BG60931B1 - NUCLEAR REACTIVE FUEL ELEMENT - Google Patents

Abstract

The fuel element has a hexagonal grid-shaped expansion element with minor manufacturing tolerances for the holes. The expansion element has a first (6) and a second (7) inner collector. The collector (7) forms a bent O-shaped edge to which the collector (6) is welded by a side edge (6a).

Description

The invention relates to a fuel element of a nuclear reactor arranged side by side and in parallel to each other, spaced apart, at least one of which is a fuel stem containing nuclear fuel and which stems are respectively passed through a loop of lattice stretching element. The fuel element has the following characteristics:

a) the lattice-stretching element has finned outer collectors (necks) of sheet metal that form the contour of a regular hexagonal outer manifold (neck) in a basic / support / plane perpendicular to these stems;

(b) the lattice-like stretching member has internal loops whose walls are formed by the fins arranged internally in this contour;

c / the contour angles of the loops of all the inner loops of the spreading element form, in the perpendicular to the stems base plane, the angles of regular hexagons of the inner manifolds which have the same length of sides;

(d) the lattice-stretching element has outer loops (openings) having at least one wall of the opening formed by an external manifold and two others, cut into the inner side of an external manifold, formed by one inner manifold, by the walls of the loop.

One such nuclear reactor fuel element is known from German prior publication DE OS 34 01 630.

With this known nuclear reactor fuel element, the internal collectors (necks) of the lattice expansion element are arranged longitudinally in the form of strips. The internal manifolds are fixed at both ends respectively to the inside of an external manifold. The walls of the loops are formed on these internal collectors by means of bent edges parallel to the stems. Then two of these internal manifolds connect straight to each other to form a loop.

It is an object of the invention to refine the construction of the known fuel element of a nuclear reactor by achieving minor manufacturing tolerances for the slots / openings / of the lattice expansion element.

In order to accomplish this task, the fuel element according to the invention is characterized in that the loop forming wall between the first and second loop of the first inner manifold, with its first parallel to the stem side edging, is fixed to a parallel to the stem bent edge, which is located in the angle of a regular hexagon of the inner manifold between two other walls formed by the second inner manifold, of which one wall of the loop belongs to the first loop and the other to the second loop. The second side edges parallel to the lateral edges of the first inner manifold and the two lateral edges parallel to the edges of the second inner manifold form a group of three lateral edges. Two of the three side edges of this group are attached respectively to the parallel stems located in the corner of the right hexagon of the inner manifold side edges of another second inner manifold, and the third side edging of this group is attached or parallel to the stems located be in the corner of a regular hexagon on the inner manifold side edges of the second inner manifold or on the inside of an external manifold.

The second inner manifold, with the first inner manifold attached to its curved edge, is a relatively small basic element for the construction of the lattice-like expansion element. The base element can be made first and foremost with a very precise respect of the nominal dimensions. A series of such prefabricated base members are mounted next to the lattice expansion element. Deviation of the base member from its nominal dimensions occurs only locally, in a small area of the lattice expansion element and does not extend to the entire lattice expansion element. This means that a predetermined nominal distance between the stems of the fuel element of the nuclear reactor can be accurately maintained in this lattice expansion element.

An advantageous embodiment of the fuel element according to the invention consists in the fact that the two cut-outs on the inner side of the outer manifold, respectively formed by one inner manifold, of the loop walls of the outer loops meet at an angle of 90 ° on the inside of the outer manifold. This facilitates the fabrication of the lattice extension element.

Another embodiment of the element is that a wall of the loop has a vault with a parallel to the stems, forming a direction parallel to the stems in the direction of the bending fixed bores for one stem. This reduces the pressure loss of the coolant flowing into the fuel element of the nuclear reactor in the longitudinal direction of the stems.

Another embodiment, which in this case results in a decrease in the pressure loss of the coolant flowing into the fuel element of the reactor in the longitudinal direction of the stem, is that one loop wall has a bend parallel to the stems forming about parallel to stems, and that a spring for a fuel stem is raised on the bending.

The invention and its advantages are better explained by the accompanying figures, of which:

Figure 1 shows a top plan view of a lattice expansion element in a basal plane perpendicular to the fuel stalks of a nuclear reactor fuel element according to the invention;

Figure 1a is an enlarged partial section of Figure 1;

FIGS. 2 and 2a are a top plan view and an enlargement of a base member for a stretching member according to FIG. 1;

FIG. 2c is a side view of a base member according to FIGS. 2 and 2a in the direction of the arrow in FIG. 2a; FIG.

FIG. 2c is a side view of this basic element in the direction of the arrow of FIG. 2a;

FIGS. 3 to 11 are a top plan view and an enlargement of other base members III to XI for a lattice expansion member according to FIG. 1;

12 is a top plan view of another embodiment of a base member for a lattice-stretching member.

The fuel element of a nuclear reactor with a lattice expansion element, the outline of which is shown in FIG. 1, there are two fixing plates, between which there is at least one such extension member. A support rod 2, whose longitudinal axis makes an angle of 90 ° with the two parallel fixing plates, is fixed at its two ends respectively to one of the two fixing plates. This locking stem 2 (support rod), which is, as a rule, open at both ends of the metal tube, passes through the loop of the lattice-like expansion element with a contour according to FIG. For example, the spreading element is secured by its shape to the locking stem 2 between two bushings that stand firmly outside the locking stem 2. Further parallel to each other and parallel to the locking stem 2, spaced apart and containing nuclear fuel, are provided. fuel stems 3. Each of these fuel stems 3 is driven through a loop (opening) of the expansion element with a contour according to FIG. 1 and is secured to this loop by a contact spring which presses said fuel stem 3 radially to two fixed contact thicknesses, respectively, on both sides of the loop in this opening. Fuel stems 3, each of which most often represents a zirconium alloy tube filled with nuclear fuel that is sealed gas-tight at both ends, must not be fastened to the two fixing plates, and in the longitudinal direction they have a gap between the two fixing plates. plates and therefore can be freely stretched, extended in the axial direction of the nuclear reactor fuel element. The lattice tilting element depicted in FIG. 1 is perpendicular to the locking stem 2 and the fuel stalks 3 the base plane / plane of the drawing / has ribbed outer collectors / necks / of sheet metal. These external manifolds form a contour in the base plane from the equally long sides 4 of a regular external hexagon manifold.

On the walls of the inner loops 9 of the lattice expansion element, the outer collectors are not separated, and the walls of these inner loops 9 are formed exclusively of ribbed inner sheet metal collectors.

These inner sheet collectors form base elements with a top view corresponding to those of Figures 2 to 7 and 11. As shown in Figures 2a through 2c, and through base element II according to Fig. 2, such a basic element has a first internal collector 6 and a second internal manifold 7 having a curved edge parallel to the retaining stem 2 and the fuel stems 3.

This curved edge is located in the middle between the two, in this case, parallel to the retaining stem 2 and the fuel stems 3, the side edges 7a and 7b of the second inner manifold 7. On this curved edge, the second inner manifold 7 forms an angle 120 on one side. ° and on the other side an angle of 240 °. On the side on which the inner manifold 7 forms an angle of 240 °, there is a flat first inner manifold 6 which encloses the second inner manifold 7 in a curved edge with two tongues spaced apart and formed on the first parallel to the stems 2 and 3, the lateral edge 6a of the first inner manifold 6. On the side of the second inner manifold 7, on which it forms an angle of 120 °, the two tabs located on the first side edge 6a of the first inner manifold 6 are welded, having this creates a weld 8 at wt second internal manifold 7.

On the side on which the second inner manifold 7 forms an angle of 120 °, at the upper and lower ends of the second inner manifold 7, in the middle between its first side edges 7 and parallel to the stems 2 and 3, the bent edges are pressed one fixed contact pins / for each fuel stem 3. Two corresponding contact pins 7c with fixed contact pins 7d are formed on the other side of the second inner collector 7 at which it forms an angle of 240 °, in the middle between the second parallel to the stems 2 and 3 lateral edge 7c and curved edge o. One of these two fixed contact thicknesses 7c is located at the upper and lower ends of the second inner manifold 7.

Finally, on one side of the first inner manifold 6, in the middle between the upper and lower ends of this first inner manifold 6, there is a punched spring tab 6c as a contact spring for the fuel stem 3 and is located in the angular space between the first inner manifold 6 and the portion of the second internal manifold 7 between the curved edge and the side edge 7a.

The base members III to VII and XI according to FIGS. 3 to 7 and 11 are respectively provided with two inner manifolds 6 and 7, of which the inner manifold 7 has a curved edge parallel to the stems 2 and 3. On this curved edge, the inner manifold 7 forms an angle of 120 ° on one side and an angle of 240 ° on the other. Moreover, these two internal manifolds 6 and 7 are equally spaced and fixed in the same manner as the internal manifolds 6 and 7 of the base member 11 of FIG. The base members III to VII and XI are distinguished from the base member II according to FIG. 2 by another arrangement of the spring tongues corresponding to the spring tongue 6c and the fixed contact thicknesses corresponding to the fixed contact thicknesses 7c and 7d on the two internal manifolds 6 and 7 .

If, in basic element II according to FIG. 2, element VI according to FIG. 6, element VII according to FIG. 7 and XI according to FIG. II one of the two internal manifolds 6 and 7 forms a wall of the loop between two outer loops 10, the distance parallel to the stems 2 and 3 of the side edge to which this inner manifold is welded on the inner wall of an external manifold to that formed by the inner manifold 7, the curved edge of the base element in question is, respectively, greater than the distance between the other two lateral edges of that base element, parallel to the stems 2 and 3, which are respectively welded into the corner of a regular hexagonal inner manifold, located to the two side edges of the internal manifolds of another, second base element.

Further, the inner collector 6 of the base elements VI and XI welded to the other internal collector 7 has neither contact thicknesses nor spring tabs, and is smooth and flat on both sides, while one welded to the internal collector 7 internal collector 6 at the base element VII according to FIG. 7 has a spring tongue between the upper and lower edge of the punch as a contact spring for a fuel stem 3. The inner manifold 7 of the curved edges VI and XI has between this curved edging and parallel to the stems 2 and 3 lateral edging not only two, formed and in the same direction contact thicker, and between these two contact thickenings are also stamped in the opposite direction spring tongue as a contact spring for a fuel rod 3.

The base members III of FIGS. 3 and IV of FIG. 4 have internal manifolds, one of which, as in FIG. 1a shows particularly well, there is bending (arching) in the direction of the stems 2 and 3 parallel with the forming parallel to the stems 2 and 3 respectively in the direction of the two contact thicknesses, one of which rises on the upper and lower ends of the base element, on bending. Thus, these two contact densities have a lower height than the contact densities of, for example, the base member II of FIG. 2, and thus counteract the cooling medium flowing through the lattice expansion member perpendicularly to the base plane and thus perpendicular to the plane of the drawing. For base member III according to FIG. 3 and for base member IV according to FIG. 4, the bend (vault) with the two contact thicknesses is between the bent edge and one of the two lateral edges 2 and 3 of the inner edge 7 of the inner manifold 7 on this internal manifold 7.

The base members VIII to X according to FIG. 8 to 10 are ordinary individual collectors having either a spring tongue corresponding to the spring tongue 6c of the base member II, or two fixed contact thicknesses, as well as the fixed contact thickness 7c and 7d of the base element II, or in addition to the spring tongue contact thickness. The distance between the two lateral edges 2 and 3 of the lateral edges of this single manifold is slightly greater than the distance of the respective two lateral edges of the inner manifold 6 of the base member II according to FIG. 2, since these individual collectors in this case must be welded to the inner wall of an external manifold.

For the fabrication of the lattice spacer according to FIG. 1, the base members II to XI according to FIGS. 2 to 11 are first made and then, as shown in FIG. 1, they are arranged inside the contour of the correct hexagonal outer manifold with sides 4 by forming internal loops 9 with a contour of FIG. the loop of regular hexagonal internal manifolds with the same length of side as the outer loops 10. The internal manifolds cut by the external manifolds are found on the respective internal sides at an angle of 90 °. After welding the lateral edges of the inner manifold of the base members in the corners of the hexagon of the inner manifold and of the inner wall of the outer manifold, a lattice-like stretching element is obtained, whereby a wall of the loop between the first and second loops of the first inner manifold is formed. one of its parallel to the stems 2 and 3, the lateral edges of the bent edges parallel to the stems 2 and 3, which stems are in one corner of a regular hexagon of the inner manifold between two others, anion by a second internal manifold walls of the loop, one of which walls belongs to the first loop while the other is the second snare. In the other corners of the hexagon of the inner manifold, three internal manifolds are welded to each other, one to one parallel to the stems 2 and 3 of the side edge.

On the finned outer collectors, fixed contact depressions 4a are formed to the inner wall of the external collector 4 for the fuel stems 3. These fixed contact depressions 4a protrude into the outer loops 10 of the lattice crucifix, which loops have at least one outer one formed by at least one outer one. manifold, loop wall. The internal manifolds that meet on the inside of the outer manifold form 10 walls belonging to the outer loops, which meet on the inside of the respective external manifold at an angle of 90 °.

The base element of FIG. 12, in which the same details have the same designations as in FIGS. 2 and 2a to 2c, there are not only bends 7e with parallel to the stems 2 and 3 forming about parallel to the stems 2 and 3 in the direction of the contact spacers 7c. and 7d, which rise on the bending in question, and also on such a bend it was possible to raise a spring tab 6c as a contact spring for the fuel stem 3. Thus, not only the fixed contact thicknesses 7c and 7d, but also the spring tabs 6c create slight resistance to the current perpendicular to the plane of the drawing a cooling medium.

Claims (4)

1. Nuclear reactor fuel element, adjacent to each other and in parallel with the distance between the stems, at least one of which is a fuel stem containing nuclear fuel and which is passed through loops of a lattice-expanding element, and with the following features : (a) the lattice-spreading member has ribbed outer sheets of sheet metal which form, in a basic plane perpendicular to these stalks, a contour of a regular hexagon of the outer manifold; b) the lattice-like stretching element has internal loops, the walls of which are formed by ribbed ribs arranged internally within this contour; c / the contour angles of the loops of all the inner loops of the lattice cruciform element form in the perpendicular to the stem base plane the angles of regular hexagons of the inner manifold having the same length of sides; d) the lattice-expanding member has outer loops having at least one wall formed by an external manifold and two other sides cut into the inner side of an external manifold formed by an internal manifold, characterized in that the wall of the loop between the first and second loops the first inner manifold / 6 / with its first, parallel to the stems side edging / 6a / is fixed to parallel to the stems / 2, 3 / bent edges, which is located in the corner of one regular hexagon of the inner manifold between two others formed by a second inner collector / 7 / walls of the loop, of which one wall of the loop belongs to the first loop and the other to the second loop; that the second, parallel to the stems / 2, 3 / side edge of the first inner manifold / 6 /, and both parallel to the stems / 2, 3 / side edges / 7a and 7c / of the second inner manifold / 7 / form a group of three lateral edges; that two of the three side edges of this group are attached respectively to the parallel stems / 2, 3 / located in the corner of the right hexagon of the inner manifold side edges of another, second inner manifold, and the third side edging of this group is fixed or the parallel to the stems / 2, 3 / located in the corner of one regular hexagon on the inner manifold side edges of another, second inner manifold, or on the inside of an external manifold. Nuclear reactor fuel element according to claim 1, characterized in that the two cut-in walls of one outer collector, respectively formed by one inner collector wall of the loop of the outer loops (10), meet at an angle of 90 ° on the inside of the outer manifold. Nuclear reactor fuel element according to claim 1, characterized in that one loop wall has a bend (vault) (7e) parallel to the stems (2, 3) forming about parallel to the stems (2,3) direction of bending / arch / fixed contact thickness / 7c, 7d / for one stem / 3 /. Nuclear reactor fuel element according to claim 1, characterized in that a loop wall is bent / was / with parallel to the stems / 2, 3 / forming in a direction parallel to the stems / 2, 3 / and that on the bending / was / raised contact spring / 6s / for fuel stem / 3 /.