EP1525591B1 - Protective wall with anti-piercing armour for a container and a container comprising at least one such wall - Google Patents

Abstract

The invention relates to a shielding wall (12) with a puncture-resistant shield for a container (1), said wall (12) comprising support means (20) as well as the following respective stacked elements (24, 26, 28, 30, 32): an outer plate (24); a first dampening layer (26); an intermediate plate (28); a second dampening layer (30); an inner plate (32). According to the invention, the intermediate plate (28) is positioned non-rigidly with respect to the support means (20). The invention likewise relates to a container (1) comprising at least one shielding wall (12) such as the one described above. Application to the field of transporting/storing nuclear materials.

Description

TECHNICAL AREA

The present invention relates to the field of containers for transporting / storing sensitive materials, such as radioactive materials. More particularly, the invention relates to anti-punched shielding protective walls used to make the side face (s), the bottom, and the removable cap (s) of such containers.

STATE OF THE PRIOR ART

In conventional manner, the containers for nuclear materials are of substantially cylindrical or parallelepipedic shape.

These containers are usually composed of one or more side faces, a fixed base, a cover, and one or more removable protective covers, the latter being respectively located at one and the other ends of the container.

The one or more side faces, the bottom and the lid of the container, define an enclosure for containment located inside the container, in which the nuclear material takes place, safely.

The one or more side faces, the bottom, and the removable protective cover or covers of the container, generally comprise a protective wall made by a stack of layers and plates each having at least one distinct function, so that the container has certain characteristics enabling it to meet regulatory safety requirements for the transport / storage of nuclear material.

Among the tests to undergo to meet these regulatory requirements, we note different tests such as those called "free fall" including the fall on punch and the fall of 9 meters, preceding the so-called "fire".

To meet the safety requirements, the layers and plates used to make the protective walls have been the subject of numerous studies, in particular to meet the specific needs of the tests concerning the fall on punch and the fall of 9 meters.

Indeed, this punching test consists of raising the container to one meter above a cylindrical punch of fifteen centimeters in diameter, then to drop by gravity on the punch. To pass this test, it is necessary that the punch does not perforate the elements of the container delimiting the containment.

It should also be noted that the protective wall is designed to fulfill other functions than those related to punching resistance. By way of example, the protective wall, in order for the container to satisfy regulatory safety constraints, must have thermal characteristics of the fire-resistant type, and / or energy absorption characteristics of the 9-meter falls. .

Thus, at the end of the free fall tests, the protective walls must still be able to preserve the containment enclosure as well as all the components such as seals, of an excessively high temperature encountered during the test. fire, also called "fire test".

In the prior art, several walls of this type have already been proposed.

Anti-punched shielding walls are known comprising three elements superimposed on each other. To achieve such walls, the elements are positioned so that an outer plate and an inner steel plate sandwich a fireproof layer, the latter being made of a material with low crushing stress allowing absorb the fall energy.

However, when performing the punching test, it was observed that the outer steel plate was perforated by the punch, which no longer allowed to preserve the layer intermediate in a confined manner. Thus, the fire resistance of the protective wall becoming too critical, this solution was deemed unsatisfactory in light of current regulatory requirements.

To cope with this problem, another type of protection wall with anti-punching has been proposed, incorporating five elements superimposed on each other. This type of wall is further described in document FR-A-2 790 589.

Among these elements, there is first a rigid outer plate steel, directly in contact with a damping layer capable of absorbing the aggressions caused by a punch. An intermediate plate, made of steel or composite material, is placed under the damping layer, and is in lower contact with a deformable layer in compression, low crush stress and may have fireproof properties. Finally, the fifth and last element of the protective wall consists of a rigid steel inner plate with high mechanical strength.

In this type of wall, the outer, intermediate and inner plates are each fixed rigidly to support means.

However, when carrying out tests using a punch, it was noted that the intermediate layer took up insufficient deformation energy, given the mass / performance compromise to be satisfied.

In the two types of wall of the prior art which have just been described, none are likely to provide a containment plate of the fireproof layer resistant to the punch, and thus to allow the container to meet the regulatory criteria, especially after the fire test. To remedy this problem, it has therefore been proposed, for the two types of wall presented, to oversize the integrated plates to the protective walls.

However, it has been found that the necessary dimensions to be applied to the plates to pass the punching test were not always compatible with the requirement of a maximum mass to be respected for the container, this mass limitation being imposed by the operating constraints.

Thus, the designers of such containers are therefore constantly confronted with a compromise between a limited total mass of the various plates constituting the wall, and a sufficient mechanical strength of this wall, in order to pass all the tests performed during safety regulatory tests. relating to the transport / storage of nuclear material.

Other protective walls have been suggested in FR 2 804 941 and US 4 190 160.

STATEMENT OF THE INVENTION

The object of the invention is first of all to provide a protection wall with anti-punching protection for a container, according to claim 1. This protective wall at least partially overcomes the disadvantages mentioned above relating to the embodiments of the art. prior.

More specifically, the object of the invention is to propose a protective wall with anti-punching shielding for container, this wall allowing the container to meet all the regulatory safety tests for the transport / storage of nuclear material, these tests being such as the punching test, the drop test of 9 meters, or the fire test.

In addition, the object of the invention is to provide a wall such that a container provided with it can satisfy a limitation of mass, imposed by the operating constraints.

The invention also aims to present a container comprising at least one protective wall such as that meeting the purposes described above.

Advantageously, the intermediate plate, in contact with the second damping layer, is not rigidly assembled with the support means. This specific characteristic of the invention makes it possible to obtain a protection wall with an anti-punching shield of restricted mass and resistant to the punching test. Indeed, after having crossed the outer plate and crushed the first damping layer, the punch urges the intermediate plate. During this stress, the intermediate plate being entirely movable or weakly maintained relative to the support means, the force transmitted to the intermediate plate is distributed almost uniformly over a large part of the surface of this plate, thus causing a displacement of this plate and a crushing of the second damping layer on a very large surface thereof.

Unlike the walls of the prior art in which the intermediate plate is embedded, the intermediate plate of the wall according to the invention is arranged to be made movable relative to the support means, under the effect of mechanical stresses generated by the punch effort. The embedding by welding of the intermediate plate on the support means, practiced in the embodiments of the prior art, leads conversely to a biasing of the intermediate plate in very localized regions, which can cause the tearing of the intermediate plate, as well as the rupture of the confinement of the second damping layer. This disadvantage of tearing is even more important when the second intermediate layer has a thermal protection function. Indeed, in such a case, the second layer The damping factor no longer satisfactorily provides fire protection for the containment.

In addition, the invention has all the features required to allow the container to meet the regulatory requirements, without having to over-dimension the plates constituting the protective wall.

Finally, the anti-punched shielding protection wall according to the invention provides a simple solution, and independent of the existing compromise of the prior art.

The outer and inner plates of the wall are rigidly connected to the support means.

The intermediate plate rests on a plurality of wedges spaced from each other and secured to the support means. In addition, it is also possible that the shims are integral with side beams belonging to the support means, and that the intermediate plate is connected to each shim with at least one frangible rivet.

The invention also relates to a container comprising at least one side face, a bottom, and at least one removable cover. According to the invention, at least one element selected from the group consisting of each side face, the bottom, and each removable cap of the container, comprises a protective wall such as that described above.

Other features and advantages of the invention will appear in the detailed description, not limiting, below.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 représente une vue partielle en coupe d'un conteneur comprenant des faces latérales comportant une paroi de protection selon un premier mode de réalisation préféré de l'invention, un fond et un capot amovible comportant une paroi de protection selon un troisième mode de réalisation préféré de l'invention ;
• la figure 2 représente une vue en coupe prise selon la ligne A-A de la figure 1 ;
• la figure 3 représente une vue partielle, à plus grande échelle, de la figure 3 ;
• la figure 4 représente schématiquement, en coupe, une paroi selon le premier mode de réalisation préféré de l'invention, après le test du poinçonnement ;
• la figure 5 représente une vue en coupe d'un capot amovible de conteneur comprenant une paroi de protection selon un second mode de réalisation préféré de l'invention ; et
• la figure 6 représente schématiquement, en coupe, une paroi selon le troisième mode de réalisation préféré de l'invention, après le test du poinçonnement.

This description will be made with reference to the appended drawings among which:

• FIG. 1 represents a partial sectional view of a container comprising lateral faces comprising a protective wall according to a first preferred embodiment of the invention, a bottom and a removable cover comprising a protective wall according to a third embodiment of FIG. preferred embodiment of the invention;
• Figure 2 shows a sectional view taken along line AA of Figure 1;
• Figure 3 shows a partial view, on a larger scale, of Figure 3;
• Figure 4 shows schematically, in section, a wall according to the first preferred embodiment of the invention, after the punching test;
• Figure 5 shows a sectional view of a removable container cover comprising a protective wall according to a second preferred embodiment of the invention; and
• Figure 6 shows schematically, in section, a wall according to the third preferred embodiment of the invention, after the punching test.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figures 1 and 2, there is shown a container 1 for carrying / storing sensitive materials, and preferably nuclear materials.

Such a container 1, preferably of substantially parallelepipedal shape, comprises four lateral faces 2, a bottom 4 fixed rigidly on the side faces 2 at a first end 1a of the container 1, a cover 16 and a removable cover 6 mounted on the lateral faces 2 at a second end 1b of the container 1.

The assembly of elements 2,4,16 constituting the container 1, leads to obtaining a containment chamber 8 in which can be based drums (not shown) of nuclear material, their loading inside the containment chamber 8 that can be carried out using guide rails 10.

In the container 1 shown in Figures 1 and 2, the side faces 2, the bottom 4 and the removable cover 6 are equipped with a protective wall 12 with anti-punching shield, of substantially parallelepiped shape, designed in particular to resist the punching test performed during regulatory safety tests for the transport / storage of nuclear material.

The protective walls 12 each rest on a rigid lattice structure 14, these structures 14 also having the function of delimiting the confinement enclosure 8.

The protective walls 12 are held on the container 1 by means of support means further comprising lateral beams 18. Each lateral beam 18, extending parallel to a longitudinal axis of the container 1, can be used for holding two protective walls 12 belonging to two side faces 2, placed at 90 ° relative to each other. Preferably, these lateral beams 18 consist of one or more sheets 20 defining a space 22 filled with wood such as balsa.

As can be seen in Figure 2, each protective wall 12 with anti-punching shield comprises five elements superimposed on each other.

Among these elements, there is first an outer plate 24, preferably metal and a thickness of about 6 mm. This plate 24 is the first element with which a punch comes into contact during the performance of a punching test.

Directly placed below this outer plate 24, there is a first damping layer 26. This first layer damping element 26 may consist of a material with low crushing stress, and is intended to partially absorb the fall energy emanating from the punching test. For example, the first damping layer 26, about 60 mm thick, is made of wood such as plywood or balsa, porous concrete, or phenolic foam. In the case of a use of balsa, the principal direction of the fibers is preferably orthogonal to the longitudinal axis of the container 1.

The protective wall 12 also comprises an intermediate plate 28, indifferently made of stainless steel with a high yield strength or a composite material. This intermediate plate 28 has a thickness of between about 6 and 10 mm, the thickness varying as a function of the total mass of the container 1.

The intermediate plate 28 constitutes the outer portion of a confinement of a second damping layer 30, in particular having an anti-fire function. This second damping layer 30, having a thickness of approximately 120 mm, is preferably made of phenolic foam. Moreover, this second damping layer 30 may also be made of wood such as plywood or balsa, whose main direction of the fibers is the same as that of the balsa fibers constituting the first damping layer 26. Note that like the first damping layer 26, the second damping layer 30 may also consist of a material such as porous concrete, and will preferably be less hard than the first damping layer 26.

Finally, the last element of the protective wall 12, also used to make the inner portion of the confinement of the second damping layer 30, is an inner plate 32 of stainless steel, with a thickness of between approximately 6 and 8 mm.

It should be noted that in order to reduce the weight of the container 1, the inner plate 32 may be common to the protective wall 12 and to the lattice structure 14.

By taking as an example a protective wall 12 of a lateral face 2 of the container 1, it should be noted that the outer plate 24 is fixed rigidly, preferably by welding, to the plates 20 of the side beams 18 holding the wall of the container. In the same way, the inner plate 32 is fixed rigidly to the plates 20 of these same lateral beams 18. In this way, the outer 24 and inner 32 plates are connected rigidly to one another via the beams. side 18 belonging to the support means of the protective walls 12 on the container 1.

On the other hand, the intermediate plate 28 is positioned non-rigidly with respect to the plates 20 of the lateral beams 18, and consequently is positioned non-rigidly with respect to the support means.

According to a first preferred embodiment of the invention and with reference to FIG. a protective wall 12 with an anti-punching shield is seen comprising an intermediate plate 28 resting on a plurality of shims 34, spaced from each other, and integral with the sheet 20 of the lateral beam 18. By way of examples, the shims 34 can be assembled by welding on the sheet 20, or simply be obtained by deformation of this sheet 20.

Preferably, the intermediate plate 28 is connected to each shim 34 with at least one frangible rivet 36, and preferably only one.

With reference to FIG. 4, during the performance of a punching test conforming to that carried out in the context of regulatory safety tests for the transport / storage of nuclear materials, the protective wall 12 hits a punch 38.

The punch 38 first passes through the outer plate 24, then comes into contact with the first damping layer 26, the latter absorbing in part the energy of falling on punch.

It is then up to the intermediate plate 28 to be mechanically stressed by the punch 38. As mentioned above, the intermediate plate 28 is positioned non-rigidly with respect to the sheet 20 of the lateral beam 18. shims 34 and the rivets 36 provided for the positioning of the intermediate plate 28 then serve only as a mechanical fuse, and are arranged so that the intermediate plate 28 is released from the sheet 20 of the lateral beam 18, after an impact of the punch 38 on the protective wall 12.

Thus, the rupture of the rivets 36 has the effect of making the edges of this plate 28 completely free or simply resting on the wedges 34. The force of the punch 38 on the intermediate plate 28 then causes a slight curvature of the latter, then a displacement of the intermediate plate 28 in a direction parallel to a longitudinal axis of the punch 38, towards the confinement enclosure 8.

In addition, the displacement of the intermediate layer 28 causes the second damping layer 30 to collapse over a large surface thereof, the intermediate plate 28 making it possible to distribute the forces over the whole of this large surface, which allows the compression energy of this second deformable damping layer 30 to be maximized.

The displacement of the intermediate plate 28, authorized by the crushing of the second damping layer 30 and the non-rigid positioning of the intermediate plate 28 on the plates 20, also makes it possible to avoid tearing of this plate 28. D On the other hand, it has been observed that the energy absorbed by bending the intermediate plate 28 was greater when it was free or simply supported on the support means than when it was embedded in these means.

It is then in the presence of a protective wall 12 resistant to punching test, and able to preserve the confinement of the second damping layer 30, without having to oversize the plates 24,28,30 constituting the protective wall 12. Note further that by preserving the confinement of the second layer of damping 30, the latter also retains its anti-fire function when it is required.

According to a second preferred embodiment of the invention, with reference to FIG. 5, there is seen a container 1 of substantially cylindrical shape, for which only the removable cover 6 is provided with a protective wall 12 with an anti-punching shield. , also of substantially cylindrical shape. Indeed, the side wall 42 of the container 1 is constituted in this case of a thick steel structure. The intermediate plate 28 is connected to a sheet 20 conforming laterally to the wall 12, and corresponding to the support means of this wall. The connection between the intermediate plate 28 and the sheet 20 is established by means of at least one flexible tongue 40, these tabs 40 being welded on the one hand to the sheets 20, and on the other hand to the intermediate plate 28.

When performing a punching test, the intermediate plate 28 reacts in a similar manner to the intermediate plate 28 of the first preferred embodiment of the invention, whose behavior following an impact of the punch 38 is shown in FIG. 4.

Indeed, the biasing of the protective wall 12 by the punch 38 causes the curvature and / or rupture of the flexible tabs 40 integral of the intermediate plate 28. This intermediate plate 28 then curves slightly, then moves by crushing the fireproof layer 30 over a large surface thereof.

According to a third preferred embodiment of the invention, with reference to FIG. 1 and more particularly to the bottom 4 of the container 1, there is seen a protective wall 12 whose outer and inner plates 24 are integral with plates 46 forming a frame. around the protective wall 12, and belonging to the support means of this wall 12. It is specified that the removable cover 6 of the container 1 also comprises a wall according to the third preferred embodiment of the invention and similar to the wall 12 of the bottom 4, and will not be further described.

In this third preferred embodiment, the intermediate layer 28 is supported firstly against the first damping layer 26, and secondly against the second damping layer 30. In addition, no specific connection n ' is provided between the plates 46 and the intermediate plate 28, so that this intermediate plate 28 is totally free with respect to the plates 46.

Referring to Figure 6, when performing a punching test, the intermediate plate 28, completely free, moves to the confinement chamber 8 retaining its substantially flat shape. Then, as in the preferred embodiments described above, there is a crushing the second damping layer 30, and preserving the confinement of this layer 30.

Note that each of the three preferred embodiments of the invention can be adopted for the design of any one of the side faces 2, the bottom 4 or any of the removable covers 6, a substantially shaped container. parallelepipedic, cylindrical or other.

Claims (9)

1. Shielding wall (12) with a puncture-resistant shield for a container (1), said wall (12) comprising support means (20, 46) as well as the following respective stacked elements (24, 26, 28, 30, 32):

   - an outer plate (24);

   - a first dampening layer (26);

   - an intermediate plate (28);

   - a second dampening layer (30);

   - an inner plate (32);

   the intermediate plate (28) being positioned in such a way as to be mobile relative to the support means (20, 46) under the effect of mechanical stresses produced by the force of a punch, and the outer (24) and inner (32) plates are connected rigidly by support means (20, 46), the intermediate plate (28) resting on a plurality of mutually spaced shims (34) integral with the support means (20), characterized in that said intermediate plate (28) is connected to each shim (34) with the aid of at least one frangible rivet (36).
2. Shielding wall (12) according to claim 1, characterized in that the outer plate (24) is a metal plate.
3. Shielding wall (12) according to either of the preceding claims, characterized in that the first dampening layer (26) is made of a material taken from the group consisting of wood, porous concrete, and phenolic foam.
4. Shielding wall (12) according to any of the preceding claims, characterized in that the intermediate plate (28) is a stainless steel plate.
5. Shielding plate (12) according to any one of claims 1 to 3, characterized in that the intermediate plate (28) is a structure made of a composite material.
6. Shielding plate (12) according to any of the preceding claims, characterized in that the second dampening layer (30) is made from a material taken from the group consisting of wood, porous concrete, and phenolic foam.
7. Shielding wall (12) according to any of the preceding claims, characterized in that the inner plate (32) is a rigid metal plate.
8. Container (1) comprising at least one side wall (2), a bottom (4) and at least one removable cover (6), characterized in that at least one element taken from the group consisting of each side wall (2), the bottom (4) and each removable cover (6) of the container (1), comprises a shielding wall (12) as claimed in any of the preceding claims.
9. Container (1) according to claim 8, characterized in that it is capable of transporting/storing nuclear materials.

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