Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Shinichi Morooka

Tadashi Narabayashi

Mikihide Nakamaru

Kenji Arai

Takehiko Saito

Hideaki Heki

Kouji Hiraiwa

Tsuyoshi Shimoda

Seijiro Suzuki

Satoru Oomizu

Makoto Yasuoka

Miyuki Akiba

The present invention is to provide a reactor core that allows a nuclear plant to continuously operate for a long term period, for example 15 years or longer, without requiring any fuel exchange, reduces the duration and number of maintenance steps involved in regular plant inspections, markedly improves plant availability and economic efficiency, and is effective in terms of nuclear nonproliferation. A plurality of fuel assemblies, themselves obtained by arranging fuel rodsand water rodsin square lattices, are arranged in a square lattice at a certain pitch. The bladesof a cross-shaped (cruciform) control rodin a cross section are inserted into four adjacent spaces formed by four fuel assembliesfacing each other. A value of 0.06 cmor greater is selected for the ratio (B/S) of the width (B) of each blade on the cruciform control rodand the surface (S) of the fuel lattice defined by the surface area of a square whose side is equal to the pitch between the fuel assemblies

Reactor core and method for operating nuclear reactor

The present invention provides a boiling water reactor nuclear power plant in which a reactor core support plate, upper grid plate, and a reactor core consisting of fuel assemblies supported by these plates are provided in the inner base portion of a nuclear reactor pressure vessel. Control rod guide tubes and a reactor core shroud are positioned over the upper grid plate, and a control rod drive mechanism is provided further above same, whereby the control rods can be inserted from above the reactor core, and natural circulation of cooling water inside the reactor can be achieved by means of a chimney effect of the control rod guide tubes. According to the above structure, there can be provided a compact and economical nuclear power plant.

Boiling water reactor nuclear power plant and its construction method

A separator/injector having an outlet pressure higher than an inlet pressure thereof is introduced instead of the dynamic equipment for a reactor recirculation system that is necessary in the prior art, to achieve both liquid-vapor separation and forced circulation. A jet pump and a recirculation flow-rate control valve are provided in a lower portion of a downcomer portion of a reactor pressure vessel. A shroud head has a double-walled structure, a two-phase liquid-vapor flow that is flowing from a lower portion of the lower shroud head is accelerated by an accelerator nozzle of the separator/injector, and a liquid component of the thus-separated flow is increased in pressure and guided into a jet pump through a space formed between the double shroud heads. Alternatively, a circular cylindrical separator/injector in which the steam nozzle and diffuser are disposed in a helical form in close proximity to the inner wall of a circular tube above the stand pipe could be provided instead of this separator/injector.

Steam separator, nuclear power generation plant, and boiler apparatus

A water level gauge for a nuclear reactor includes heat conduction means for absorbing and conducting heat to the outside of the drywell, the heat being supplied to reference water head water inside a reference water head tube defining a reference water level inside a reference water level container, and to water inside a lower part pressure pipe connecting a nuclear reactor pressure vessel with a differential pressure detector. The water level gauge further includes heat exchanger for removing the heat. With this device, the water level of the nuclear reactor may be correctly detected even in the case of leakage accident of the coolant of the nuclear reactor.

Water level gauge for a nuclear reactor

According to a level meter of this invention, a pressure corresponding to a fixed water level formed by means of a reference chamber and a vertical pipe is applied to one pressure inlet port of a differential pressure detector, and a pressure corresponding to a water surface or water level inside a container to be measured is applied to the other pressure inlet port of the differential pressure detector by means of a lower pipe. Then, the water level inside the container is measured through the difference between these two pressures, the density of water to generate the pressures to be applied to the differential pressure detector, and the density of steam inside the container and the reference chamber. Adiabatic jackets are attached to the peripheries of the vertical pipe and the lower pipe.

Growing community of inventors

Tokyo, Japan

Shinichi Morooka