Hitachi, Ltd.

Iwao Takase

Masahisa Inagaki

Hideo Maki

Junjiro Nakajima

Isao Masaoka

Masayoshi Kanno

Toshimi Yoshida

Jiro Kuniya

Hajime Umehara

Tetsuo Yasuda

Tadashi Fujieda

Keiichi Kuniya

Takehiro Seto

Ryutarou Jimbow

Kenichi Ito

Junichi Yamashita

Noriyuki Ohnaka

Hiromasa Hirakawa

Akihiro Yamanaka

Shinzo Ikeda

Kimihiko Akahori

Yoshitaka Nishino

Akira Maru

Hideaki Ishizaki

Toraki Sakuma

Kouichi Matsumoto

Nobukazu Yamamoto

Tetsuro Yasuda

Toshitaka Kida

Nobuhiro Okazaki

Rinichi Asano

A channel box for a nuclear-reactor fuel assembly (MOX fuel assembly) containing plutonium, capable of properly controlling the excess reactivity without mixing neutron absorber or burnable poison into a fuel rod, and a channel box for a nuclear-reactor fuel assembly which does not form any gap between the channel box and members containing burnable poison in the channel box and in which the burnable poison does not directly contact with reactor water.

Fuel assembly channel box having burnable poison

The present invention provides a zirconium based alloy member which has very small deformation of elongation and bow occurring due to irradiation growth, a method of manufacturing it, and particularly an channel box for an atomic reactor fuel assembly. A zirconium based alloy plate member having a width of not less than 100 mm and a long length, containing not more than 5 wt % Nb and/or not more 5 wt % Sn, the member having (0001) orientation (Fl value) of hexagonal Zr with respect to longitudinal direction ranging from 0.20 to 0.35, the difference in Fl between the middle and the end being not more than the value calculated from (0.0935.times.Fl-0.00585) and an amount of bow at neutron irradiation of 35 GWd/t which bow occurs in the channel box for a reactor being not more than 2.16 mm.

Zirconium based alloy of low irradiation growth, method of producing the

In a method of fabricating a channel box for use in a nuclear reactor, Zr-alloy sheet material is formed into a tubular channel box. The method includes solution heat treatment of the Zr-alloy sheet material including quenching from a temperature at which .beta.-phase is present. After the solution heat treatment, portions of the Zr-alloy sheet are thinned relative to other portions by a non-stressing thinning process, such as chemical etching in a bath. The corrosion resistance imparted by heat treatment is retained, and the heat treatment itself is easily performed on material of uniform thickness.

Method of fabricating a channel box or other part for a nuclear reactor

A fuel assembly for a nuclear reactor comprising a fuel cladding tube of three-layer structure having an outer surface in contact with reactor water of the nuclear reactor, an inner surface layer in contact with the nuclear fuel, and an intermediate layer interposed between the outer surface layer and the inner surface layer. the outer surface layer is made of a Zr-based alloy containing Nb, Sn and Mo. The inner surface layer is made of pure zirconium. The intermediate layer is made of a high ductility alloy which is higher in ductility than the outer surface layer and is higher in strength than the inner surface layer.

Fuel assembly for nuclear reactor, method for producing the same and

A zirconium based alloy plate of low irradiation growth, containing not more than 5 wt % Sn and/or not more 5 wt % Nb, and the balance Zr of not less than 90 wt %. The alloy plate has a texture that &lt;0001&gt; orientation (Fr value) with respect to direction perpendicular to the surface of the plate ranges from 0.20 to 0.50. This alloy plate is effective in being used to form a fuel channel box. Also a fuel assembly using this channel box is provided in which the crystal orientation of the zirconium alloy is made random by a heat treatment. Specifically, by the heat treatment, the Fr, Ft, and Fl values thereof are set to 0.25 to 0.50, 0.25 to 0.36, and 0.25 to 0.36, respectively.

Zirconium based alloy plate of low irradiation growth, method of

A channel box and/or a spacer of a fuel assembly is a welded construction and made of a Zr-Nb-Sn alloy comprising 0.5-2.2 wt % Nb, 0.5-1.5 wt % Sn contained so as to satisfy the relation of Sn(wt %) 22.times.Nb(wt %)--3.0, and balance Zr or a Zr-Nb-Sn-Mo alloy comprising 0.5-2.2 wt % Nb, 0.5-1.5 wt % Sn contained so as to satisfy the relation of Sn(wt %).gtoreq.2.times.Nb(wt %)--0.3, 0.1-0.8 wt % Mo, and balance Zr. The welded portion, its heat affected zone and the unwelded portion of the channel box and/or the spacer have substantially the whole equilibrium phase structure.

Nuclear reactor fuel assembly

A zirconium-based alloy with a high corrosion resistance, consisting essentially of 1 to 2 wt % Sn, 0.20 to 0.35 wt % Fe, 0.03 to 0.16 wt % Ni and the balance substantially Zr. The Fe/Ni content ratio of the alloy ranges between 1.4 and 8. The structure of the alloy has fine intermetallic compound of Sn and Ni is precipitated within the zirconium crystal grain of .alpha.-phase. The alloy may further contain 0.05 to 0.15 wt % Cr. This alloy exhibits reduced hydrogen absorption rate and suffers from no nodular corrosion, so that it can suitably be used as a material of nuclear fuel cladding tubes. The nuclear fuel cladding tube made of this alloys exhibits extended service life when used in a nuclear reactor of high degree of burn-up.

Zirconium-based alloy with high corrosion resistance

A method of producing cladding tube comprises a step of temperature-gradient annealing in which the inner surface of the tube is heated to a temperature higher than the recrystallization temperature thereof, while the outer surface of the tube is cooled, after the tube has been hot-extruded. The temperature-gradient annealing is effected while a temperature gradient is maintained between the inner surface and the outer surface of the cladding tube. While keeping the inner surface at a temperature higher than the recrystallization temperature, and the outer surface at a temperature lower than the recrystallization temperature. The cladding tube is obtained with the outer surface which has an excellent resistance to nodular corrosion and a soft inner surface which has an excellent resistance to stress corrosion cracking.

Method of producing a cladding tube for reactor fuel

In a process for producing a zirconium-based alloy in which after the zirconium-based alloy is subjected to hot plastic working, it is subjected to cold plastic working and then to annealing and these steps are repeated at least twice, the present invention provides a process for producing a zirconium-based alloy characterized in that after the alloy is subjected to solid solution treatment in which it is heated to a temperature within the range including the .alpha. phase and the .beta. phase of the alloy, or within the range of the .beta. phase and is then quenched, cold plastic working is effected at least twice.

Process for producing zirconium-based alloy

Process for producing zirconium-based alloy and the product thereof

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Ibaraki, Japan

Iwao Takase