Mitsubishi Heavy Industries Limited

Mitsubishi Nuclear Fuel Co., Ltd.

Mitsubishi Genshiryoku Kogyo Kabushiki Kaisha

Nuclear Development Corporation

Yasunao Yamaguchi

Jun Shimizu

Akihiro Kato

Hideyuki Sakata

Shigeyuki Watanabe

Masaji Mori

Toshiyuki Kawagoe

Kimio Nakayama

Atsushi Baba

Hiroaki Kadono

Toshiya Kido

Kinichi Sugai

Masahiko Imaizumi

Provided is a fuel assemblyfor a PWR nuclear reactor capable of stably creating transverse flows of coolant for pressing and securing control rods so as to restrain vibration of the control rods in order to restrain the outer surfaces of the control rods and the inner surfaces of control rod guide tubes from being worn, wherein an upper nozzle arranged above the fuel assembly comprises an adapter plateconstituting the lower structure of the upper nozzle, a side wall extended along the periphery of the adapter plate, an overhang projected into a space above the adapter plate from the upper part of the side wall, and apertures for attaching control guide tubes and passage holes, which are formed in the passage surface of the adapter plate, and wherein thoseA,B,C of the passage holes which are located at positions where the coolant impinges upon the overhang are generally arranged, line-symmetric with respect to diagonal lines of the passage surface serving as symmetric axes Q, and ligamentsaround the passage holes located inside and outside of thoseof the attaching apertures which are located on the outer peripheral side are set to be larger than ligamentsaround the passage holes which are located on opposite transverse sides of those of the attaching apertures.

Fuel assembly for PWR nuclear reactor

One object of the present invention is to provide a production method for a nuclear fuel assembly support grid that improves the corrosion resistance of welded parts without impairing the characteristics of the support grid so as to be able adequately withstand highly efficient operation. In order to achieve the object, the present invention provide a production method for a nuclear fuel assembly support grid comprising the steps of: assembling a plurality of straps in a grid form; welding intersections of each strap; and carrying out annealing thereafter to precipitate an intermetallic compound on the welded parts.

Production method for a nuclear fuel assembly support grid and a nuclear fuel assembly support grid produced by the same

A grid structure is presented in which grid cells are formed by orthogonally intersecting straps prefitted in the longitudinal direction with a plurality of slitted spring frame members. Therefore, when the straps are assembled, the spring frame members are also orthogonally intersected. The spring frame members are made of Inconel and provided with welding tabs while the straps are made of zircalloy and provided with their own welding tabs. Therefore, welding can be performed to firmly join the spring frame members to each other while the straps can also be welded firmly to weld the like metals. The spring sections are thus firmly joined and attached to the straps which are firmly joined. The grid of this configuration thus provides an excellent service life without the losing The fuel rod retaining power, which would result from neutron radiation and thermal damages on holding devices made of zircalloy.

Fuel rod support grids for fuel assembly

Growing community of inventors

Kobe, Japan

Yasunao Yamaguchi