Hitachi-ge Nuclear Energy, Ltd.

Hitachi, Ltd.

Junichi Miwa

Kumiaki Moriya

Renzo Takeda

Motoo Aoyama

Koji Fujimura

Tomohiko Ikegawa

Renzou Takeda

Kazuhiro Fujimata

Sho Fuchita

Motohiko Ikegawa

A fast reactor core includes a sodium plenum installed above the fuel. The sodium plenum is capable of reducing a void reactivity. During operation, a tip of a primary control rod is inserted in a core fuel region, and a tip of a backup control rod is arranged near an upper end of the sodium plenum.

Fast reactor with primary and backup control rods

The fuel element of the present invention includes a cladding tube and a metal fuel contained in the cladding tube, in which a gas plenum region is formed above the metal fuel and inside the cladding tube and has a small-diameter portion in the gas plenum region. Further, the fuel assembly of the present invention includes the fuel element of the present invention and a wrapper tube surrounding the fuel element, in which a coolant material passage is formed between the fuel element and the fuel element. Further, the core of the present invention includes an inner core fuel region loaded with the fuel assembly according to the present invention, and an outer core fuel region loaded with the fuel assembly of the present invention.

Fuel element, fuel assembly, and core

A core of a light water reactor has a plurality of fuel assemblies. The fuel assemblies include a plurality of fuel rods in which a lower end is supported by a lower tie-plate and an upper end is supported by an upper tie-plate. The fuel rods form plenums above a nuclear fuel material zone and have a neutron absorbing material filling zone under the nuclear fuel material zone. Neutron absorbing members attached to the upper tie-plate are disposed between mutual plenums of the neighboring fuel rods above the nuclear fuel material zone. The neutron absorbing members have a length of 500 mm and are positioned at a distance of 300 mm from the nuclear fuel material zone. Even if the overall core is assumed to become a state of 100% void, no positive reactivity is inserted to the core.

Core of light water reactor and fuel assembly

A boiling water reactor has a core disposed in the reactor pressure vessel and loaded with a plurality of fuel assemblies including transuranic nuclides. A ratio of Pu-239 in all of the transuranic nuclides included in the fuel assembly, which is loaded in the core, with a burnup of 0 is 3% or more but 45% or less. In the fuel assembly having a channel box and a plurality of fuel rods disposed in the channel box, a transverse cross section of a fuel pellet in the fuel rod occupies 30% or more but 55% or less of a transverse cross section of a unit fuel rod lattice in the channel box.

Boiling water reactor, core of boiling water reactor and fuel assembly

A core of a light water reactor having a plurality of fuel assemblies, which are loaded in said core, having nuclear fuel material containing a plurality of isotopes of transuranium nuclides, an upper blanket zone, a lower blanket zone, and a fissile zone, in which the transuranium nuclides are contained, disposed between the upper blanket zone and the lower blanket zone, wherein a ratio of Pu-239 in all the transuranium nuclides contained in the loaded fuel assembly is in a range of 40 to 60% when burnup of the fuel assembly is 0, sum of a height of the lower blanket zone and a height of the upper blanket zone is in a range of 250 to 600 mm, and the height of said lower blanket zone is in a range of 1.6 to 12 times the height of the upper blanket zone.

A core of a light water reactor having a plurality of fuel assemblies, which are loaded in said core, having nuclear fuel material containing a plurality of isotopes of transuranium nuclides, an upper blanket zone, a lower blanket zone, and a fissile zone, in which the transuranium nuclides are contained, disposed between the upper blanket zone and the lower blanket zone;

A ratio of the number of fuel assemblies loaded on a core to the number of control rod drive mechanisms is 3 or more. The fuel assembly itself contains mixed oxides of a low enrichment concentration uranium oxide containing 3 to 8 wt % in the average enrichment concentration of the fuel assembly, or mixed oxide containing not less than 2 wt %, but less than 6 wt % in the average enrichment concentration of fissile plutonium of. In the burner type BWR core on which the fuel assemblies are loaded, an average weight density of uranium, plutonium and minor actinides is 2.1 to 3.4 kg/L as a conversion at the value of unburned state.

Boiling water reactor core and fuel assemblies therefor

There are provided a light water reactor core which has the same levels in cost efficiency and degree of safety as those of an existing BWR under operation now, that is, which is oriented to plutonium multi-recycle having a breeding ratio near 1.0 or slightly larger and having a negative void coefficient with minimizing modification of the reactor core structure of the existing BWR under operation now, and to fuel assemblies used for the boiling water reactor. The light water reactor core having an effective water-to-fuel volume ratio of 0.1 to 0.6 is formed by combining closed compact lattice fuel assemblies each composed of fuel rods having fuel which is enriched by adding plutonium or plutonium and an actinide to a uranium containing at least one of a depleted uranium, natural uranium, a degraded uranium and a low enriched uranium; high void fraction coolant of 45% to 70%; and large-diameter control rods to be inserted into the fuel assemblies, the large-diameter control rod comprising at least one absorption rod having a transverse cross-sectional area larger than a cross-sectional area of a unit lattice cell of the fuel rod.

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Mito, Japan

Junichi Miwa