The way to prevent the formation of burrs on the fuel elements and the spacer grid

 

(57) Abstract:

Usage: in the Assembly of fuel elements (FE) in the fuel assemblies of nuclear reactors to improve the quality of Assembly, durability, and reducing the cost of manufacture. The inventive arrangement of grid spacers begin with the placement of their paleologou with placing them in sections, made from a single strip of zirconium some poliacek. The width of the zirconium strip equal to the height of the cell over the whole length of the line from side face to side face of the rim. The placement of the fuel Rods is carried out by their placement in the half cell, then laid in a half cell of the fuel Rods in probody set the second partition with the response Poluchenie for lower polacek sections and the upper Poluchenie for regular Rods and sections, press the second section to the first in each polyamide with the formation of hollow cells and carry out spot welding joints of zigzag ribbons between cells and paleobotany and so on until the complete formation of the cells of the grid spacers along the length of the formed fuel assemblies with point welding of the second paleologou collected on a field of cells with the fuel elements inside. 2 S. and 1 C. p. F.-ly, 6 ill.

Izobreteniya Assembly, mainly to power nuclear reactors VVER-10000, VVER-440.

There is a method of preventing the formation of burrs on the fuel elements in the manufacture of fuel assemblies, including parallel equidistant arrangement dicttionary grids cells are placed coaxially to each other, the preparation of the fuel rod to the Assembly of the fuel Assembly (FA) and the placement of the fuel elements in the cells of the spacer grids (see U.S. Patent N A published 02.07.96,, IPC G 21 C 3/32. Similar applications USA: 95389861 from 22.02.95, and 93142265 from 25.10.93 year).

For U.S. patent N A when placing Rods in the cells based on the principle push of a fuel rod in the tube, which previously entered in coaxial cell grid spacers with subsequent fixation of a fuel rod and remove the pipe from the grid spacers, i.e., when assembling the fuel Assembly, the fuel Rods of the double-contact with the pipe wall at the push of a fuel rod in the pipe and remove the pipe from the fuel rod, that does not preclude scratches and scuffs on the shell of the fuel element.

It is known that the main material of the cladding water water (PWR) and boiling power reactors is zirconium alloy (see Development, production and operation of TVEL energy. Energoatomizdat, 1995, page 127).

It is also known that zirconium is prone to corrosive corrosion, resulting from the abrasion of metal between the contact surfaces even in the absence of a corrosive environment (see metallurgy of zirconium. Translation from English. Edited by G. A. Meyerson, and Y. C. Gagarin. Publishing house of foreign literature. M., 1959, page 298).

When assembling the subassemblies for U.S. patent N 5533077 double contact with a pipe wall of the shell under axial movement of the fuel rod in the pipe does not exclude the formation on the membrane of a fuel rod scratches or scuffs that cause corrosive corrosion and possible destruction of the membrane of a fuel rod in a nuclear reactor. When the input pipe into the cells of the spacer grid with a diameter larger than the diameter of the fuel rod is not excluded that the walls of the cells of the spacer grid after removal of the pipe due to residual stresses will be larger than the diameter of a fuel rod, which will lead to vibration of the fuel rod in the flow of coolant and to the inevitable destruction (see metallurgy of zirconium, page 298).

To prevent damage to the sheath of a fuel rod during Assembly of the fuel Rods in the fuel assemblies known to the application of the Fuel cladding prior to their Assembly in the FA protective coating odorant 3/09. Line preparation of fuel elements to the Assembly in FA).

There is a method of preventing the formation of burrs on the fuel Rods in the manufacture of fuel assemblies, including parallel equidistant arrangement of the spacer grids cells are placed coaxially to each other, the preparation of the fuel rod to the Assembly of the fuel Assembly and placement of the fuel elements in the cells of the spacer grids (see the Patent of Russian Federation N 2126739 from 27.03.97, published 27.02.99, IPC 6B 23 P 15/26, B 21 D 53/08. Automatic line Assembly fuel rod in the fuel Assembly). Unlike U.S. patent N 5533077 the patent of Russian Federation N 2126739 in addition to Lakokraska according to the patent of Russian Federation N 2127002 provides equipment lakokrasocnij TVEL removable tip having a diameter larger than the diameter of a fuel rod and the injection into the cells of the spacer grids of the fuel rod tip forward with application to the FE lubrication at the time of pressing. However, protection varnish, grease and the use of removable tips for easing the friction of the walls of the cells of the grid spacers on the fuel rod at the moment of pulling the fuel Rods in the cells of the spacer grids does not exclude the formation of scratches, scuffing and wear on the Fuel cladding, which reduces the build quality of FA and does not give the possibility the sun, including the high cost of manufacturing grid spacers Zirconia thin-walled pipes for the production of these cells, and the installed cost of Lakokraska TVEL before their Assembly in FA.

The closest in technical essence and the achieved effect is a method of preventing the formation of burrs on the fuel Rods in the manufacture of fuel assemblies for a nuclear reactor, comprising parallel equidistant arrangement of the spacer grids cells are placed coaxially to each other, the preparation of the fuel rod to the Assembly of the fuel Assembly and placement of the fuel elements in the cells of the spacer grids (see the Patent of Russian Federation N 2127001 from 27.03.97, published 27.02.99, MCI 6 G 21 C 3/34. The spacer lattice fuel assemblies of a nuclear reactor).

The method involves the use of grid spacers with cells having internal projections and notching, ensure the contact of a fuel rod cell in four points and pushing Fuel cells grid spacers when assembling the fuel assemblies (see section 10 of the patent 2127001).

Since in the method of FA based on the principle of pushing Fuel through the aligned cells of the spacer grids (see section 10 of the patent 2127001), then cancel Lakokraska of Fe and CR is received by the high quality workmanship of the tabs with the slots in the cells of the spacer grids, because otherwise inevitable scuffs and scrapes at the push of a fuel rod through the aligned cells of fifteen grid spacers the VVER-1000 and ten grid spacers the VVER-440.

Similar damage to the sheath of the fuel element is possible if the misalignment of the cells, the use of fuel Rods with deviations in diameter, curvature and exceeding the efforts of integrating Fuel cells installed in parallel grid spacers.

When moving to a five-year lifetime fuel assemblies in the nuclear reactor, the degree of risk should be excluded.

Known spacer lattice fuel assemblies of a nuclear reactor having a hexagonal rim, inside which there are connected to the rim and between the cells, made of ribbon with internal projections and slots (see German Patent N DE 2839211, MKI G 21 C 3/34, 1979). The disadvantage of the spacer grid is the impossibility of its use in nuclear fuel assemblies of VVER-1000 reactor having a tubular channels to accommodate rods of the control and protection of a nuclear reactor, because the holes for the placement of channels design known the spacer grid is not provided.

The organization of such holes and the spacer grid is impossible.

Known spacer grid when building assemblies, installed in parallel with coaxially placed cells include pushing through the Fuel cell that does not exclude damage to the Fuel cladding (scratches, scuffs, scrapes, and the occurrence of pitting corrosion in areas of damage to the sheath of a fuel rod (see metallurgy of zirconium, English Translation, 1959, page 298).

Closest to the technical essence and the achieved effect is the spacer lattice fuel assemblies of a nuclear reactor having a hexagonal rim, inside which there are connected to the rim and between a cell made of zirconium tape with internal projections and slots, and a cell for the Central pipe and channel guides (see the Patent of Russian Federation N EN 2127001, MKI 6G 21 C 3/34 from 27.03.97, published 27.02.99 year).

The spacer grid according to the patent RU 2127001 has the same drawback, that the spacer grid according to patent DE 2839211 in terms of placement in the cells of the fuel rod in the Assembly in their FA pushing the fuel element through the cell parallel to the established grid spacers that does not exclude damage membranes TVEL on the walls of the cells, the occurrence of pitting corrosion and trelat in the Assembly FA is inevitable, which limits the service life of the fuel assemblies in a nuclear reactor. Possible damage to the membrane of a fuel rod may cause the misalignment of the cells, the curvature of a fuel rod, the curvature of a fuel rod at the Annex effort push, as well as variations in the diameter of a fuel rod.

An object of the invention is to improve the quality of Assembly of the fuel assemblies, increasing the service life of the fuel assemblies in a nuclear reactor and reducing the cost of manufacture of fuel assemblies. This technical problem is solved in that in the method of preventing the formation of burrs on the fuel Rods in the manufacture of fuel assemblies, including parallel equidistant arrangement of grid spacers with the coaxial arrangement of cells, preparation of the fuel rod to the Assembly in the fuel Assembly and placement of the fuel elements in the cells of the grid spacers

according to the invention parallel equidistant arrangement of grid spacers with the coaxial arrangement of the cells begins with the placement of their paleologou with placing them in the first sections of the pre-made from a single strip of zirconium some polacek, fixing the spot weld section to the bottom face of each polwood grid spacers, the preparation of the fuel rod to the Assembly FA is carried out by set TVEL in number, arranged in a half cell of the fuel Rods in probody set the second partition with the response Poluchenie for lower polacek sections and the upper Poluchenie for the next TVEL and sections, press the second section to the first section in each polyamide the entire length of the collected fuel assemblies with the formation of full cells and carry out spot welding joints of zigzag ribbons between cells and paleobotany, and the subsequent formation of grid spacers Assembly with fuel Rods with the formation of the FA exercise alternating stacking of the fuel Rods in the half cell with the installation of the next sections, with their clamping and spot welding to complete formation of the cells of the grid spacers along the length of the formed fuel assemblies with point welding of the second paleologou collected on a field of cells with the fuel Rods inside.

This technical problem is solved by the fact that for the implementation of the method in the spacer grid for a fuel Assembly of a nuclear reactor, mainly type reactors with hexagonal rim, inside of which is placed cells Zirconia ribbon with tabs and slots

according to the invention rim made of composite of two paleologou, fixed between a point welding, each row of cells parallel to the axis of the bottom edge of the rim and adjacent to it is made of a composite of poliacek in section zigzag form from one of zirconium strip with a width equal to the height of the cell over the whole length of number ousa section is equipped with a return Poluchenie, forming a number of full cells with lower number of polachek and a number of polacek on the other hand zirconium strip zigzag form, forming a complete cell with a return Poluchenie the next sections and securing the sections to each other and to the rim carried out by point welding. Another difference is that the spacer grid for nuclear fuel assemblies of VVER-1000 reactor is supplied in sections of the composite cells for Central pipe and channel guides a larger diameter than the cells for the fuel Rods in these sections.

Pre-production sections polacek grid spacers and build them with alternating stacking of the fuel Rods with the formation of FA and grid spacers will improve the build quality of the fuel assemblies by eliminating the use of expensive zirconium tubes for the manufacture of the cells of the spacer grids. Manufacturing sections polacek by stamping from a Zirconia tape with simultaneous implementation of punching, joining the ranks of polachek when assembling the FA after laying them TVEL will allow you to achieve the complete elimination of Lakokraska surface of the fuel elements and removal of the varnish after Assembly FA, exceptions, lubricating, and cleaning after Assembly FA and exclude the use of the armed forces of a nuclear reactor VVER-1000 and VVER-440.

The drawings show a method of preventing the formation of burrs on the fuel elements in the manufacture of fuel assemblies and the spacer grid:

in Fig. 1 - method of preventing the formation of burrs on the fuel elements in the manufacture of fuel assemblies.

Fig. 2 - spacer grid for the VVER-1000;

Fig. 3 - spacer grid for the VVER-440;

Fig. 4 - slice locations of the first and second sections of the spacer grid in the rim with the fuel Rods;

Fig. 5 is a fragment of a cell with polevkami Assembly with TVEL;

Fig. 6 - lug and slot on the cell with the fuel rod inside.

Spacer grid for a fuel Assembly of a nuclear reactor, mainly for VVER reactors with hexagonal rim of the fixed spot welding two paleologou 1, 2, inside of which is placed in the cell 3 of zirconium tape (an alloy of zirconium, 1% niobium), equipped with ledges 4 and slots 5. In Fig. 5, the protrusions 4 are made in the form of poklevki.

Each row of cells 3 which is parallel to the axes of the bottom face 6 of the rim and adjacent thereto, made of a composite of polachek 7 section 8 from one of zirconium strip zigzag shape with a width equal to the height of Acacias.

Each subsequent section 9 contains a response half cell 10 forming at Assembly FA full cell with the lower number of polachek 7 and the number of polachek 11, on the other hand zirconium strip zigzag form in this section 9, forming a complete cell with a return Poluchenie the next section "n" in the Assembly FA, etc.

The spacer grid for nuclear fuel assemblies of VVER-1000 reactor equipped with a composite cell 12 of larger diameter Central pipe and the composite cells 13 of larger diameter for the channels of the guides than cells for the fuel Rods 14 in the same sections. The cells 3 are designed to contain the fuel elements 14.

The way to prevent the formation of burrs on the fuel Rods in the manufacture of fuel assemblies is as follows.

Parallel equally spaced apart arrangement of grid spacers with the coaxial arrangement of the cells 3 begin with the placement of their paleologou 1 with placing them in the first sections 8 of the pre-made from a single strip of zirconium alloy of zirconium, 1% niobium) number of polachek 7, the fixing section 8 is spot welded to the bottom face 6 of each polwood 1 spacer grid.

The preparation of the fuel rod 14 to the Assembly in FA implemented the way they are laid horizontally in half cell 7, then laid in a half cell 7, the Rods 14 in probody 1 set section 9 with a return Poluchenie 10 for the lower polacek 7 section 8 and the upper Poluchenie 11 for the next fuel rod 14 section "H", press section 9 to section 8 in each polyamide 1 along the entire length of the collected fuel assemblies with the formation of full cells 3 and carry out spot welding joints of zigzag ribbons between cells 3 and paleobotany 1. The subsequent formation of grid spacers Assembly with fuel Rods 14 with the formation of the FA exercise alternating stacking of the fuel Rods 14 in the half cell with the installation of the next sections, clamping and spot welding to complete formation of the cell 3 grid spacers along the length of the formed fuel assemblies with spot welding paleologou 2 assembled on a field of cells 3 with the fuel Rods 14 in them.

In the process of assembling the fuel assemblies of the Assembly, the fuel rod 14 with a range of diameter 9,05 - 9,26 mm, to prevent backlash or preload provides elastic compensation in the form of elastic protrusions 4 with the slots 5 in each cell 3 in the amount of four elastic protrusions 4 are diametrically opposed.

In the spacer grid for a fuel Assembly for a nuclear reactor VVER-1000 provided by the Central cell 12 for RTR inscribed circle for a fuel rod 14.

1. The way to prevent the formation of burrs on the fuel elements comprising parallel equidistant arrangement of grid spacers with the coaxial arrangement of cells, preparation of fuel elements for the Assembly in the fuel Assembly and placement of fuel elements in the cells of the grid spacers, characterized in that the parallel equidistant arrangement of grid spacers with the coaxial arrangement of the cells begins with the placement of their paleologou with placing them in the first sections of the pre-made from a single strip of zirconium some polacek, fixing spot weld section to the bottom face of each polwood grid spacers, preparation of fuel elements for the Assembly in the fuel Assembly is carried out by way of a set of fuel elements in number equal to the number of polachek section, the placement of the fuel elements is carried out by their placement in the half cell, then laid in a half cell fuel elements in probody set the second partition with the response Poluchenie for lower polacek section and the upper Poluchenie for the next fuel elements of the second Assembly with the formation of full cells and carry out spot welding joints of zigzag ribbons between cells and paleobotany, and the subsequent formation of grid spacers in the Assembly of fuel elements with the formation of the fuel Assembly is performed by alternating stacking of fuel elements in the half cell with the installation of the next sections, with their clamping and spot welding to complete formation of the cells of the grid spacers along the length of the formed fuel Assembly with spot welding the second paleologou collected on a field of cells with the fuel elements inside.

2. The spacer grid with hexagonal rim, inside of which is placed cells Zirconia ribbon with tabs with the slots, wherein the rim is made of a composite of two paleologou, fixed between a point welding, each row of cells parallel to the axis of the bottom edge of the rim, and adjacent to it is made of a composite of poliacek in section of one of zirconium strip zigzag shape with a width equal to the height of the cell over the whole length of the line from side face to side face of the rim and secured to the said faces of the rim spot welding, each subsequent section is equipped with a return Poluchenie, forming a number of full cells with lower number of polachek and a number of polachek and the next sections, and securing the sections to each other and to the rim carried out by point welding.

3. The spacer grid according to p. 2, characterized in that, for a fuel Assembly of a nuclear reactor VVER-1000 it is provided in the sections of the composite cells for Central pipe and channel guides a larger diameter than the cells for fuel elements in these sections.

 

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