Packaging for transporting and / or storing radioactive material, with simplified radiation protection devices that reduce the risk of radiation leakage

Abstract

The present invention relates to a container (1) for transporting and / or storing radioactive material. The container (1) comprises a body defining a cavity (12) for containing radioactive material (3). The container comprises at least one radiation protection enclosure (14, 14a, 24) formed by enclosure wall elements (30, 32). Each enclosure defines a single space (26) with its elements (30, 32). Disposed within this space (26) is a radiation protection device (28) comprising a plurality of prefabricated blocks (30a, 30b) arranged successively in a given direction (13) and thus facing each other. At least a plurality of the blocks are held relative to at least one of the elements (30, 32) by at least one holding member (36a, 36b) cooperating with the block and at least one of the corresponding enclosure wall elements.

Description

[Technical Field]

[0001] The present invention relates to the field of containers for transporting and / or storing radioactive material, such as for example nuclear fuel assemblies or radioactive waste.

[0002] More particularly, the present invention relates to a container having a radiation protection device formed from a plurality of prefabricated blocks. [Background technology]

[0003] From the prior art it is known to provide a container with one or more radiation protection devices arranged around a cavity intended to contain radioactive material or in a lid intended to close said container, the function of which is required to comply with regulatory radiation standards for the container by protection from gamma rays and / or absorbing neutrons when the container is loaded with radioactive material.

[0004] To achieve this, one solution consists of inserting radiation protection elements into an enclosure, for example an enclosure that defines an annular space around the central longitudinal axis of the container, around the cavity containing the radioactive material. These radiation protection elements usually take the form of prefabricated blocks that can be inserted into this space by means of a cold gap that allows the thermal expansion of the radiation protection elements and thus limits the thermomechanical stresses of these blocks on the parts of the container that define this space.

[0005] During transport operations carried out with this type of container and during handling of this container, the radiation protection blocks can move and slide relative to each other within the design space, and the cumulative movements between these blocks can result in local gaps between two adjacent blocks with unacceptable values ​​for radiation leakage.

[0006] A solution to this problem has already been developed by the applicant and is disclosed in document FR3114907A1. Although this solution correctly meets the above-mentioned objective of reducing the risk of radiation leakage, there is still a need to optimize the design of radiation protection devices, in particular to facilitate their manufacture and installation. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] FR3114907A1 Summary of the Invention [Means for solving the problem]

[0008] To meet this need, the present invention relates to a container for transporting and / or storing radioactive material. The container includes a container body formed by body sides, a bottom, and a removable lid. The bottom and lid are spaced apart from one another along a central longitudinal axis of the container, and the body defines a cavity for containing the radioactive material. The container includes at least one radiation protection enclosure formed by enclosure wall elements, each radiation protection enclosure defining a single space with its enclosure wall elements, within which a radiation protection device is disposed.

[0009] According to the present invention, the radiation protection device comprises a plurality of prefabricated radiation protection blocks that are arranged successively in a given direction of the container, so that the prefabricated radiation protection blocks face each other in said direction within said single space.

[0010] Furthermore, at least some of the plurality of blocks are respectively held on at least one of the enclosure wall elements by at least one retaining member that cooperates with the block and at least one of the corresponding enclosure wall elements.

[0011] Finally, the plurality of prefabricated blocks define a plurality of inter-block gaps in the given direction within the single space, each inter-block gap being defined between two blocks arranged directly adjacent to each other in the given direction.

[0012] Advantageously, the present invention makes it possible to limit or prevent spacing between radiation protection blocks in a radiation protection enclosure in a simple manner, which has the effect of significantly reducing the risk of radiation leakage between these prefabricated blocks.

[0013] The presence of gaps between the blocks is not detrimental to the radiation protection function, since the retention members of these blocks ensure that accumulation remains limited or even reduced to zero, while the gaps between the blocks allow for thermal expansion of the prefabricated blocks without the risk of over-constraining the wall elements of the enclosure in which they are placed.

[0014] Furthermore, embodiments of the present invention advantageously allow the shape of the prefabricated radiation protection block to be kept simple and therefore inexpensive. Furthermore, retaining the block against the enclosure wall element via a retaining member is an easy and inexpensive solution to implement.

[0015] It should be noted that another advantage of the proposed solution is that it allows the positioning of prefabricated radiation protection blocks relative to the wall elements of the enclosure, which can be useful, for example, if the blocks are made using different materials and are appropriately positioned in the enclosure for a local adaptation to the observed radiation levels.

[0016] Finally, another advantage of the present invention is that it is possible to create a mechanical assembly of these elements from prefabricated components. Indeed, prefabricating the radiation protection block in parallel with the manufacture of other components of the container, such as the lid, side body, etc., makes it possible to reduce the manufacturing time of the container. In particular, there is no need to provide a resin casting step or to carry out a resin degassing treatment.

[0017] Furthermore, the present invention provides at least one of the following optional features, either alone or in combination:

[0018] According to a first preferred embodiment of the invention, a radiation protection enclosure is arranged in the lid and is formed by enclosure wall elements of the lid, the single space extending over a given angular amplitude along the circumferential direction of the enclosure and the container, and first prefabricated radiation protection blocks are arranged successively in the circumferential direction so as to face each other in said direction.

[0019] Furthermore, at least some of the plurality of first blocks are held in two directions, that is, in both longitudinal directions, relative to at least one of two enclosure wall elements of the lid that define a single space along the longitudinal direction of the enclosure and the container, by first holding members that are received in first orifices of the first blocks and also in first orifices made in at least one of the two corresponding enclosure wall elements.

[0020] Preferably, each first block held by a corresponding first holding member is further held by a second holding member, the second holding member being received in a second orifice of the first block and further received in a corresponding second orifice made in at least one of the two enclosure wall elements, Preferably, said second orifice in the first block is radially spaced from the first orifice in the first block.

[0021] Preferably, the first orifice and / or the second orifice in the first holding block have an elongated shape, and the length of the elongated shape is oriented radially or substantially radially. Preferably, only one of the two orifices, which is located radially farthest from the longitudinal central axis, has an elongated shape. This allows for thermal expansion of the first block in the radial direction. Alternatively, the elongated shape can be applied to both orifices, or only to the orifice radially closest to the longitudinal central axis of the container. Similarly, when each first block has only a first orifice and no second orifice, the first orifice can have an elongated shape extending radially or substantially radially.

[0022] If the orifice does not have an elongated shape, a circular shape is preferably used.

[0023] It should further be noted that in this first preferred embodiment and all other embodiments of the present invention, each orifice is either a blind hole or a through hole, while the retaining member is preferably a pin, rod, tie rod, bolt, rivet, or any other similar member.

[0024] According to one possibility realized by this first embodiment, the single space further accommodates second prefabricated radiation protection blocks, which are arranged consecutively in the circumferential direction and thus face each other in said direction. At least several of the second blocks are respectively held against at least one of the two enclosure wall elements of the lid by the first retaining members, which are received in first orifices of the second blocks and correspondingly in the first orifices made in at least one of the two enclosure wall elements. Furthermore, each first block covers the circumferential inter-block gaps between two immediately adjacent second blocks in the longitudinal direction, and vice versa.

[0025] Advantageously, this configuration allows for two longitudinal rows of stacked blocks, dramatically reducing leakage through gaps between the blocks. In this case, the same first retaining member is preferably used to retain both the first prefabricated block and the second prefabricated block, although a separate retaining member could be provided for the second block without departing from the scope of the present invention.

[0026] In this regard, it is noted that, like the first holding block, the second holding block can also be provided with second orifices, preferably having the same design as the first and second orifices of the first holding block.

[0027] It should be further noted that preferably, both the first block and the second block have the same design, and the second block is arranged in an inverted position relative to the position of the first block in the single space, which significantly reduces the manufacturing cost and the risk of assembly errors of the blocks in the radiation protection enclosure.

[0028] To achieve this, preferably, each of the first block and the second block has an imaginary radial centerline that defines two block portions on either circumferential side of the imaginary radial centerline, and the two block portions each have a retaining portion with a first orifice that is disposed along the imaginary radial centerline of the retaining portion. The same applies when a second orifice is provided in the first block and the second block.

[0029] Preferably, the single space extends circumferentially over an angular amplitude of 360°, but alternatively, it is possible to use multiple circumferentially divided enclosures to replicate 360° radiation protection, each enclosure extending over an angular amplitude of less than 360° and housing its own radiation protection device in accordance with the principles of the present invention.

[0030] Thus, in this first preferred embodiment of the invention, the first blocks form a ring using blocks that form an angular sector of the ring, and these blocks are, in at least some instances, spaced apart from one another by a circumferential inter-block gap, and the same is true for the second blocks, which are preferably arranged in phase opposition to the first blocks, thereby covering the circumferential inter-block gap.

[0031] The following preferred embodiment applies to a radiation protection enclosure arranged around a cavity for containing radioactive material.

[0032] According to a second preferred embodiment of the invention, the enclosure wall elements are arranged around a central longitudinal axis, and said single space extends over a given height along the longitudinal direction of the container, with the prefabricated radiation protection blocks being arranged consecutively in the longitudinal direction and facing each other in said direction.

[0033] Furthermore, at least some of the blocks are held against at least one of two enclosure wall elements, which define the single space in each of the two radial directions of the enclosure and the container, said holding being achieved by holding elements housed in orifices in the blocks and in orifices made in at least one of the two corresponding enclosure wall elements.

[0034] Preferably, the two enclosure wall elements define an inner shroud and an outer shroud, respectively, about the central longitudinal axis, the inner shroud being disposed around or formed by the vessel side body.

[0035] Preferably, immediately adjacent blocks in the longitudinal direction partially overlap each other in the radial direction to suppress radiation leakage in said radial direction. An alternative is to provide two longitudinal rows of blocks overlapping each other in the radial direction, so that the same or similar principles as those described for the first preferred embodiment can be realized with said first and second blocks.

[0036] According to a third preferred embodiment of the present invention, a radiation protection enclosure comprises two longitudinally stacked enclosure wall elements, each in the form of an annular structure. Each annular structure is centred on the central longitudinal axis and comprises a radially outer portion and a radial portion extending radially from the radially outer portion towards the central longitudinal axis and defining the single space in the longitudinal direction. The annular structures define openings on opposite sides of the radial portion in the longitudinal direction, which openings are sealed by the radial portions of the other stacked annular structures.

[0037] Furthermore, the single space extends over a given angular amplitude along the circumferential direction of the enclosure and the container, and the first prefabricated radiation protection blocks are arranged consecutively in the circumferential direction, thereby facing each other in said direction. At least some of the first blocks are held against at least one of two enclosure wall elements in the form of annular structures. This holding is achieved by first holding elements that are housed in orifices of the first blocks and in corresponding first orifices made in at least one of the two wall elements, preferably in a radial portion of this at least one.

[0038] According to one possibility realized by this third preferred embodiment of the present invention, the single space further accommodates second prefabricated radiation protection blocks, which are arranged consecutively in the circumferential direction and thus face each other in said direction. At least some of the second blocks are respectively held against at least one of two enclosure wall elements in the form of annular structures by second retaining elements, which are housed in orifices of the second blocks and in corresponding second orifices made in at least one of the two wall elements, preferably in a radial portion of the at least one. Furthermore, each first block covers the circumferential inter-block gap between two immediately adjacent second blocks in the radial direction, and vice versa.

[0039] The first and / or second retaining members implemented in this third embodiment may be of the type described above, preferably in the form of pins or penetrating rods, in the latter case each of which is capable of penetrating each of the blocks of a plurality of radiation-protective enclosures arranged successively along the length of the container.

[0040] Other advantages and features of the present invention will become apparent in the following non-limiting detailed description.

[0041] This description is made with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a schematic longitudinal section of a container for transporting and / or storing radioactive material according to the present invention; FIG. [Figure 2] 2 is a plan view of the lid of the container shown in FIG. 1 in the form of a first preferred embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4]FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 1 is a plan view of one of the first prefabricated radiation protection blocks implemented in a first preferred embodiment of the present invention. [Figure 7] FIG. 10 is a plan view of one of the second prefabricated radiation protection blocks implemented in the first preferred embodiment of the present invention. [Figure 8] FIG. 2 is a partial longitudinal cross-sectional view of a container according to a second preferred embodiment of the present invention. [Figure 9] 9 is a cross-sectional view of a container presented as an alternative to the second embodiment of FIG. 8. [Figure 10] 10 is a partial longitudinal half-section of a container according to a third preferred embodiment of the present invention, which corresponds to the cross section along line XX in FIG. [Figure 11] FIG. 11 is a partial cross-sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 12 is a partial perspective view of one of the annular structures forming one of the radiation protection enclosures on the vessel shown in FIGS. 10 and 11. [Figure 13] 13 is a cross-sectional view of a container presented as an alternative to the third embodiment of FIGS. 10-12. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0043] Referring initially to Figure 1, there is shown a vessel 1 for transporting and / or storing radioactive material, such as nuclear fuel assemblies 3 or radioactive waste (shown only partially and diagrammatically in Figure 1).

[0044] The container 1 is shown in a vertical storage / preservation position, with its central longitudinal axis 2 oriented vertically. The container 1 has a container bottom 4 as its bottom, which is located opposite a removable lid 6 along a height direction 8 parallel to the central longitudinal axis 2. Thus, the height direction 8 shown schematically in FIG. 1 corresponds to the longitudinal direction of the container, its radial direction is indicated by arrow 11, and its circumferential / tangential direction is indicated by arrow 13. These directions 8, 11, 13 relate not only to the container 1 as a whole, but also to each component of the container 1, and in particular to the radiation protection enclosure described below.

[0045] The container 1 comprises a side body 10 extending about an axis 2 between a bottom 4 and a lid 6, the side body 10 defining a cavity 12 therein for containing radioactive material 3. The cavity 12 can form a containment enclosure intended to receive the radioactive material, for example placed in a storage basket which is also placed in the containment enclosure. Alternatively, the containment enclosure is entirely constituted by a case, also known as a "canister", placed in the aforementioned cavity 12. The canister is closed axially at the top by a lid 6 and at the bottom by a bottom 4. The bottom 4 can be made as a single piece together with the side body 10 of the container. These elements 4, 6 and 10 form the container body and are designed to maintain the airtightness of the containment enclosure by ensuring the mechanical strength of the container, especially in the event of a fall.

[0046] Furthermore, the vessel 1 comprises a radiation protection enclosure 14 around its periphery and around the axis 2, which defines an annular space, within which a neutron protection device 16 is disposed. This device 16 may be conventional or may be in accordance with the principles of the present invention, as will be described in detail below in the second preferred embodiment of the present invention. It should be noted that the enclosure 14 is formed using a number of enclosure wall elements that define the annular space 15, specifically an inner shroud 20 and an outer shell 22 centered around the axis 2. Here, the inner shroud 20 is an additional portion around the periphery of the vessel's side body 10, although alternatively, the inner boundary of the annular space 15 could be formed directly by the outer surface of the side body 10. Furthermore, the outer shell 22 forms the lateral periphery of the vessel 1.

[0047] The radiation protection device 16 here is a neutron protection device, which is made, for example, using prefabricated blocks stacked along the direction 8 in the annular space 15. Each prefabricated radiation protection block is preferably made from a casting resin. The resin may contain boron or any other neutron-eating or neutron-absorbing element. By "neutron-absorbing element" is meant an element whose effective cross section for thermal neutrons is greater than 100 barns.

[0048] The elements 10, 20, 22 of the vessel may be metallic, for example made of steel or cast iron. Preferably, no heat conductors other than protective blocks are provided in the annular space 15, also called the intershroud space. This particular example corresponds to a vessel intended for the transport of radioactive materials that emit little or no heat power. By "thermal conductor" is meant a conductor conventionally implemented in the vessel, which generally alternates with neutron protective blocks and connects the inner shroud 20 to the outer shell 22. However, heat conductors in the form of annular disks are also conceivable. In this case, the blocks alternate with the heat conducting disks in the direction 8.

[0049] The lid 6 is provided with another radiation protection enclosure 24, which here is the only one provided inside the lid and which defines a single annular space 26 centered on the axis 2. In this space 26, which is in the form of a ring, a neutron protection device 28 is arranged, which is specific to the present invention and is the subject of a first preferred embodiment of the invention.

[0050] 1-7 collectively, the enclosure 24 of the first embodiment is formed using multiple wall elements of the lid, specifically an inner cowl 30 and an outer cowl 32. The inner cowl 30 and the outer cowl 32 are spaced apart from each other along direction 8 and are orthogonal to said direction 8. The cowls 30, 32 may form the axially inner and outer walls of the lid, respectively, or may be housed within the lid. Other enclosure wall elements are provided to radially enclose a single annular space 26, thus extending continuously through 360° around axis 2, which is also the center of the lid 6. Alternatively, multiple radiation-protective enclosures in the form of individual angular sectors may be arranged adjacent to each other along the circumferential direction 13 without departing from the scope of the present invention. In such an example, each single space 26 corresponding to a given enclosure 24 extends along the circumferential direction 13 with an angular amplitude of less than 360°.

[0051] The radiation protection device 28 is a neutron protection device and is produced using prefabricated radiation protection blocks 30a, 30b. Each prefabricated block 30a, 30b is preferably made from a casting resin. A final cut is then made in the casting resin, for example with a water jet, to set their size. This resin may contain boron or any other neutron-eating element in the sense described above.

[0052] The enclosure wall elements 30, 32 of the vessel lid may be metallic, for example made of steel or cast iron. Preferably, no heat conductors other than the protective blocks are provided within a single annular space 26 in the form of a ring centered on the axis 2. Preferably, this space 26 is occupied only by the blocks 30 a, 30 b and their retaining members, which will be described hereinafter.

[0053] In this first preferred embodiment of the invention, the blocks are distinguished into a first block 30a forming a first annular row of blocks centered on the axis 2, and a second block 30b forming a second annular row of blocks centered on the axis 2. In this case, each of these two rows of blocks corresponds to a ring formed by a number of blocks, each block forming an angular sector of said ring, which are superimposed on each other inside the space 26 along the direction 8. In these figures, the row of first blocks 30a corresponds to the row located furthest from the cavity 12 for containing radioactive material.

[0054] Thus, for this annular row of first blocks 30a, these first blocks 30a are arranged consecutively along the circumferential direction 13 and face each other in said direction within a single space 26. At least some of these first blocks 30a define circumferential inter-block gaps 34 between them, each gap 34 corresponding to the space left empty between two immediately successive blocks 30a along the direction 13. Preferably, such gaps 34 are provided on both sides of each block 30a of the device 28, although it is also possible for some blocks to be in contact with each other in the direction 13 without departing from the scope of the invention.

[0055] Preferably, all first blocks 30a are identical or substantially identical. Typically, each block 30a is made from a single piece of angular sector shape, extending over an amplitude of, for example, 15 to 45 degrees and flat along direction 8.

[0056] One feature of the present invention is that it provides a means for limiting / preventing the circumferential spacing between adjacent first blocks 30 a, and thus preventing the accumulation of such spacing from resulting in unacceptable levels of neutron leakage between two immediately adjacent blocks 30 a. In other words, the present invention provides a practical solution that makes it possible to maintain all or part of the inter-block gap 34 and ensure that, if spacing between adjacent blocks accumulates, the degree of accumulation remains controlled and acceptable.

[0057] For this purpose, a number of first blocks 30a, or preferably all or almost all of the first blocks 30a, are held on at least one of the two cowls 30, 32 that define the space 26 along the direction 8, in both directions of this direction 8, i.e. above and below. This implementation, in addition to limiting the risk of accumulation of circumferential inter-block gaps 34, makes it possible to maintain and preserve the positioning of these blocks 30a relative to the other elements 30, 32 of the lid, by connecting these blocks 30a to one or both cowls 30, 32 of the lid.

[0058] For each first block 30a in question, it is held by a first retaining member 36a housed in a first orifice 38a of this first block and also housed in a first orifice 40a made in at least one of the two cowls 30, 32. Preferably, the retaining member 36a is a pin of circular cross section oriented along direction 8. The retaining member 36a is fixed at its two ends in the orifices 40a relative to the two cowls 30, 32 and passes, with or without a gap, through the first orifice 38a of the block 30a.

[0059] Preferably, the first holding member 36a is disposed near the radially inner end of the block 30a, which makes it possible to suppress / prevent the two first blocks 30a located on both sides in the circumferential direction 13 from moving relative to each other in the circumferential direction.

[0060] To strengthen the retention and positioning of each of these first blocks 30a held by the first member 36a, each block is further retained by a second retaining member 36b housed in a second orifice 38b of this first block and housed in a second orifice 40b made in each of the two cowls 30, 32. The second orifice 38b passing through the block 30a is radially spaced from the first orifice 38a and located near the radially outer end of this block. The second orifice 38b therefore takes the form of a pin with a circular cross section that is completely penetrated by the second retaining member 36b and is preferably oriented along direction 8. This second retaining member 36b is fixed at its two ends in the orifices 40b relative to the two cowls 30, 32 and passes through the second orifice 38b of the block 30a with a gap. The second orifice 38b is shaped to have a long radial or substantially long radial length, which allows the block 30a to thermally expand along the radial direction 11.

[0061] As described above, all of the first blocks 30a have the same or substantially the same design, which facilitates their manufacture. As shown in FIG. 6, the first block 30a has an imaginary radial centerline 42 that defines, on either side in the direction 13, a solid portion 44 and a retaining portion 46 having two orifices 38a, 38b. These two portions 44, 46 form two block half-sectors with the same angular amplitude. Two through holes 38a, 38b, whose axes are perpendicular to the plane inscribed by the ring sector 30a, are arranged along the imaginary radial centerline 48 of the retaining portion 46.

[0062] This special design allows block 30a to be inverted to form a second block 30b for forming a second annular row. The positions of the retaining orifices in second block 30b are inverted relative to the positions of the retaining orifices in first block 30a. In fact, as can be seen in Figure 7, which shows second block 30b in plan view, the positions of solid portion 44 and retaining portion 46 are inverted in direction 13.

[0063] Therefore, all blocks 30a, 30b of the radiation protection device 28 have the same or substantially the same design, and only their position differs depending on whether the block belongs to the first annular radiation protection row or the second annular radiation protection row.

[0064] With respect to the annular row of second blocks 30b, these second blocks 30b are arranged consecutively along the circumferential direction 13 and also face each other in said direction within a single space 26. At least some of these second blocks 30b define circumferential inter-block gaps 50, each gap 50 corresponding to the space left empty between two immediately successive blocks 30b along the direction 13. Preferably, such gaps 50 are provided on both sides of each block 30b of the device 28, although it is also possible for some blocks 30b to be in contact with each other in the direction 13 without departing from the scope of the invention.

[0065] In order to limit / prevent circumferential spacing between adjacent second blocks 30b, and thus to prevent the accumulation of such spacing resulting in an unacceptable level of neutron leakage between two directly adjacent blocks 30b, a plurality of second blocks 30b, or preferably all or substantially all of the second blocks 30b, are configured to be respectively held on at least one of the two cowls 30, 32. With respect to each second block 30b, it is now held by a first holding member 36a received in the first orifice 58a of that second block, passing through the first orifice 38a of one of the adjacent first blocks 30a in direction 8 and aligned with this first orifice 38a.

[0066] Furthermore, the second block 30b is held by a second holding member 36b, which passes through a second orifice 58b of the second block, which is aligned with a second orifice 38b of one of the adjacent first blocks 30a in direction 8. Again, this passage is achieved with a gap in the radial direction 11, because the second orifices 58b of the blocks 30b have the same shape with a long length oriented in the radial or substantially radial direction.

[0067] Thus, a first block 30 a in the first annular row is circumferentially offset from a second block 30 b in the second annular row that it covers in the axial direction. This offset corresponds to half the angular amplitude of each of these blocks 30 a, 30 b, resulting in a so-called “out-of-phase” arrangement of the two rows. Thus, with this arrangement, each first block 30 a covers one of the inter-block gaps 50 between two immediately consecutive second blocks 30 b in the second row in direction 8, in the same way that each second block 30 b covers one of the inter-block gaps 34 between two immediately consecutive first blocks 30 a in the first row, also in direction 8.

[0068] According to a second preferred embodiment of the present invention, shown in FIG. 8, the principles of the present invention are implemented around a cavity 12 for containing radioactive material, i.e., in the aforementioned enclosure 14. In this case, the enclosure 14 is formed using a plurality of enclosure wall elements, which define an annular space 15 and are arranged about the axis 2. In particular, this involves an outer shell 22 and side bodies 10, each of which is shrouded in shape, defining a single annular space 15 in both directions in the radial direction 11. Alternatively, as explained with reference to FIG. 1, an inner shroud can be arranged around the side bodies 10 to define the space 15 in the radial direction. Preferably, this single annular space 15 extends over the entire height of the cavity 12 in the direction 8. However, while maintaining the principles of the second preferred embodiment described hereinafter, it is also possible for enclosure 15 to be divided in direction 8 and / or direction 13 to form multiple adjacent enclosures along one and / or the other of these two directions.

[0069] The prefabricated radiation protection blocks 60 are arranged successively along direction 8 and face each other in said direction. Each block takes the form of a thin ring that is arranged successively along direction 8 while leaving longitudinal inter-block gaps 62 between them. Each inter-block gap 62 corresponds to the space left empty between two blocks 60 that are directly adjacent in direction 8. Preferably, such gaps 62 are provided on both sides of each block 60 of device 16, although it is also possible for several blocks to be in contact with each other in direction 8 without departing from the scope of the invention.

[0070] Even in this case, preferably, all first blocks 60 are identical or substantially identical. Typically, each block 60 is made from a single piece, and the half cross section of each block has a substantially Z-shape, with its central arm oriented along direction 11 and its two other arms oriented perpendicular to direction 11 and along direction 8. This particular shape allows directly successive blocks 60 to partially overlap each other in radial direction 11, thereby suppressing radiation leakage.

[0071] At least some of the blocks 60, i.e., for example, all or most of the blocks 60, or for example, each of two blocks 60, are held on the outer shell 22 by retaining members 36 in the form of pins received in orifices 38 of the blocks 60 and also in orifices 40 made in the outer shell 22. The pins 36 can be fixed in the orifices 40, which preferably extend through the outer shell 22, and the other ends of the pins 36 are received in orifices 38, which are preferably blind holes, of the blocks 60, either fixed or simply inserted therein. The pins 36 and their corresponding orifices 38, 40 are preferably oriented along or substantially along the radial direction 11.

[0072] According to an alternative form of the second preferred embodiment shown in FIG. 9 , the single annular space 15 is filled with blocks 60, each of which extends over the entire height of the space and thereby defines a single angular sector. The blocks 60 thus replicate a ring about the axis 2 and are arranged successively along the direction 13, defining circumferential inter-block gaps 62 between them. Again, the blocks 60 are preferably identical or substantially identical. Typically, each block 60 is made from a single piece and has a generally Z-shaped cross section, with its central arm oriented along the direction 11 and two other arms oriented perpendicular to the direction 11 and along the direction 13. This particular shape allows immediately successive blocks 60 to partially overlap each other in the radial direction 11, thereby suppressing radiation leakage.

[0073] At least some of the blocks 60 are held in the same or similar manner as disclosed above, with the pins 36 extending radially through holes 38, 40 in the blocks 60 and the outer shell 22, respectively.

[0074] According to a third preferred embodiment of the present invention shown in Figures 10 to 12, the principles of the present invention are still implemented around a cavity 12 for containing radioactive material, but with a reduced height of a radiation protection enclosure 14a in the form of a ring around the cavity 12.

[0075] In practice, a number of different annular enclosures 14a are arranged successively in direction 8 along cavity 12. Each of these annular enclosures is formed essentially using two enclosure wall elements 64, each in the form of an annular structure, stacked one on top of the other in direction 8. The stacked enclosures 14a extend over the entire height of cavity 12 or substantially over this entire height.

[0076] Each annular structure 64 is centered on axis 2 and comprises a radially outer portion 66, a radially inner portion 68, and a radial portion 70 extending radially from the radially outer portion to the radially inner portion 68. The substantially U-shaped half-section of an annular structure 64 defines an opening 71 on the opposite side of the radial portion 70 in direction 8, which opening 71 is sealed by the radial portion 70 of the annular structure 64 arranged immediately adjacent to it. Thus, annular space 15a is radially bounded in both directions by the two walls 66, 68 of one of the annular structures 64, respectively, and axially bounded in both directions by the radial portion 70 of said structure 64 and the radial wall 70 of the structure 64 arranged immediately adjacent to it in the form of a stack in direction 8, respectively.

[0077] Alternatively, each annular structure 64 may not include a radially inner portion 68 and thus have a generally L-shaped half-section. In this case, the radially inner definition of each annular space 15a is achieved by the radially outer surface of the container side body 10. Similarly, it should be noted that although the radial portion 70 is shown as planar, it may also include a step along direction 8.

[0078] It is also possible for any two annular structures 64 directly adjacent in direction 8 to be divided along the circumferential direction 13, provided that they also form a single space 15a of annular shape, without departing from the scope of the present invention.

[0079] The radiation protection device 16a housed in the space 15a of each enclosure 14a is also made up of blocks, here a first block 72a and a second block 72b, which are each intended to form a concentric annular row around the axis 2. Preferably, both the first block 72a and the second block 72b have the same or substantially the same shape, for example being approximately parallelepiped or having a shape that is slightly curved along the circumferential direction to match the curvature of the single space 15a along said circumferential direction.

[0080] More specifically, the first prefabricated radiation-shielding blocks 72a form an inner row and are successively arranged in direction 13 so as to face each other in said direction, thereby forming a plurality of circumferential inter-block gaps 74 in the same direction as described above. Similarly, the second prefabricated radiation-shielding blocks 72b form an outer row and are successively arranged in direction 13 so as to face each other in said direction, thereby forming a plurality of circumferential inter-block gaps 76 as shown in FIG.

[0081] To ensure the retention of some or all of the first blocks 72a, each of the first blocks 72a is held against the radial portion 70 of the annular structure 64 on which it is located by a first retaining pin 78a. The first retaining pin 78a is received in an orifice 80 of the block 72a and also in a first orifice 82a made in the radial portion 70 and opening into the single annular space 15a. The first pin 78a can be fixed or simply inserted into each of the two orifices 80, 82a, which are preferably blind holes.

[0082] Preferably, the pin 78a and corresponding orifices 80, 82a in the bottom of the space 15a are oriented along or substantially along the longitudinal direction 8.

[0083] Similarly, to ensure the retention of several or all of the second blocks 72b, each second block 72b is held against the radial portion 70 of the annular structure 64 on which it is located by a second retaining pin 78b. The second retaining pin 78b is received in an orifice 80 of the block 72b and also in a second orifice 82b made in the radial portion 70. Again, the second pin 78b can be fixed or simply inserted into each of these two corresponding orifices 80, 82b, which are preferably blind holes. Preferably, the second pin 78b in the bottom of the space 15a and the two corresponding orifices 80, 82b are also oriented along or substantially along the longitudinal direction 8.

[0084] The first blocks 72 a in the first annular row are circumferentially offset from the second blocks 72 b in the second annular row. This offset corresponds to half the angular amplitude of each of these blocks 72 a, 72 b, resulting in a so-called “out-of-phase” arrangement of the two rows. This arrangement therefore results in each first block 72 a covering one of the inter-block gaps 76 between two immediately consecutive second blocks 72 b in the second row in direction 11, in a similar manner to how each second block 72 b covers one of the inter-block gaps 74 between two immediately consecutive first blocks 72 a in the first row, also in direction 11.

[0085] According to an alternative embodiment shown in FIG. 13, a single first penetrating rod 84a oriented along direction 8 is used to hold the first blocks 72a of multiple stacked enclosures 14a. In fact, this rod 84a penetrates multiple first blocks 72a aligned along direction 8 and belonging to different enclosures 14a. The rod 84a may also penetrate the first blocks of all annular enclosures 14a constituting the vessel 1. In this case, at least some of the orifices 80, 82a are open so that the rod 84a can pass through. Thus, multiple first rods 84a of this type can cooperate with the blocks 72a of the first row.

[0086] One or more second through rods (not shown) of the same type may be implemented to hold the second blocks 72b of the second annular row.

[0087] Naturally, those skilled in the art may make various modifications to the embodiments of the invention described solely as non-limiting examples, within the scope defined by the appended claims. In particular, the various preferred embodiments described above may be combined, while their features remain compatible. For example, a solution involving blocks partially overlapping each other within the same column may be replaced by a solution in which blocks from two different columns overlap each other, and vice versa. [Explanation of symbols]

[0088] 1 container 2. Longitudinal central axis 3 Nuclear fuel assembly, radioactive material 4 Bottom of container, bottom 6 Detachable lid, lid 8 Height direction, length direction 10 Side body 11 Radial direction 12 Cavity 13 Circumferential / Tangential 14 Radiation Protection Enclosure 14a Radiation protection enclosures, annular enclosures 15 Annular Space 15a Annular Space 16 Neutron protection devices, radiation protection devices 16a Radiation protection devices 20 Inner Shroud 22 outer shell 24 Radiation Protection Enclosure 26 Single annular space 28 Neutron protection devices, radiation protection devices 30 Inner cowl 30a First Block, First Prefabricated Radiation Protection Block 30b Second Block, Second Prefabricated Radiation Protection Block 32 Outer cowling 34 Interblock gap 36 Retaining member, pin 36a first holding member 36b Second holding member 38 Orifice, hole 38a First orifice 38b Second orifice 40 Orifice, hole 40a First orifice 40b Second orifice 42 Imaginary radial centerline 44 Solid part 46 Holding part 48 Imaginary radial centerline 50 Block Gap 58a First Orifice 58b Second orifice 60 Prefabricated Radiation Protection Blocks, First Block 62 Interblock gap 64 Enclosure wall element, annular structure 66 Radial outer part 68 Radial inner part 70 Radial section 71 Aperture 72a 1st Block, 1st Prefabricated Radiation Protection Block 72b Second Block, Second Prefabricated Radiation Protection Block 74 Interblock gap 76 Interblock gap 78a First retaining pin 78b Second retaining pin 80 Orifice 82a First Orifice 82b Second orifice 84a First through rod

Claims

1. A container (1) for transporting and / or storing radioactive material, the container comprising a container body formed by a side body (10), a bottom (4), and a removable lid (6), the bottom and the lid being spaced apart from one another along a central longitudinal axis (2) of the container, the body defining a cavity (12) for containing the radioactive material (3), the container comprising at least one radiation protection enclosure (14, 14a, 24) formed by enclosure wall elements (20, 22, 30, 32, 64), each radiation protection enclosure defining a single space (15, 15a, 26) by its enclosure wall elements, and a radiation protection device (16, 16a, 28) disposed within the single space (15, 15a, 26), the radiation protection device comprises a plurality of prefabricated radiation protection blocks (30a, 30b, 60, 72a, 72b), the prefabricated radiation protection blocks (30a, 30b, 60, 72a, 72b) being arranged successively in a given direction (8, 13) of the container so as to face each other in said direction within the single space (15, 15a, 26); at least some of the plurality of blocks (30a, 30b, 60, 72a, 72b) are respectively held on at least one of the enclosure wall elements (20, 22, 30, 32, 64) by at least one retaining member (36, 36a, 36b, 78a, 78b, 84a) cooperating with the block and the at least one of the corresponding enclosure wall elements; The plurality of prefabricated blocks define a plurality of inter-block gaps (34, 50, 62, 74, 76) in the given direction (8, 13) within the single space, each inter-block gap being defined between two blocks arranged directly adjacent to each other in the given direction. A container characterized by:

2. the radiation protection enclosure (24) is arranged in the lid (6) and is formed by enclosure wall elements (30, 32) of the lid, the single space (26) extending over a given angular amplitude along the circumferential direction (13) of the container, and first prefabricated radiation protection blocks (30 a) are arranged successively in the circumferential direction (13) so as to face each other in said direction; At least some of the plurality of first blocks (30a) are held in two directions, that is, in both directions of the longitudinal direction (8), relative to at least one of the two enclosure wall elements (30, 32) of the lid that define the single space (26) along the longitudinal direction (8) of the enclosure and the container, and the holding is realized by a first holding member (36a), which is received in a first orifice (38a) of this first block and also in a first orifice (40a) made in at least one of the two corresponding enclosure wall elements (30, 32). The container according to claim 1, characterized in that

3. 3. The container according to claim 2, characterized in that each first block (30a) held by a corresponding first holding member (36a) is further held by a second holding member (36b), the second holding member (36b) being housed in a second orifice (38b) of this first block and further housed in a second orifice (40b) made in at least one of the two corresponding enclosure wall elements (30, 32), preferably the second orifice (38b) in the first block being radially spaced from the first orifice (38a) in this first block.

4. 4. A container according to claim 2 or claim 3, characterized in that the first orifice and / or the second orifice (38b) in the first holding block (30a) have an elongated shape, the length direction of the elongated shape is oriented radially or substantially radially, and preferably only one of the two orifices, which is located radially farthest from the longitudinal central axis (2), has an elongated shape.

5. the single space (26) further accommodates second prefabricated radiation protection blocks (30b), the second prefabricated radiation protection blocks (30b) being arranged successively in the circumferential direction (13) so as to face each other in the circumferential direction; at least a plurality of the second blocks (30b) are held against at least one of the two enclosure wall elements (30, 32) of the lid by the first retaining members (36a), the first retaining members (36a) being received in the first orifices (58a) of the second blocks and further received in the first orifices (40a) made in at least one of the corresponding two enclosure wall elements (30, 32); Each first block (30a) covers an inter-block gap (50) in the circumferential direction (13) between two immediately adjacent second blocks (30b) in the longitudinal direction (8), and vice versa.

5. A container according to any one of claims 2 to 4, characterized in that

6. 6. The container according to claim 5, wherein both the first block and the second block (30a, 30b) have the same design, and the second block (30b) is arranged in an inverted position relative to the position of the first block (30a) within the single space (26).

7. 7. The container according to claim 6, wherein each of the first block and the second block has an imaginary radial centerline, the imaginary radial centerline defining two block portions on either circumferential side of the imaginary radial centerline, and the two block portions each have a retaining portion including the first orifice, the first orifice being disposed along the imaginary radial centerline of the retaining portion.

8. 8. A container according to any one of claims 2 to 7, characterized in that the single space (26) extends over an angular amplitude of 360° in the circumferential direction (13).

9. 2. The container according to claim 1, characterized in that the radiation protection enclosure (14, 14a) is arranged around the cavity for containing the radioactive material.

10. the enclosure wall elements (10, 22) are arranged around the longitudinal central axis (2), the single space (15) extends over a given height along the longitudinal direction (8) of the container, and prefabricated radiation protection blocks (60) are arranged successively in the longitudinal direction (8) so as to face each other in said direction; At least some of the blocks (60) are held against at least one of two enclosure wall elements (20, 22), which define the single space (15) in each of the two radial directions (11) of the enclosure and the container, and the holding is achieved by holding elements (36), which are housed in orifices (38) of the blocks and in corresponding orifices (40) made in at least one of the two enclosure wall elements (20, 22).

10. The container according to claim 9,

11. Container according to claim 10, characterized in that the two enclosure wall elements (20, 22) form an inner shroud and an outer shroud, respectively, centered on the central longitudinal axis (2).

12. Container according to claim 10 or 11, characterized in that the blocks (60) that immediately follow each other in the longitudinal direction (8) partially overlap each other in the radial direction.

13. the radiation protection enclosure (14a) comprises two enclosure wall elements (64) each in the form of an annular structure stacked along the longitudinal direction (8), each annular structure (64) having a center on the longitudinal central axis having a radially outer portion (66) and a radial portion (70) extending radially from the radially outer portion toward the longitudinal central axis (2) and defining the single space (15a) in the longitudinal direction (8), the annular structure (64) defining an opening (71) on the opposite side of the radial portion (70) in the longitudinal direction, the opening (71) being sealed by the radial portion (70) of the other annular structure (64); the single space (15a) extends over a given angular amplitude along a circumferential direction (13) of the enclosure and the container, and the first prefabricated radiation protection blocks (72a) are arranged successively in the circumferential direction, thereby facing each other in the circumferential direction; At least some of the first blocks (72a) are held against at least one of the two enclosure wall elements (64) in the form of an annular structure, said holding being achieved by first holding members (78a, 84a) housed in orifices (80) of the first blocks and in corresponding first orifices (82a) made in at least one of the two wall elements (64), preferably in the radial portion (70) of said at least one.

10. The container according to claim 9,

14. the single space (15a) further accommodates second prefabricated radiation protection blocks (72b), the second prefabricated radiation protection blocks (72b) being arranged successively in the circumferential direction (13) so as to face each other in the circumferential direction; at least some of the second blocks (72b) are held against at least one of the two enclosure wall elements (64) in the form of an annular structure by second holding members (78b), the second holding members (78b) being housed in orifices (80) of the second blocks and in second orifices (82b) made in at least one of the corresponding wall elements (64), preferably in the radial portion (70) of the at least one of the wall elements (64); Each first block (72a) covers an inter-block gap (76) in the circumferential direction (13) between two immediately adjacent second blocks (72b) in the radial direction (11), and vice versa. Container according to claim 13, characterized in that

15. Container according to claim 13 or 14, characterised in that the first and / or second retaining members (78a, 78b, 84a) are in the form of pins or through-rods.

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