JPS6331079B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a storage cradle for spent fuel elements from a nuclear power plant, which consists of a number of tubes, the tubes having a rectangular or square cross section and a storage frame for spent fuel elements from a nuclear power plant. of the type having one or more chambers for accommodating.

A storage frame is known from DE 27 30 850 A1. In this case, each tube has a threaded pin with a cutout on the underside, which pin is supported on a ball segment fixed to the bottom of the storage pool. In order to absorb the tilting moments acting on the individual tubes in the case of horizontal shocks, such as occur, for example, during earthquakes, the legs of adjacent tubes are connected to a unit or storage cradle. In this way, a large rigid plate assembled from individual leg plates is formed. Acceleration forces caused by horizontal impacts therefore cannot lift the storage pedestal by the ball segments. This type of storage cradle construction requires that the individual tubes be joined either before or after insertion into the storage pool. In the case of first joining, a storage cradle is produced which can no longer be transported, so that relatively small units are produced which are submerged in a storage pool and then joined there. However, this procedure is extremely difficult when the storage pool is high, especially if the screws are insufficiently tightened at this location, bending will occur on horizontal impacts.

The object of the invention is to provide a storage frame of the type mentioned at the outset, in which each individual tube is safe against horizontal impacts, and in which the defined locks in the storage pool are only limited by the weight of the tubes with settling elements. Therefore, the lock is automatically unlocked when the pipe is removed.

The problem is that each tube has at least three horizontal pins, the central axes of which intersect in a point, and a leg plate assigned to the pins is fixed at the bottom of the storage pool, and the leg plates are fixed at the bottom of the storage pool. The side wall of the pipe has a diagonal notch, the notch widens upward into a wedge shape, and the central axis passing through the notch at the submerged position of the pipe coincides with the central axis passing through the bolt. This can be solved by configuring it so that

The invention will now be explained in detail with reference to the illustrated embodiments.

The storage pedestal 1 consists of a number of tubes 2 with a rectangular or square cross-section, in which case the tubes 2 are used for accommodating individual spent fuel elements or
It may be arranged to accommodate a corresponding number of fuel elements by dividing it into a number of chambers 3 as shown in the figures. In this case, the cross section of the chamber 3 is adapted to the external dimensions of the fuel element.

The storage pedestal 1 can be used for intermediate storage of fuel elements which still require a certain decay stage after removal from the reactor and before loading into a reprocessing facility. In addition, this cradle is also suitable for the reprocessing plant itself, in order to store the supplied fuel elements until they are reprocessed.

The tubes 2 are covered on the lower side by a plate 4 which has holes 5 leading into the chambers 3 so that the cooling water can reach the fuel elements in the respective chambers 3.
At least three pins 6, four in the case of FIG. have the same spacing with respect to point M. In order to obtain as large a base as possible for absorbing tilting moments in the case of horizontal impacts, in this embodiment the pins 6 are arranged diagonally in the area of the corners of the tube 2.

On the bottom of the storage pool, as shown in FIG. 1, a square leg plate 7 is fixed with upwardly projecting side walls 8, corresponding to the number of tubes to be accommodated, in this case The side walls 8 form a rectangle or a square in plan view and the lateral half center lines advantageously form an axial extension of the central axis a. The side wall 8 of the husband has an inclined and further upwardly opening notch 9, which is widened in the shape of a wedge. Moreover, the wedge surfaces 10 and 11 act as a guide mechanism for the pin 6. In this case, the diameter of the recess 9 corresponds to the cross section of the pin 6 to be accommodated, in order to achieve as free a guidance and a play-free bearing in the recess 9 as possible.

The tube 2 is lowered into the storage pool by means of a hoist in a known manner, in which case the respective pin 6 is driven by the weight of the tube 2 and the corresponding recess in the side wall 8 with simultaneous rotational movement by means of the wedge surface 10 or 11. 9 and is held against lifting in the vertical direction by a projection 12 formed by a wedge surface 10 in the recess. In this case, the side walls 8 can be flat or curved inwardly, corresponding to the installation circle around the point M. Vertical forces from the weight of the tube 2 as well as acceleration forces from horizontal impacts on the leg plate are transmitted to the leg plate 7 via the pins 6. As can be seen in FIG. 1, four leg plates 7 are assigned to each tube 2, each leg plate being designed for locking four tubes 2.

FIG. 3 shows a circular foot plate for accommodating the tube 2, which foot plate is formed as a counter for transmitting the vertical force from the tube 2 to the bottom of the storage pool. . The circular side wall 8 coincides with the installation circle centered on the point M and has a cutout 9 of the type described above. In this case, pin 6 exclusively transmits acceleration forces.

[Brief explanation of the drawing]

The drawings show embodiments of the invention, and FIG.
The horizontal sectional view of the embodiment, FIG.
A cross-sectional view along the line and FIG. 3 are horizontal cross-sectional views of the second embodiment. 2...Pipe, 3...Chamber, 4...Plate, 5...Opening,
6... Pin, 7... Leg plate, 8... Side wall, 9... Notch, 10, 11... Wedge surface, 12... Protrusion,
a... Central axis, M... point.

Claims (1)

[Scope of Claims] 1. A storage frame for spent fuel elements from a nuclear power plant, consisting of a number of tubes, the tubes having a rectangular or square cross section and for accommodating fuel elements. of the type with one or more chambers, each tube 2 has at least three horizontal pins 6 whose central axes a intersect at a point M and which are attached to the bottom of the storage pool. A leg plate 7 assigned to 6 is fixed, the side wall 8 of said leg plate having an oblique notch 9 which widens upward in the form of a wedge, and which prevents the settling of said tube 2. A storage frame for spent fuel elements from a nuclear power plant, characterized in that the central axis passing through the notch coincides with the central axis a passing through the bolt 6 at a position. 2. Storage rack according to claim 1, wherein the cutout 9 widens upward in the form of a wedge and the wedge surfaces 10 and 11 form a guide mechanism for the pin 6. 3. The storage frame according to claim 1 or 2, wherein the diameter of the notch 9 is equal to the diameter of the pin 6. 4. Storage frame according to claim 1, in which the tube 2 is covered on the underside by a plate 4, which plate has a pin 6 and has an opening 5 leading to a chamber 3 in the tube 2. . 5. The storage frame according to any one of claims 1 to 4, wherein the end faces of the pins 6 of the tubes 2 have the same distance from the point M. 6. Storage frame according to claim 5, in which the pins 6 are arranged diagonally in the area of the corners of the tubes 2. 7 The upper wall of the recess 9 and the wedge surface 10 form a protrusion 12 which covers the pin 6 in the state of storage in the recess at least up to the vertical central plane. The storage frame according to item 2. 8. The side walls 8 form a rectangle or square on the leg plate 7 in plan view and are fixed on the bottom of the storage frame in such a way that the lateral half-center lines form an axial extension of the central axis a; A storage frame according to claim 1. 9. Storage rack according to claim 1, in which each tube 2 is assigned four leg plates 7, and the tubes are supported and secured on the leg plates only via pins 6. 10 A ring-shaped leg plate 7 is assigned to each tube 2, and a side wall 8 of the leg plate, which is circular and coincides with the installation circle centered on the point M, has cutouts 9 corresponding to the number of pins 6 attached thereto. A storage frame according to claim 1, comprising: a storage frame according to claim 1; 11. Storage frame according to claim 10, in which the tubes 2 are supported on the leg plates 7 only by the plates 4.