukuda

Hideyasu Furukawa

Tsutomu Masumoto

Noriaki Matsuda

Kenzi Aizawa

Yuko Koguchi

Kasunori Sato

Terunobu Koike

A preventive maintenance method and apparatus for a structural member in a reactor pressure vessel according to the present invention reduce a tensile residual stress on a surface of the structural member by impinging a water jet from a nozzle onto a plane surface of a deflector to thereby change direction of flow of the water jet, and impinging the water jet after being deflected onto the surface of the structural member. This method and apparatus are applicable to a narrow space portion, and can improve a residual stress on the surface of the structural member and can also prevent damage such as stress corrosion cracking.

Preventive maintenance method and apparatus of a structural member in a reactor pressure vessel

A liquid crystal display device, a liquid crystal display device cutting method, and a liquid crystal display device cutting apparatus that prevents damaging attached flexible conductive lines by providing a rounded water jet cut edge of a glass liquid crystal panel. The liquid crystal display device cutting apparatus includes a pump for increasing the pressure of a liquid, a nozzle with a throat that receives the pressurized liquid, a movable nozzle support that is movable at least in a plane parallel to the liquid crystal display, and a conveyor supporting the liquid crystal display device.

Liquid crystal glass substrate, method of cutting the liquid crystal glass substrate, cutter for the liquid crystal glass substrate and display using the liquid crystal glass substrate

A water jet peening apparatus which can carry out an efficient peening work on a large-diameter cylindrical structure by injecting a jet stream which contains air bubbles caused by cavitation at a low angle of incidence is provided. The apparatus is comprised of a nozzle which introduces a high pressure water and injects a water jet stream containing air bubbles caused by cavitation at the cylindrical structure disposed in water, wherein the angle of injection of the jet stream is smaller than 45 degrees relative to a tangent of the cylindrical structure.

Water jet peening apparatus

A method of performing maintenance on a structural member inside a reactor pressure vessel includes lowering an annular guide rail having a second lug until the guide rail rests on an upper flange of a core shroud provided inside the reactor pressure vessel, detachably mounting the second lug of the guide rail to a first lug mounted on the core shroud, positioning a discharging nozzle at a position at which compressive remaining stress is added to a surface of the core shroud by moving the discharging nozzle in a radial direction and an axial direction of the core shroud by a discharging nozzle moving apparatus mounted on a turnable revolving on the guide rail and discharging water to add compressive remaining stress to a surface of the core shroud from the discharging nozzle.

Preventive maintenance apparatus for structural members in a nuclear pressure vessel

A preventive maintenance apparatus for structural members inside a nuclear reactor pressure vessel includes a ring-shaped guide rail having a plurality of lugs which is placed on an upper flange of a core shroud provided inside a reactor pressure vessel. At least some of lugs separately engage with a plurality of guide rods provided on an inner surface of the reactor pressure vessel. A turntable is rotated on the guide rail. A first discharging nozzle moving apparatus placed on the turntable moves a first discharging nozzle for adding compressive remaining stress to an outer surface of the core shroud in a radial direction of the core shroud and in an axial direction of the core shroud. A second discharging nozzle moving apparatus placed on the turntable moves a second discharging nozzle for adding compressive remaining stress to an inner surface of the core shroud in a radial direction of the core shroud and in an axial direction of the core shroud.

Preventive maintenance apparatus for structural members in a nuclear

A fluid jet nozzle has a water chamber accommodating therein pressurized fluid, an orifice communicating with the water chamber and contracting the fluid from the water chamber, a throat communicating with the orifice and through which the fluid from the orifice passes, a multiplication chamber communicating with the throat and receiving the fluid from the throat for multiplying cavitation, and a diffusion chamber receiving the fluid from the multiplication chamber for diffusing the fluid.

Fluid jet nozzle and stress improving treatment method using the nozzle

An apparatus preventive maintenance having a driving mechanism capable of driving a jet nozzle 24 to cause it to travel upward-and-downward, to rotate and to swing is settled on the top of a housing in the bottom portion of a reactor pressure vessel and on a hole for a fuel support piece, water pumped by a high pressure pump is spouted from a jet nozzle, and cavitation bubbles generated during the spouting are supplied to the positions to be treated for preventive maintenance, such as housings in the bottom portion of the reactor pressure vessel. Therewith, the residual tensile stress in the position to be treated is improved in a releasing direction by the energy generated by the collapsing of the cavitation bubbles.

Method and apparatus for performing preventive maintenance on the bottom

Low temperature water in a low temperature water tank 12 installed outside a reactor pressure vessel 9 is pumped by a high pressure pump 15 and supplied through a conductor 17 under pressure. The supplied water is ejected, as a stream of cold water jet 8, from a nozzle 14 connected to the conductor 17 and introduced into the reactor pressure vessel 9 by a driving mechanism. The stream of cold water jet 8 ejected from the nozzle 14 is directed to impinge against a predetermined position of a core shroud 13 in reactor water 11 filled in the reactor pressure vessel 9 and being at temperature higher than the low temperature water. Then, while continuing to eject the cold water jet 8 from the nozzle 14, the nozzle 14 is moved away from the predetermined position, or the ejection of the cold water jet 8 from the nozzle 14 is stopped, allowing the predetermined position to be heated again with the temperature of the reactor water 11. A thermal shock is thereby applied to the predetermined position for improvement in residual stress of the core shroud 13.

Residual stress improving method for members in reactor pressure vessel

A fluxmeter includes an application unit for applying a magnetic field, a superconducting quantum interference element and a flux transmitting circuit. The flux transmitting circuit includes a pickup coil formed of a superconducting print coil and a core for the pickup coil. The core is formed of a soft magnetic material. The core serves to suppress the leakage of magnetic flux to magnetically couple the pickup coil and the superconducting quantum interference element efficiently to improve the sensitivity and resolution of the fluxmeter. The pickup coil may be manufactured by photolithography, sputtering, laser beam deposition, MBE deposition, MOCVD or spray pyrolysis.

Fluxmeter including squid and pickup coil with flux guiding core and

A method of maintaining the housing of a reactor pressure vessel having: a reactor pressure vessel into which cooling water is introduced; a cylindrical housing which penetrates an end bracket of the reactor pressure vessel; and a circumferential weld for securing the intermediate portion of the housing to the reactor pressure vessel by welding, the method of maintaining a housing of a reactor pressure vessel comprising the steps of: remaining the cooling water in the reactor pressure vessel; preventing leakage of the cooling water in the reactor pressure vessel through the housing by sealing the housing; making the inside portion of the housing lower than the seal to be a hollow space of a gas atmosphere; heating a heat affected zone due to welding by using a heating device inserted into the hollow space from a lower portion so as to compressive-yield the inner surface of the housing in the heat affected portion upper than the circumferential weld and tensile-yield the outer surface; and cooling heated portion inside of the housing, which has been yielded, so as to tensile-yield the inner surface of the housing by using a cooling device inserted into the housing from a lower portion, whereby compressive stress is allowed to remain in the tensile-yielded portion.

Method of maintaining housing of reactor pressure vessel and heat

A water jet peening method in which a pressurized water jet flow containing cavities is jetted through a nozzle having a velocity increasing orifice portion and a horn-like jetting hole formed continuously with the velocity increasing orifice portion to impinge against a surface of a metallic material immersed in water and to cause the cavities to collapse at the surface of the metallic member, and a tensile plastic deformation is caused in a surface layer of the metallic material by a local high pressure generated by the impingement and the collapse so that a residual tensile stress in the surface of the metallic member is reduced. In this method, the nozzle is vibrated so that vibration-induced cavities are formed in the vicinity of a nozzle wall surface, and the vibration-induced cavities are caused to impinge against the surface of the metallic member by the pressurized water jet flow containing cavities. It is thereby possible to promote the generation of cavities even in a case where pure water existing in a nuclear reactor and scant of nuclei from which cavities will be generated is used in peening of an internal structual member of the reactor.

Method of and apparatus for water-jet peening

A method for strengthening a pressure resistant property of a hollowed structure made of a metallic material and a pressure resistant hollowed structure made by such method. The method includes providing a temperature differential in a thickness direction between an outer side and an inner side of the metallic material with an arranged sufficient to generate a stress not exceeding a yielding stress of the metallic material. The outer side and inner side are pressurized so as to superimposed a stress generated by the pressurizing and the stress caused by the temperature differential reaching the yielding stress of the metallic material. The pressure is released subsequent to the superimposed stress reaching a level of the yielding stress of the metallic material. The compressive residual stress has a larger absolute value than a tensile stress caused in the inner side of the hollowed structure by the internal pressure, with the tensile residual stress in an outer side of the hollowed structure having a value of less than the tensile yielding stress of the metallic material even though the tensile stress is superimposed in the outer side of the hollowed structure by the internal pressure.

Method for strengthening pressure resistance of a hollowed metallic

Growing community of inventors

Tokai-mura, Japan

Kunio Enomoto