Package for transporting and / or storing radioactive materials, comprising a radiological protection device reducing risks of radiological leaks

Abstract

The present invention relates to a package for transporting and / or storing radioactive material (3), and to a package comprising a cavity (12) for receiving radioactive material and a radioactive protection device (14) comprising a radioactive protection element (16) arranged in an annular space (18). According to the present invention, a locking member (32) is provided that is associated with at least two consecutive radiation protection elements (16) along a given direction of an annular space from the longitudinal direction (8) and the circumferential direction (28), and is designed to limit / prevent the distancing of the two radiation protection elements (16) from each other in the given direction.

Description

Technology Field

[0001] The present invention relates to the field of packages for the transport and / or storage of radioactive materials, for example, nuclear fuel assemblies or radioactive waste.

[0002] More specifically, the present invention relates to a package comprising a radiation protection device formed by a plurality of individual elements, for example, a cast resin radiation protection element. Background Technology

[0004] It is known from the prior art to provide a package equipped with a radiation protection device arranged around a cavity for exhausting radioactive material. The function sought by this device is protection against gamma rays, and / or neutron absorption in the lateral aspect to meet regulatory radiation standards around the package when radioactive material is loaded in the package.

[0005] To this end, one solution consists of inserting a radiation protection element into an annular space centered on the longitudinal axis of the package. These elements typically take the form of blocks, which can be inserted into the annular space due to a cold gap. Furthermore, since this cold gap allows for the thermal expansion of the radiation protection material, the thermomechanical stress of these blocks on the portion of the package defining the annular space is limited.

[0006] During transport operations performed with this type of package, radiation protection elements may move and slide relative to each other in an annular space. Cumulative movement between these elements can result in gaps of unacceptable values ​​regarding localized radiation leakage between two adjacent elements.

[0007] Therefore, to compensate for the aforementioned disadvantages, it is necessary to optimize the design of the existing package. means of solving the problem

[0009] To meet these requirements, the present invention relates to a transport and / or transport package for radioactive material, comprising a cavity for receiving radioactive material and a radiation protection device arranged around the cavity for receiving radioactive material in an annular space centered on the longitudinal central axis of the package, wherein the radiation protection device comprises a radiation protection element arranged in the annular space.

[0010] According to the present invention, at least two consecutive radioactive protection elements are associated in a given direction of an annular space from the longitudinal and circumferential directions of the annular space, and a locking member is provided designed to limit / prevent distancing between the two radioactive protection elements in a given space, wherein the locking member is coupled to or integrated with a first element in the radioactive protection elements and cooperates with a hollow formed on a second element in the two radioactive protection elements.

[0011] The present invention advantageously enables limiting the spacing between radiation protection elements in the annular space of the package, thereby substantially reducing the risk of radiation leakage between these radiation protection elements.

[0012] In addition, the present invention has at least one of the following optional features taken alone or in combination.

[0013] According to a preferred embodiment of the present invention, the locking member is integral with the first radiation protection element.

[0014] Preferably, the locking member is a long linear member, and preferably has a cross-section in the shape of a cut disc, square, or trapezoid. Other shapes may obviously be selected without departing from the scope of the invention.

[0015] Preferably, the long linear locking member extends orthogonally or substantially perpendicularly to the given direction.

[0016] According to a further preferred embodiment of the present invention, the locking member is a part separated from the first and second radiation protection elements, and the locking member also cooperates with the hollow formed on the first radiation protection element.

[0017] Preferably, the locking member is a part smaller in size than the first and second radiation protection elements, and is preferably made of a different material.

[0018] Preferably, the locking member is a pin, a key, or a clip.

[0019] Preferably, the locking member extends only to a portion of the radial thickness of the annular space.

[0020] According to a preferred embodiment of the present invention, the first and second radiation protection elements are directly continuous in the given direction in a single annular row of radiation protection elements.

[0021] According to a more preferred embodiment of the present invention, the first and second radiation protection elements each belong to two concentric annular rows of radiation protection elements, and the first and second radiation protection elements are partially overlapped radially in an annular space and are offset circumferentially from each other.

[0022] Preferably, the locking member is located at the level of the radially overlapping zone of the first and second radiation protection elements.

[0023] Preferably, the annular space is defined by an inner ferrule and an outer casing. In this regard, the inner ferrule may form all or part of the side body of the package, and in practice, this inner ferrule may be additionally provided to the side package body to define the boundary of the cavity for accommodating radioactive material.

[0024] Preferably, the annular space does not have a heat conductor connecting the inner ferrule to the outer casing.

[0025] Preferably, the radiation protection element is a neutron protection element, preferably a cast resin block.

[0026] Preferably, at least one radiation protection element of a radiation protection device, and preferably several of these elements, or even each of these, are associated with two locking members designed to limit / prevent its distancing in the same given direction for each of two radiation protection elements located on both sides thereof in the same given direction.

[0027] Further advantages and features of the present invention will be shown in the following non-limiting detailed description. Brief explanation of the drawing

[0029] Refer to the attached drawings for the description, here; FIG. 1 shows a schematic longitudinal axial cross-sectional view of a package for transporting and / or storing radioactive material according to a preferred embodiment of the present invention; FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1; FIG. 3 shows a perspective view of a radiation protection element used in the package illustrated in FIG. 1 and FIG. 2; FIG. 4 shows a longitudinal axial cross-sectional view of a portion of a package provided according to a more preferred embodiment of the present invention; FIG. 5 shows a drawing similar to that of FIG. 4 with a package provided according to an alternative; FIG. 6 is a drawing similar to that of FIG. 4, with a package provided according to a more preferred embodiment of the present invention; FIG. 7 is a schematic diagram showing a more preferred embodiment of a radiation protection device equipped with a package; FIG. 8 is a drawing similar to FIG. 2, wherein a radiation protection device in a package provided according to a more preferred embodiment of the present invention has two concentric annular rows of radiation protection elements; FIG. 9 is a schematic diagram showing another form of a locking member equipped with a radiation protection device; FIG. 10 is a partially exploded cross-sectional view showing a more preferred embodiment of a radiation protection device having two concentric annular rows of radiation protection elements; and FIG. 11 shows a drawing similar to that of FIG. 8, with a package provided in the form of a more preferred embodiment of the present invention. Specific details for implementing the invention

[0030] First, referring to FIG. 1, a package (1) for transporting and / or storing radioactive materials such as nuclear fuel assemblies (3) or radioactive waste (shown only partially and schematically in FIG. 1) is shown.

[0031] The above package (1) is indicated in a vertical storage position, where its longitudinal central axis (2) is oriented vertically. This is based on the package base (4) opposite the removable cover (6) along the direction of height (8) parallel to the longitudinal axis (2). Thus, the direction of height (8) corresponds to the longitudinal direction of the package.

[0032] Between the bottom (4) and the cover (6), the package (1) extends about the axis (2) and includes a side body (10) that internally defines a cavity (12) for receiving radioactive material (3). The cavity (12) may also form a containment enclosure intended to receive radioactive material arranged in a storage tray located, for example, within a containment enclosure. Alternatively, the containment enclosure is entirely defined by a case, also known as a "canister," placed in the cavity (12) cited above. The enclosure is closed at the top by the cover (6) and at the bottom by the bottom (4), which may be integral with the side body (10) of the package. In practice, these elements (4, 6 and 10) form the body of the package intended to maintain the tightness of the containment enclosure by ensuring the mechanical strength of the package, particularly during a drop.

[0033] In the vicinity, the package (1) is also equipped with a radiological protection device, in this case, a neutron protection device (14). The device is formed using several neutron protection elements (16) that extend along all or part of the length of the side body (10) of the package along the direction of (8). Alternatively, the device (14) may be formed using stacked blocks (16) along the direction of (8). Each radiological protection element (16) preferably takes the form of a prefabricated block made of casting resin. The resin may contain boron or any other neutron-absorbing element, i.e., a neutron-absorbing element. The term "neutron-absorbing element" refers to an element having an effective cross-section for zero neutrons greater than 100 barn.

[0034] Hereinafter, the neutron protection element (16) will be referred to as the "protection block (16)" or "block (16)". The latter is arranged in an annular space (18) around an axis (2) and is defined by an inner ferrule (20) and an outer casing (22). In the preferred embodiment shown in FIG. 1, the inner ferrule (2) is a part added around the side body (10) of the package, but alternatively, the inner delimitation of the annular space (18) can be performed directly by the outer surface of the side body (10). The outer casing (22) forms the side periphery of the package (1).

[0035] The elements (4, 6, 10) of the package body may be metals, for example, made of steel or cast iron. The inner ferrule (2) and the outer casing (22) may also be made of metal, for example, steel. It is preferable that no heat conductors other than the protection blocks (16) are provided in the annular space (18), also known as the inter-ferrule space. The specific case above corresponds to a package for transporting radioactive material that emits only low heat or no heat at all. The term "heat conductors" generally refers to conductors commonly used in packages that are arranged alternately with neutron protection blocks and connect the inner ferrule (20) to the outer casing (22). Nevertheless, heat conductors in the form of annular discs can be conceived. Then, the blocks (16) appear alternately with the heat conductor discs in the direction of (8). Now, referring to FIGS. 2 and FIGS. 3, the shape of a continuous block (16) is illustrated along the circumferential direction (28) of an annular space (18) with respect to the axis (2). In the preferred embodiment, all blocks (16) form a single annular row of blocks centered on the axis (2) and having a thickness slightly smaller than the total thickness "E1" of the annular space (18) along the radial direction (30) of the space.

[0036] Here, each block (16) of the annular row is preferably identical, that is, identical in shape and size. Generally, each block (16) is formed as a single piece by two substantially parallelepipedal parts (16a, 16b) that are offset from each other in the circumferential direction (28) and radially (30). In practice, the first part (16a) forms the radially outer part of the block (16) and is circumferentially connected and offset from the second part (16b), which forms the radially inner part of the same block (16).

[0037] Because of the continuity of blocks (16) along the circumferential direction (28), the first part (16a) of the first block covers at least partially in a radial direction the second part (16b) of the second block (16) which is directly continuous in the circumferential direction (28), and the second part (16b) of the first block covers at least partially in a radial direction the first part (16a) of the third block (16) which is directly continuous in the circumferential direction (28) in the same way, but is arranged on the opposite side of the second block.

[0038] One of the specific features of the present invention is the use of means to limit / prevent circumferential distancing between adjacent blocks (16), thereby preventing the accumulation of such distancing from causing an unacceptable level of neutron leakage between two directly consecutive blocks (16). For this purpose, preferably several blocks (16) of a single annular row, preferably all or nearly all of them, are provided connected to two locking members (32) each intended to limit / prevent circumferential distancing for each of the two blocks (16) located on either side of it, respectively, in the circumferential direction (28).

[0039] In all preferred embodiments, as can be seen from the full description, it should be noted that the annular space (18) of the package is a space in which the radiation protection element (16) and the locking member (32) are arranged, and is radially limited outward by an outer casing (22) centered on the axis (2).

[0040] Since the arrangement between the locking member (32) and the two blocks (16) limits / prevents separation that is equal at the level of each locking member, only one will be described in detail below.

[0041] In the above preferred embodiment, each locking member (32) located in the annular space (18) is integrated with the first part (16a) of its associated first block (16). Alternatively, without departing from the scope of the invention, it may be integrated with the second part (16b).

[0042] When a locking member (32) is incorporated into the first part (16a) of the first block (16), the member (32) takes the form of an inward radial projection that extends in a long linear manner along the longitudinal direction (8), that is, locally perpendicular or substantially orthogonal to the circumferential direction (28). Thus, the long linear projection (32) preferably extends continuously along the entire length of the first associated block (16) or only along a part thereof. In a cross-section such as FIG. 2, the projection (32) has a truncated disk shape, e.g., a half-disk, or any other shape such as a square, rectangle, trapezium, etc.

[0043] The protrusion (32) is provided to the second part (16b) of the second block (16) directly adjacent to the first block along the circumferential direction (28) and is received in a complementary hollow that is open outwardly in a radial shape. Due to the cooperation between the protrusion (32) and the hollow (34), the first and second protective blocks (16) cannot be spaced apart from each other along the circumferential direction (28), or cannot be spaced apart by more than a limited amplitude through the use of a circumferential gap between the two parts (32, 34).

[0044] Finally, it should be noted that cooperation between the protrusion (32) and the hollow (34) of the other block (16) is achieved by each protrusion sliding relative to and being inserted within the associated hollow (34) in the form of a groove in the annular space (18).

[0045] In the preferred embodiment described above, the series of protective blocks (16) in the annular space (18) may also be switched along the longitudinal direction (8). The above case is shown in FIG. 4, where the locking member (32) is still in the form of a radial protrusion, but here it extends in a long linear manner along the circumferential direction (28), such as a hollow into which this protrusion is inserted.

[0046] According to the indication, during the manufacture of the package, the insertion of the locking member (32) of the block (16) into the hollow (34) of the block that is directly continuous in the longitudinal direction (8) is performed before the corresponding portions of the two blocks (16) are inserted longitudinally into the annular space (18).

[0047] FIG. 5 illustrates an alternative to the solution proposed in FIG. 4. Here, the locking member (32) still protrudes radially inward and forms the longitudinal end of the first part (16a) of the block (16). Additionally, the hollow (34) of the protective block (16) is formed on one side between the joint between the two parts (16a, 16b) and on the other side between additional protrusions (16') that protrude radially outward and form the opposite longitudinal end of the protective block (16) providing the second part (16b).

[0048] Once again, regarding a single row of protective elements (16), mutual retention of the blocks (16) can be provided by the locking member not being integrated into the blocks but operating separately with them. A preferred embodiment in this regard is illustrated in FIG. 6, where the blocks (16) are written in the same general form together with the two parts (16a, 16b). The locking member (32) takes the form of a clip or similar element and connects each of the two directly consecutive blocks (16) in the longitudinal direction (8) to limit / prevent their relative distancing along the same direction in the annular space (18).

[0049] Accordingly, each clip (32) has two tabs that are respectively received in the hollows (34) of the first and second protective blocks (16) connected by it. The central body of each clip (32) extends along the circumferential direction (25), and the tabs arranged at the ends of the body protrude radially to be received in the corresponding hollows (34) of the blocks (16).

[0050] As illustrated in FIG. 6, the clip (32) is arranged at the height of the longitudinal joint between the blocks (16) and is located on the outer side of the annular row of blocks positioned between the latter and the outer casing (22). Alternatively, the clip (32) may be located on the inner side of the annular row between the blocks and the inner ferrule (20).

[0051] The above clip system can also be used in a similar manner to limit / prevent relative separation between blocks (16) along the circumferential direction (28) without going outside the scope of the present invention.

[0052] Now, referring to FIG. 7, an additional preferred embodiment is illustrated for combining a block (16) with a locking member (32) separated from the block in the longitudinal direction (8). This includes a key type or similar design, each having two opposing longitudinal sections (32') in the shape of a dovetail, and each is received in a complementary hollow (34) formed at the longitudinal end facing the two blocks (16) in question. In this embodiment, each block (16) has a curvature along the circumferential direction (28) to follow the general shape of the annular space (18) in which it is located.

[0053] In all embodiments where a locking member (32) is expected to be separated from a protective block (16) connected by this, the member (32) each forms a portion smaller in size than the block (16). Furthermore, each locking member (32) extends along a portion of the radial thickness E1 of the annular space (18), for example, along 5 to 30% of this thickness.

[0054] The locking member (32) is preferably made of a material different from the block (16), for example, a metal material.

[0055] All principles related to the preferred embodiment described above are applicable to a design in which the protective device (14) comprises two or more concentric annular rows of protective blocks (16) centered on an axis (2).

[0056] In a preferred embodiment of FIG. 8, this consists of two concentric rows (36a, 36b) arranged in an annular space (18), each of which is formed by a series of protective blocks (16) along the circumferential direction (28). Each block (16) extends along all or part of the length of the side body (10) of the package along the direction of (8). It follows a simple shape, for example, generally a parallelepipedal, optionally a curvature formed along the circumferential direction (28) to follow the general shape of the annular space (18) in which it is located. Here, each block (16) of each of the two rows (36a, 36b) is preferably manufactured as a single piece comprising a first part (16a) and a second part (16b) located at a circumferential extension of the first part (16a). An angular positioning offset is adopted between the blocks (16) of the first row (36a) located radially outward and the blocks (16) of the second row (36b) located radially inward, so that the interface between the blocks (16) of the first row (36a) is not radially aligned with the interface between the blocks (16) of the second row (36b). Such an arrangement, similar to a staggered row arrangement of blocks (16) forming two rows (36a, 36b), makes it possible to limit neutron leakage through these interfaces.

[0057] In the above configuration, each block (16) of the first row (36a) has its first part (16a) covered by a second part (16b) of one of the blocks of the second row (36b), and in the same way, its second part (16b) is covered by a first part (16a) of a block directly adjacent to the second row (36b). The same applies to each block (16) of the second row (36b), where the first part (16a) is covered by a second part (16b) of one of the blocks of the first row (36a), and the second part (16b) is covered by a first part (16a) of a block directly adjacent to the first row (36a). Thus, a circumferential offset can be observed between two blocks (16) that belong to the two rows (36a, 36b) respectively and partially overlap each other.

[0058] In other words, the first part (16a) of the first block (16) of the second row (36b) is covered radially (30) by the second part (16b) of the second block (16) of the first row (36a), and the second part (16b) of the first block is still covered radially (30) by the first part (16a) of the third block (16) of the first row (36a), and the second and third blocks (16) are directly continuous in the circumferential direction (28) from the first row (36a). Similarly, the first part (16a) of the first block (16) of the first row (36a) is covered radially (30) by the second part (16b) of the second block (16) of the second row (36b), and the second part (16b) of the first block is still covered radially (30) by the first part (16a) of the third block (16) of the second row (36b), and the second and third blocks (16) are directly continuous in the circumferential direction (28) in the second row (36b). Also, when two blocks (16) partially cover each other radially (30), these same blocks (16) are considered continuous along the circumferential direction (28), even if they do not belong to the same circular row.

[0059] In this preferred embodiment of the present invention, each protective block (16) of the second row (36b) comprises two locking members (32) spaced circumferentially apart from each other, the first locking member being in the first part (16a) and the second locking member being in the second part (16b). Furthermore, each protective block (16) of the first row (36a) comprises two hollows (34) spaced circumferentially apart from each other, the first hollow being in the first part (16a) and the second hollow being in the second part (16b). Accordingly, each protective block (16) of the second row (36b) has its first locking member (32) inserted into the second hollow (34) of the block (16) of the first row (16a), while its second locking member (32) is inserted into the first hollow (34) of the block (16) that is directly consecutive to the first row (16a). Accordingly, in the above embodiment, the locking member (32) is positioned at the level of the radially overlapping zone of the two blocks (16) to help hold them against each other, thus helping to limit / prevent a relative gap between the two identical blocks in the circumferential direction (28).

[0060] Naturally, without departing from the scope of the present invention, the design can be reversed by providing a protruding member (32) in the block of the first row (36a) and a hollow (34) in the block of the second row (36b).

[0061] In a preferred embodiment of FIG. 8, the radially protruding locking member (32) is identical or similar to that described with reference to FIG. 2, and in particular, has a half-disk shape in cross-section. However, all other features described with reference to FIG. 2, such as the long linear characteristic of the member (32) along the longitudinal direction (8), are also applicable.

[0062] According to an additional possible embodiment briefly illustrated in FIG. 9, the radially protruding locking members (32) may have a trapezoidal shape such as the hollow (34) with which they cooperate.

[0063] According to an additional preferred embodiment illustrated in FIG. 10, two concentric annular rows (36a, 36b) are each formed by a block (16) having a general U-shaped cross section. The second row (36b) comprises a U-shaped block (16) with two opposing arms protruding radially outward, whereas the first row (36a) comprises a U-shaped block (16) with two opposing arms protruding radially inward.

[0064] While the two arms of each block (16) of the second row (36b) each form two locking members (32) of the block, the space (40) defined between the two arms of each block (16) of the first row (36a) forms two adjacent hollows (34) that merge with each other in the circumferential direction and is intended to accommodate two arms / members (32) belonging to each of the two directly consecutive blocks (16) of the second row (36b). In the above scenario, the two adjacent locking members (32) belonging to the two individual blocks (16) have a shape complementary to the shape of the space (40) into which the two members are inserted together.

[0065] The above configuration having U-shaped protective blocks (16) is also applicable even when the latter exist continuously along the axial direction (8) in an annular space (18), and the U-shaped arms of the second row (36b) serve to limit / prevent axial separation between the blocks (16) by combining with the space (40) defined between the U-shaped arms of the first row (36a).

[0066] Clearly, due to the desirable shape identity between the U-shaped blocks of the two rows (36a, 36b), alternatively, the two arms of each block (16) of the first row (36a) form the two locking members (32) of this block, whereas the space defined between the two arms of each block (16) of the second row (36b) forms two adjacent hollows (34) that merge with each other in the circumferential direction and is intended to accommodate two arms / members (32) belonging to each of the two directly consecutive blocks (16) of the first row (36b).

[0067] Furthermore, in the case of a design having a double annular row of blocks (16), it is possible to provide a configuration having a locking member (32) that is separated from and not integrated with the blocks (16). For example, in FIG. 11, the protruding member is replaced by a radially oriented pin (32), where two opposing ends are received in two hollows (34) belonging to each of the two blocks (16), one of which belongs to the first row (36a) and the other to the second row (36b). For a given two blocks (16), multiple pins (32) may be provided spaced apart from each other along the axial direction (8). Alternatively, the pin(s) (32) may be replaced by a key extending in the same longitudinal direction (8) having two opposing ends that are received in each of the two hollows (34) in the form of axial grooves.

[0068] Clearly, various modifications to the invention described above may be made by a person skilled in the art merely as a non-limiting example and within the scope defined by the appended claims. In particular, the different preferred embodiments described above may be combined, and their features are maintained to be interchangeable.

Claims

Claim 1 A package (1) for transporting and / or storing radioactive material (3) comprises a cavity (12) for receiving radioactive material and a radiological protection device (14) arranged around the cavity receiving in an annular space (18) centered on the longitudinal central axis (2) of the package, wherein the radiological protection device (14) comprises radiological protection elements (16) arranged in the annular space (18), and a locking member (32) is provided that is associated with at least two successive radiological protection elements (16) in a given direction of the annular space from the longitudinal direction (8) and circumferential direction (28) of the space (18) and is designed to limit / prevent the distancing of the two radiological protection elements (16) from each other in a given direction of the space, wherein the locking member A package for transporting and / or storing radioactive material (3), characterized by being combined with or integrated with the first element (16) in the two radioactive protection elements and cooperating with the hollow (34) formed on the second element (16) in the two radioactive protection elements. Claim 2 A package according to claim 1, characterized in that the locking member (32) is integral with the first radiation protection element (16). Claim 3 A package according to claim 2, wherein the locking member (32) is a long linear member having a cross-section in the shape of a truncated disk, a square, or a trapezium. Claim 4 In claim 3, the package is characterized in that the long linear locking member (32) extends orthogonally with respect to the given direction. Claim 5 A package according to claim 1, wherein the locking member (32) is a part separated from the first and second radiation protection elements (16), and the locking member (32) also cooperates with a hollow (34) formed on the first radiation protection element (16). Claim 6 In claim 5, the package is characterized in that the locking member (32) is a part smaller in size than that of the first and second radiation protection elements (16) and is made of a different material. Claim 7 A package according to claim 5, wherein the locking member (32) is a pin, a key, or a clip. Claim 8 A package according to claim 5, wherein the locking member (32) extends along only a portion of the radial thickness (E1) of the annular space (18). Claim 9 A package according to claim 1, wherein the first and second radiation protection elements (16) are directly continuous in the given direction in a single annular row of the radiation protection elements (16). Claim 10 A package according to claim 1, wherein the first and second radiation protection elements (16) each belong to two concentric annular rows (36a, 36b) of the radiation protection elements (16), and thus the first and second radiation protection elements (16) partially overlap in the radial (30) of the annular space (18) and are offset circumferentially from each other. Claim 11 A package according to claim 10, wherein the locking member (32) is located at the level of the radial overlapping zone of the first and second radiation protection elements (16). Claim 12 A package according to claim 1, characterized in that the annular space (18) is defined by an inner ferrule (20) and an outer casing (22). Claim 13 A package according to claim 12, wherein the annular space (18) is characterized by not having a heat conductor connecting the inner ferrule (20) to the outer casing (22). Claim 14 A package according to claim 1, characterized in that the radiation protection element (16) is a neutron protection element. Claim 15 A package according to claim 1, characterized in that at least one radiation protection element (16) of the radiation protection device (14), some of these elements, or each thereof is associated with two locking members (32) designed to limit / prevent its distancing in the given direction for each of the two radiation protection elements (16) located on both sides in the same given direction.

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