RU199744U1 - Device for producing uranium and plutonium oxides - Google Patents

Abstract

The utility model refers to a device for the manufacture of uranium oxide fuel or mixed uranium-plutonium oxide fuel or as a starting material for the manufacture of mixed uranium-plutonium nitride fuel for nuclear power plants. The device for producing uranium and plutonium oxides under the action of microwave radiation contains a microwave generator and a reaction chamber, inside which a stirring device is installed. Moreover, the reaction chamber is a split cylindrical body, and the shaft of the mixing device is made hollow to supply a reducing gas atmosphere to the reaction zone and reflective elements are fixed on it. The stirring device is additionally equipped with toothed elements for grinding the mixed oxides of uranium and plutonium formed under the action of microwave radiation, and the lower part of the reaction chamber is made of heat-resistant stainless steel and is a crucible. The technical result is the possibility of obtaining a mixture of uranium and plutonium dioxides, increasing the intensity of the processes of evaporation, concentration and denitration of solutions, combining the operations of mixing and grinding. 1 ill.

Description

The utility model relates to radiochemical technology and can be used to produce uranium oxide powders, which can be used to manufacture uranium oxide fuel or mixed uranium-plutonium oxide fuel or as a starting material for the manufacture of mixed uranium-plutonium nitride fuel for nuclear power plants.

Known device for denitration of nitrate solutions by microwave heating [US 4727231 H05B 6/64, publ. 02.23.88], in which the heating of solutions of uranyl nitrate, plutonium or their mixtures is carried out under the action of microwave radiation. The reaction chamber has a cylindrical shape. The lower part of the reaction chamber is used as a closed-bottom vessel for receiving the substance to be treated. A waveguide is installed on the upper wall of the reaction chamber and is blown into the gas cleaning device. The waveguide is connected to a microwave generator. The blow-off serves to release the waste gases. Waste gas is generated during the heating / denitration process of the material to be treated. The device allows you to evaporate, that is, to concentrate nitrates until a dry powder is obtained, which is denitrated in the same device.

The disadvantages of this technical solution are:

- the need to install an additional detector device to protect the microwave generator from reflected waves, part of the microwaves is absorbed by the processed substance, and the other part of the microwaves is reflected from the walls of the reaction chamber and returns through the waveguide back to the microwave generator, which reduces the specific power of the device;

- the absence of a stirring device, which does not allow cleaning the bottom of the crucible from the processed material, which makes it difficult to completely unload it.

The closest is a batch device for microwave processing of materials [RU 2693820 C1, IPC Н05В 6/64, publ. 09/08/2019), consisting of a microwave generator, a reaction chamber, which is a cylindrical body, inside which a mixing device with fixed blades is installed, installed with the possibility of rotation and movement along its axis, a feed device for the initial solution, a gas cleaning device are placed on the body. The reaction chamber is fixed with a winch and mounted on a swivel arm, in the lower part of the reaction chamber there is a ceramic insert made of a material fired at a temperature of 1200-1300 ° C, consisting of a mixture of aluminum oxide powder with a microwave-absorbing powder. On the upper part of the reaction chamber there is an overflow valve, inside the reaction chamber there is a grinder, the shaft of which is located coaxially with the hollow shaft of the mixing device. The microwave generator is hermetically connected to the reaction chamber by a microwave energy waveguide, which consists of three tubes. The device allows simultaneous evaporation of uranyl nitrate solution, its denitration, mixing of the evaporated solution and then the resulting powder with simultaneous grinding.

The disadvantages of the prototype are:

- the use of a ceramic crucible with a microwave absorber, which causes a loss of microwave power and does not allow reaching the temperature required to obtain uranium dioxide;

- corrosion and abrasive wear of a ceramic crucible with a microwave absorber causes contamination of uranium oxides;

- the absence of reflective elements in the reaction chamber, which does not allow focusing the microwave radiation on the processed material and leads to an increase in the time of the processes of evaporation, concentration and denitration of solutions;

- the complexity of the design of providing adjustable speeds of rotation of the grinder and mixing device when placing the shaft of the grinder inside the hollow shaft of the mixing device;

- the supply of the reducing medium to the upper part of the reaction chamber does not provide the necessary contact between the processed material and the reducing gas.

The indicated design flaws of the prototype do not allow to obtain with its help a mixture of uranium and plutonium (cerium) dioxides of a given phase composition and increase energy consumption due to heating of a ceramic insert with a microwave absorbing material and dispersion of microwave radiation outside the zone of the processed material.

The technical problem of the claimed utility model is the creation of a batch device for microwave processing of materials used as part of a module for processing mixed uranium-plutonium nitride (MNUP) irradiated nuclear fuel (SNF), that is, obtaining a powder of mixed oxides of uranium and plutonium (cerium) of a given phase composition, including in the form of dioxides, for further production of fuel pellets from it, as well as reducing the time of these processes.

The technical result is the possibility of obtaining a mixture of uranium and plutonium dioxides, increasing the intensity of the processes of evaporation, concentration and denitration of solutions, combining the operations of mixing and grinding.

The technical result is achieved in a device for producing uranium and plutonium oxides under the action of microwave radiation containing a microwave generator and a reaction chamber, inside which a stirring device is installed, and the reaction chamber is a split cylindrical body, and the stirring device shaft is hollow for supplying a reducing gas atmosphere to the reaction zone and reflective elements are fixed on it, while the mixing device is additionally equipped with toothed elements for grinding mixed uranium and plutonium oxides formed under the action of microwave radiation, and the lower part of the reaction chamber is made of heat-resistant stainless steel and is a crucible.

The claimed technical solution is illustrated in the drawing.

The figure shows a schematic longitudinal section of the proposed device.

The proposed device contains a microwave generator (not shown in the figure), a resonator chamber, which is a split cylindrical body, the lower part 1 of which is a crucible and is made of heat-resistant stainless steel, with a high reflectivity of microwave radiation. The shell of the upper part 2 of the split cylindrical body is equipped with a window 5 made of microwave-transparent material. Hollow shaft 3 is located in the resonator chamber coaxially with the cylindrical body. The hollow shaft 3 is equipped with reflective elements 4 and a mixing device-grinder 7 with toothed elements 8, which simultaneously performs the functions of mixing and grinding the mixed oxides of uranium and plutonium (cerium) formed under the action of microwave radiation.

The claimed device operates as follows:

The initial solution is poured through a feeding device (not shown in the figure) into the lower part 1 of the reaction chamber, which is a crucible. Include a microwave generator. A stirring device is turned on at a speed of 6-12 rpm. Microwave radiation, through the waveguides, enters through the window 5 onto the reflecting elements 4, and, being reflected, is focused in the lower part of the reaction chamber (in the crucible) 1 on the processed material 6. The stirring device-grinder 7 provides temperature equalization throughout the volume of the solution. When a solid crust forms on the surface of a thickening solution, the mixing device-grinder 7 breaks it and grinds it with the gear elements 8 during rotation. After the end of evaporation, the powder crushed during the mixing process is heated to the oxide reduction temperature, while through the hollow shaft of the mixing device into the lower part of the reaction chamber, directly into the reaction zone, with constant mixing of the powder, a reducing argon-hydrogen mixture is supplied, providing an effective, intensive interaction of gas with powder in the crucible.

Thus, due to the high efficiency of the effect of microwave radiation, focused reflective elements on the material, the time for the evaporation, concentration and denitration processes is reduced. Due to the supply of a gaseous medium or air directly to the reaction zone, the interaction of the entire volume of the powder with the reducing gas is ensured and the production of uranium and plutonium (cerium) oxide powders of a given phase composition. By using a stainless steel crucible, powders are obtained that are not contaminated with the materials of the ceramic insert of the crucible according to the prototype. Stirring the solution with simultaneous grinding eliminates the cooling operation before grinding.

Claims (1)

A device for producing uranium and plutonium oxides under the action of microwave radiation, containing a microwave generator and a reaction chamber, inside of which a stirring device is installed, characterized in that the reaction chamber is a split cylindrical body, and the stirring device shaft is hollow for supplying a reducing gas atmosphere to the reaction zone and reflective elements are fixed on it, while the mixing device is additionally equipped with toothed elements for grinding mixed uranium and plutonium oxides formed under the action of microwave radiation, and the lower part of the reaction chamber is made of heat-resistant stainless steel and is a crucible.

Images