Hitachi, Ltd.

Hitachi Plant Engineering Construction Co., Ltd.

Koichi Saito

Eiichi Nishimura

Shunsuke Uchida

Kouichi Ushiroda

Tatsuo Hayashi

Akinori Tajiri

Naoto Yoshida

Masao Kitamura

Masakazu Nagase

Tadashi Matsuura

Tatsuo Makita

Eishi Ibe

Shigeru Nanba

In a method of construction of a reinforced concrete diaphragm floor of a nuclear reactor reinforced concrete containment vessel, a bottom surface of the diaphragm floor is provided in the form of an iron plate. The iron plate, an iron bar beam portion for supporting the load provided by concrete during a concrete pouring time, and a reinforcing bar member to be buried in the concrete of the diaphragm floor are assembled outside of a building in which the nuclear reactor is to be embodied. The above members are carried using lifting machinery and are set in a permanent receiving member which is provided on both a main body of the nuclear reactor pressure vessel and a steel member serving as a concrete mold frame of an outer wall of the nuclear reactor reinforced concrete vessel. A concrete pouring is carried out in stages so as to form successive layers of concrete during plural pouring times. After a first concrete layer has completed and the strength of the concrete layer has been established after hardening, the second concrete layer is poured on the first layer, which aids in supporting the weight of the poured concrete.

Construction method of nuclear reactor reinforced concrete containment

A control rod for a boiling-water reactor having blades arranged in the form of a cross in transverse cross section includes a plurality of poison tubes disposed therein. Boron carbide powder which is a neutron absorbing material causing an (n, .alpha.) reaction to take place is charged in the poison tubes. The control rod has plates of Hf-Zr alloy arranged in the blades in a position nearer to a forward end of the control rod at which the control rod is inserted in a reactor core than the poison tubes. The plates of Hf-Zr alloy are formed of an alloy of Hf having a large neutron absorption cross section and Zr having a small neutron absorption cross section. The concentration of Hf in the plates of Hf-Zr alloy is successively reduced in going from an end thereof adjacent the poison tubes toward and end thereof at the inserting end of the control rod. The plates of Hf-Zr alloy and the poison tubes have the same neutron absorbing capacity at the boundary therebetween at which they are in contact with each other.

Control rods and method of producing same

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Hitachinaka, Japan

Koichi Saito