EP1576621A2

EP1576621A2 - Container for the storage/transport of unirradiated radioactive materials such as nuclear fuel assemblies

Info

Publication number: EP1576621A2
Application number: EP03786049A
Authority: EP
Inventors: Benoit Alaurent; Christian Reynaud; Jean-Pierre Bersegol
Original assignee: Cogema Logistics SA; TN International SA
Current assignee: TN International SA
Priority date: 2002-11-06
Filing date: 2003-11-04
Publication date: 2005-09-21
Anticipated expiration: 2023-11-04
Also published as: FR2846778B1; EP1576621B1; JP4727229B2; EP1576621A3; JP2006505780A; FR2846778A1; WO2004044925A3; AU2003295054A1; DE60318625D1; WO2004044925A2; DE60318625T2

Abstract

The invention relates to a container (1) which is intended for the storage/transport of unirradiated radioactive materials. The inventive container consists of a main structure (4) and a casing (2) comprising an inner lateral wall defining a cavity in which the main structure (4) can be housed. The aforementioned main structure defines a plurality of housings (26) which can receive at least one fuel assembly. According to the invention, the container also comprises separation means (3) between the main structure and the casing, which prevent any direct contact between the inner lateral wall (24) and the main structure (4), such as to enable localised deformation of the inner lateral wall of the casing during punch testing.

Description

CONTAINER FOR STORAGE / TRANSPORT OF MATERIALS

NON-IRRADIATED RADIOACTIVES SUCH AS ASSEMBLIES

NUCLEAR FUEL

DESCRIPTION

TECHNICAL FIELD The present invention relates to a container for the storage / transport of non-irradiated radioactive materials such as fresh nuclear fuel assemblies, intended to constitute the energy source of nuclear power plants.

STATE OF THE PRIOR ART

Conventionally, the containers for non-irradiated radioactive materials are of substantially cylindrical or parallelepiped shape.

These containers usually include an outer packaging, consisting of one or more side faces, a fixed bottom, a cover, and one or more removable protective covers.

Each of the elements constituting the packaging, and more particularly the side face (s) of the latter, is composed of a single layer or of a stack of layers made of various materials.

In this regard, when the side (s) of the packaging are ^• in the form of a stack of layers, this _. last one has a layer from the inner end, generally taking the form of a metal plate. Thus, the metal plate (s) form an internal lateral wall of the packaging, the latter defining a cavity inside which the radioactive materials are able to be housed. Typically, the cavity defined by the lateral internal wall is substantially cylindrical with a circular section. It is also specified that the cavity is completely closed by means of the fixed bottom and the cover of the packaging, situated respectively at the ends of the lateral internal wall.

Non-irradiated radioactive materials, such as fresh nuclear fuel assemblies composed for example of a mixture of uranium and plutonium oxides, extend longitudinally and have a square section.

In order to precisely position these assemblies in the container cavity, the latter also has a main structure of usually substantially cylindrical shape of circular section, this structure defining a plurality of housings each capable of receiving at least one fuel assembly. The main structure, also called “basket” or “rack” ^for storage, is then designed so that it can be introduced into the cavity of the packaging, so as to be held there in relation to the packaging, once inserted . ^• The main structure generally has .a diameter substantially identical to inside diameter of the lateral internal wall of the package, to the clearance.

In the most widespread solutions, the main structure can then be in the form of discs spaced or stacked on each other, along a longitudinal main axis of the container. The discs generally each comprise a plurality of orifices. In this regard, when the discs are spaced, each orifice can be traversed by a tube designed to receive one or more assemblies of nuclear fuel.

In addition, the main structure is positioned in the cavity of the packaging so that the clearance between the main structure and the lateral internal wall is low or zero, in order to ensure satisfactory heat exchanges between these two components of the container.

When designing such containers, it is necessary to take into account the technical requirements dictated by regulatory safety requirements for the storage / transport of nuclear materials.

Among the tests to undergo to meet these regulatory requirements, there are various tests such as those called "free fall", including in particular the fall on a punch and the fall from 9 meters, preceding that called "fire".

To meet safety / criticality requirements, the stacks of layers making up the container packaging have been the subject of numerous studies, in particular to meet the needs specific to the tests concerning the fall on a punch and the fall from 9 meters, these tests must be passed in an order such that it provides the maximum damage. As an indication, the punching test consists in raising the container one meter above a cylindrical punch fifteen centimeters in diameter, then dropping it by gravity on the punch. To pass this test as well as that of falling from nine meters, it is necessary to demonstrate that the main structure of the container, that is to say the basket in which the nuclear fuel assemblies rest, does not undergo any deformation. In the containers known from the prior art, these various requirements have hitherto always been translated by the need to design a package whose inner end layer (s) in contact with the main structure, namely the inner wall and more particularly the lateral internal wall defining the cavity, did not deform following the completion of the various tests, and more specifically following the punching test. Furthermore, it should be noted that when designing such containers, economic constraints are also taken into account. In fact, this type of constraint aims to increase the payload of a container whose maximum mass, ^' when it is loaded with its fuel assemblies, is ^' limited by operational constraints. The goal is consequently to propose technical solutions making it possible to lighten the packaging as much as possible, while satisfying regulatory safety constraints.

As such, it is specified that when it comes to transporting irradiated fuel assemblies, the punching test does not reflect any design difficulty, due to the significant thickness of the lateral face of the packaging, necessary to meet the radiation protection criteria. A container designed for the transport of irradiated fuel assemblies is described in document US-A-4,800,283. It indeed has a steel side face 30 cm thick, consequently generating an excessively high mass, and thus making this type of container totally incompatible with the economic constraints mentioned above, encountered during the design of containers intended for the storage / transport of non-irradiated radioactive materials. Several solutions were then proposed in an attempt to fulfill all of the technical and economic requirements required.

It was first proposed to design multi-layer packaging, each of these layers being intended to contribute to obtaining a packaging ensuring the preservation of the main structure.

Among these multi-layer packaging, there are first known stacks with anti-punch armor comprising three elements superimposed on each other. To achieve such stacks, the elements are positioned so that an external plate and an internal steel plate sandwich a fire-resistant layer, the latter being made of a material with low crushing stress making it possible to absorb the falling energy .

However, when carrying out the punching test, it was observed that the external and internal steel plates were respectively perforated and deformed by the punch, which directly caused a deformation of the main structure in contact with the internal plate. . Furthermore, the perforation of the external plate does not allow _^ more, .de. _preserve,. .coμche _. .intermediate _. re _^ _^ confined to fashion and the fire resistance of the stack then becoming too critical, this solution was deemed unsatisfactory with regard to regulatory requirements.

To deal with this problem, another type of stack with anti-punching shielding has been proposed, integrating 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 of all a rigid external steel plate, directly in contact with a damping layer capable of absorbing the aggressions caused by a punch. An intermediate plate, of steel or composite material, is placed under the damping layer, and is in lower contact with one. deformable layer in compression,. with low crushing stress and which may have fire-fighting properties. Finally, - the fifth and last element "of the protective stack consists of a rigid internal steel plate with high mechanical resistance.

In the same manner as previously, it has been noted that the proposed stacking of five layers does not allow the container to meet the regulatory criteria, in particular because of the deformation of the rigid internal plate, likely to cause deformation of the main structure 0 of the container, in direct contact with the lateral internal wall of this rigid internal plate.

To remedy this problem, it has therefore been proposed, for the two types of stacking presented, to oversize the integrated plates. 5 However, it turned out that the dimensions necessary to apply to the plates to pass the punching test were not always compatible with the requirement of a maximum mass to be observed for the container, this limitation 0 of mass being imposed by operational constraints.

Thus, the designers of such containers are constantly confronted with a compromise between a limited total mass of the different plates

25 constituting the elements of the packaging, and a sufficient mechanical resistance of these elements so that the lateral internal wall of this packaging does not deform, always with the aim of passing all the tests carried out during the regulatory tests of

3 _. 0 safety related to the transport / storage of nuclear materials. STATEMENT OF THE INVENTION

The object of the invention is therefore to propose a container for the storage / transport of non-irradiated radioactive materials such as nuclear fuel assemblies, the container comprising a main structure and a package comprising a lateral internal wall defining a cavity inside. which is able to accommodate the main structure, the container at least partially overcoming the drawbacks mentioned above relating to the embodiments of the prior art.

More specifically, the object of the invention is to present a container whose design makes it possible to meet regulatory safety requirements relating to the transport / storage of nuclear materials, while having a total mass which is greatly weakened compared to the containers of the prior art, in order to comply with ever greater operating constraints. To do this, the subject of the invention is a container for the storage / transport of non-irradiated radioactive materials such as nuclear fuel assemblies, the container comprising a main structure and a package comprising a lateral internal wall defining a cavity at the inside of which the main structure is capable of being housed, the latter defining a plurality of housings each capable of receiving at least one fuel assembly. According to the invention, the container further comprises spacer means of the main structure with respect to ^'packaging, spacing means being able to avoid any direct contact between the lateral internal wall and the main structure, so as to allow a punctual deformation of this lateral internal wall of the packaging during a punching test.

Advantageously, the specific design of the container according to the invention results from an approach completely different from the conventional approach previously practiced for designing such containers. Indeed, the main condition for satisfying the regulatory safety requirements relating to the transport / storage of nuclear materials being to demonstrate that the main structure containing the fuel assemblies is not damaged following the various drop tests of the container, this technical constraint has always been interpreted as a need to preserve the lateral internal wall of the packaging intact, following the implementation of these various tests. However, the invention has been made by departing from this conventional practice, by providing a package whose lateral internal wall is capable of deforming in a punctual manner following mechanical stresses exerted on the packaging externally, such as those exerted by a punch during the punching test. So that a deformation of the lateral internal wall does not damage the main structure of the container, unlike all the containers of the prior art, no direct contact has been provided between this lateral internal wall and the main structure, so that the deformation cannot be transmitted.

Thus, the main structure of the container containing the fuel assemblies is able to remain intact following the completion of the various drop tests, despite the deformation of the lateral internal wall of the packaging caused. Consequently, the design of this package can then be considerably simplified. Indeed, the specific design retained for the container according to the invention allowing the lateral internal wall of the packaging to be deformed during the drop test on punch, this packaging no longer needs to be produced using 'complex stacks of oversized layers, and can therefore undergo large simplifications as well as a significant reduction in mass and thickness compared to previously offered packaging.

The aforementioned advantages then translate directly into a reduction in the production costs of the containers, as well as the possibility of increasing the number of nuclear fuel assemblies that can be contained in each of these containers, while satisfying the operating constraints. existing.

According to a first preferred embodiment of the present invention, the means for spacing the main structure relative to the packaging are provided between the main structure and the lateral internal wall of the packaging, the spacing means having '' a fuse function mechanical in order to deform during a punctual deformation of the lateral internal wall of the packaging, occurring following the punching test. On the other hand, it is indicated that the spacing means are also designed to resist, and therefore not to deform, following the mechanical stresses encountered during falls from 9 meters.

In this preferred embodiment, the space provided between the lateral internal wall of the packaging and the main structure is at least partially filled by the spacing means, so as to provide an additional function of heat transfer between these elements. Note that this function is made possible due to the small or zero clearance existing between on the one hand the spacing means and the main structure, and on the other hand the lateral internal wall of the packaging and these same means of spacing.

The spacing means are advantageously designed to fulfill the role of a mechanical fuse during a fall on a punch, the latter generally causing a punctual deformation of the lateral internal wall of the packaging. Thus, the spacing means are directly damaged under the effect of the deformation of the lateral internal wall, without transmitting this deformation to the main structure of the container, which remains completely intact.

In addition, the spacing means are also designed not to deform during the 9 meter drop tests, more particularly during horizontal falls, under the inertia of the main structure responsible for fuel assemblies. Thus, the spacing means are designed so as to be able to fully fulfill the functions of a mechanical fuse, even when the falls on a punch are made after the falls from 9 meters.

Preferably, the spacing means are composed of a plurality of deformable sectors distributed around the main structure of the container, these sectors extending over the entire length or only over part of the length of the main structure of the packaging. , or being stacked on top of each other in a direction parallel to a longitudinal main axis of the container. Note that in another variant, the deformable sectors are arranged next to each other so as to form strips encircling the main structure.

In this first preferred embodiment, it is equally possible to provide that the deformable sectors are made of a material with low crushing stress such as wood, plastic foam or honeycomb confined between two metal sheets, or still metallic elements taking the form of two concentric sheets separated by reinforcements.

In the latter case, the metal elements are preferably made of aluminum or one of its alloys. Preferably, the deformable sectors are fixed to the main structure of the packaging, and completely or only partially cover the main structure of the container.

According to a second preferred embodiment of the present invention, the means for spacing the main structure relative to the packaging are provided on a cover and / or a fixed bottom of the packaging, the lateral internal wall of the packaging and the main structure being separated by an empty space. This solution remains very advantageous insofar as it makes it possible to obtain a relatively light container, due to the absence of material between the lateral internal wall of the packaging and the main structure. Preferably, for the two preferred embodiments mentioned above, the main structure of the container has a substantially cylindrical shape of circular section, and the inner side wall of the package and the main structure are separated by a form space. substantially annular.

Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS

This description will be made with reference to the accompanying drawings, among which; Figure 1 shows a perspective view of a container ^' for the storage / transport of non-irradiated nuclear material, according to a first mode. preferred embodiment of the present invention; - Figure 2 shows a partial sectional view of the container shown in Figure 1, along a plane perpendicular to the main longitudinal axis of this container; 3 shows a perspective view of a deformable sector such as that used in the spacing means of the container shown in Figure 1; 4 shows a schematic perspective view of a main structure of the container shown in Figure 1, provided with a plurality of deformable sectors; 5 shows a schematic sectional view explaining the behavior of a container such as that shown in Figure 1, following the execution of a punching test;

- Figure 6 shows a partial perspective view of a container for the storage / transport of non-irradiated nuclear material, according to a second preferred embodiment of the present invention; and

- Figure 7 shows a partial sectional view of the container shown in Figure 6, along a plane perpendicular to the main longitudinal axis of this container.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figures 1 and 2, we see a container 1 for the storage / transport of non-irradiated radioactive material such as fresh nuclear fuel assemblies (not shown) ^' , according to a first preferred embodiment of the present invention.

The container 1 comprises a packaging 2 as well as a main structure 4 of the basket type, capable of being housed inside the packaging 2 of the container 1.

The package 2 consists of a side face 6 of substantially annular shape, a fixed bottom 8, a cover 10, and two removable protective covers 12 and 14 arranged at the ends of the package 2.

Note that in this first preferred embodiment of the present invention, the side face 6 of the package 2 is unique, but could of course be composed of several elements attached to each other, without departing from the scope of the invention.

This lateral face 6 is composed of an internal ferrule 16 and an external ferrule 18 centered on a main longitudinal axis 19 of the container 1, these ferrules 16 and 18 being spaced and held relative to one another by the 'through stiffeners 20, which also have the function of conducting heat through a neutron protection 22, also located between the two ferrules 16 and 18.

The internal ferrule 16 of the lateral face 6 of the package 2 has a lateral internal wall 24, defining a cavity inside which is able to be housed the main structure 4 of the container 1. As can be seen in Figures 1 and

2, the main structure 4 resting in the cylindrical cavity defined by the lateral internal wall 24 comprises a plurality of housings 26, each capable of receiving an assembly of fresh nuclear fuel.

The main structure 4 of the container 1 preferably has a substantially cylindrical shape of circular section, and can be produced according to known conventional techniques. In this regard, it should be noted that in the embodiment shown, the structure 4 is obtained by a stack of discs 28 along the longitudinal main axis 19 of the container 1. A plurality of orifices made on each of the discs 28 allows thus defining the housings 26, into which the nuclear fuel assemblies may be introduced.

Furthermore, the container 1 also comprises means for spacing the main structure 4 relative to the packaging 2, the spacing means being able to avoid any direct contact between the lateral internal wall 24 and the main structure 4, so as to allow a specific deformation of this lateral internal wall 24 of the package 2 during a punching test. '

In this first preferred embodiment of the present invention, the spacing means 30 are provided between the main structure 4 and the lateral internal wall 24 of the package 2, in order to ensure in particular a heat transfer function between the elements 2 and 4. As can be seen in FIG. 2, the main structure 4 indeed has an outside diameter smaller than the diameter of the lateral internal wall 24, this specific design of the container 1 resulting in the formation of a space of substantially annular shape. , inside which the spacing means 30 can be accommodated. The particular arrangement of the spacing means 30 can then allow these means to fulfill a mechanical fuse function allowing punctual deformations of the internal lateral wall 24 of the packaging 2. This function will be more fully explained below.

Referring to Figures 2 to, it can be seen that the spacing means 30 consist of a plurality of deformable sectors 32, distributed around the main structure 4, on which they are preferably assembled by screwing.

More specifically with reference to FIG. 4 intended to better understand the different possibilities of arrangement of the sectors 32, these can first of all extend over substantially the entire length of the main structure 4, as shown by the strip 34. Furthermore, the deformable sectors 32 can also be stacked on top of each other in a direction parallel to the main longitudinal axis 19 of the container 1, as shown by the strip 36.

On the other hand, in addition to the possibility of providing strips 34, 36 of deformable sectors 32 over substantially the entire length of the structure main 4, it is also possible to produce bands 38 consisting of one or more sectors 32, and only partially covering the length of this main structure 4. Finally, the deformable sectors 32 can also be arranged one beside the other so as to form annular bands (not shown) encircling the main structure 4 and distributed over the entire length of this structure 4 or only at the two ends thereof.

Thus, as can be seen, the diversity of arrangements of the deformable sectors 32 on the main structure 4 is very large, and can lead to total or partial covering of the main structure 4 of the container 1.

As such, the location of the sectors 32 on the structure 4 can therefore be judiciously chosen, in order to best respond to the mass constraints and the mechanical constraints to be met by the container 1.

According to a nonlimiting example given only by way of illustration, the outside diameter of the lateral face 6 of the package 2 is around 1400 mm for an inside diameter around 1000 mm. In addition, the annular space provided between the lateral internal wall 24 and the main structure 4, like the deformable sectors 32 in contact with these two elements 4 and 24, has a thickness of approximately 30 to 35 mm. In the first preferred embodiment of the invention shown in Figures 1 to 4, each deformable sector 32 consists of a metallic element preferably made of aluminum or one of its alloys, this element taking the form of two concentric sheets 40 and 42 of identical axis to the main longitudinal axis 19 of the container 1, the sheets 40 and 42 being separated by reinforcements 44 (Figure 3). Preferably, the metal elements constituting the deformable sectors 32 are extruded, but could also be produced by mechanical welding or any other conventional technique, without departing from the scope of the invention.

Note that the sheet-like parts 40 and 42 are respectively in contact with the main structure 4, and the lateral internal wall 24. In addition, still preferably, the elements 40, 42 and 44 each have a lower thickness. about half the thickness of the inner shell 16.

The reinforcements 44 each extend over the entire length of the sheet-shaped parts 40 and 42, and are inclined with respect to a radius of circle concentric with the sheet-shaped parts 40 and 42. In addition, the reinforcements 44 are arranged so that two successive reinforcements 44 are inclined in an opposite direction, so as to be in phase opposition. By way of nonlimiting example, the angle of inclination of the reinforcements can be around ± 20 °.

Of course, the deformable sectors 32 can take any other form and be formed using other materials, insofar as these are capable of spacing the main structure 4 from packaging 2,. and likely to fulfill the role of mechanical fuse described below. Still by way of nonlimiting example, the deformable sectors 32 can then be made of a material with low crushing stress such as plastic foam, honeycomb, or wood such as balsa, confined or not between two metal sheets.

With reference to FIG. 5, a description will now be given of the mechanical behavior of the container 1 during a punching test, such as that carried out during regulatory safety tests relating to the transport / storage of nuclear materials. Note that this description will be made for deformable sectors 32 of the metal element type shown in FIG. 3. However, it is specified that the behavior of the container 1 remains similar regardless of the type of spacing means 30 interposed between the structure main 4 and the lateral internal wall 24 of the package 2, provided that these means 30 are capable of fulfilling a mechanical fuse function between the two elements 2 and 4.

When the packaging 2 of the container 1 comes into contact with a punch 46 of approximately 150 mm in diameter, this punch 46 causes significant local mechanical stresses on the packaging 2, so that the lateral face 6 is deformed over its whole thickness in an area located opposite the punch 46. Note that the packaging 2 is preferably designed so that following such a punching test, the internal shell 16 of this packaging 2 is deformed but not perforated. In this way, the internal shroud 16 of the packaging 2 is deformed by penetrating into the annular space of axis 19 initially provided between the internal lateral wall 24 and the main structure 4 of the container 1, this annular space being occupied by the spacing means 30.

The deformable sector or sectors 32 of the spacing means 30 located opposite the deformation of the lateral internal wall 24 then play their role of mechanical fuse by degrading directly following the impact of the lateral internal wall 24, without transmitting the deformation to the main structure 4 of the container 1. It is also indicated that the deformation of the lateral internal wall 24 takes place as if no element existed between the structure 4 and this lateral internal wall 24. In fact, the sectors 32 are designed so that their deformation energy is negligible compared to the energy involved when falling on the punch 46, largely absorbed by the point deformation of the side face 6 of the package 2.

In the case shown in FIG. 5, the sheet metal part 42 is deformed under the effect of the deformation of the lateral internal wall 24. In addition, the reinforcement 44 located near this deformation are also deteriorated, always so that the deformation of the lateral internal wall 24 is not transmitted to the main structure 4 of the container 1. The deformable sectors 32 do not necessarily follow the entire surface of the internal wall lateral 24, it is therefore possible to encounter cases in which the deformation of this lateral internal wall 24 is located in an area devoid of spacing means 30, and therefore of deformable sectors 32. The lateral internal wall 24 then deforms quite simply in the vacuum of the annular space formed between the elements 2 and 4, according to substantially the same amplitude as that which would have been obtained in the presence of deformable sectors 32, still due to the main function of mechanical fuse of these sectors.

Thus, the spacing means 30 of the container 1 allow a punctual deformation of the lateral internal wall 24, the amplitude of this deformation being limited by the initial thickness of the space present between the lateral internal wall 24 and the main structure. 4, so that this wall 24 does not directly strike the structure 4 of the container 1. When designing such a container 1, for a given structure of the packaging 2, the thickness of the annular space may for example be fixed so that the maximum deformation of the lateral internal wall 24, caused by a punch 46 under stress conditions similar to those encountered during regulatory tests, is compatible with this thickness.

Finally, preferably, the spacing means 30 are also advantageously designed so as to generally resist mechanical stresses due to the significant inertia of the main structure 4 generated during falls of 9 meters, more particularly during horizontal falls, usually not causing deformation of the side face 6 of the package 2.

Referring to Figures 6 and 7, there is shown partially a container 100 for the storage / transport of non-irradiated radioactive material such as fresh nuclear fuel assemblies (not shown), according to a second preferred embodiment of the present invention. In these figures, the elements bearing the same numerical references as those attached to the elements represented in FIGS. 1 to 5, correspond to identical or similar elements.

In this second preferred embodiment of the present invention, only the spacing means 130 of the main structure 4 relative to the package 2 differ from the first preferred embodiment. The other elements of the container 100 are thus identical or similar to those of the container 1 according to the first preferred embodiment described above.

Indeed, the annular space provided between the main structure 4 and the lateral internal wall 24 is no longer partially or completely filled by the deformable sectors 32 of the first embodiment, but remains an empty space 150 avoiding any direct contact between the lateral internal wall 24 and the main structure 4, so as to allow a punctual deformation of this lateral internal wall 24 of the package 2 during a punching test. In this second preferred embodiment, the spacing means 130 are provided on the fixed bottom 8 or on the cover 10 of the package 2, or preferably on both. These spacing means 130 thus make it possible to center the main structure 4 on the main longitudinal axis 19 of the container 100, so as to obtain an empty annular space 150 of substantially constant thickness.

As can be seen in FIG. 6, the spacing means 130 comprise for example a plurality of centering means 152, provided on the fixed bottom 8 and on the cover 10 and directed towards the interior of the container 100 (only the means centering 152 integral with the cover 10 being shown). Each centering means 152 is arranged along an axis identical to that of a housing 26 of the main structure 4, so as to be able to penetrate this same housing 26. In this way, the centering means 152 placed on the cover 10 and the bottom 8 of the packaging 2 are able to laterally support the main structure 4, in order to maintain it with respect to the lateral internal wall 24 of the container 100. By thus providing several centering means 152 each cooperating with a housing 26, the main structure 4 of the container 100 can be maintained centered on the packaging 2, when the cover 10 is assembled on the side face 6 of this packaging 2.

Of course, in this second preferred embodiment of the invention, any other spacing means 130 can be envisaged between a share the main structure 4 and secondly the fixed bottom 8 and / or the cover 10 of the package 2, without departing from the scope of the invention.

In addition, it is specified that during a punching test, the behavior of the container

100 is analogous to that presented above for the container 1 according to the first preferred embodiment of the invention.

Indeed, as in the case encountered in the first preferred embodiment where the deformation of the lateral internal wall 24 is located in an area devoid of spacing means 30, the lateral internal wall 24 of the container 100 then simply deforms in the void of the annular space 150 formed between the elements 2 and 4, according to substantially the same amplitude as that which would have been obtained in the presence of spacing means acting as a mechanical fuse, interposed between the internal lateral wall 24 and the main structure 4. Of course, various modifications can be made by those skilled in the art to 1,100 containers for the storage / transport of non-irradiated radioactive materials which have just been described, only by way of non-limiting examples.

Claims

1. Container (1,100) for the storage / transport of non-irradiated radioactive materials such as nuclear fuel assemblies, said container (1,100) comprising a main structure (4) and a package (2) having a lateral internal wall (24) defining a cavity inside which is able to be accommodated said main structure (4), the latter defining a plurality of housings (26) each suitable for receiving at least one fuel assembly, characterized in that the container (1,100 ) further comprises spacing means (30,130) of the main structure (4) relative to the packaging (2), the spacing means (30,130) being able to avoid any direct contact between said lateral internal wall ( 24) and the main structure (4), so as to allow a point deformation of this lateral internal wall (24) of the packaging (2) during a punching test.

2. Container (1) according to claim 1, wherein the spacing means (30) of the main structure (4) relative to the packaging (2) are provided between said main structure (4) and the internal wall side (24) of the packaging (2), said spacing means (30) having a mechanical fuse function in order to deform during a punctual deformation of the lateral internal wall

(24) of the packaging (2), occurring during a punching test.

3. Container (1) according to claim 2, wherein the spacing means (30) are composed of a plurality of deformable sectors (32) distributed around the main structure (4) of the container (1).

4. Container (1) according to claim 3, wherein at least one deformable sector (32) extends over substantially the entire length of the main structure (4) of the container (1).

5. Container (1) according to claim 3 or claim 4, wherein at least two deformable sectors (32) are stacked on each other in a direction parallel to a main longitudinal axis (19) of the container (1).

6. Container (1) according to any one of claims 3 to 5, wherein at least one deformable sector (32) is made of a material with low crushing stress.

7. Container (1) according to claim 6, wherein said material is an element taken from a group consisting of wood, plastic foam and honeycomb.

8. Container (1) according to any one of claims 3 to 5, in which at least one deformable sector (32) is a metallic element taking the form of two concentric sheets (40,42) separated by reinforcements (44) .

9. Container (1) according to claim 8, wherein the reinforcements (44) are inclined relative to a radius of a circle concentric with said sheets (40,42), and arranged. so that two successive reinforcements (44) are inclined in an opposite direction.

10. Container (1) according to claim 8 or claim 9, wherein the metal elements are made of aluminum or one of its alloys.

11. Container (1) according to any one of claims 3 to 10, in which the deformable sectors (32) are fixed on said main structure (4) of the container (1).

12. Container (1) according to any one of claims 2 to 11, in which the spacing means (30) completely cover the main structure (4) of the container (1).

13. Container (1) according to any one of claims 2 to 11, wherein the spacing means (30) only partially cover the main structure (4) of the container (1).

14. Container (100) according to claim 1, wherein the spacing means (130) of the main structure (4) relative to the packaging (2) are provided on at least one of the elements taken from a group consisting a cover (10) and a fixed bottom

(12) of the package (2), the lateral internal wall (24) of the package (2) and the main structure (4) being separated by an empty space (150).

15. Container (1,100) according to any one of the preceding claims, in which the main structure (4) of the container (1,100) has a substantially cylindrical shape of circular section.

16. Container (1,100) according to any one of the preceding claims, in which the lateral internal wall (24) of the package (2) and the main structure (4) are separated by a space of substantially annular shape.

17. Container (1,100) according to any one of the preceding claims, in which the packaging (2) comprises a lateral face (6) of substantially annular shape, constituted by an internal ferrule (16) and an external ferrule (18) , said ferrules (16,18) being spaced and held relative to each other by means of stiffeners

(20).