RU2428755C1 - Coverless fuel assembly with hexagonal fuel grid of water-cooled power reactor (versions) - Google Patents

Abstract

FIELD: power industry. ^ SUBSTANCE: fuel assembly includes tail and head parts of assembly and spacer grids located between them and the rim of which has the shape of regular hexagon. Spacer grids include cells for fuel elements, which are installed along triangular net so that coaxial hexagonal rows are formed inside the rim. Guide channels for displacers are installed between cells, namely in the centre of spacer grid, at the corners of the fourth row of the rim, at the corners of the eighth row of the rim and in middles of the sides of the fourth row of the rim. ^ EFFECT: increasing burnup fraction and breeding ratio of nuclear fuel. ^ 30 cl, 8 dwg

Description

FIELD OF THE INVENTION

The invention relates to nuclear energy, in particular to the construction of shellless fuel assemblies (FAs) with a hexagonal fuel grid of the active zones of water-cooled hull nuclear reactors of the WWER type, especially in the development and construction of new generation domestic nuclear reactors.

State of the art

In existing water-cooled hull nuclear reactors of the WWER and PWR type, the fuel burn-up reactivity margin is compensated by the absorbers of control systems: the boron system and mechanical control and protection systems (CPS), as well as burnable absorbers.

Excess neutrons throughout the entire fuel cycle are absorbed by the substance introduced into the active zone and gradually extracted with a large neutron capture cross section. Thus, the operation of the reactors is ensured by the useless, from the point of view of fuel use, loss of the excess part of neutrons. Changing the neutron spectrum in the core allows you to redistribute the neutron balance. A decrease in the initial water content in the fuel grate leads to an increase in the number of divisions of the feed isotope (U-238), to an increase in the formation of secondary isotopes fissile by thermal neutrons (Pu), and to a decrease in the absorption of neutrons in the coolant and in the absorbers, i.e. ultimately, an increase in fuel reproduction rate.

Reducing the total number of fissile isotopes during fuel burn-up while slag is simultaneously accumulated requires reducing the neutron capture by raw isotopes in order to maintain the propagation characteristics of the fuel gratings, which can be achieved by softening the neutron spectrum by increasing the amount of water in the fuel assemblies.

To obtain the greatest depth of fuel burnup for a given initial enrichment, spectrum control can play a decisive role, since maintaining a continuous chain reaction due to a certain part of neutrons, the rest of their excess can be used to form new fissile isotopes from U-238.

Known fuel assembly containing cells mounted on a triangular grid, and intended for installation in them of fuel elements, guide channels for absorbing rods and channels filled with water (US 5555281, G21C 3/30, 09/10/1996). In this fuel assembly, channels filled with water (water rods) are used to spectrally mitigate the neutron flux.

However, despite the location of the cells in the assembly along a triangular grid, the location of the water rods cannot be used in a fuel assembly whose perimeter has the shape of a regular hexagon, since the perimeter of the known assembly has the shape of a square.

The closest in technical essence and the achieved result to the fuel assembly of the present invention is a fuel assembly of a VVER-1000 nuclear reactor containing a bundle of fuel elements, a tail and a head part, and at least one spacing grid surrounded by a rim located between them, which form a regular hexagon, and including cells for fuel elements, mounted on a triangular grid so that they form a coaxial hexagonal the inner rows of the rim of the spacer grid, and between the cells there are guide channels for displacers, the longitudinal axes of which are placed in the same plane with the longitudinal axes of the fuel elements located on the same side of the same coaxial row and / or in the same plane with the longitudinal axes of the fuel elements located on the large diagonal of the hexagon (RU 2248630, G21C 3/32, 05/10/2004). In the known design of the fuel assembly provides only the ability to install guide channels for displacers without indicating their number and location.

Disclosure of invention

The objective of the present invention is the creation and development of a case-free fuel assembly with a hexagonal fuel grid of a pressurized water reactor with improved nuclear fuel burning characteristics and an extended duration of the fuel campaign.

As a result of solving this problem, new technical results can be obtained, consisting in the fact that the burnup depth and the reproduction coefficient of nuclear fuel are increased.

The indicated technical results according to the first embodiment of the present invention are achieved in that, in a case-free fuel assembly with a hexagonal fuel grid of a pressurized water reactor containing the tail and head parts of the assembly and located between them at least one spacer grid surrounded by the rim, the sides which form a regular hexagon, and including cells for fuel elements, mounted on a triangular grid so that they form a coaxial rectangular rows inside the rim of the spacer grid, and between the cells there are guide channels for displacers, the longitudinal axes of which are placed in the same plane with the longitudinal axes of the fuel elements located on the same side of the same coaxial row and / or in the same plane with the longitudinal axes of the fuel elements, located on the large diagonal of the hexagon, in addition, the guide channel or the beam of the guide channels is located in the center of the spacer grid and / or three, equidistant apart from each other, or six guide channels or bundles of guide channels are placed at the corners of the fourth from the rim of the row, and / or three equally spaced from each other, or six guide channels or bundles of guide channels are placed at the corners of the eighth of the rim of the row, and / or three equidistant from each other, or six guide channels or bundles of guide channels are located in the middle of the sides of the fourth row from the rim.

The indicated technical results according to the second embodiment of the present invention are achieved by the fact that in the case-free fuel assembly with a hexagonal fuel grid of a pressurized water reactor containing the tail and head parts of the assembly and located between them at least one spacer grid surrounded by the rim, the sides which form a regular hexagon, and including cells for fuel elements, mounted on a triangular grid so that they form a coaxial rectangular rows inside the rim of the spacer grid, and between the cells there are guide channels for displacers, the longitudinal axes of which are placed in the same plane with the longitudinal axes of the fuel elements located on the same side of the same coaxial row and / or in the same plane with the longitudinal axes of the fuel elements, located on the large diagonal of the hexagon, in addition, the guide channel or the beam of the guide channels is located in the center of the spacer grid and / or three, equidistant apart from each other, or six guide channels or bundles of guide channels are placed at the corners of the second row from the rim, and / or three equally spaced from each other, or six guide channels or bundles of guide channels are placed at the corners of the sixth from the rim of the row, and / or three equally spaced from each other, or six guide channels or bundles of guide channels are placed in the middle of the sides of the second row from the rim.

The indicated technical results according to the third embodiment of the present invention are achieved by the fact that in the case-free fuel assembly with a hexagonal fuel grid of a pressurized water reactor containing the tail and head parts of the assembly and located between them at least one spacer grid surrounded by the rim, the sides which form a regular hexagon, and including cells for fuel elements, mounted on a triangular grid so that they form coaxial hexagonal rows inside the rim of the spacer grid, and between the cells there are guide channels for displacers, the longitudinal axes of which are placed in the same plane with the longitudinal axes of the fuel elements located on the same side of the same coaxial row and / or in the same plane with the longitudinal axes of the fuel elements, hexagons located on a large diagonal, in addition, a guide channel or a bundle of guide channels is located in the center of the spacer grid and / or three, equidistance allen from each other, or six guide channels or bundles of guide channels are placed at the corners of the second row from the rim, and / or three equally spaced from each other, or six guide channels or bundles of guide channels are placed at the corners of the eighth from the rim of the row, and / or three equally spaced from each other, or six guide channels or bundles of guide channels are placed in the middle of the sides of the second row from the rim.

A distinctive feature of each of the options is the choice of the installation location of the guide channels for displacers. It was experimentally established and confirmed by calculations that the installation of channels for propellants in these places improves the water-uranium ratio of the core and allows to increase the fuel burnup depth.

For all variants of the present invention: it is preferable to choose the number of cells for fuel elements and guide channels, respectively, from 264 pcs. up to 390 pcs. and from 1 pc. up to 133 pcs., and the diameter of the fuel elements is from 7.8 mm to 9.15 mm, and the step t of the triangular mesh is preferably selected from 11.5 mm to 11.7 mm.

Also, for all variants of the present invention, it is preferable that the guide channel bundle contains three, or six, or seven parallel guide channels rigidly interconnected, and the diameter of the guide channel is larger than the diameter of the fuel element, and the guide channels should preferably be separated from each other with at least one fuel element.

In addition, it is preferable for all variants of the present invention to make the displacer made of zirconium alloy monolithic or with a sealed longitudinal cavity, and the cavity of the displacer should be filled with gas and / or uranium dioxide with natural or dump enrichment of uranium-235, and the guide channels for displacers must be hydraulically connected to the surrounding space, and displacers with a cavity must be made with the possibility of hydraulic connection of the cavity with the surrounding industry.

An analysis of the solutions known from the prior art did not reveal a device that matches the options of the present invention for the entire set of essential features included in the independent claims, which indicates that the present invention meets the patentability condition of "novelty."

The prior art fuel assembly of a nuclear reactor containing a portion of features similar to those of the described invention is RU 2248630, G21C 3/32, 05/10/2004.

Common features of the known and present inventions are those regarding the presence of channels for propellants.

However, the known solution does not indicate for what purpose the channels for the displacers are installed, it is not shown where they are located, and what technical result can be obtained. Therefore, the present invention meets the condition of patentability "inventive step".

List of drawings

Figure 1 shows a General view of the fuel assembly of a nuclear reactor, figure 2 shows (enlarged) the cell spacer lattice, figure 3 shows the first variant of the cross-section aa in figure 1, figure 4 shows the second variant of the cross section a- And in Fig. 1, Fig. 5 shows a third variant of section AA in Fig. 1, Fig. 6 shows a fragment of a spacer grid with a hexagonal guide channel, Fig. 7 shows a fragment of a spacer grid with a cylindrical guide channel, in Fig. .8 shows a fragment of a spacer grid from a displacer mi and absorbing element.

The implementation of the invention

The caseless fuel assembly with a hexagonal fuel grid of a pressurized water reactor contains interconnected guide channels 1 tail 2 and head 3 parts of the assembly. Between the tail and the head parts of the assembly are spacing grids 4, the rim 5 of which has the shape of a regular hexagon (see figure 1.). Each spacer grid includes cells 6 for fuel elements 7 (see figure 2.). Cells 6 are installed on a triangular grid with the formation of 5 coaxial hexagonal rows inside the rim, the number of which is eleven. The number of cells 6 for fuel elements 7 in the spacer grid is from 264 pcs. up to 390 pcs., and the diameter of the fuel elements selected from 7.8 mm to 9.15 mm. Between cells 6 there are guide channels 8 for displacers 9 and absorbing rods 10. The number of guide channels 8 (respectively, displacers) in the inventive fuel assembly is from 1 pc., Placed in the center of the spacer grid, up to 133 pcs. in the case of using bundles of guide channels with seven displacers (see Fig.3 - Fig.8). The bundle of guide channels 8 may contain three, or six, or seven parallel guide channels rigidly connected to each other. In accordance with the first embodiment, the guide channels (bundles of guide channels) are surrounded by heat-generating elements. Moreover, according to three options, all the guide channels and the beams of the guide channels are separated from each other by at least one fuel element, and the diameter of the guide channels is selected to be larger than the diameter of the fuel elements.

According to the first embodiment of the present invention, the guide channels 8 can be installed as follows:

- from one (with a hexagonal or cylindrical cross section) to seven guide channels (one bundle of guide channels for seven displacers) in the center of the spacer grid;

- from three equidistant from each other (with a hexagonal or cylindrical cross-section) to twenty-one guide channels (for three beams of displacers) at the corners of the fourth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the fourth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from three equidistant from each other (with a hexagonal or cylindrical cross-section) to twenty-one guide channels (three bundles of guide channels for twenty-one displacers) at the corners of the eighth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the center line of the centers of the cells of the eighth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from three equidistant from each other (with a hexagonal or cylindrical cross section) to twenty-one guide channels (three bundles of guide channels for twenty-one displacers) in the middle of the fourth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the fourth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the midpoints of the opposite sides of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) at the corners of the fourth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the fourth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) at the corners of the eighth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the center line of the centers of the cells of the eighth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) in the middle of the fourth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the fourth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the midpoints of the opposite sides of the rim;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in three corners of the fourth row equally spaced from each other;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in three angles of the eighth from the rim of the row equidistant from each other;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in the three midpoints of the fourth row from the rim of the row;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and at six corners of the fourth row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and at six corners of the eighth row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and in six midpoints of the fourth row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, at three equally spaced corners of the fourth from the rim of the row and at three equally spaced corners of the eighth from the rim of the row;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, at three equally spaced corners of the fourth from the rim of the row and at three middles of the sides of the fourth from the rim of the row;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row and at three middles of the sides of the fourth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row, at three equally spaced corners of the fourth from the rim of the row and at three equally spaced from the other midpoints of the fourth from the rim row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the fourth from the rim of the row and at six corners of the eighth of the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the fourth from the rim of the row and six midpoints of the fourth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, in the three midpoints of the fourth from the rim of the row and at the six corners of the fourth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, in three midpoints of the fourth from the rim of the row and six corners of the eighth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row and at six corners of the fourth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row and six midpoints of the fourth from the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the fourth from the rim of the row and at six corners of the eighth of the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the fourth from the rim of the row and at six midpoints of the fourth from the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the eighth from the rim of the row and at six midpoints of the sides of the fourth from the rim of the row;

- from nineteen to one hundred thirty-three guide channels (nineteen bundles of guide channels for one hundred thirty-three displacers) in the center of the spacer grid, at six corners of the eighth from the rim of the row, at six corners of the fourth from the rim of the row and in six midpoints of the fourth from the rim of the row.

According to a second embodiment of the present invention, the guide channels 8 can be installed as follows:

- from one (with a hexagonal or cylindrical cross section) to seven guide channels (one bundle of guide channels for seven displacers) in the center of the spacer grid;

- from three equidistant from each other (with a hexagonal or cylindrical cross-section) to twenty-one guide channels (for three beams of displacers) at the corners of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from three equidistant from each other (with a hexagonal or cylindrical cross-section) to twenty-one guide channels (three bundles of guide channels for twenty-one displacers) at the corners of the sixth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the center line of the centers of the cells of the sixth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from three equidistant from each other (with a hexagonal or cylindrical cross section) to twenty-one guide channels (three bundles of guide channels for twenty-one displacers) in the middle of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the midpoints of the opposite sides of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) in the corners of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) at the corners of the sixth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the center line of the centers of the cells of the sixth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) in the middle of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the midpoints of the opposite sides of the rim;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in three corners of the second row equidistant from each other;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and at three equally spaced corners of the sixth from the rim of the row;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in the three middle equally spaced middle of the second row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and at six corners of the second row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and at six corners of the sixth row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and in the six midpoints of the second row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, at three equally spaced corners of the second from the rim of the row and at three equally spaced corners of the sixth from the rim of the row;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, in three equally spaced corners of the second from the rim of the row and in three middles of the sides of the second from the rim of the row;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, in three equally spaced corners of the sixth from the rim of the row and in three middies of the sides of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the sixth from the rim of the row, at three equally spaced corners of the second from the rim of the row and in three equally spaced from the other mid-sides of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the second from the rim of the row and at six corners of the sixth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the second from the rim of the row and at six midpoints of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, in the three midpoints of the second from the rim of the row and at the six corners of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, in three midpoints of the second from the rim of the row and at six corners of the sixth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the sixth from the rim of the row and at six corners of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the sixth from the rim of the row and at six midpoints of the second from the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the second from the rim of the row and at six corners of the sixth from the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the second from the rim of the row and at six midpoints of the sides of the second from the rim of the row;

- from thirteen to ninety-one guide channels (thirteen tufts of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the sixth from the rim of the row and at six midpoints of the sides of the second from the rim of the row;

- from nineteen to one hundred thirty-three guide channels (nineteen bundles of guide channels for one hundred thirty-three displacers) in the center of the spacer grid, at six corners of the sixth from the rim of the row, at six corners of the second from the rim of the row, and at six midpoints of the sides of the second from the rim of the row.

According to a third embodiment of the present invention, the guide channels 8 can be installed as follows:

- from one (with a hexagonal or cylindrical cross section) to seven guide channels (one bundle of guide channels for seven displacers) in the center of the spacer grid;

- from three equidistant from each other (with a hexagonal or cylindrical cross-section) to twenty-one guide channels (for three beams of displacers) at the corners of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from three equidistant from each other (with a hexagonal or cylindrical cross-section) to twenty-one guide channels (three bundles of guide channels for twenty-one displacers) at the corners of the eighth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the center line of the centers of the cells of the eighth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from three equidistant from each other (with a hexagonal or cylindrical cross section) to twenty-one guide channels (three bundles of guide channels for twenty-one displacers) in the middle of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the midpoints of the opposite sides of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) in the corners of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) at the corners of the eighth row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the center line of the centers of the cells of the eighth row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the opposite vertices of the rim;

- from six (with a hexagonal or cylindrical cross-section) to forty-two guide channels (six bundles of guide channels for forty-two displacers) in the middle of the second row from the rim, i.e. the longitudinal axis of the guide channels or bundles of guide channels are located at the intersection of the axial line of the centers of the cells of the second row from the rim (parallel to the side of the rim) and the line passing through the center of the spacer grid and connecting the midpoints of the opposite sides of the rim;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in three corners of the second row equidistant from each other;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in three angles of the eighth from the rim of the row equidistant from each other;

- from four to twenty-eight guide channels (four bundles of guide channels for twenty-eight displacers) in the center of the spacer grid and in the three middle equally spaced middle of the second row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and at six corners of the second row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and at six corners of the eighth row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid and in the six midpoints of the second row from the rim;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, at three equally spaced corners of the second from the rim of the row and at three equally spaced corners of the eighth from the rim of the row;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, in three equally spaced corners of the second from the rim of the row and in three middles of the sides of the second from the rim of the row;

- from seven to forty-nine guide channels (seven bundles of guide channels for forty-nine displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row and at three middles of the sides of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row, at three equally spaced corners of the second from the rim of the row and at three equally spaced from the other mid-sides of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the second from the rim of the row and at six corners of the eighth from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the second from the rim of the row and at six midpoints of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, in the three midpoints of the second from the rim of the row and at the six corners of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, in three midpoints of the second row from the rim of the row and six corners of the eighth of the row from the rim;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row and at six corners of the second from the rim of the row;

- from ten to seventy guide channels (ten bundles of guide channels for seventy displacers) in the center of the spacer grid, at three equally spaced corners of the eighth from the rim of the row and at six midpoints of the second from the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the second from the rim of the row and at six corners of the eighth of the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the second from the rim of the row and at six midpoints of the sides of the second from the rim of the row;

- from thirteen to ninety-one guide channels (thirteen bundles of guide channels for ninety-one displacers) in the center of the spacer grid, at six corners of the eighth from the rim of the row and at six midpoints of the sides of the second from the rim of the row;

- from nineteen to one hundred thirty-three guide channels (nineteen bundles of guide channels for one hundred thirty-three displacers) in the center of the spacer grid, at six corners of the eighth from the rim of the row, at six corners of the second from the rim of the row, and at six midpoints of the sides of the second from the rim of the row.

The step t of the triangular grid along which the cells 6 are located is selected from 11.5 mm to 11.7 mm.

The displacer 9 is made of a zirconium alloy, for example, in the form of a cylindrical rod or in the form of a sealed tubular shell with end caps. Moreover, the hollow displacer is configured to fill, long-term and reliable retention and release of gas or primary coolant from it. Guide channels 8 for displacers 9 are configured to connect their cavity with the surrounding space. As a result, during operation of the fuel assembly, the cavities of the guide channels (with monolithic displacers removed) and / or hollow displacers are filled with water, which leads to an improvement in the water-uranium ratio in the fuel assembly and in the reactor core.

The operation of the fuel Assembly of the present invention is as follows. At the first stage, displacers are introduced into the guide channels and thus reduce the water-uranium ratio, i.e. provide a rigid spectrum of the neutron flux needed to produce plutonium. At the second stage, displacers are removed and water is introduced in their place and thereby increase the water-uranium ratio, providing an increase in the burnup of nuclear fuel. Thus, the increase in energy production is provided by changing the spectrum of the neutron flux during the fuel burnout, which is achieved by the claimed placement of guide channels with water displacers among the fuel elements in the first stage of fuel burnout. In the second stage, the fuel burns out without propellants in the guide channels filled with water and / or with introduced hollow propellants, but filled with water. Preliminary neutron-physical calculations of one of the possible options for the specified geometry of the fuel assembly showed that the duration of burnup of nuclear fuel increases by ~ 20% and it is not intended to optimize fuel use in a closed fuel cycle.

In addition, with this design of the fuel assembly as displacers, hollow displacers with uranium dioxide can be used with the natural (or dump) content of uranium-235. In this case, an additional quantity of fissile plutonium isotopes can be obtained as a result of fuel processing (closed cycle). ~ 500 kg of uranium dioxide can be placed in the guide channels of one fuel assembly with the claimed geometry for irradiation and processing. In displacers, a high reproduction rate of ~ 2.0 is achieved. The average reproduction coefficient for the fuel assembly will be ~ 0.81, and the conversion coefficient ~ 0.94.

The fuel assembly in accordance with the present invention can be manufactured using known technologies on known equipment and does not require the creation of special tools and equipment.

Claims (30)

1. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor, comprising a tail and a head part of the assembly and located between them, at least one spacer grid surrounded by a rim, the sides of which form a regular hexagon, and including cells for fuel elements installed along a triangular grid in such a way that they form coaxial hexagonal rows inside the rim of the spacer grid, moreover, between the cells channels for propellants, the longitudinal axes of which are located in the same plane with the longitudinal axes of the fuel elements located on the same side of the same coaxial row, and / or in the same plane with the longitudinal axes of the fuel elements located on a large diagonal of the hexagon, characterized in that a guiding channel or a bundle of guiding channels is located in the center of the spacer grid, and / or three equally spaced apart or six guiding channels or bundles of guiding channels are sized puppies in the corners of the fourth row from the rim, and / or three equally spaced from each other or six guide channels or bundles of guide channels are placed at the corners of the eighth from the rim of the row, and / or three equally spaced from each other or six guide channels or bundles of guide channels in the middle of the sides of the fourth row from the rim. 2. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the number of cells for the fuel elements in the spacer grid and the number of guide channels are selected from 264 to 390, respectively. and from 1 to 133 pcs. 3. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the diameter of the fuel elements is selected from 7.8 to 9.15 mm. 4. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the step t of the triangular grid is selected from 11.5 to 11.7 mm. 5. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the beam of the guide channels contains three, or six, or seven parallel guide channels rigidly connected to each other. 6. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the diameter of the guide channels is larger than the diameter of the fuel elements. 7. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the guide channels are separated from each other by at least one fuel element. 8. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the displacer is made of a zirconium alloy in a monolithic or sealed longitudinal cavity. 9. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the displacer cavity is filled with gas and / or uranium dioxide with natural or dump uranium-235 enrichment. 10. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 1, characterized in that the guide channels are hydraulically connected to the surrounding space, and the displacers with the cavity are made with the possibility of hydraulic connection of the cavity with the surrounding space. 11. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water power reactor, comprising a tail and head parts of the assembly and located between them, at least one spacer grid surrounded by a rim, the sides of which form a regular hexagon, and including cells for fuel elements installed along a triangular grid in such a way that they form coaxial hexagonal rows inside the rim of the spacer grid, moreover, between the cells extending channels for displacers, the longitudinal axes of which are placed in the same plane with the longitudinal axes of the fuel elements located on the same side of the same coaxial row, and / or in the same plane with the longitudinal axes of the fuel elements, located on a large diagonal of the hexagon, characterized in that a guiding channel or a bundle of guiding channels is located in the center of the spacer grid, and / or three equally spaced apart or six guiding channels or bundles of guiding channels are sized even at the corners of the second row from the rim, and / or three equally spaced from each other or six guide channels or bundles of guide channels are located at the corners of the sixth from the rim of the row, and / or three equally spaced from each other or six guide channels or bundles of guide channels the midpoints of the sides of the second from the rim row. 12. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the number of cells for the fuel elements in the spacer grid and the number of guide channels are selected from 264 to 390 and from 1 to 133, respectively. 13. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the diameter of the fuel elements is selected from 7.8 to 9.15 mm. 14. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the step t of the triangular grid is selected from 11.5 to 11.7 mm. 15. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the beam of the guide channels contains three, or six, or seven parallel guide channels rigidly interconnected. 16. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the diameter of the guide channels is larger than the diameter of the fuel elements. 17. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the guide channels are separated from each other by at least one fuel element. 18. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the displacer is made of zirconium alloy in a monolithic or sealed longitudinal cavity. 19. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the displacer cavity is filled with gas and / or uranium dioxide with natural or dump uranium-235 enrichment. 20. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 11, characterized in that the guide channels are hydraulically connected to the surrounding space, and the displacers with a cavity are made with the possibility of hydraulic connection of the cavity with the surrounding space. 21. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water power reactor, comprising a tail and head parts of the assembly and located between them, at least one spacer grid surrounded by a rim, the sides of which form a regular hexagon, and including cells for fuel elements installed along a triangular grid in such a way that they form coaxial hexagonal rows inside the rim of the spacer grid, with extending channels for displacers, the longitudinal axes of which are placed in the same plane with the longitudinal axes of the fuel elements located on the same side of the same coaxial row, and / or in the same plane with the longitudinal axes of the fuel elements, located on a large diagonal of the hexagon, characterized in that a guiding channel or a bundle of guiding channels is located in the center of the spacer grid, and / or three equally spaced apart or six guiding channels or bundles of guiding channels are sized even at the corners of the second row from the rim, and / or three equally spaced from each other or six guide channels or bundles of guide channels are placed at the corners of the eighth from the rim of the row, and / or three equally spaced from each other or six guide channels or bundles of guide channels the midpoints of the sides of the second from the rim row. 22. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the number of cells for the fuel elements in the spacer grid and the number of guide channels are selected from 264 to 390, respectively. and from 1 to 133 pcs. 23. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the diameter of the fuel elements is selected from 7.8 to 9.15 mm. 24. Shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, wherein the step t of the triangular grid is selected from 11.5 to 11.7 mm. 25. A shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the guide channel bundle comprises three, or six, or seven parallel guide channels rigidly interconnected. 26. A shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the diameter of the guide channels is larger than the diameter of the fuel elements. 27. A shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the guide channels are separated from each other by at least one fuel element. 28. A shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the displacer is made of zirconium alloy in a monolithic or sealed longitudinal cavity. 29. A shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the displacer cavity is filled with gas and / or uranium dioxide with natural or dump uranium-235 enrichment. 30. A shellless fuel assembly with a hexagonal fuel grid of a pressurized water reactor according to claim 21, characterized in that the guide channels are hydraulically connected to the surrounding space, and the displacers with a cavity are made with the possibility of hydraulic connection of the cavity with the surrounding space.

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