Abstract: A channel box in an embodiment includes a tubular portion. The tubular portion includes a first tubular layer, a second tubular layer, and an intermediate tubular layer. The first tubular layer contains silicon carbide as a major component. The second tubular layer is in parallel to and surrounds or is surrounded by the first tubular layer and contains silicon carbide fibers and silicon carbide complexed with the silicon carbide fibers. The intermediate tubular layer is disposed between the first tubular layer and the second tubular layer and contains a solid lubricant.

Abstract: There are provided a continuous fiber-reinforced silicon carbide member and the like which allow sufficient improvement in a mechanical property and environmental resistance. The continuous fiber-reinforced silicon carbide member of an embodiment is a tubular shape and has a first composite material layer and a second composite material layer. In the first composite material layer, continuous fibers of silicon carbide are combined with a matrix of silicon carbide. In the second composite material layer, continuous fibers of carbon are combined with a matrix of silicon carbide. Then, the first composite material layer and the second composite material layer are stacked.

Abstract: A channel box in an embodiment includes a tubular portion. The tubular portion includes a first tubular layer, a second tubular layer, and an intermediate tubular layer. The first tubular layer contains silicon carbide as a major component. The second tubular layer is in parallel to and surrounds or is surrounded by the first tubular layer and contains silicon carbide fibers and silicon carbide complexed with the silicon carbide fibers. The intermediate tubular layer is disposed between the first tubular layer and the second tubular layer and contains a solid lubricant.

Abstract: 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 103, themselves obtained by arranging fuel rods 100 and water rods 107 in square lattices, are arranged in a square lattice at a certain pitch. The blades 102a of a cross-shaped (cruciform) control rod 102 in a cross section are inserted into four adjacent spaces formed by four fuel assemblies 100 facing each other. A value of 0.

Abstract: 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.

Abstract: The present invention provides a boiling water-type nuclear power plant comprising: a passive safety system having depressurization valves and a gravity driven core cooling system as an emergency core cooling system; a passive containment vessel cooling system in which reactor steam released in the containment vessel is cooled by a heat exchanger in a cooling water pool installed in the upper portion of the containment vessel; and a containment vessel flooding system which injects cooling water into a dry well of the containment vessel on an accident; wherein a containment vessel spray cooling system for injecting cooling water into the containment vessel via a pump is further added as a safety system.

Abstract: 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.

Abstract: 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.

Abstract: An insulating shield plate (1) divides a room of an electrolysis bath (2) into an anode chamber (13) and a cathode chamber (14). An anode (5) is disposed in the anode chamber (13), and a cathode (6), metallic waste (7) and heater (4) are disposed in the cathode chamber (14). An electrolyte (3) stored in the electrolysis bath (2) flows in a circulation path from a circulating pump (10) through a circulating line (12) and filter (11) to return the electrolysis bath (2). An exhaust gas processing device 9 is connected to the electrolysis bath (2). When a voltage is supplied to the anode (5) and cathode (6), a surface of the metallic waste (7) is charged in a positive polar to dissolve a base metal of the metallic waste (7). Further, a cylindrical anode (33) is arranged in an electrolyte (32) in an electrolysis bath (31), and a cylindrical metal (34) as a metallic waste is arranged in the cylindrical anode (33).

Abstract: An ultrasonic cleaning device for cleaning a fuel assembly constituting an item to be cleaned, includes: a plurality of ultrasonic transducers which irradiate the outside of this item to be cleaned with ultrasonic waves from at least two directions; an ultrasonic transducer translating mechanism which moves ultrasonic transducers vertically along a support member and which is provided with a steel housing constituting an ultrasonic wave reflecting structure which reflects ultrasonic waves from ultrasonic transducers towards the item to be cleaned a feed pump arranged outside the item to be cleaned and constituting a cleaning liquid supply mechanism which supplies cleaning liquid in a pressurized condition into the interior of the item to be cleaned; and a discharge pump including a cleaning liquid discharge mechanism that discharges cleaning liquid from the cleaning liquid supply mechanism to a filter device.

Abstract: A crawler driven vehicle is utilized in a dangerous environment and remotely controlled and operated. The crawler vehicle comprises a vehicle body, four arcuate front and rear crawler assemblies respectively attached to the bilateral sides of the vehicle body, each crawler assembly comprises a crawler formed by an endless belt and stretched over the periphery of the crawler assembly so as to exhibit arcuate surface contacting the running floor, a drive mechanism for driving the crawler assembly through a power transmission mechanism, and a steering mechanism for steering the front crawler assemblies.

Abstract: An effluent gas monitoring apparatus for detecting radioactivities in water, carbon dioxide, and rare gases recovered by introducing the radioactive effluent gas to a water recovery section, a carbon dioxide recovery section and, if necessary, a rare gas concentration section which are arranged parallel to each other. The capacities, scales and gas flow rates of the respective sections which are arranged parallel to each other may be freely selected.

Abstract: Disclosed is an apparatus for detecting the location of failed fuel in a reactor, the apparatus comprising means for collecting tag gas from cover gas containing tag gas at ambient temperature and enriching the collected tag gas to an analyzable concentration and tag gas analysis means for analyzing the enriched tag gas to determine the composition thereof.

Abstract: A gas separator which comprises a first separation cell provided with a membrane; a second separation cell similarly fitted with a membrane; a feed pipe for conducting a gas mixture being separated to a high pressure chamber of the first separation cell; a leadout pipe for drawing off from the first separation cell either the gas which has permeated the membrane of the first separation cell or that which has not passed through the membrane thereof; a connection pipe for carrying the other gas from the first separation cell to the high pressure chamber of the second separation cell; a feedback pipe for returning to the feed pipe either the gas which has permeated the membrane of the second separation cell or that which has not flowed through the membrane; and a discharge pipe for removing the other gas from the second separation cell.