Nuclear reactor fuel assembly

FIELD: nuclear power engineering; fuel assembly manufacture.

SUBSTANCE: proposed fuel assembly has hexahedral spacer grid with coolant passage holes made in the form of equilateral triangles with rounded-off angles symmetrically disposed relative to holes for bottom plugs of fuel elements or tubular channels in the amount of six ones around each of them, their rounded-off angles being directed toward them; it also has similarly designed round holes for coolant passage.

EFFECT: enhanced flow section of holes for coolant passage through bottom support grid at same desired stiffness; reduced labor consumption and metal input.

2 cl, 7 dwg

 

The invention relates to atomic energy and can be used in the manufacturing of fuel assemblies, primarily for water-cooled power reactors VVER-1000, VVER-440.

Known fuel Assembly of a nuclear reactor VVER-440, including a bunch of fuel elements installed in the frame of the grid spacers hex form, mounted on a Central tubular channel, fixed together with the fuel elements in the lower supporting bars, a shank connected with the lower grille, head fixed to one end of the cover with fasteners other end of the cover to the shank (see D. Dementyev Nuclear power reactors. M.: Energoatomizdat, 1990, p.31-35).

In the known fuel Assembly against axial movement of the fuel elements down relative to the lower support grid used annular ledge on each bottom flap over the upper end of the lower support grid, and move up the ends of the bottom stub of the fuel elements is mounted at the bottom end of the lower support grid having apertures for the passage of coolant (see ibid., p.31-32). For fuel Assembly, representing the beam rod fuel elements typical mechanical perforating device intended is to secure fuel elements on the ends, and intermediate spacer device. This undoubtedly contributes to the mixing and turbulence in the coolant and intensification of heat exchange. At the same time, the spacer devices increase the hydraulic resistance (see ibid., str). It follows that the increase in rigidity of the bottom of the grid by reducing the cross section of the holes for the flow of coolant is not valid, and the increase in thickness to increase the rigidity of the support of the lower grille is in conflict with the requirements for fuel assemblies with minimal input into the active zone of the nuclear reactor “parasitic” material.

Closest to the technical conditions and the achieved effect is a fuel Assembly of a nuclear pressurized water reactor VVER-1000, which includes the bundle of fuel elements installed in the frame of the hexagonal grid spacers mounted on the tubular channels fastened together with fuel elements of the lower plugs in the lower supporting bars having openings for flow of fluid, a shaft fixed to the lower grille, and a head fixed on the upper ends of the tubular channels (see ibid., p.43-44, is a fuel Assembly of the reactor VVER-1000).

A fuel Assembly VVER-1000 bisceglia that about which has a mixing fluid in a radial direction and prevents the difference of pressure drops in the parallel channels - mean chekhlova forming the channels of the fuel assemblies of WWER-440 (see ibid., p.43).

In the fuel Assembly of the reactor VVER-1000 (see ibid., RIS, p.44) in the lower support grid 10 holes 7 for passage of a coolant made of oval form of the two openings between them with the remote jumper (RIS hole 7 shown in black).

These oval holes are located throughout the lower supporting bars and are focused (see the fragment of figure 4). In the core of a nuclear reactor fuel Assembly is operated under a high temperature 290-322°and high pressure 16 MPa (see ibid., p.48, tabl.), and its structural reliability should be high. However, one-sided orientation of holes for the passage of coolant in the lower supporting bars and the implementation of their oval shape dramatically reduces the force on the flexure supporting the bottom of the lattice parallel to the axes of the holes are lined up with the remote bridge between them (oval holes). Increasing the size of the bridges between the holes for the fixing of the fuel element and oval holes for flow of coolant will reduce the flow area flow of coolant through the lower grille and increase the hydraulic resistance of the fluid.

The increase in the thickness of the lower support grid to improve its W is strasti in conflict with the requirement of fuel elements and fuel assemblies with minimal input in the reactor core of parasitic material. This path walked design of fuel assemblies and supporting the bottom of the lattice used in modern fuel assemblies of WWER-1000, have an increased thickness to increase their rigidity.

An object of the invention is the development of fuel assemblies with greater pass-section of the holes flow of coolant through the lower anchor bars while maintaining the required stiffness, the minimum thickness of the lower support grid and reduce the labor intensity and the metal.

This technical problem is solved in that in the fuel Assembly of a nuclear reactor, mainly VVER-1000, which includes the bundle of fuel elements installed in the frame of the hexagonal grid spacers mounted on the tubular channels fastened together with fuel elements of the lower plugs in hex lower supporting bars having openings for flow of fluid, a shaft fixed to the hexagonal lower supporting bars and a head fixed on the upper ends of the tubular channels; according to the invention in a hexagonal lower supporting lattice openings for flow of fluid made in the form of equilateral triangles with rounded corners, arranged symmetrically relative to the holes of the lower C is gluski fuel elements and tubular channels of six pieces around each of them with the direction of the rounded corners in their direction, while on the periphery of each face of a hexagonal bottom support grid are located on eleven holes for the bottom plugs fuel elements forming the perpendicular from the opposite face of the hexagonal bottom support grid parallel between an alternating rows of holes for the bottom stub of the fuel elements and coupled through the jumper grounds triangular with rounded angles holes for flow of the heat carrier.

The technical problem is solved also by the fact that the holes for flow of the heat carrier is made of a round shape with the same location as triangular with rounded corners openings for flow of fluid.

This embodiment of the hexagonal bottom support grid will allow you to evenly distribute across the field hex of the lower support grid openings for flow of coolant and to equalize respectively rigidity that does not require increasing the thickness of the hexagonal lower grille, but on the contrary, to be able to reduce its thickness, and reduce the metal and thus reduce the input parasitic material in the active zone of the nuclear reactor. The flow area of the coolant flow from the proposed grid increased by 900 mm2while maintaining the desired rigidity, and the opportunity to reduce its casinos 18 to 13 mm, accordingly, reduced the complexity of its manufacture.

The invention is illustrated by drawings.

The drawings show a fuel Assembly, where:

- figure 1 - General view of the fuel Assembly;

on figa, b - fragment hex bottom support grid (options);

on figa, b - hex lower support grid (options);

- figure 4 is a fragment of a hexagonal bottom support grid (prototype);

- figure 5 - fuel Assembly (prototype).

A fuel Assembly of a nuclear reactor, mainly VVER-1000, includes a bundle of fuel elements 1 mounted in the frame of the hexagonal grid spacers 2, mounted on the tubular channels 3, secured together with heat-generating elements 1 lower plug 4 in hex lower supporting bars 5 having apertures 6 for the flow of fluid, the shaft 7 fixed to the hexagonal lower supporting bars 5 and the head 8 mounted on the upper ends of the tubular channels 3.

In hex the lower supporting bars 5 holes 6 for the flow of fluid made in the form of equilateral triangles with rounded corners (figa) or round (figb)arranged symmetrically about the hole 9 under the lower plug 4 fuel elements 1 and tubular channels 3 in the amount of the if the pieces around each of them with the direction of the rounded corners in their direction (figa).

While on the periphery of each face 10, 11, 12, 13, 14, 15 hex bottom support grid 5 are located on eleven holes 9 for the lower stub 4 fuel elements 1 forming the perpendicular from the opposite side, i.e. between the faces 10-13, 11-14, 12-15 hex bottom support grid 5, the parallel between the rows of 16 alternating holes 9 for the lower stub 4 fuel elements 1 and coupled through the jumper grounds triangular with rounded corners (figa) and round shape (figb) holes 6 for the flow of fluid.

Fuel Assembly assemble as follows. Pre-made hex lower support bars 5 with holes 6 for the flow of coolant and 9 holes under the bottom of the stub 4 for fuel elements 1 and tubular channels with 3 faces 10, 11, 12, 13, 14, 15 with alternating holes 9 and coupled through the jumper holes 6 arranged perpendicular to the opposite faces, i.e. 10-13, 11-14, 12-15 and in parallel rows 16.

Assemble the frame of the grid spacers 2, hex lower support grid 5 on tubular channels 3, fuel elements 1 are pressed through the spacer grid 2 bottom plugs 4 holes 9 hex bottom support grid 5, where they are secured together with plugs, trobc the mentioned channels 3.

To hex the lower supporting bars 5 secured to the shank 7, and the upper ends of the tubular channels fixed head 8.

Tested hexagonal bottom support grid 5 showed that the flow area of the holes 6 for the flow of coolant increased by 900 mm2, weight decreased at 120 grams and the thickness reduced from 18 to 13 mm while maintaining the desired rigidity, which helped to solve the technical problem.

1. A fuel Assembly of a nuclear reactor comprising a bundle of fuel elements installed in the frame of the hexagonal grid spacers mounted on the tubular channels fastened together with fuel elements of the lower plugs in hex lower supporting bars having openings for flow of fluid, a shaft fixed to the hexagonal lower supporting bars, and a head fixed on the upper ends of tubular channels, characterized in that hex lower supporting lattice openings for flow of fluid made in the form of equilateral triangles with rounded corners, arranged symmetrically relative to the holes of the bottom stub of the fuel elements and the tubular channels of six pieces around each of them with the direction of the rounded corners in their direction, if e is ω on the periphery of each face of a hexagonal bottom support grid are located on eleven holes for the bottom stub of the fuel elements, forming a perpendicular from the opposite face of the hexagonal bottom support grid parallel between an alternating rows of holes for the bottom stub of the fuel elements and coupled through the jumper grounds triangular with rounded angles holes for flow of the heat carrier.

2. A fuel Assembly of a nuclear reactor comprising a bundle of fuel elements installed in the frame of the hexagonal grid spacers mounted on the tubular channels fastened together with fuel elements of the lower plugs in hex lower supporting bars having openings for flow of fluid, a shaft fixed to the hexagonal lower supporting bars, and a head fixed on the upper ends of tubular channels, characterized in that hex base grille openings for flow of the heat carrier is made of a round shape and are arranged symmetrically with respect to the holes of the bottom stub of the fuel elements and the tubular channels of six pieces around each of them, with on the periphery of each face of a hexagonal bottom support grid are located on eleven holes for the bottom plugs fuel elements forming the perpendicular from the opposite face of the hexagonal lower bearing is esedi parallel between an alternating rows of holes for the bottom stub of the fuel elements and coupled through the jumper holes round shape for flow of the heat carrier.



 

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FIELD: nuclear power engineering; fuel assemblies for pressurized-water reactors.

SUBSTANCE: proposed fuel assembly manufactured using prior-art technology and characterized in enhanced in-service bending stiffness has fuel element bundle, spacer grids disposed through height of fuel assembly, top and bottom nozzles joined together by means of added-stiffness elements connected to spacer grids and bottom nozzle. Added-stiffness elements are made in the form of tubes or cylindrical rods and substitute at least one fuel element in other-than-peripheral line of fuel element bundle. As an alternative, fuel element may have added-stiffness elements made in the form of tubes or cylindrical rods substituting one of fuel elements on each edge of peripheral line of fuel element bundle. There is still another alternative in which added-stiffness elements substitute central fuel element on each other-than-adjacent edge of fuel element bundle. Added-stiffness elements may be joined with top nozzle for longitudinal displacement.

EFFECT: enhanced stability of thermomechanical behavior of reactor core in promising cycles, facilitated transport and in-process handling.

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A fuel assembly // 2220464
The invention relates to energy and can be used in devices for heating water, for example, in nuclear power plants

FIELD: nuclear power engineering; fuel assemblies for pressurized-water reactors.

SUBSTANCE: proposed fuel assembly manufactured using prior-art technology and characterized in enhanced in-service bending stiffness has fuel element bundle, spacer grids disposed through height of fuel assembly, top and bottom nozzles joined together by means of added-stiffness elements connected to spacer grids and bottom nozzle. Added-stiffness elements are made in the form of tubes or cylindrical rods and substitute at least one fuel element in other-than-peripheral line of fuel element bundle. As an alternative, fuel element may have added-stiffness elements made in the form of tubes or cylindrical rods substituting one of fuel elements on each edge of peripheral line of fuel element bundle. There is still another alternative in which added-stiffness elements substitute central fuel element on each other-than-adjacent edge of fuel element bundle. Added-stiffness elements may be joined with top nozzle for longitudinal displacement.

EFFECT: enhanced stability of thermomechanical behavior of reactor core in promising cycles, facilitated transport and in-process handling.

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FIELD: nuclear power engineering; fuel assembly manufacture.

SUBSTANCE: proposed fuel assembly has hexahedral spacer grid with coolant passage holes made in the form of equilateral triangles with rounded-off angles symmetrically disposed relative to holes for bottom plugs of fuel elements or tubular channels in the amount of six ones around each of them, their rounded-off angles being directed toward them; it also has similarly designed round holes for coolant passage.

EFFECT: enhanced flow section of holes for coolant passage through bottom support grid at same desired stiffness; reduced labor consumption and metal input.

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FIELD: nuclear power engineering.

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FIELD: nuclear power engineering.

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FIELD: nuclear power engineering.

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FIELD: nuclear power engineering.

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FIELD: nuclear power engineering.

SUBSTANCE: the invention may be used in nuclear reactors, in particular in the high-power channel nuclear reactors. The proposed assembly of these reactors is a framework with fuel elements, located in it. The framework has a central tube with the end grates and multi-tier system of spacers, fixed on the tube. This system is fabricated in the form of bent closed ships, skirting the fuel elements. The ships have the spacing bosses and are fastened between themselves. Besides, the fuel elements of internal and external rows contact with the ships, skirting them, in the places more than two. The external and internal rims, fastened with the ships, skirting the fuel elements, are the part of the multi-tier system of spacers. The ships and rims may be fastened between themselves with a shelf and may be fabricated from one sheet.

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