RU29800U1 - Nuclear reactor fuel assembly - Google Patents

Abstract

Fuel assembly of a nuclear reactor, including a bundle of fuel elements (fuel rods) installed in a frame of spacer grids mounted on tubular channels, fixed together with the fuel rods at the lower ends in the lower lattice equipped with adapters, a shank with support ribs adjacent to the lower lattice between the rows of cells for fuel elements, connected to the adapters of the lower grid, a head fixed at the upper ends of the tubular channels, and elements that secure the fuel elements in the lower grid, and the elements that secure the fuel elements from longitudinal movement upward are parts of the lower plugs protruding from the lower grid from below, cut in the longitudinal direction, characterized in that the portions of the lower plugs protruding from the bottom lattice from below are additionally provided with an annular groove, the edges of which in the assembled fuel assembly are in engagement with the edges of the cell of the lower lattice.

Description

The utility model relates to nuclear energy and can be used at enterprises engaged in the manufacture of fuel assemblies (FA) for power reactors primarily of the WWER-1000 type.

Known fuel assemblies of a nuclear reactor (see, B. Dementyev, Nuclear Power Reactors: Textbook for Universities, - 2nd ed., Revised and additional - M .: Energoatomizdat, 1990, p. 41-45), including a bundle of fuel elements mounted in a frame of hexagonal spacing grids mounted on tubular channels fixed together with fuel rods with lower ends in the lower grate, a shank connected to the lower grating using adapters in the form of bent plates fixed in the corners of this grating, a head and elements providing fixing the fuel rods in the lower re shtetke. Tubular channels are fixed in the lower lattice by their tips inserted into its cells by welding. To do this, at the lower end of the lower lattice there are abrasions in which welded seams are placed so that they do not interfere with the fastening of the fuel rods, the fuel rods are fixed in the lower lattice with their lower plugs inserted in its corresponding cells, from longitudinal movement relative to this lattice, both up and down . As an element that prevents the longitudinal movement of the fuel rods relative to the lower lattice down, a ledge was used; be present on each lower plug above the upper end of this lattice. The longitudinal movement of the fuel rods relative to the lower lattice up is limited by means of a cotter pin located in the groove cut on the lower end of this lattice along the entire row of cells for the lower plugs, a hole made in each lower plug at the level of the mentioned slot for the passage of the split pin, and a slot located at the end each lower plug for installing a fuel rod with the named hole towards the cotter pin. The number of cotter pins corresponds to the number of rows of fuel rods in a fuel assembly. Both ends of each cotter pin are bent to the side faces of the lower lattice and are prevented from falling out by welding. The shank is equipped with a system of support ribs for the lower lattice, which are adjacent to its lower end under some rows of fuel cells, and the head is mounted on the upper ends of the tubular channels protruding from the fuel bundle for the control rods.

The disadvantage of this fuel assembly is the high complexity of its manufacture due to the high complexity of the cotter pin assembly operation, since before installing each cotter pin in its place, it is necessary to deploy all the fuel rods with a slot so that they harden; L // 3 //

The positions in their lower caps coincided with the direction of movement of the cotter pin, and after installing these cotter pins in place, the ends of each of them must be bent and locked by welding. All these works are practically not mechanized and are performed manually.

Also known is the fuel assembly of a nuclear reactor (RF patent No. 2079170, 1997, prototype), including a first bundle of fuel rods mounted in a spacer frame; their grids mounted on tubular channels fixed together with fuel rods with lower ends in a lower grid equipped with adapters , a shank with supporting ribs attached to the adapters of the lower lattice, which are plates, size, mounted on two opposite faces of the lattice, a head mounted on the upper ends of the tubular channels, and elements that secure the TV fishing in the lower lattice, support ribs shank formed adjacent to the lower lattice cells between rows for tyulov, and as elements providing fixation rods against longitudinal movement upwards projecting used reschetki from this bottom portion of the lower plugs dissected longitudinally. The fastening is carried out by sliding the parts of the lower stub protruding from the lower lattice from the bottom in different directions until they overlap the passage section of the cell of the fuel element 11J.

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This fuel assembly, in comparison with the one described above, has a less labor-intensive fastening of fuel rods in the lower lattice, and this operation can be mechanized. In addition, this fuel assembly is more maintainable, since to replace a damaged fuel rod, it is enough to return the parts of the lower plugs protruding from the lower lattice to their original state in order to free it from fastening. The disadvantage of this fuel assembly is the low resistance force of the assembly of the fuel element in the lower lattice to its upward movement, which during the long-term operation of the fuel assembly can lead to the unfastening of the fuel elements.

The utility model is based on the task of improving fuel assemblies, in which by changing the design of its components an increased, as compared with the prototype, resistance is achieved for the fuel assembly of the fuel assembly in the lower lattice moving upward, while maintaining the low complexity of mounting the fuel elements in the lower lattice and high maintainability of the fuel assembly .

To solve this problem, in a known fuel assembly of a nuclear reactor comprising a bundle of fuel rods installed in a frame of spacer grids mounted on tubular channels fixed together with fuel rods with lower ends in a lower grid equipped with adapters, a shank with supporting ribs adjacent to the lower grid between the rows fuel cells connected to

adapters of the lower lattice, a head fixed to the upper ends of the tubular channels, and elements that secure the fuel rods in the lower lattice, and as elements, we provide; their fastening of the fuel rods from longitudinal mixing, upwards, we use the parts of the lower caps protruding from this lattice from the bottom, dissected in the longitudinal direction, these parts are additionally equipped with an annular groove, the edges of which in the assembled fuel assembly are meshed with the edges of the cell of the lower lattice.

The essence of the utility model is illustrated by drawings, where in FIG. 1 presents a fuel assembly of a nuclear reactor, general view; in FIG. 2a - the assembly of the fuel element to the lower fuel assembly lattice in the initial state, FIG. 2.6 - the assembly of the fuel rod to the lower fuel assembly lattice in the assembled state.

A fuel assembly of a nuclear reactor (see Fig. 1) consists of a beam (set) of fuel rods 1 installed in the frame as a separate element (not shown in the drawing) from spacing grids of hexagonal shape 2 mounted on tubular channels 3 fixed together with fuel rods 1 at the lower ends in the lower grill 4, equipped with adapters 5, as well as from the shank 6 and the head 7.

The shank 6 is attached to the adapters 5 of the lower lattice 4 and is equipped with supporting ribs 8 d. For this lattice.

St € fML / ZL Head 7 is mounted on the upper ends of the tubular channels 3.

The lower ends of the fuel rods 1 are equipped with lower caps 9, which protrude from the lower lattice 4 from the bottom (see Fig. 2, a). The protruding ends of the lower plugs 9 are provided with a groove 11 and are cut in the longitudinal direction into two equal parts 10, which are used as elements that secure the fuel rods 1 in the lower grill 4 from longitudinal movement up. Such fastening is carried out by sliding the parts 10 of the lower plug 9 in different directions until the edges of the groove 11 engage with the edges of the holes in the lower grill 4 (see Fig. 2.6).

The use of fuel assemblies of the proposed design will significantly increase the reliability of fixing the fuel rods in the lower lattice in comparison with the prototype, without increasing the complexity of manufacturing fuel assemblies.

In addition, in a specific implementation form of the proposed design, characterized by the ratios of the parameters shown in Table 1 shown in FIG. 3, the following technical result is achieved: the extension of the protruding parts of the lower plug is limited by the walls of the holes in the lower grill, which ensures the symmetry of the expansion of these parts and does not exceed the calculated degree of plastic deformation of the material of the plug.

ABOUT

Table 1

.

The operability of the TV with the proposed design is confirmed by testing samples of the mount of the fuel elements in the lower grill;

Fuel assemblies of nuclear power reactors VVER-1000.

Claims (1)

A fuel assembly of a nuclear reactor, including a bunch of fuel elements (fuel elements) installed in a frame of spacer grids mounted on tubular channels fixed together with fuel elements with lower ends in a lower grid equipped with adapters, a shank with supporting ribs adjacent to the lower grid between rows of cells for fuel rods attached to the adapters of the lower lattice, a head mounted on the upper ends of the tubular channels, and elements that secure the fuel rods in the lower lattice, when than the elements that secure the fuel rods from longitudinal movement upwards, are the protruding parts from the lower lattice from the bottom of the bottom caps, dissected in the longitudinal direction, characterized in that the protruding from the lower lattice from the bottom of the lower caps, are additionally provided with an annular groove, the edges of which are in the assembled fuel assembly meshing with the edges of the cell lower grid.