The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 12, 1998
Filed:
Mar. 24, 1995
Eisaku Hayashi, Hitachi, JP;
Koichi Kurosawa, Hitachi, JP;
Fujio Yoshikubo, Mito, JP;
Hideyasu Furukawa, Hitachi, JP;
Ren Morinaka, Hitachi, JP;
Kunio Enomoto, Tokai-mura, JP;
Masahiro Otaka, Hitachi, JP;
Noboru Chiba, Tokai-mura, JP;
Kazunori Sato, Kure, JP;
Hitachi, Ltd., Tokyo, JP;
Babcock-Hitachi Kabushiki Kaisha, Tokyo, JP;
Hitachi Nuclear Engineering Co., Ltd., Ibaraki, JP;
Hitachi Kiso Co., Ltd., Ibaraki, JP;
Abstract
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.