Hitachi, Ltd.

Other

Babcock-hitachi Kabushiki Kaisha

Hitachi Nuclear Engineering Co., Ltd.

Hitachi Kiso Co., Ltd.

Noboru Chiba

Kunio Enomoto

Ren Morinaka

Eisaku Hayashi

Sadato Shimizu

Koichi Kurosawa

Fujio Yoshikubo

Kazunori Sato

Shigeru Tanaka

Katsuhiko Hirano

Tetsuya Ishikawa

Minoru Ootaka

Katsuya Hamamoto

Masayuki Nishino

Akira Takahashi

Kazunori Hashimoto

Kenta Kumagai

Masahiro Otaka

Yukio Kuroiwa

Hideyo Hyuga

Yuichi Kosukegawa

Fumio Toyoda

Hideyasu Furukawa

Masakatu Iwasaki

Syoji Tsubokuda

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

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.

Growing community of inventors

Ibaraki, Japan

Noboru Chiba