Hitachi, Ltd.

Toru Kanazawa

Koji Nishida

Akihito Orii

Osamu Yokomizo

Shin-ichi Kashiwai

Junjiro Nakajima

Masao Chaki

Junichi Koyama

Kumiaki Moriya

Tatsuo Hayashi

Fuel assembly

An object of the present invention is to provide a boiling water reactor wherein two phase flow instability in a fuel assembly occurs scarcely. A bottom flow path is formed beneath a partition plate which is supported by control rod driving mechanism housings in a reactor pressure vessel, and coolant guide tubes which open beneath the partition plate stands perpendicularly on the partition plate. An upper end portion of the coolant guide tube is restrained at outer periphery by a fixing portion of a square grid, and a coolant entrance of a fuel assembly is connected through to the coolant guide tube. Pressure loss of the coolant decreases and flow instability of the coolant in the fuel assembly occurs scarcely, lowering of a critical power ratio at a pump trip can be suppressed.

Boiling water reactor

A fuel assembly included a plurality of fuel rods, fuel spacers for maintaining gaps between the fuel rods and a channel box. The channel box includes spacer support portions projecting inwardly from an inner surface of the channel box and supporting the fuel spacer in a transverse direction and creep deformation inhibition portions disposed at the lower end portion of the channel box and projecting inwardly. The distance between the spacer support portions disposed to oppose one another in a horizontal direction is smaller than the distance between the creep deformation inhibition portions opposing one another in the horizontal direction.

Fuel assembly, channel box, production method of channel box, and core

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Hitachi, Japan

Toru Kanazawa