Heat-generating element for research reactors and a based on it heat-generating assembly (versions)

FIELD: nuclear power engineering; production of heat-generating elements and heat-generating assemblies for research reactors.

SUBSTANCE: the invention is pertaining to the field of nuclear power engineering, in particular, to production of heat-generating elements (further - fuel elements) and the heat-generating assemblies (further - fuel elements assemblies) for research reactors using a low (less than 20 %) enriched nuclear material. The technical result of the invention is enhancement of production capabilities for upgrading the existing research reactors, the fissile regions of which differ in dimensions and forms, using the universal rod-shaped fuel element and the based on it fuel elements assembly. The fuel element is made in the form of a tubular sealed on its end faces by plugs shell made out of an aluminum alloy of 0.30 up to 0.45 mm thick with four distancing screw-type ribs on the outer surface. The diameter of a circumscribed circle of a fuel element cross section makes from 4.0 - 8.0 mm. Each rib protrudes above the shell from 0.4 up to 1,0 mm in height and is placed in the cross section plane at an angle of 90° to the neighboring rib and twisted in spiral with a step from 100 up to 400 mm, predominantly from 300 up to 340 m. Inside the shell there is a fuel core made out of a dispersive composition of uranium-containing particles and an aluminum alloy, in which a volumetric content of uranium-containing particles makes up to 45 %, the uranium-containing particles dimension makes from 63 up to 315 microns, and the shell and the core have a diffusion cohesion among themselves, formed at the fuel elements manufacture by the method of a joint extrusion through a forming array of a composite cylindrical blank consisting of the fuel element core, the plugs and the shell. On the basis of the aforesaid fuel element the versions of the heat-generating assemblies are developed for research reactors of different types with various geometrical forms of the fissile regions.

EFFECT: the invention ensures enhancement of production capabilities to upgrade the existing research reactors with different dimensions and forms of their fissile regions with the help of the universal rod-shaped fuel element and the based on it fuel elements assembly.

9 cl, 6 dwg

The invention relates to nuclear power and can be used for the manufacture of fuel elements (cartridges) and fuel assemblies for research reactors, nuclear fuel is low (less than 20%enrichment.

In connection with the need to reduce several times enrichment of nuclear fuel from research reactors, there was a problem changing the design and technology of fuel rods and fuel assemblies that could be used in existing reactors in Russia and abroad. The use of the upgraded rods and fuel assemblies should not entail significant costs for the reconstruction of the reactor or the degradation of the performance of active zones.

The known results of the study on the improvement of plate-type fuel elements with oxide uranium fuel with an enrichment of 20%, the aluminium matrix and the aluminium shell for use in research reactors ("Trans. Amer. Nucl. Soc.", 1979, 32, Suppl. No. 1, 32). In this work on a specific type of reactor has been shown that 18-plate fuel assemblies with highly-enriched uranium oxide may be replaced by a 14-plate with 20 percent enriched with a corresponding increase in the fuel component in the fuel core. Reduction of heat transfer surface with this solution can be to perseroan executing on a surface plate of a fuel rod grooves.

However, this and many other solutions for upgrading obtained by rolling a plate of the fuel rods cannot be used for most existing Russian research reactors, which were designed for tubular or rod fuel elements.

Known fuel Assembly with tubular fuel rods, which are used in the Russian research reactors basin type, such as reactor IRT-M, WWR-M, TRS-M (Goncharov V.V. and others "proceedings of the Second International conference on peaceful uses of atomic energy. Geneva, 1958". Vol.2. M, Atomizdat, 1959, str; Goncharov V.V. and others Report No. 323 (USSR), presented at the third international conference on the peaceful uses of atomic energy (Geneva, 1964). Each fuel Assembly consists of an outer bearing, of a fuel rod with a square, hexagonal or round shape in cross section, to which is attached rigidly to the upper and lower end parts, fixing with a gap between several internal concentrically arranged tubular fuel elements. Depending on the reactor type number of tubular fuel rods in the fuel assemblies can vary from three to eight. In the cross section of the active portion of the tubular fuel rod consists of an outer and inner membranes, e.g. made of aluminum alloy, between which is located the dispersion of the fuel and the heart is nick. On the ends of the fuel rods of the core is sealed by end plugs of an annular shape. To reduce thermal resistance and reduce the temperature of the fuel element sheath core and plugs have a diffusion bond.

However, when using fuel with enrichment in u-235 to less than 20% manufacture of tubular fuel elements with the desired characteristics on existing technology joint extrusion poses significant technological challenges. These difficulties are connected with the limitation of the maximum value of the volume fraction of the fuel component in the core, which can not, for this technology to exceed 30%.

Known Assembly rod fuel elements comprising a sealed cylindrical shell with fuel, which made the spacer helical ribs (U.S. Pat. Germany No. 1815100, CL G 21 With 3/32). The Assembly is enclosed in a casing, and a spiral rib of the adjacent fuel rods in the Assembly overlap and contact the end edges in several transverse planes. Some fuel rods placed on the periphery of the Assembly at the wall of the casing, it is proposed to increase the number of edges is twice or decrease by 1/3 step of their wound.

Known for the invention allows to optimize the distribution of the coolant flow, but it cannot be used for modernization of the research reactor basin. This solution is the closest to the claimed fuel element and fuel Assembly based on it and made for protopic.

The technical task of the invention is the expansion of technological possibilities for modernization of existing research reactors, active zones which differ in their size and shape, based on the universal core of fuel elements and fuel assemblies.

This object is achieved in that the fuel elements for research reactors designed in the form of a tubular shell, sealed at the ends by caps, shell made of aluminium alloy and is made with the spacer helical ribs on the outer surface, and placed inside the shell of the fuel core, and the shell thickness is from 0.30 to 0.45 mm, the outer surface of the shell is equipped with four spacers spiral ribs, the diameter of the circumscribed circle of the cross section of the fuel element is from 4.0 to 8.0 mm, each helical rib protrudes from the shell to a height of from 0.4 to 1.0 mm, is located in the plane of the cross-section at an angle of 90° to the adjacent rib and twisted in a spiral with a pitch of 100 to 400 mm, mainly from 300 to 340 mm, the fuel core is made of a dispersive whom is osili uranosoderzhashchih particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles ranges from 63 to 315 μm, and the shell and the fuel core are diffusive coupling between them, obtained by the method of joint extrusion through a forming matrix composite cylindrical billet of metal-ceramic core, plugs and shell.

In the private version of the fuel core is made in the cross section in the shape of a circle.

In another private version of the fuel core is made in the cross section in the shape of a square and spiral ribs made on the outer surface of the shell at the corners of the square.

In another private version of the fuel core is made in the cross section in the form of a four-pointed star, the perimeter of which is formed by four identical curves, and spiral ribs made on the outer surface of the tubular shell on the vertices of the four-pointed star.

The task is achieved by the fact that a fuel Assembly on the basis of fuel elements for research reactors (RTI) includes a casing, made in cross-section in the shape of a square, the sides of which are placed end components inside the enclosure are fuel elements and the spacer grid for their accommodation, and fuel the th element is designed in the form of a tubular shell, sealed on the ends of the plugs, the shell is made of aluminium alloy and are made with four spacers spiral ribs on the outer surface, and placed inside the shell of the fuel core, the shell thickness is from 0.30 to 0.45 mm, the diameter of the circumscribed circle of the cross section of the fuel element is from 4.0 to 8.0 mm, each helical rib protrudes from the shell to a height of from 0.4 to 1.0 mm, is located in the plane of the cross-section at an angle of 90° to the adjacent rib and twisted in a spiral with a pitch of 100 to 400 mm, mainly from 300 to 340 mm, fuel the core is made from a dispersion composition uranosoderzhashchih particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles ranges from 63 to 315 μm, and the shell and the fuel core are diffusive coupling between them, and the number of fuel elements ranges from 144 to 225.

In the private version of the inside of the housing are made of the longitudinal cavity without fuel elements, which is limited by the walls of the inner casing and the outer surface of the walls of the casing in contact with the helical ribs of all the surrounding fuel elements.

The task is achieved by the fact that a fuel Assembly on the basis of the e fuel elements for research reactors (type BD) includes a casing, made in cross-section in the shape of a hexagon, the sides of which are placed end components inside the enclosure are fuel elements and the spacer grid for their placement, and the fuel element is designed in the form of a tubular shell, sealed at the ends by caps, shell made of aluminium alloy and are made with four spacers, bentovim ribs on the outer surface, and placed inside the shell of the fuel core, the shell thickness is from 0.30 to 0.45 mm, the diameter of the circumscribed circle of the cross section of the fuel element is from 4.0 to 8.0 mm, each helical rib protrudes from the shell to a height of from 0.4 to 1.0 mm situated in the plane of the cross-section at an angle of 90° to the adjacent rib and twisted in a spiral with a pitch of 100 to 400 mm, mainly from 300 to 340 mm, the fuel core is made from a dispersion composition uranosoderzhashchih particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles ranges from 63 to 315 μm, and the shell and the fuel core are diffusive coupling between them, and the fuel elements are placed within the casing in a triangular package and their number ranges from 37 to 55 pieces.

Private var the ante inside the casing is made of longitudinal cavity without fuel elements, which is limited by the walls of the inner casing and the outer surface of the walls of the casing in contact with the spacer ribs all nearby fuel elements.

The task is achieved by the fact that a fuel Assembly on the basis of fuel elements for research reactors (RTI) includes a casing, made in cross-section in the shape of a hexagon, the sides of which are placed end components inside the enclosure are fuel elements and the spacer grid for their placement, and the fuel element is designed in the form of a tubular shell, sealed at the ends by caps, shell made of aluminium alloy and are made with four spacers spiral ribs on the outer surface, and placed inside the shell of the fuel core, the shell thickness is from 0.30 to 0.45 mm, the diameter of the circumcircle of the transverse cross-section of the fuel element is from 4.0 to 8.0 mm, each helical rib protrudes from the shell to a height of from 0.4 to 1.0 mm, is located in the plane of the cross-section at an angle of 90° to the adjacent rib and twisted in a spiral with a pitch of 100 to 400 mm, mainly from 300 to 340 mm, placed inside the shell of the fuel core, made from a dispersion composition uranate the containing particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles ranges from 63 to 315 μm, and the shell and the fuel core are diffusive coupling between them, and the fuel elements are placed within the casing in a triangular package and their number ranges from 144 to 225 pieces, and two opposite walls of the casing, which is converted to interleaved rows of fuel elements made corrugated to provide their contact with the helical ribs of the peripheral fuel elements in each row.

In the private version of the inside of the housing are made of the longitudinal cavity without fuel elements, which is limited by the walls of the inner casing and the outer surface of the walls of the casing in contact with the helical ribs of all the surrounding fuel elements.

Square bore fluid, the total area of the fuel rods, the fuel cores and heat transfer surfaces in the unit cell of the reactor can be adjusted by changing the dimensions of the cross-section of a fuel rod and its shape in the above range.

The essence of the invention is illustrated by drawings.

Figure 1 shows the external view (a) and longitudinal section (b) multi-core fuel rod.

Figure 2 shows variations of the cross-sectional shape topl the main core of a fuel rod: a - square; - round; - four-pointed star.

Figure 3 shows a cross section of fuel Assembly with an active area of a square shape and a square packing of the fuel elements.

Figure 4 shows the cross-section of the fuel Assembly with an active area of a hexagonal shape and a triangular packing of the fuel elements.

Figure 5 shows a cross section of fuel Assembly with an active area of square and triangular packing of the fuel elements.

Figure 6 shows the cross-section of the fuel Assembly with an active area of a square shape, a triangular packing of rods, in which the longitudinal cavity.

Rod fuel rod in accordance with the claimed invention includes (see figure 1 - figure 2) shell 1, sealed at the ends of the plugs 2, the shell and end caps made of aluminium alloy. Inside the shell 1 is placed in the fuel core 3 of the dispersion composition based on a matrix of an alloy of aluminum and fuel particles containing uranium. In areas adjacent to the ends of the fuel rod can be made grooves or holes (figure 1 and figure 2 are not shown) for positioning and fixing of the fuel rods in the spacer grids of the fuel assemblies. The shell 1 has a thickness of from 0.30 to 0.45 mm, the outer surface of the shell 1 has four spacer helical ribs 4. The diameter of the circumscribed circle of the cross-section of a fuel rod is from 4.0 to 8.0 mm, each rib 4 is on the shell 1 to a height of from 0.4 to 1.0 mm, situated in the plane of the cross-section at an angle of 90° adjacent and twisted in a spiral with a pitch of 100 to 400 mm, mainly from 300 to 340 mm Volumetric content of the fuel particles in the core, made, for example, uranium dioxide, up to 45%, particle size ranges from 63 to 315 μm. The shell 1 and the core have a diffusion bond between them. The core of a fuel rod 3 in the cross-section can be performed (see figure 2) in the form of a circle, in the shape of a square or in the form of a four-pointed star, the perimeter of which is formed by four identical curves. In the case of execution of a fuel rod with the cross-sectional shape in the form of a square or four-pointed star spacer helical ribs made on the shell at the corners of the square or the vertices of the star.

In FA with poperechnyy section of the casing 5 in the shape of a square (see figure 3), which are used, for example, in the research pool type reactor IRT described above core fuel rods 6, are placed inside the casing 5 TVs in a square package. The number of fuel rods, depending on the design of the fuel assemblies and spacing of the fuel rods in the fuel assemblies, is from 144 to 225 pieces.

Square bore fluid, the total area of the fuel rods, the fuel cores and heat transfer surfaces in the unit cell of the reactor can be adjusted by changing the size poperen the th section of a fuel rod and its shape in the above range. On the step length of twist of the cross section of each fuel rod has 20 taps with the surrounding four adjacent fuel rods in two mutually perpendicular directions in five areas satisfaction.you-tion. The length of the zone of satisfactionary is directly proportional to the thickness of the rib and the magnitude of the step twist.

In FA with poperechnyy section of the casing 7 in the form of a regular hexagon (see figure 4), which are used, for example, in the research pool type reactor WWR described above core fuel rods are placed inside the casing 7 FA in a triangular package. The number of fuel rods, depending on the design of the fuel assemblies and spacing of the fuel rods in the fuel assemblies is from 37 to 55 pieces. Square bore fluid, the total area of the fuel rods, the fuel cores and heat transfer surfaces in the unit cell of the reactor can be adjusted by changing the dimensions of the cross-section of a fuel rod and its shape in the above range. On the step length of twist of the cross section of each fuel rod has 26 touch with the surrounding adjacent fuel rods in a certain direction in thirteen areas satisfactionary. The length of the zone of satisfactionary is directly proportional to the thickness of the rib and the step size twist.

In FA with a cross-section of the casing 8 in the shape of a square (see figure 5), which use the Xia, for example, in the research pool type reactor IRT described above core fuel rods 6, are placed inside the casing 8 FA in a triangular package, the number of fuel rods, depending on the design of the fuel assemblies and spacing of the fuel rods in the fuel assemblies, is from 144 to 225 pieces. Square bore fluid, the total area of the fuel rods, the fuel cores and heat transfer surfaces in the unit cell of the reactor can be adjusted by changing the dimensions of the cross-section of a fuel rod and its shape in the above range. On the step length of twist of the cross section of each fuel rod has 20 taps with the surrounding four adjacent fuel rods in two mutually perpendicular directions in five areas satisfactionary. The length of the zone of satisfactionary is directly proportional to the thickness of the rib and the magnitude of the step twist.

In private versions of the above-described fuel Assembly (see Fig.6) inside the casing 8 are longitudinal cavity 9 no fuel rods, which is limited by the inner wall of the casing 10, and the outer surface of the walls of the casing to secure the rows of fuel rods need to contact with the spacer helical ribs of all the surrounding fuel rods.

Thus, in the invention the calculation-experimental method was found to be optimal ranges of parameters is terravore of a fuel rod, which can be used for upgrading existing research reactors with different geometries of the active zone. The creation of such a universal core of TVEL simple design and technology, with high technical and economic parameters, ensuring the conservation of the dimensions and operational characteristics of existing FA of any research reactor basin type, allows to solve the problem of reducing enrichment of nuclear fuels at the lowest cost.

In the proposed fuel assemblies for research reactors basin type, the entire available range of tubular fuel elements is replaced by one universal TVEL change characteristics in the stated ranges. This saves the size and operational characteristics of the known assemblies, which gives the possibility to use the existing design of research reactors and to keep their main parameters: the shape and dimensions of the unit cell, the design of the handling device, the composition of the active zones, the ratio of the metal - water in the reactor, the operating conditions of the active zones and others.

1. Fuel elements for research reactors, made in the form of a tubular shell, sealed at the ends of the plugs, the shell is made of an alloy of the aluminum and completed with the spacer helical ribs on the outer surface, and placed inside the shell of the fuel core, wherein the shell thickness is between 0.30-0.45 mm, the outer surface of the shell is equipped with four spacers spiral ribs, the diameter of the circumscribed circle of the cross section of the fuel element is 4.0 mm to 8.0 mm, each helical rib protrudes from the shell to a height of 0.4-1.0 mm, is located in the plane of the cross-section at an angle of 90° to the adjacent rib and twisted in a spiral with a pitch 100-400 mm, mainly 300-340 mm, the fuel core is made from a dispersion composition uranosoderzhashchih particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles is 63-315 μm, and the shell and the fuel core are diffusive coupling between them, obtained by the method of joint extrusion through a forming matrix composite cylindrical billet of metal-ceramic core, plugs and shell.

2. Fuel element according to claim 1, characterized in that the fuel core is made in the cross section in the shape of a circle.

3. Fuel element according to claim 1, characterized in that the fuel core is made in the cross section in the shape of a square and spiral ribs made on the outer surface of the shell at the corners of the square.

4. Th is emitting element according to claim 1, characterized in that the fuel core is made in the cross section in the form of a four-pointed star, the perimeter of which is formed by four identical curves, and spiral ribs made on the outer surface of the tubular shell on the vertices of the four-pointed star.

5. A fuel Assembly on the basis of fuel elements for research reactors, comprising a casing, made in cross-section in the shape of a square, the sides of which are placed end components inside the enclosure are fuel elements and the spacer grid for their placement, characterized in that the fuel element is designed in the form of a tubular shell, sealed at the ends by caps, shell made of aluminium alloy and are made with four spacers spiral ribs on the outer surface, and placed inside the shell of the fuel core, the shell thickness is between 0.30-0.45 mm, the diameter of the circumscribed circle of the cross section of the fuel element is 4.0-8.0 mm each helical rib protrudes from the shell to a height of 0.4-1.0 mm, is located in the plane of the cross-section at an angle of 90° to the adjacent rib and twisted in a spiral with a pitch 100-400 mm, mainly 300-340 mm, the fuel core is made from a dispersion composition uranotaenia the particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles is 63-315 μm, and the shell and the fuel core are diffusive coupling between them, and the number of fuel elements is 144-225 pieces.

6. A fuel Assembly according to claim 5, characterized in that the inside of the housing are made of the longitudinal cavity without fuel elements, which is limited by the walls of the inner casing and the outer surface of the walls of the casing in contact with the helical ribs of all the surrounding fuel elements.

7. A fuel Assembly on the basis of fuel elements for research reactors, comprising a casing, made in cross-section in the shape of a hexagon, the sides of which are placed end components inside the enclosure are fuel elements and the spacer grid for their placement, characterized in that the fuel element is designed in the form of a tubular shell, sealed at the ends by caps, shell made of aluminium alloy and are made with four spacers spiral ribs on the outer surface, and placed inside the shell of the fuel core, the shell thickness is between 0.30-0.45 mm, the diameter of the circumscribed circle of the cross section of the fuel element SOS is to place 4,0-8.0 mm, each helical rib protrudes from the shell to a height of 0.4-1.0 mm, is located in the plane of the cross-section at an angle of 90°to the adjacent rib and twisted in a spiral with a pitch 100-400 mm, mainly 300-340 mm, the fuel core is made from a dispersion composition uranosoderzhashchih particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles is 63-315 μm, and the shell and the fuel core are diffusive coupling between them, and the fuel elements are placed within the casing in a triangular package and their number is 37-55 pieces.

8. A fuel Assembly according to claim 7, characterized in that the inside of the housing are made of the longitudinal cavity without fuel elements, which is limited by the walls of the inner casing and the outer surface of the walls of the casing in contact with the spacer ribs all nearby fuel elements.

9. A fuel Assembly on the basis of fuel elements for research reactors, comprising a casing, made in cross-section in the shape of a hexagon, the sides of which are placed end components inside the enclosure are fuel elements and the spacer grid for their placement, characterized in that the fuel element is ispolnen in the form of a tubular shell, sealed on the ends of the plugs, the shell is made of aluminium alloy and are made with four spacers spiral ribs on the outer surface, and placed inside the shell of the fuel core, the shell thickness is between 0.30-0.45 mm, the diameter of the circumscribed circle of the cross section of the fuel element is 4.0 mm to 8.0 mm, each helical rib protrudes from the shell to a height of 0.4-1.0 mm, is located in the plane of the cross-section at an angle of 90° to the adjacent rib and twisted in a spiral with a pitch 100-400 mm, mainly 300-340 mm, placed inside the shell of the fuel core, made of a dispersive composition uranosoderzhashchih particles and aluminium alloy, in which the volumetric content of uranosoderzhashchih particles up to 45%, size uranosoderzhashchih particles is 63-315 μm, and the shell and the fuel core are diffusive coupling between them, and the fuel elements are placed within the casing in a triangular package and their number is 144-225 pieces, and two opposite walls of the casing, which is converted to interleaved rows of fuel elements made corrugated to provide their contact with the helical ribs of the peripheral fuel elements in each row.

10. A fuel Assembly according to claim 9, characterized in that inside the skin is and the longitudinal cavity without fuel elements, which is limited by the walls of the inner casing and the outer surface of the walls of the casing in contact with the helical ribs of all the surrounding fuel elements.