Packaging for transport and / or storage of radioactive materials, having an improved design limiting the risks of contamination of its constituent elements

Abstract

The invention relates to a packaging (1) for the transport and / or storage of radioactive materials, comprising an outer radiologically protective casing produced using a plurality of stacked unitary annular structures (16), an elastic annular sealing gasket (40) being arranged at an interface between a first and a second outer annular wall (24), belonging respectively to a first and a second unitary annular structure (16), the gasket, arranged in at least one recess (46, 48), being arranged radially around the first and second outer annular walls (24), and comprising a first part (42) cooperating with the radially outer surface (24a) of the first outer annular wall (24), and a second part (43) cooperating with the radially outer surface (24a) of the second outer annular wall (24).

Description

[0001] PACKAGING FOR TRANSPORT AND / OR STORAGE OF RADIOACTIVE MATERIALS WITH AN IMPROVED DESIGN LIMITING THE RISKS OF CONTAMINATION OF ITS CONSTITUENT ELEMENTS

[0002] TECHNICAL FIELD

[0003] The present invention relates to the field of packaging for transporting and / or storing radioactive materials, for example nuclear fuel assemblies or radioactive waste.

[0004] More specifically, the present invention relates to a package comprising at its periphery an outer radiological protection envelope.

[0005] STATE OF THE PRIOR ART

[0006] From the prior art, it is known to provide an outer radiological protection envelope around a side body of a package. The function sought with this envelope lies in protection against gamma radiation, and / or in neutron absorption, in order to comply with the regulatory radiological criteria around the package, when it is loaded with radioactive materials.

[0007] This envelope can be obtained by stacking unitary annular structures welded to each other, as is known for example from the document

[0008] EP 2 041 753 Al.

[0009] More recently, a design has been proposed described in the document

[0010] FR 3 080 705 A1, which provides that each unitary annular structure comprises an outer annular wall and a radial heat conduction wall having an outer end secured to the outer annular wall, and an inner end in contact with the lateral packaging body. In addition, two directly consecutive unitary annular structures in the stack delimit at least in part an annular cavity housing at least one radiological protection element, this cavity being closed radially towards the outside by the outer annular wall of one or of the two directly consecutive unitary annular structures, and closed axially on either side respectively by the radial heat conduction wall of one and the other of said two directly consecutive unitary annular structures.

[0011] This design allows for an easily decontaminable outer packaging envelope to be obtained, achieved by the multiplicity of external annular walls of the unitary structures, while improving the thermal conduction function thanks to the radial thermal conduction walls which can have a more direct radial path. However, there is a need to further improve the packaging design, in order to limit the risks of contamination, in particular at the interfaces between the unitary annular structures which are stacked. Indeed, the solution of a bead of sealing mastic can be considered between the unitary annular structures, but it has drawbacks, in particular the difficulty of its removal when the unitary annular structures must be dismantled from the packaging, or simply when such a bead must be replaced.

[0012] SUMMARY OF THE INVENTION

[0013] To meet this need, the subject of the invention is a packaging for the transport and / or storage of radioactive materials, the packaging comprising a lateral packaging body extending around a longitudinal central axis and partly delimiting a housing for the radioactive materials, the packaging also comprising, arranged around the lateral packaging body, an outer radiological protection envelope produced using a plurality of unitary annular structures, succeeding one another along the longitudinal central axis and arranged around the lateral packaging body, each unitary annular structure comprising an external annular wall, the external annular wall having a radially external surface with a diameter greater than or equal to 1 m.

[0014] According to the invention, the packaging comprises an elastic annular sealing gasket arranged at an interface between a first and a second outer annular wall, respectively belonging to a first and a second unitary annular structure directly consecutive along the longitudinal central axis, the gasket being arranged radially around the first and second outer annular walls, and the gasket comprising a first part cooperating with the radially outer surface of the first outer annular wall and designed to ensure sealing between the gasket and the first outer annular wall, as well as a second part cooperating with the radially outer surface of the second outer annular wall and making it possible to ensure sealing between the gasket and the second outer annular wall, the gasket being at least partly housed in at least one annular recess open radially towards the outside,said at least one recess being formed on the radially outer surface of one or both of said first and second outer annular walls.,

[0015] The invention thus defined advantageously avoids possible introduction of water at the interfaces between the unitary annular structures, and consequently avoids the risks of contamination. Similarly, the risks of oxidation of the radiological protection elements, usually made of resin, are also reduced, when such elements are present within the unitary annular structures.

[0016] The proposed technical solution is also easy to assemble / disassemble, due to the elastic / stretchable nature of the seal, and its housing in a recess such as a groove, open radially outwards. Also, unlike the previous solution obtained with a bead of mastic, the sealing of the proposed technical solution does not rely on a notion of adhesion to the annular structures. This particularity thus greatly facilitates the removal of the seal.

[0017] The seal can thus easily be stretched radially outwards and cut in order to be extracted from its recess, with a view to being replaced, for example after wear. After this removal, no residue is observed on the unitary annular structures, unlike for example a solution of sealing mastic bead. The intervention time is advantageously reduced, which is of real interest with regard to the radiological and thermal exposure of operators when the packaging is loaded with radioactive materials.

[0018] Furthermore, the easy disassembly of the seal makes it easier and quicker to disassemble the individual annular structures when they need to be removed from the side body of the packaging for various reasons, such as maintenance, replacement of radiological protection elements, dismantling, etc.

[0019] The invention furthermore has at least one of the following optional features, taken alone or in combination.

[0020] According to a first preferred embodiment of the invention, the seal cooperates with a first and a second recess, respectively in the form of first and second annular grooves open radially outwards, and respectively formed on the radially external surface of the first external annular wall and on the radially external surface of the second external annular wall.

[0021] Preferably, the seal comprises a first and a second radial leg respectively forming said first and second parts of the seal, and respectively housed in the first and second annular grooves.

[0022] According to an alternative, the seal comprises a first and a second radial leg respectively housed in the first and second annular grooves, and said first and second parts of the seal, preferably in the form of lips, are located respectively on either side of the assembly formed by the first and second legs, along the longitudinal central axis.

[0023] According to a second preferred embodiment of the invention, the seal is housed in the recess made partly on the radially external surface of the first external annular wall, and partly on the radially external surface of the second external annular wall.

[0024] Preferably:

[0025] - a first lateral flank of the recess is produced on the radially external surface of the first external annular wall, the first part of the seal being in axial support against the first lateral flank;

[0026] - a second lateral flank of the recess, opposite the first, is produced on the radially external surface of the second external annular wall, the second part of the seal being in axial support against the second lateral flank; and

[0027] - a bottom of the recess is made on the radially outer surface of the first outer annular wall and / or the second outer annular wall. Preferably, the first part of the seal comprises at least one first sealing lip projecting from a seal body, and the second part of the seal comprises at least one second sealing lip projecting from the seal body.

[0028] Preferably, the seal is axially compressed between the first and second lateral flanks of the recess.

[0029] According to an alternative, the seal comprises an annular hollow open radially outwards, delimiting respectively on either side of this hollow said first and second parts of the seal, and a pressurizing member is introduced into the annular hollow of the seal, so as to place each of the first and second parts of the seal in axial compression between the pressurizing member, and the corresponding lateral flank of the recess.

[0030] Preferably, the seal comprises, in half-cross section, a closed annular hollow.

[0031] Whatever the embodiment envisaged, the elastic seal preferably has a stretching capacity of between 200 and 300%, even if this stretching capacity may be lower or higher, without departing from the scope of the invention.

[0032] Preferably, the elastic seal is made of elastomeric material.

[0033] Preferably, the outer annular wall of at least one of the unitary annular structures is equipped with cooling fins, made in one piece with the annular structures, or attached to them.

[0034] Preferably, the seal is radially constrained around the first and second outer annular walls.

[0035] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] This description will be made with regard to the attached drawings, among which;

[0038] [Fig. 1] represents a longitudinal axial sectional view of a package for the storage and / or transport of radioactive materials, according to a preferred embodiment of the present invention; [Fig. la] represents a cross-sectional view of the package shown in Figure 1, along the line la-la of this figure;

[0039] [Fig. 2] represents a perspective view of the packaging shown in Fig. 1;

[0040] [Fig. 3] represents a partial perspective view of one of the unitary annular structures which form an outer radiological protection envelope of the package shown in the preceding figures;

[0041] [Fig. 4] is a cross-sectional view of the structure shown in Fig. 3;

[0042] [Fig. 5] is a cross-sectional view of the structure shown in Fig. 3, according to an alternative;

[0043] [Fig. 6] schematically represents a manufacturing process of the packaging shown in the preceding figures;

[0044] [Fig. 7] represents a part of the packaging, in longitudinal half-section, according to a first preferred embodiment of the invention;

[0045] [Fig. 8] represents the seal shown in the previous figure, in diametrical section;

[0046] [Fig. 9] shows a partial sectional view similar to that of Fig. 7, with the packaging being in the form of an alternative;

[0047] [Fig. 10] shows a partial sectional view similar to that of Fig. 7, with the packaging being in the form of another alternative;

[0048] [Fig. 11] shows a partial sectional view similar to that of Fig. 7, with the package being in the form of a second preferred embodiment of the invention;

[0049] [Fig. 12] shows a partial sectional view similar to that of Fig. 11, with the packaging being in the form of an alternative;

[0050] [Fig. 13]

[0051] [Fig. 14]

[0052] [Fig. 15]

[0053] [Fig. 16]

[0054] [Fig. 17] show partial sectional views similar to that of Fig. 11, with the packaging being in the form of other alternatives. DETAILED DISCLOSURE OF THE INVENTION

[0055] Referring firstly to figures 1 and 2, there is shown a packaging 1 for the storage and / or transport of radioactive materials, such as nuclear fuel assemblies or radioactive waste (not shown).

[0056] This packaging 1 is shown in a vertical storage position, in which its longitudinal central axis 2 is oriented vertically. It rests on a packaging base 4, opposite a removable cover 6 in the direction of the height 8, parallel to the longitudinal central axis 2. Between the base 4 and the cover 6, the packaging 1 comprises a lateral body 10 extending around the axis 2, and internally delimiting a housing 12 for the radioactive materials. This housing may constitute a containment enclosure 12 intended to receive the radioactive materials, for example arranged in a storage basket also located in the containment enclosure. Alternatively, the containment enclosure is defined entirely by a case, also called a “canister”, placed in the aforementioned housing 12. The latter is closed axially upwards by the cover 6, and downwards by the base 4.

[0057] The lateral body 10 can be made in one piece, as shown in Figure 1, or by several concentric ferrules.

[0058] Around the lateral body 10, the packaging 1 comprises an outer radiological protection envelope 14, specific to the present invention.

[0059] The envelope 14 is produced using the axial stacking of a plurality of unitary annular structures 16, for example provided in a number between 10 and 35, over a cumulative height “H” of the order of 1 to 4 m. This height “H” of the outer envelope 14 corresponds substantially to that of the housing 12 along the direction 8.

[0060] Here, all the structures 16 stacked along the axis 2 are identical, each integral and in contact with an external radial surface 18 of the lateral body 10. At one of the ends of the stack, corresponding to the lower end in Figure 1, the last structure 16 can nevertheless be covered with a closing plate 20.

[0061] Referring now to Figures 3 to 5, the design of one of the unitary annular structures 16 will be detailed, shown in its position as adopted when it is on the package in an upright position, with the lid upwards as in Figures 1 and 2.

[0062] The structure 16, preferably made in one piece, has a half-cross section in the general shape of an inverted U, with its base oriented upwards. A reverse orientation with the base downwards would be conceivable, without departing from the scope of the invention. This half-cross section retains a constant shape, whatever the section plane along the circumferential direction of this structure 16.

[0063] The base of the U forms a radial heat conduction wall 22. It adopts the shape of a straight line segment which is preferably orthogonal to the axis 2, for a more direct conduction path towards the outside of the packaging. The inner end of the radial heat conduction wall 22 is intended to be in contact and integral with the outer radial surface 18 of the lateral body 10. At its opposite end, namely the outer radial end, the radial wall 22 is integral with an outer annular wall 24. In half-cross section, this wall 24 takes the shape of a straight line segment parallel to the axis 2, and which projects downwards until it radially covers the outer radial end of the radial wall 22. The outer annular wall 24 has a radially outer surface 24a, with a diameter preferably greater than or equal to 1.2 m. Much higher values ​​can be adopted, without departing from the scope of the invention.

[0064] Furthermore, according to an alternative shown in Figure 5, the outer annular wall 24 of the one or more unitary annular structures 16 may be provided with cooling fins 25, projecting radially outwardly from the radially outer surface 24a.

[0065] Finally, at its inner end, the radial wall 22 may be integral with an internal annular wall 26 forming a second branch of the U. In half-cross section, this wall 26 also takes the form of a straight line segment parallel to the axis 2, and which projects downwards from the inner end of the radial wall 22.

[0066] The annular structures 16 are preferably made of cast iron, while the packaging body 10 is preferably made of forged steel. Alternatively, the annular structures 16 may be made of steel or aluminum. Thanks to the design of these unitary annular structures 16, when they are stacked around the lateral body 10, they form annular cavities housing radiological protection elements. More precisely, with reference again to FIG. 1, each annular cavity 30 is delimited by two directly consecutive structures 16 in the stack. Here, the cavity 30 is closed radially outwardly by the external annular wall 24 of one of the two directly consecutive annular structures 16, and closed radially inwardly by the internal annular wall 26 of this same annular structure 16.Furthermore, the annular cavity 30 is closed axially upwards by the radial wall 22 of this same structure 16, and closed axially downwards by the radial wall 22 of the annular structure 16 directly consecutive in the stack, which closes the opening between the two branches of the U of the first structure 16.

[0067] Once the annular structures are stacked, the outer annular walls 24 are adjacent along the direction 8, and together they form an outer radial surface of the packaging which is substantially continuous and easily decontaminable. According to a feature of the invention which will be described later, seals are arranged at the interfaces between the annular structures 16.

[0068] The annular cavities 30 thus follow one another along the axis 2, each being filled entirely or almost entirely with a radiological protection material. As mentioned previously, this may be a material for protection against gamma radiation, and / or a neutron absorption material intended to satisfy the regulatory radiological criteria around the packaging when the latter is loaded with radioactive materials. In each cavity 30, the radiological protection material is for example in the form of one or more cast elements, preferably a single continuous ring cast over 360° in the cavity 30. It may alternatively be in the form of one or more prefabricated elements, arranged in the cavity 30. In the latter case shown diagrammatically in FIG. 1a, a radiological protection ring 34 is formed discontinuously using several protection elements 32 arranged end-to-end.According to an alternative not shown in the figures, the unitary annular structures 16 may be devoid of cavities 30 and of added radiological protection elements. Indeed, the external annular wall may for example fulfill the function of protection against gamma radiation, implying a simplified design for the annular structures, which no longer require the delimitation of a cavity.

[0069] Figure 6 represents an example of a method for manufacturing the packaging 1, for the steps which concern the assembly of the outer casing 14 of radiological protection around the lateral body 10. This method comprises the repetition of two successive steps. The first of these two steps consists of placing one of the unitary annular structures 16 in the stack around the lateral body 10, even though its annular cavity 30 is not yet filled by the radiological protection element(s). This step is shown diagrammatically by the arrow 36 in Figure 6. To carry out this insertion, the structure 16 may be heated beforehand, for example to a temperature of the order of 200°C. It is brought into contact with the rest of the stack, so as to close the cavity 30 of the structure 16 previously placed in the stack, and which is filled with the radiological protection material.

[0070] Once the structure has cooled, for example to a temperature below 160°C, it adheres by shrinking to the outer radial wall 18 of the lateral body, via the inner end of the radial wall 22 and via the inner annular wall 26.

[0071] The radiological protection material can then be placed in the annular cavity 30 of the cooled structure 16, without risk of thermal degradation of this material. In this regard, it is noted that these steps are carried out with the package 1 in a vertical position, but with its bottom facing upwards so that each cavity 30 to be filled is open upwards. The material is placed by pouring or by arranging the prefabricated elements in the cavity 30, then the radiological protection thus obtained is inspected before repeating these same two first and second steps.

[0072] Alternatively, the structures 16 may be inserted in series around the body 10, and not one by one. The seals, which will now be described with reference to the following figures, may be put in place at the interfaces between the structures 16 after all of them have been mounted around the body 10, or progressively, one by one after each of these structures 16 has been mounted around the body.

[0073] Referring now to Figures 7 and 8, there is shown a portion of a package according to a first preferred embodiment of the invention.

[0074] An elastic annular sealing gasket 40 is arranged at an interface between the first external annular wall 24 and the second external annular wall 24 belonging respectively to a first and a second unitary annular structure 16, directly consecutive along the longitudinal central axis 2.

[0075] This seal 40, preferably made of elastomeric material, has a high stretching capacity, for example between 200 and 300%. This implies that it can be stretched in an elastic range, up to increasing its initial circumferential length by 200 to 300%. These properties are particularly beneficial for the installation of the seal, since as will be indicated below, its placement on the packaging is carried out by stretching it to make it slide axially along the packaging, before releasing the stretching stress so that it contracts and comes to cooperate with the two unitary annular structures 16 associated with it. It is noted that when the annular structures 16 have fins, the seal 40 must be stretched significantly to be able to be moved axially along the packaging, before the stress is released.

[0076] In the mounted state shown in Figure 7, the seal 40 is arranged radially around the first and second outer annular walls 24. Preferably, the seal 40 is also radially constrained around these walls 24, this feature being preferentially implemented when the package is designed so that the radioactive materials are loaded underwater into the housing 12. This preferred feature is applicable to all preferred embodiments of the invention. More specifically, the seal 40 comprises a first seal portion 42 in the form of a radial leg 44, cooperating with the radially outer surface 24a of the first outer annular wall 24, the one located uppermost in Figure 7. The first radial leg 44 is designed to ensure sealing between the seal and the first outer annular wall 24.Similarly, the seal 40 comprises a second seal part 43 also in the form of a radial leg 45, cooperating with the radially external surface 24a of the second external annular wall 24, the one located lowest in FIG. 7. The second radial leg 45 is also designed to ensure sealing between the seal and the second external annular wall 24.

[0077] To ensure these seals, the two radial legs 44, 45 are respectively housed in first and second recesses in the form of annular grooves 46, 48, open radially outwards. The first groove 46 is formed on the radially external surface 24a of the first wall 24, while the second groove 48 is formed on the radially external surface 24a of the second wall 24.

[0078] The two legs 44, 45 are connected to each other by a joint body 50, of generally axial orientation, and at the axial ends of which the two legs 42, 43 extend respectively, radially inwards. The joint body 50, of annular shape centered on the axis 2, may have an axial flexibility zone 52, for example in the shape of a V.

[0079] The seal 40 thus has a half-cross section in the general shape of a lying U, the hollow 54 of the U of which opens radially inwards, accommodating portions of the two external annular walls 24. In this regard, it is noted that after the assembly of the two adjacent structures 16 around the packaging body, an axial clearance 56 can be observed between the first and second external annular walls 24 of these structures 16. Alternatively, these walls 24 could be in axial contact, without departing from the scope of the invention.

[0080] It is the seal body 50 which preferentially presses radially inwards against the two radially external surfaces 24a of the first and second structures 16, outside the grooves 46, 48, so that it is preferentially radially stressed, in particular when it is loaded under water and the hydrostatic pressure exerts radial pressure on the seal. A radial clearance is preferentially observed between each leg end 44, 45, and the bottom of its corresponding groove 46, 48.

[0081] In order to obtain the desired seals described above, the first radial leg 44 has at least one axially constrained portion between a first lateral flank 58 of the first groove 46, and a second lateral flank 62 of this first groove 46, the second flank 62 being opposite the first flank of this first groove 46 in the direction 8. Similarly, the second radial leg 45 has at least one axially constrained portion between a first lateral flank 66 of the second groove 48, and a second lateral flank 70 of this second groove 48, the second flank 70 being opposite the first flank of this second groove 48 in the direction 8.

[0082] Thanks to the proposed design, water cannot enter at the axial interface between the first and second structures 16, the seal 40 effectively forming a sealing barrier at each of the two radial legs 44, 45, connected by the seal body 50. This avoids the risk of contamination, as well as the risk of oxidation of the radiological protection elements 32 housed in the cavities delimited by the annular structures 16.

[0083] In addition, the proposed technical solution is easily mounted / dismounted, due to the elastic / stretchable nature of the seal, and its housing in the grooves 46, 48 open radially outwards. For mounting, it is sufficient to stretch the seal so as to increase its diameter, then to move it axially around the packaging body and the unitary annular structures 16. Once the appropriate axial position is obtained, the stretching stress on the seal is released, so that by retracting, the radial legs 44, 45 penetrate radially into their respective grooves 46, 48, compressing axially. The shrinkage of the diameter of the seal 40 is stopped when its body 50 comes into contact with the radially external surface 24a of the first and second external annular walls 24, a configuration in which the seal remains radially constrained around the packaging body and the structures 16, due to the aforementioned contact.In addition to the natural retraction of the seal, manual radial force may be required to obtain the correct positioning of the radial legs in their respective grooves.

[0084] The removal of the seal 40 can be carried out according to a sequence of reverse operations, with a view to being replaced, for example after wear. After this removal, no residue of the seal 40 is observed on the radially external surface 24a of the first and second external annular walls 24, so that the intervention times remain particularly short. Such dismantling of the seal 40 also makes it possible to envisage more easily, and in a reduced time, the dismantling of the annular structures 16, when these must be removed from the lateral body of the packaging for various reasons, such as maintenance, replacement of the radiological protection elements 32, dismantling of the packaging, etc.

[0085] According to an alternative, shown in Figure 9, the annular seal 40 comprises the first and second radial legs 44, 45, respectively housed in the first and second annular grooves 46, 48, here without necessarily the legs being axially constrained within the grooves. Nevertheless, a fitting may be provided at the level of one or both of these legs, for the mechanical maintenance of the seal 40 on the unitary annular structures 16. A seal may also be produced at the level of these fittings of the legs, but preferably, the seal 40 comprises its first and second parts 42, 43 in the form of lips 72 to produce these seals. Indeed, the two lips 72 are located respectively at the level of the two opposite axial ends of the seal body 50, and they are each in radial support against the radially external surface 24a of the corresponding external annular wall 24, outside the grooves 46, 48.

[0086] Preferably, the two lips 72 are located respectively on either side of the assembly formed by the first and second radial legs 44, 45, in the axial direction 8.

[0087] According to another alternative shown in Figure 10, the seal 40 still has its two lips 72 axially on either side of the seal body 50 which they extend. Nevertheless, a single radial leg 44 is provided here, corresponding to the first leg in the previous alternative, which also cooperates by fitting with its associated groove 46, made on the surface 24a of the first external annular wall 24. This cooperation could alternatively be carried out at the level of the radially external surface 24a of the second external annular wall 24, without departing from the scope of the invention.

[0088] Here again, the first and second parts 42, 43 of the seal, in the form of lips 72 cooperating respectively with the two surfaces 24a, are located respectively on either side of the single radial leg 44, in the axial direction. In addition to the two lips, the two pairs of half-toruses distributed on either side of the interface make it possible to reinforce the desired level of sealing.

[0089] A second preferred embodiment of the invention is shown in Figure 11. The seal 40 is here housed in a recess 49 made partly on the radially external surface 24a of the first external annular wall 24, and partly on the radially external surface 24a of the second external annular wall 24. This recess 49 can thus be likened to two half-grooves together forming the same groove present on the two annular structures 16, at the axial interface between them.

[0090] More precisely, a first lateral flank 76 of the recess 49 is produced on the radially external surface 24a of the first external annular wall 24. In addition, the first part 42 of the seal here comprises at least one sealing lip 84 projecting axially from the seal body 50, of a half-section of general U-shaped or V-shaped cross-section lying flat, or C-shaped open radially inwards. These are, for example, two lips 84 which bear axially against the first lateral flank 76, as can be seen in FIG. 11.

[0091] Similarly, a second lateral flank 78 of the recess 49 is produced on the radially external surface 24a of the second external annular wall 24. In addition, the second part 43 of the seal 40 here also comprises at least one sealing lip 86 projecting axially from the seal body 50, in an axial direction opposite to that of the aforementioned lips 84. These are, for example, two lips 86 which are in axial support against the second lateral flank 78.

[0092] As can be seen in Figure 11, the sealing lips 84, 86 are arranged on or near the ends of branches of the U, V or C formed by the seal body 50. Furthermore, the seal 40 can, in this second preferred embodiment of the invention, be housed entirely or partly in the recess 49, the bottom 80 of which is produced on the radially external surface 24a of the first external annular wall 24, and on that of the second external annular wall 24. Alternatively, the bottom 80 of the recess 49 could be produced on only one of the two surfaces 24a, the other surface 24a then defining only one of the two lateral flanks of this recess. With this design, the seal 40 is axially compressed between the first and second lateral flanks 76, 78 of the recess 49.Optionally, mechanical strapping can be considered in order to increase the force required to insert the seal into the recess and thus increase the level of axial compression to obtain an even more satisfactory seal.

[0093] In the alternative shown in Figure 12, the annular seal body 50 is devoid of a lip. It has a half-section in the general shape of a disc or a ring, Figure 12 representing the first of these two solutions. An axially upper part 84 and an axially lower part 86 of this disc respectively axially contact the lateral flanks 76, 78 of the recess 49, always formed by two joined half-grooves. Once housed in the recess 49, the seal has an ovalized half-section due to the axial compression between the first and second lateral flanks 76, 78 of the recess 49. The axial compression makes it possible to increase the contact surfaces of the parts 84, 86 of the seal, with the lateral flanks. The level of sealing is thus improved. The axial contact parts 84, 86 of the seal thus form the aforementioned first and second parts 42, 43.

[0094] Just as for the second preferred embodiment shown in Figure 11, the seal body 50 is also preferentially radially constrained around the two annular walls 24, against the bottom 80 of the recess 49. The seal thus tends to naturally return to its initial diameter after it has been stretched during its assembly. According to still other alternatives shown in Figures 13 to 17, the seal 40 housed in the recess 49 comprises an annular hollow 88 open radially towards the outside. Respectively on either side of this hollow 88, in the axial direction, the seal delimits its first and second parts 42, 43, in the form of axial bosses. These two seal parts 42, 43 are connected to each other at their internal radial ends, by the axially oriented seal body 50, delimiting the radial bottom of the hollow 88 and preferably but not necessarily radially constrained against the bottom 80 of the recess 49.

[0095] One of the particularities here lies in the implementation of a member 90 for pressurizing the first and second seal parts 42, 43. This rigid member 90 is introduced into the annular hollow 88 of the seal, so as to put each of the first and second parts 42, 43 in axial compression between the pressurizing member 90, and the corresponding lateral flank 76, 78 of the recess 49. To remove the seal 40, it is sufficient first to extract the pressurizing member 90 outside the hollow 88 defined by the seal, then to extract by stretching the seal 40 from its recess 49, in the form of a reconstituted groove.

[0096] In Figure 13, the seal has a half-section of general shape of a C or U lying down, open radially outwards. The same is true for the seal 40 of Figure 17. In the alternative of Figure 15, this half-section of the seal 40 is more lyre-shaped, while in that of Figure 16, the seal body 50 has lips / grooves contacting the lateral flanks 76, 78 of the recess 49. In this embodiment of Figure 16, a pressurizing member 90 may or may not be implanted in the hollow of the seal defined between the two lateral flanks 76, 78. The same is true for all the embodiments representing the seal in association with such a member 90.

[0097] In Figure 14, the seal has a half-cross section of generally octagonal external shape, with a closed annular hollow 88 preferably of circular section. This type of seal is then preferably devoid of a pressurizing member 90, and therefore has a half-cross section of closed shape, with consequently a hollow 88 also closed which extends along the entire length of the seal, unlike for example the embodiment of the seal of Figure 13 where the annular hollow remains open. Of course, various modifications can be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples and according to the scope defined by the appended claims. In particular, the different embodiments and their alternatives can be combined.

Claims

CLAIMS 1. Packaging (1) for the transport and / or storage of radioactive materials, the packaging comprising a lateral packaging body (10) extending around a longitudinal central axis (2) and partly delimiting a housing (12) for the radioactive materials, the packaging also comprising, arranged around the lateral packaging body, an outer radiological protection envelope (14) produced using a plurality of unitary annular structures (16), succeeding one another along the longitudinal central axis (2) and arranged around the lateral packaging body (10), each unitary annular structure (16) comprising an outer annular wall (24), the outer annular wall having a radially outer surface (24a) with a diameter greater than or equal to 1 m, characterized in that it comprises an elastic annular sealing joint (40) arranged at an interface between a first and a second outer annular wall (24),belonging respectively to a first and a second unitary annular structure (16) directly consecutive along the longitudinal central axis (2), the seal (40) being arranged radially around the first and second external annular walls (24), and the seal comprising a first part (42) cooperating with the radially external surface (24a) of the first external annular wall (24) and designed to ensure sealing between the seal and the first external annular wall (24), as well as a second part (43) cooperating with the radially external surface (24a) of the second external annular wall (24) and making it possible to ensure sealing between the seal and the second external annular wall (24), the seal (40) being at least partly housed in at least one annular recess (46, 48, 49) open radially towards the outside,said at least one recess being formed on the radially outer surface (24a) of one or both of said first and second outer annular walls (24)., 2. Packaging according to claim 1, characterized in that the seal (40) cooperates with a first and a second recess, respectively in the form of first and second annular grooves (46, 48) open radially towards the outside, and respectively formed on the radially outer surface (24a) of the first outer annular wall and on the radially outer surface (24a) of the second outer annular wall.

3. Packaging according to claim 2, characterized in that the seal (40) comprises a first and a second radial leg (44, 45) respectively forming said first and second parts of the seal (42, 43), and respectively housed in the first and second annular grooves (46, 48).

4. Packaging according to any one of the preceding claims, characterized in that the seal (40) has a half-cross section in the general shape of a lying U, the hollow of the U (54) of which opens radially inwards.

5. Packaging according to claim 2, characterized in that the seal (40) comprises a first and a second radial leg (44, 45) respectively housed in the first and second annular grooves (46, 48), and in that said first and second parts of the seal (42, 43), preferably in the form of lips (72), are located respectively on either side of the assembly formed by the first and second legs (44, 45), along the longitudinal central axis (2).

6. Packaging according to claim 1, characterized in that the seal (40) is housed in the recess (49) made partly on the radially external surface (24a) of the first external annular wall (24), and partly on the radially external surface (24a) of the second external annular wall (24).

7. Packaging according to claim 6, characterized in that: - a first lateral flank (76) of the recess (49) is produced on the radially external surface (24a) of the first external annular wall, the first part of the seal (42) being in axial support against the first lateral flank (76); - a second lateral flank (78) of the recess (49), opposite the first flank (76), is produced on the radially external surface (24a) of the second external annular wall, the second part of the seal (43) being in axial support against the second lateral flank (78); and - a bottom (80) of the recess is produced on the radially external surface (24a) of the first external annular wall and / or of the second external annular wall (24).

8. Packaging according to claim 7, characterized in that the first part of the seal (42) comprises at least one first sealing lip (84) projecting from a seal body (50), and in that the second part of the seal (43) comprises at least one second sealing lip (86) projecting from the seal body (50).

9. Packaging according to claim 8, characterized in that the seal (40) is axially compressed between the first and second lateral flanks (76, 78) of the recess (49).

10. Packaging according to claim 7, characterized in that the seal (40) comprises an annular hollow (88) open radially outwards, delimiting respectively on either side of this hollow said first and second parts (42, 43) of the seal, and in that a pressurizing member (90) is introduced into the annular hollow (88) of the seal, so as to place each of the first and second parts (42, 43) of the seal in axial compression between the pressurizing member (90), and the corresponding lateral flank (76, 78) of the recess (49).

11. Packaging according to claim 7, characterized in that the seal (40) comprises, in half-cross section, a closed annular hollow (88).

12. Packaging according to any one of the preceding claims, characterized in that the elastic seal (40) has a stretching capacity of between 200 and 300%.

13. Packaging according to any one of the preceding claims, characterized in that the elastic seal (40) is made of elastomer material.

14. Packaging according to any one of the preceding claims, characterized in that the outer annular wall (24) of at least one of the unitary annular structures (16) is equipped with cooling fins (25).

15. Packaging according to any one of the preceding claims, characterized in that the seal (40) is radially constrained around the first and second external annular walls (24).

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