Method for producing spacer grid from zirconium alloy

FIELD: nuclear power engineering.

SUBSTANCE: proposed method is used for manufacturing fuel assemblies for type VVER-1000 and VVER-440 reactors. In order to check spacer grid for passability it is placed in machine between two covers with depressions that follow grid outline and blind holes coaxial to each subchannel of grid accommodating calibrated balls, then it is tuned together with covers through 180 deg., subchannels of inadequate caliber are detected and burnished by means of drift. For checking diameter of circumference inscribed in subchannel the grid is placed in machine equipped with large-diameter calibrating balls, subchannels through which these balls have passed are detected and squeezed by means of clamping tool with jaws disposed in holes between subchannels. Decision on quality of spacer grid subchannels is taken by sticking of balls in them as spacer grid is turned in machine through 180 deg. Balls of different diameters are differently colored.

EFFECT: enhanced quality and yield of spacer grids.

2 cl, 4 dwg

 

The invention relates to nuclear power and may find application in the manufacture of fuel assemblies for nuclear reactors, mostly in water-cooled power reactors VVER-1000 and VVER-440.

A known method of manufacturing the spacer lattice of an alloy of zirconium, including set and spot welding figured cells interconnected by education fields curly cells to pass through them fuel elements (FE), manufacturing hexagonal rim spacer lattice of an alloy of zirconium, typed fields curly cells in the rim of the spacer grid and spot welding the peripheral figured cells to the rim of the lattice (see “Development, production and operation of fuel cell power reactors” edited Fgurative, book 1. M.: Energoatomizdat, 1995, table 7.1. on page 184, and p. 187). It is known that curly cells from an alloy of zirconium, made of thin-walled tubes have fluctuations as the wall thickness and diameter in accordance with the specifications. This leads to the fact that typed in the box curly cells included in the rim without gaps or proslavlenie or tightness, but in both cases these variations can adversely affect the quality of the spacer grid and the performance of additional work: the case of typed fields of cells with proslavlenie required before spot welding the rim and peripheral cells pull the rim to the cells, which leads to deformation of the middle portion of the face of the rim, whereas in the corners of the rim gaps remain, and increased the gap between the rim and the field of figured cells leads to burn-through during welding of the peripheral cells to the rim and to marriage; in the case of typed fields of cells with tightness of the deformation of the peripheral figured cells, loss of the established step between cells and appears obstruction holes for the fuel elements during Assembly.

A known method of manufacturing the spacer grid comprising a set of curly cells, spot welding figured cells between themselves and bond outside part of the rim with the subsequent fastening point welding each pair of parts to one, adjacent to the junction of the peripheral shape cell (see Patent RU 2155998 from 04.08.1998, publ. 10.09.2000, MPK7 G 21 C 3/34. “The spacer lattice fuel Assembly of a nuclear reactor and method of its manufacture”).

The known method eliminates the disadvantages of the known technical solutions, but in the process of manufacturing the spacer grids generate internal stresses, which can lead to obstruction of the fuel rod through the cell during Assembly FA or Vice versa patency of a fuel rod through cell proslavlenie. In this case, when the operation of the fuel assemblies in the reactor core of a nuclear reactor may occur fret the ing-corrosion and depressurization of the Fuel elements.

The closest in technical essence and the achieved effect is a method of manufacturing the spacer lattice of the zirconium alloy, comprising manufacturing a hexagonal rim and cells with internal protrusions, placement and fixation spot welded to each other and to the rim of cells with subsequent thermal annealing at a temperature, time and pressure sufficient to relieve internal stresses, and the formation of a protective oxide film in the process of its cooling temperature to prevent corrosion destruction (see patent RU 2195721 published 27.12.2002, MPK7 G 21 3/34, 21/00 “Method of manufacturing the spacer lattice of the zirconium alloy”).

Prototype method provides removal of residual internal stresses, however, if in the process of manufacturing the cells were allowed mismatch inscribed circle in the cell in a direction more or less, this discrepancy is difficult to identify visual method and it can be detected only when assembling the fuel rod in the fuel Assembly in the event of an obstruction of Fuel into the cell. And if the permeability of the fuel rod through the cell with proslavlenie, then this point can be observed when assembling the FA and will be dealt with fretting corrosion in the core of a nuclear reactor, i.e. in the destruction of the fuel element.

In the method prototype in ways analogous to not reveal you control the means of cells of non-compliance, presented to the spacer grids, and not disclosed to remedy defects of the cells in the finished spacer grids.

The technical challenge is to improve the quality and yield grid spacers by identifying cells that do not meet the requirements of the spacer grids, and resolve identified defects in the finished spacer grid.

This technical problem is solved in that in the method of manufacturing the spacer lattice of the zirconium alloy, comprising manufacturing a hexagonal rim and cells with internal protrusions, placement and fixation spot welded to each other and to the rim of cells with subsequent thermal annealing at a temperature, time and pressure sufficient to relieve internal stresses, and the formation of a protective oxide film in the process of its cooling temperature to prevent corrosion destruction; according to the invention the spacer grid is subjected to the control of the traffic to the minimum acceptable diameter of the inscribed circles in the cells to which the spacer bars are placed in the device between the two covers, with deepening that follows the contour of the spacer grid with blind holes, aligned to each cell of the spacer grid, placed in g is which the holes of one of the covers of the calibration beads, turn the spacer bars with the cap 180°, identify those cells through which the calibration beads were not, and Razdolnaya their Dorn, after Razdolnoe spacer bars together with lids turn 180° and having passed through the cells of the spacer grid calibration beads conclude that the minimum allowable diameter of the inscribed circle in a cell match, then the spacer bars are subjected to control by the maximum allowable diameter of the inscribed circles in the cells to which the spacer grid is placed between two covers similar constructs mentioned above, with calibration beads slightly larger diameter, turn 180°, identify those cells through which the calibration beads were, compresses them using the crimp device with the placement of sponges in the holes between cells, perform a final inspection by 180° the spacer grid with the cap and hung in all the cells of the spacer grid calibration beads make a decision about the suitability of the spacer grid for use in the fuel Assembly.

Another difference is that the use of calibration beads of the same color to control the minimum diameter wpisane the circles in the cell and another color to control the maximum diameter of the inscribed circles in the cells.

This embodiment of the method of manufacturing the spacer grids of the fuel assemblies will improve the quality and yield grid spacers by identifying cells with a deviation of the dimensions along the entire height of the cells and to remedy any deficiencies in the finished spacer grid.

The use of calibration beads of different colors, i.e. to control the minimum diameter of the inscribed circle of the same color, and for the maximum inscribed circle diameter of a cell of a different color, will eliminate the possibility of confusing the calibration balls and eliminate the misinformation about the quality of the manufacture of the spacer grid.

A method of manufacturing the spacer grid is illustrated by drawings, where:

- figure 1 - the spacer grid;

- figure 2 - monitoring device on the permeability of the cell (side view);

- figure 3 is a device on the permeability of the cell (top view);

- figure 4 - swaging device.

A method of manufacturing the spacer lattice of the zirconium alloy includes the steps of: manufacturing a hexagonal rim 1 and cell 2 with internal projections 3, the placement and fixation spot welded to each other and to the rim 1 cell 2. The spacer bars 4 are annealed at 580±15°With at least 180 mi is. At a residual pressure of 2×10-3mm Hg, the Temperature is reduced to 500±20°and form a protective oxide film using as the oxidizing environment of atmospheric air.

An example of the method.

The spacer bars 4 are placed in the device 5 between the two covers 6, 7 having recesses that follows the contour of the spacer grid 4, with blind holes 8, 9, coaxially to each cell 2 spacer grid 4, placed in blind holes of one of the covers of the calibration beads 10.

When controlling for mobility on the minimum allowable diameter of the inscribed circle in the cell 2 using calibration beads 10 with a diameter of 8.9 mm, so that when the Assembly of fuel Rods with diameter D=9.1 mm occurred Assembly of a fuel rod in a cell with tension. Turn the spacer bars 4 with the device 5 to 180° and identify those cells 2 through which a calibrated balls 10 is not passed, which is a consequence of the fact that in these cells 2 is an obstruction. Not removing cell 2 hung calibration beads 10, push mandrel (not shown) and simultaneously Razdolnaya cell 2. Then turn the spacer bars 4 with the device 5 to 180° and having passed through the calibration cell 2 to 10 balls without them hang conclude with the accordance of the inscribed circles in the cells to the minimum acceptable diameter.

Then the spacer bars are subjected to control by the maximum allowable diameter of the inscribed circles in the cell for which the spacer bars 4 is placed between two covers similar constructs mentioned above, with calibration beads 10 somewhat larger diameter, i.e. D1=remaining 9.08 mm, and turned 180°, identify those cells 2 through which the gauge 10 passed balls, compresses them using the reducing device 11 with the placement of the jaws 12 in the openings 13 between cells 2, perform a final inspection by 180° the spacer grid 4 with the cap and hung in all the cells 2 spacer grid 4 calibration beads with diameter D1make a decision about the suitability of the spacer grid for use in the fuel Assembly.

Calibration beads 10 in order to avoid mixing them have different color, i.e. balls with a diameter of D have the same color, and with a diameter of D1the other.

1. A method of manufacturing the spacer lattice of the zirconium alloy, comprising manufacturing a hexagonal rim and cells with internal protrusions, placement and fixation spot welded to each other and to the rim of cells with subsequent thermal annealing at a temperature, time and pressure sufficient to remove the internal the stress and the formation of a protective oxide film in the process of its cooling temperature to prevent corrosion destruction, characterized in that the spacer grid is subjected to the control of the traffic to the minimum acceptable diameter of the inscribed circles in the cells to which the spacer bars are placed in the device between the two lids that have cavities that follows the contour of the spacer grid, with blind holes, aligned to each cell of the spacer grid placed in blind holes of one of the covers, gauge bulbs, turn the spacer bars with the cap 180°, identify those cells through which the calibration beads were not, and Razdolnaya their Dorn, after Razdolnoe spacer bars together with lids turn 180° and having passed through the cells of the spacer grid calibration beads conclude that the minimum allowable diameter of the inscribed circle in a cell match, then the spacer bars are subjected to control by the maximum allowable diameter of the inscribed circles in the cells to which the spacer grid is placed between two covers similar constructs mentioned above, with calibration beads of larger diameter, turn 180°, the detection of the Ute those cells, through which the calibration beads were, compresses them using the crimp device with the placement of sponges in the holes between cells, perform a final inspection by 180° the spacer grid with the cap and hung in all the cells of the spacer grid calibration beads make a decision about the suitability of the spacer grid for use in the fuel Assembly.

2. The method according to claim 1, characterized in that the use of calibration beads of the same color when you control the minimum diameter of the inscribed circles in the cell and another color to control the maximum diameter of the inscribed circles in the cells.



 

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