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Method for producing tubular three-layer fuel elements. RU patent 2248049.

IPC classes for russian patent Method for producing tubular three-layer fuel elements. RU patent 2248049. (RU 2248049):

G21C3/02 - Fuel elements

G21C21/02 - Manufacture of fuel elements or breeder elements contained in non-active casings

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FIELD: nuclear power engineering; tubular dispersed-core three-layer fuel elements.

SUBSTANCE: proposed method includes production of powder mixture, powder mixing in plasticizer environment, cold molding in core billet with plasticizer, thermal sintering, hot molding-calibration of fuel core, core placing in can made in the form of sleeve with annular slot, calibration, hot molding through die, and drawing; inner surface of external can of sleeve is provided with longitudinal bulges and outer surface bears bulge location marks; fuel core is provided with longitudinal flats and placed in sleeve taking care to align bulges of the latter with core flats; in the course of drawing marks are aligned on arbor ribs.

EFFECT: enhanced stability of active layer and can thickness in shaping polyhedral fuel elements.

1 cl, 4 dwg

The invention relates to nuclear power and may find application in the manufacture of three-layer tubular fuel elements (Fe) of different geometry with the core of the dispersion type.

Fuel elements of this type are in the form of tubes of circular or polygonal cross-section consisting of an inner layer (core) and bilateral protective shell of corrosion-resistant material, such as aluminum alloy.

A known method of manufacturing fuel elements joint pressing shell and core (Sikorski YU. and other Uranium and its alloys, M, Atomizdat, 1971, s-419).

The disadvantage of this method is the instability of active layer thickness in the formation of Fe multifaceted profile.

The closest in technical essence and the achieved result - the prototype is a method of manufacturing a three-layered tubular billet fuel elements for RF patent No. 2091872, MKI G 21 3/00, 21/02, 21/10, 1997, including the mixture of powders, their mixing in the presence of plasticizer, cold pressing into the material of the core with the plasticizer, thermal sintering, hot pressing-calibration of the core, placing the core in the shell, made in the form of a Cup with an annular groove, calibration, hot pressing in a die and drawing.

The disadvantage of this method is the instability of active layer thickness in the formation of Fe multifaceted profile.

The objective of the invention is to increase the operational reliability of the fuel rod due to the receipt of the active layer of stable thickness on the sides and corners in a three-layer tubular fuel elements multifaceted profile.

The problem is solved due to the fact that in the method of manufacturing a three-layered tubular fuel elements, comprising the mixture of powders, their mixing in the presence of plasticizer, cold pressing into the material of the core with the plasticizer, thermal sintering, hot pressing-calibration of the core, placing the core in the shell, made in the form of a Cup with an annular groove, calibration, hot pressing in a die and drawing, according to the formula of the invention, the inner surface of the outer shell of the Cup comply with longitudinal thickenings, and on the outer surface of perform label the location of the swelling, the core performs with longitudinal flats and place it in the glass, combining thickening the glass faces of the core, and when you combine drawing marks on the edges of the mandrel.

This set of features is a new, unknown in the prior art and solves the problem as the run flats on the core reduces the thickness of the active layer in the corners of a fuel rod. The active layer in the area of the angle feels as deformation strain (half the thickness of the active layer adjacent to the outer shell), and the compression deformation (half the thickness of the active layer adjacent to the inner membrane). The active layer contains particles of uranium dioxide, which are not deformed, and the deformation is only subjected to the aluminum matrix. The presence of the fuel component affects the thickening of the active layer in the corners during the formation of a multifaceted profile. The reduction of the fuel component (run flats) allows to obtain an active layer of stable thickness on the sides and corners.

At the bend in the angle area, the outer casing feels deformation strain, as it increases the length of the angular sector of the square of the outer shell relative to the sector of the outer shell, round tube, and as a result, the outer shell becomes thinner in the abs, and unevenly distributed around the perimeter of the angle, the maximum thinning of the shell corresponds to the vertex of the angle TVEL. Performing longitudinal thickenings on the inner surface of the outer shell of glass can reduce the thinning of the outer shell at the corners during the formation of the square profile.

The proposed method is illustrated by drawings.

Figure 1 shows the annular core with flats on figa and PIGB - glass with longitudinal thickenings in figure 3 - cross section of a fuel rod in the form of a round pipe, figure 4 is a cross section of a fuel rod in the form of a square tube.

A method of manufacturing a three-layered tubular fuel elements is as follows.

Get a mixture of fine powders for the manufacture of fuel cladding by powder metallurgy, mixed powders of starting materials in the presence of a liquid plasticizer, pressed into a billet core with the use of a plasticizer, perform hot pressing-calibration of the core 1, after which it perform longitudinal flats 2 in number equal to the number of edges of the mandrel.

Manufacturing shell carried out by the method of backward extrusion. Using a punch, providing thickening 3 on the inner surface of the outer shell of the Cup 4. On the outer surface of the glass do labels the location of the swelling. The amount of thickening is equal to the number of flats on the core. In the annular groove 5 cups 4 install fuel core 1 so that its longitudinal flats on 2 coincides with the longitudinal thickenings 3 cups 4. The resulting billet gauge, perform hot pressing and drawing on a round mandrel. Tubular fuel rod of circular cross section 6 is formed in a polyhedron 7 of the drawing. Combine labels with the edges of the mandrel and is passed through the matrix.

An example of the method.

Made two core fuel elements. The cores have performed longitudinal flats in four places 90°.

Geometrical dimensions of the cores are given in table 1.

Table 1

no heart condition-nick D tube od in., mm ø EXT., mm N, mm Size turnkey in flats S1 S2 1 79,6 65,1 32,5 77,1 77,0 2 79,6 65,0 32,5 77,0 77,0

Made glasses by the method of backward extrusion with longitudinal thickenings of the outer shell in four places 90°.

On the outer surface of the glass did label the location of the swelling.

In the annular groove of the shell has established fuel core so that its longitudinal flats coincided with the longitudinal thickenings of the glass. The resulting workpiece is changed, had hot pressing and drawing on a round mandrel.

Combined label with edges of the mandrel.

In the final passages of the lug has provolokami mandrel square section with a corner radius of 3 mm (cores No. 1), and the other pipe has provolokami mandrel with corner radius edits 4.6 mm (cores No. 2). After the final passage of the fuel cut samples of data samples produced cross sections. Cross-sections made measurements of the thicknesses of the shells and the active layer. The average thickness of the shells and the active layer, and the percentage exceeding the thickness of the active layer at angles with respect to the average value of active layer thickness on the edges are given in table 2.

Table 2 No. of fuel rod (core) the Average value of thicknesses. The excess of the thickness of the active layer at angles with respect to the average value of active layer thickness on sides, % corner Radius of the mandrel, mm Outer sheath, mm Active layer, mm Angle Face Angle Face 1 0,4485 0,5105 0,5675 0,5478 14,85 3 2 0,4705 0,4735 0,4825 0,4725 to 4.23 4,6

Thus, the proposed method allows to produce a three-layer tubular fuel elements with a stable thickness of the active layer and the membrane during the formation of Fe multifaceted profile.

A method of manufacturing a three-layered tubular fuel elements, comprising the mixture of powders, their mixing in the presence of plasticizer, cold pressing into the material of the core with the plasticizer, thermal sintering, hot pressing-calibration of the core, placing the core in the shell, made in the form of a Cup with an annular groove, hot pressing in a die and drawing, characterized in that the inner surface of the outer shell of glass perform longitudinal thickenings, and on the outer surface of perform label the location of the swelling, the core performs with longitudinal flats and place it in a glass of combining thickening of the glass faces of the core and when you combine drawing with tags the edges of the mandrel.