Hitachi, Ltd.

Yoshinori Karatsu

Hisanao Kita

Yoji Akutsu

Takamitsu Nakazaki

Makoto Hayashi

Takeshi Wada

Motoya Ito

Kunio Enomoto

Koichi Kurosawa

Masahiro Otaka

Shinji Sakata

Takashi Saito

Hideyo Saito

Kunio Hasegawa

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 method of connecting superconducting wires have the steps of preparing a connecting superconducting wire piece, exposing the filaments of the superconducting layers to be connected and the filaments of the connecting superconducting wire piece by partially dissolving and removing the coating layers, inserting the filaments of the superconducting wires to be connected into the filaments of the connecting superconducting wire piece such that the filaments of the connecting superconducting wire piece cross and envelope the filaments of the superconducting wires to be connected, fitting a metallic connecting pipe on the region where the filaments cross each other, and crimping the metallic connecting pipe onto the crossing filaments thereby tightly fixing and connecting the exposed filaments to each other.

Method of connecting superconducting wires

A vacuum chamber for welding in which to place a workpiece is hermetically connected to a vacuum chamber for an electron beam gun in which to place an electron beam gun, and the former is kept at a vacuum of 1.times.10.sup.-4 Torr while the latter, at a vacuum of 1.times.10.sup.-6 Torr. The distance between the electron beam gun and the surface of the workpiece is made greater than the mean free path of gas molecules and metal vapor molecules generated in treating, e.g., 1.85 m. Two focusing coils are arranged to prevent the expansion of the electron beams.

Method of treating a workpiece with electron beams and apparatus therefor

An electron beam welding machine comprises an electron gun including a first beam adjusting means, a second beam adjusting means disposed spaced from the first beam adjusting means so as to be movable in the direction of an electron beam path, and position adjusting means for adjusting the position of the second beam adjusting means through rotary movement about an axis perpendicularly crossing the electron beam path and linear movements on a plane perpendicular to the electron beam path. The machine further includes a mirror and light source mounted on the electron gun to emit light on the electron beam path, and photodetectors mounted on the opposite sides of the second beam adjusting means so as to face the electron gun and a workpiece, whereby the correct position of the second beam adjusting means is detected.

Electron beam welding machine

Growing community of inventors

Takahagi, Japan

Yoshinori Karatsu