RU2408095C1 - High-temperature gas-cooled fast neutron nuclear reactor - Google Patents

Abstract

FIELD: power industry. ^ SUBSTANCE: active zone of reactor includes vertical cylindrical unit with annular cavity for arrangement of fuel elements, which has radial through holes for passage of gas heat carrier. Holes provide connection of inlet and outlet headers to the space between fuel elements; at that, one of headers which is internal is formed with the walls of the unit and located along its axis, and the other one which is external is formed with its side surface and side surface of the unit. Axes of the unit and active zone coincide, fuel elements of pin type, which are arranged parallel to active zone axis, are used. Unit is made from heat-resistant stainless steel, and in its annular cavity there installed are transverse spacing partitions made from the same material and in which there are holes for arrangement of fuel elements; at that, distance between neighbouring partitions is comparable to diametre of fuel elements. ^ EFFECT: decreasing overall dimensions of reactor and increasing heat removal from active zone. ^ 2 dwg

Description

The invention relates to the field of nuclear engineering and can be used in nuclear energy, mainly for power or research installations using a high-temperature gas-cooled nuclear reactor with fast neutrons.

Various designs of fast neutron reactors are known, in the active zone (AZ) of which the fuel elements (fuel rods) of the rod type are parallel to each other and the axis of the AZ. To cool these fuel rods, a liquid metal coolant is used, most often sodium (for example, RF patent No. 2088981, publ. 08.27.97). The use of rod fuel rods for such types of reactors with a high effective density of the fuel composition (loading heavy atoms per unit length of a fuel rod) is currently traditionally and fairly well developed.

A specific problem of such reactors is the great positive value of the sodium void reactivity effect. This problem requires large expenditures in improving the design, for example, changing the design of the active zone, placing the sodium cavity above or inside the active zone, organizing gas volumes, etc. It should also be noted that a large volume of liquid metal coolant concentrated in the volume of the reactor vessel creates an increased seismic hazard and increased fire hazard in case of damage to the vessel.

Known high-temperature gas-cooled nuclear reactor with fast neutrons (RF patent No. 2236047, publ. 20.10.03), comprising an active zone with fuel assemblies, each of which consists of vertical cylindrical graphite blocks mounted one above the other, input and output collectors. Each block contains fuel elements, and radial through holes are made in it for the passage of the gas coolant. The block has an internal cavity in the form of an annular channel formed by the side walls of the block in this cavity and microfuel elements are placed free of charge. One of the collectors is made - internal and located along the axis of the block, and the other - external and is formed by its lateral surface and lateral outer surface of the block. The collectors communicate with the space between the fuel rods through the radial through holes of the blocks. Each of the collectors can be either input or output. The blocks may take the form of a truncated pyramid or an overturned truncated pyramid with alternating through one at the height of the assembly. This design of the reactor for the largest number of similar features with the claimed solution and the overall problem to be solved with it is selected as a prototype.

A disadvantage of the known design is the low efficiency of heat transfer in fuel assemblies due to thermal resistance arising from the transfer of heat from microfuel to the heat transfer medium. In addition, the design of the fuel rods, the large size of A3, the presence of mounting gaps and a graphite block increase the amount of coolant required and, consequently, the dimensions of the reactor.

The objective of this technical field is to create a small-sized nuclear reactor with improved technical and economic indicators. To solve this problem, it is proposed to use a gas coolant and rod type fuel rods in a fast neutron reactor. The layout of the reactor core with rod-type fuel rods is widely used in the design of fast reactors with a liquid metal coolant, and when using a gas coolant, ball fuel rods or microfuel are used. For fast reactors with a gas coolant, the layout of the core using rod rods was not used.

The technical result of the proposed solution is to reduce the size of the reactor and increase the heat removal from the core.

The specified technical result is achieved due to the fact that in a high-temperature gas-cooled fast neutron reactor, which includes common features with the prototype, namely:

the active zone includes a vertical cylindrical block with an annular cavity for the placement of fuel rods, made with radial through holes for the passage of the gas coolant, providing the connection of the input and output collectors with the space between the fuel rods, while one of the collectors is made - internal, formed by the inner side surface of the block and is located along its axis, and the other is outer and is formed by its lateral surface and lateral outer surface of the block, there are distinctive signs, and about:

the axes of the block and the core coincide, rod type fuel rods are used as fuel rods, which are placed parallel to each other and the axis of the core, and the block is made of heat-resistant stainless steel and transverse distance baffles are installed inside the same material, in which holes are made for placement fuel rods, while the distance between adjacent baffles corresponds to the diameter of the fuel rods.

The use of rod-type fuel rods, which are placed parallel to each other and to the axis of the core, makes it possible to optimally layout the core, make the core more heterogeneous and increase the effective density of the fuel composition (fuel loading, for example, uranium).

The implementation of the block of steel simplifies the design, eliminates the disadvantages inherent in the prototype and associated with the use of graphite in AZ, reduces its dimensions and increases heat removal.

The presence of partitions allows you to optimize the design and give a transverse direction to the flow of coolant through the fuel rods along the entire height of the active zone.

The choice of the distance between the partitions is associated with ensuring maximum heat removal.

Figure 1 schematically shows the design of the claimed device (side view),

figure 2 is a top view where:

1 - core block;

2 - input collector;

3 - output collector;

4 - fuel elements.

A nuclear reactor contains an active zone along the axis of which a block of heat-resistant stainless steel is installed. The block contains an annular cavity for accommodating rod fuel elements formed by the outer and inner cylindrical side surfaces. Each fuel rod is a rod with a core of uranium dioxide, with a diameter of about 1 cm, enclosed in a steel sheath. The rods above and below are fixed in the tube plates. The block has radial openings for the passage of coolant. Around the outer side surface of the block is placed an external collector, which is the input and is formed by its own surface and the surface of the block, and the output collector is placed inside the block and is formed by its inner side surface. The block is made of heat-resistant stainless steel, and inside it there are transverse spacing baffles made of the same material, in which holes are made for placing fuel rods, the distance between adjacent baffles being comparable with the diameter of the fuel rods. It is also possible to use a reactor with a changed flow direction of the coolant, while the internal collector will be inlet and the external one will be output. Such a scheme will require the implementation of a reactor vessel made of heat-resistant steel. It is possible to use air or an inert gas as a heat carrier.

The reactor operates as follows.

Cold coolant enters the inlet manifold 2, then through the holes of block 1 it enters the space between the fuel rods 4, where it contacts them and is heated by the fission reaction in nuclear fuel. The transverse spacing partitions, installed along the height of the block, give the coolant flow transverse flow through the rod rods 4, which increases the heat removal from the core. Next, the heated coolant enters the output manifold 3 and leaves the active zone. When the external collector 2 is inlet when the cold coolant is pumped through it, it forms a gas cavity around the active zone and performs an additional function - it separates the active zone from the external environment. The use of a gas, which is a low-absorbing neutron medium, makes it possible to simplify the design of the core and reduce its size, and the layout of the fuel rods and the transverse flow around their coolant can increase heat transfer. Thus, the proposed design of the reactor allows you to make it compact with improved technical and economic indicators.

Claims (1)

A high-temperature gas-cooled fast neutron nuclear reactor, the active zone of which includes a vertical cylindrical block with an annular cavity for placing fuel rods, made with radial through holes for the passage of the gas coolant, connecting the input and output collectors with the space between the fuel rods, one of the collectors being internal , formed by the walls of the block and located on its axis, and the other is the outer one, formed by its lateral surface and the lateral surface of the block, about characterized in that the unit is installed coaxially with the core, rod type fuel rods are used as fuel rods, which are placed parallel to each other and the axis of the core, and the block is made of heat-resistant stainless steel and transverse spacing baffles with holes for the placement of the fuel rods, while the distance between adjacent baffles is commensurate with the diameter of the fuel rods.

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