Kabushiki Kaisha Toshiba

Kazuki Hida

Kouji Hiraiwa

Koji Hirukawa

Yasushi Hirano

Koichi Nittoh

Tsuyoshi Nakajima

Yoshihira Ando

Tadashi Ikehara

Jun Saeki

Junko Watanabe

Yamato Hayashi

Fuel assembly and nuclear reactor

Gadolinium is provided which is adapted for nuclear fuel as a burnable poison, having a plurality of isotopes in an isotopic composition such that the content of at least one even mass numbered isotope is smaller than the content of the same isotope in natural gadolinium. A fuel assembly is also provided having a plurality of nuclear fuel rods arrayed as a lattice in which at least one of the fuel rods contains the gadolinium burnable poison of the present invention. Also, a fuel assembly is described which has a plurality of nuclear fuel rods arrayed as a lattice which includes at least a first group and a second group of nuclear fuel rods containing gadolinium. The content of Gd-157 in the gadolinium is larger than that found in natural gadolinium. Further, the gadolinium concentrations in the first and second groups are different from each other.

Nuclear fuel containing gadolinium

A moderator rod provided with a burnable poison and disposed in a fuel assembly of a reactor core comprises an outer tube, an inner tube disposed in the outer tube, the outer and inner tubes constituting a double tube structure between which an annular section is formed, and a burnable poison charged in said annular section. A containing amount of the burnable poison per unit area of the annular section is distributed at least one of peripheral direction and axial direction of the double tube structure of the inner and outer tubes. A fuel assembly of a nuclear reactor comprises an upper tie plate, a lower tie plate, a number of fuel rods supported at their upper ends by the upper tie plate and at their lower ends by the lower tie plate and filled up in their inner spaces with a plurality of fuel pellets, at least one of moderator rods containing burnable poison in various states and a channel box. The moderator has an outer tube and an inner tube disposed coaxially in the outer tube. An area of a metal, ceramics or thermet containing the burnable poison is formed at a portion except for portions having axial length corresponding to 1/24 to 1/12 length of the fuel effective length from the upper and lower ends thereof.

Moderator rod containing burnable poison and fuel assembly utilizing same

A fuel assembly for a boiling water reactor comprising an upper and lower tie plates, a plurality of fuel rods filled therein with a plurality of fuel pellets, a fuel bundle comprising the fuel rods retained with a plurality of spacers in spaced relation and disposed between the upper and lower tie plates, and a polygonal tube-like channel box which encloses the fuel bundle and constitutes flow paths for coolant. The fuel rods comprise long fuel rods and short fuel rods which are each shorter in the effective portion than each of the long fuel rods. The concentration of fissile material in each of the short fuel rods is lower than the mean concentration of fissile material in the cross section of the fuel bundle. In the case the fuel bundle is vertically subdivided into two regions, an upper and lower one, with the upper end of the effective portion of each of the short fuel rods as a border, the mean concentration of fissile material in the cross section of the fuel bundle in the region lower than the border is lower than that in the cross section of the fuel bundle in the region above the border.

Fuel assembly for boiling water reactor and core

Growing community of inventors

Tokyo, Japan

Kazuki Hida