Hitachi, Ltd.

Babcock-hitachi Kabushiki Kaisha

Shimizu Construction Co., Ltd.

Hitachi Nuclear Engineering Co., Ltd.

Hitachi Kiso Co., Ltd.

Hideyasu Furukawa

Kenji Sekiguchi

Kunio Enomoto

Ren Morinaka

Koichi Kurosawa

Masahiro Otaka

Eisaku Hayashi

Kouichi Ushiroda

Noboru Chiba

Fujio Yoshikubo

Tadao Suzuki

Akinori Tajiri

Kazunori Sato

Yasuyoshi Shimazaki

Keiji Nakanishi

Masami Hosoda

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

A method of constructing a top slab to provide a containment roof over a nuclear-power generating building, in particular, a method for utilizing overhead spaces bounded by a wall of the containment building and a shielding wall of the pressure vessel building, wherein the sequential steps involve; erecting a plurality of paired support columns on tops of the wall and of the shielding wall; building upper structural components across said paired support columns; installing a slab liner equipped with slab anchors beneath said lower structural components by suitable joining means; constucting a reinforcing network above said lower structural components; encasing said lower structural components and said reinforcing network; and pouring concrete over the slab liner to a suitable depth.

Method of construction of top slab for a nuclear containment building

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Hitachi, Japan

Hideyasu Furukawa