Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F1/00—Shielding characterised by the composition of the materials
  • G21F1/02—Selection of uniform shielding materials
  • G21F1/08—Metals; Alloys; Cermets, i.e. sintered mixtures of ceramics and metals
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F3/00—Shielding characterised by its physical form, e.g. granules, or shape of the material
  • G21F3/04—Bricks; Shields made up therefrom
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F5/00—Transportable or portable shielded containers
  • G21F5/005—Containers for solid radioactive wastes, e.g. for ultimate disposal
  • G21F5/008—Containers for fuel elements

Definitions

• the present invention relates generally to the field of transport and / or storage of nuclear materials, such as fresh or irradiated nuclear fuel assemblies.
• the invention relates to a package for the transport and / or storage of nuclear material, of the type comprising a radiological protection device made from lead or one of its alloys, in order to form an effective barrier against gamma radiation.
• storage devices are used, also called “basket” or “rack” storage.
• These storage devices usually of cylindrical shape and of substantially circular section, have a plurality of adjacent housings each adapted to receive a nuclear fuel assembly.
• the storage device is intended to be housed in the cavity of a package in order to form together with it a container for transport and / or nuclear fuel assembly storage, wherein the nuclear material is perfectly confined.
• the aforementioned cavity is generally defined by a lateral body extending in a longitudinal direction of the package, this lateral body comprising for example two concentric metal ferrules jointly forming an annular space inside which is housed a radiological protection device, in particular to form a barrier against gamma radiation emitted by the fuel assemblies housed in the cavity.
• the radiological protection device is made using several prefabricated elements made of lead or in one of its alloys, distributed around the cavity, in the appropriate annular space defined by the two metal ferrules.
• each prefabricated element in lead or in one of its alloys is likely to undergo significant plastic deformations during regulatory tests called free fall on target deformable.
• drop tests are performed by orienting the longitudinal axis of the packaging and its cavity either substantially perpendicular to the impact surface (usually referred to as axial or vertical drop), or substantially parallel thereto (generally referred to as a lateral or horizontal fall).
• the plastic deformations observed take the form of a settlement of the prefabricated elements in lead, in the longitudinal direction, the material actually tending to fill a set of operation necessary for the introduction of these prefabricated elements between the two ferrules of the lateral body.
• the packing of lead generates the appearance of empty spaces between the two lateral body ferrules, these longitudinally oriented empty spaces being located at one end of the package, opposite the end intended for hit the undeformable target during the vertical free fall.
• these empty spaces create longitudinal discontinuities in the radiological protection, which, locally, can no longer be satisfactorily provided. These discontinuities can then be the cause of leaks gamma radiation, detrimental to compliance with the regulatory criteria.
• the object of the invention is therefore to remedy at least partially the disadvantages mentioned above, relating to the embodiments of the prior art.
• the subject of the invention is a package for the transport and / or storage of nuclear materials, such as irradiated nuclear fuel assemblies, said package comprising a lateral body extending in a longitudinal direction of said package, said body lateral forming a housing cavity nuclear material and being equipped with a radiological protection device.
• said radiological protection device comprises at least one radiological protection structure comprising at least one reinforcing metal reinforcement extending in said longitudinal direction and matched by a block made of lead or one of its alloys, poured on said reinforcing metal reinforcement, the latter being equipped with at least one cast block retaining element, in said longitudinal direction.
• said reinforcing metal reinforcement is embedded in the cast block over at least a part of its length in said longitudinal direction, and preferably over its entire length.
• each retaining element of the reinforcing reinforcement makes it possible to achieve a mechanical connection with the cast block made of lead or one of its alloys, prohibiting the relative displacement of these two entities relative to each other, in the longitudinal direction. This makes it possible to avoid / limit the settling of the lead in the event of a vertical free fall of the package, according to its longitudinal direction.
• the invention makes it possible to prevent the formation of detrimental longitudinal discontinuities in the radiological protection device, and thus advantageously prohibits the leakage of gamma radiation through the lateral body of the package.
• the reinforcing metal reinforcement and the lead block preferably form an integral unit in one piece, thanks in particular to the presence of each element of the block. retained by the lead.
• the lead block and the metal frame are embedded in one another.
• longitudinal part "flooded” here must be understood as a part not laterally more apparent from the outside, namely covered by cast lead.
• at least one longitudinal portion of said metal frame is covered laterally around its entire circumference, that is to say on an angular range of 360 ° around the longitudinal direction.
• This specificity firstly makes it possible to reinforce the mechanical connection between the lead block and the reinforcement metal reinforcement integrating the retaining elements.
• metal frame on its periphery which would make its machining much more delicate.
• said reinforcing metal reinforcement has, in any cross section, a non-straight form. In general, this allows it to exhibit good mechanical behavior in compression, according to the longitudinal direction in which it extends.
• the cross section may be of the zigzag type, with wave, crenellated, V, or other patterns.
• said metal frame may take the form of a hollow structure defining an inner side wall delimiting a recess extending in said longitudinal direction, and an outer side wall, said inner and outer side walls being then matched by said block cast, preferably along their entire length for obtaining a better anchoring of the reinforcement in this block.
• the cross section defining a hollow may be open or closed, without departing from the scope of the invention.
• the metal structure preferably takes the form of a hollow beam, for example of rectangular, square, or parallelogram section, but could alternatively be of substantially circular, oval, or U-shaped section.
• the metal reinforcement having in any cross section a non-straight form, preferably adopts a substantially cylindrical geometry, parallel to the longitudinal direction.
• the preferred geometry can be obtained by a straight line parallel to the longitudinal direction, moving along a path corresponding to the non-straight cross section.
• said metal armature is equipped with a plurality of block retention elements cast in said longitudinal direction, distributed along the same direction.
• this advantageously leads to a multiplication of the mechanical links between the lead block and its associated metal reinforcement, making it possible to further limit the risks of longitudinal settlement of the block, in the event of a vertical fall.
• At least one retaining element of the cast block takes the form of a through hole made in said metal frame, and traversed by said cast block.
• the mechanical connection The above is achieved by passing the lead block through the hole provided on the reinforcing reinforcement, the hole preferably being completely filled by the lead.
• the axis of the holes is oriented substantially orthogonal to the longitudinal direction, in order to obtain maximum efficiency of these links.
• At least one retaining element of the cast block takes the form of a projection provided on said metal frame, and embedded in said cast block.
• the mechanical connection results from the embedded character of the projection, in the lead block.
• said projection is oriented so to extend substantially upwards away from it.
• the length of the metal reinforcement, in said longitudinal direction is substantially identical to the length along this same direction of the block made of lead or in one of its alloys, poured on this frame and embedding it.
• This configuration in which the armature is matched throughout its length by the lead block, advantageously limits the risk of packing the block, along the longitudinal direction, over the entire length thereof.
• the reinforcement extending from one end of the structure to the other radiological protection can then be requested in compression, for a better recovery of the vertical forces.
• the armature can be made in one piece, or with the aid of fixed portions of the others, for example by welding.
• a lead block of a protection structure can integrate several separate frames, which, in the preferred case just mentioned, each extend over the entire length of this block, without depart from the scope of the invention.
• said radiological protection device comprises a plurality of radiological protection structures distributed around the cavity, for example between two concentric shells of the lateral body of the package, so as to fill the annular space formed between them.
• each radiological protection structure is housed in a metal profile open in a circumferential direction, allowing the introduction of the radiological protection structure in its associated profile in a relative movement along the same direction.
• These profiles are preferably made of aluminum or in one of its alloys. It is therefore preferably provided that each profile then has two opposite flanks facing each other and in contact with or in close proximity to the two concentric ferrules respectively, in order to facilitate heat transfer between them.
• the radiological protection device is no longer segmented into several structures each extending in a given angular sector and all positioned adjacent to each other in the tangential / circumferential direction, but takes the form a ring-shaped one-piece block surrounding the housing cavity.
• the radiological protection device can be directly cast between the two concentric rings, with one or more reinforcement initially present in the inter-ring annular space.
• the invention also relates to a method of manufacturing a package for the transport and / or storage of nuclear materials as described above, comprising a step of manufacturing said radiological protection structure, made by casting lead or one of its alloys in a mold in which said reinforcing metal reinforcement has been previously put in place.
• radiological protection structure thus obtained can be machined before being housed in the space provided for this purpose on the lateral body of the package.
• the lead can then be directly cast between two concentric shells of the lateral body forming the above-mentioned mold, one or more reinforcing reinforcements initially being arranged in the inter-ring annular space.
• FIG. 1 represents a schematic view of a container for the transport and / or storage of nuclear fuel assemblies, comprising a package according to a preferred embodiment of the present invention, only represented roughly;
• Fig. 2 is a more detailed cross-sectional view of the package taken along line II-II of Fig. 1;
• FIG. 3 represents a perspective view of one of the radiological protection structures equipping the package shown in the preceding figures;
• FIG. 4 represents a cross-sectional view of the radiological protection structure shown in FIG. 3;
• FIGS. 5 to 5b show views similar to that shown in FIG. 4, the radiological protection structure being in the form of an alternative embodiment;
• FIG. 6 represents a view similar to that shown in FIG. 5, the radiological protection structure being in the form of an alternative embodiment;
• FIG. 7 represents a view similar to that shown in FIG. 2, with radiological protection structures such as that shown in FIG. 6;
• FIGS. 8a to 8c show views similar to those shown in FIGS. 4 to 5b, the radiological protection structure being in the form of other alternative embodiments, with reinforcements adopting a zigzag configuration;
• FIG. 9 also shows a view similar to those shown in Figures 4 to 5b, the radiological protection structure being in yet another alternative form of embodiment.
• the container 1 generally comprises a packaging 2 object of the present invention, inside which is a storage device
• the device 4 also referred to as a storage basket.
• the device 4 is intended to be placed in a housing cavity 6 of the package 2, as shown schematically in FIG. 1 on which it is also possible to see the longitudinal axis 8 of this package, coinciding with the longitudinal axes of the device storage and cavity housing.
• longitudinal should be understood as parallel to the longitudinal axis 8 and the longitudinal direction X of the package, and the term “transverse” should be understood as orthogonal to the same longitudinal axis 8.
• the storage device 4 comprises a plurality of adjacent housings arranged parallel to the axis 8, the latter being each adapted to receive at least one fuel assembly of square or rectangular section , and preferably only one.
• the container 1 and this device 4 have been shown in a vertical loading / unloading position of the fuel assemblies, different from the horizontal / recumbent position usually adopted during the transportation of the assemblies.
• the package according to the invention has an extremely satisfactory behavior in case of vertical free fall, during which this package moves in the longitudinal direction in its vertical position shown.
• the package 2 has essentially a bottom 10 on which the device 4 is intended to rest in a vertical position, a cover 12, and a lateral body 14 extending around and along the longitudinal axis 8, parallel to the direction X.
• this lateral body 14 which defines the housing cavity 6, with the aid of a lateral inner surface 16 of substantially cylindrical shape and of circular section, and of axis coincident with the axis 8.
• the bottom 10 which defines the bottom of the open cavity 6 or level of the cover 12, can be made in one piece with at least a portion of the lateral body 14, without departing from the scope of the invention.
• FIG. 2 a part of the lateral body 14 can be seen in detail, which firstly has two concentric metallic shells jointly forming an annular space 18 centered on the longitudinal axis of the package (not visible in this figure), this space 18 being filled by a radiological protection device 20 specific to the present invention.
• This protection device 20 is in particular designed to form a barrier against gamma radiation emitted by the irradiated fuel assemblies housed in the cavity 6. Thus, it is housed between the inner shell 22 whose inner surface corresponds to the inner lateral surface 16 of the cavity 6, and the outer shell 24.
• the protection device 20 comprises a plurality of radiological protection structures 26, preferably all substantially identical, and positioned adjacent to each other in a tangential / circumferential direction T associated with the annular space 18.
• the radiological protection device 20, which extends all around the cavity 6 by filling the gap annular space 18, is segmented into several structures 26 each extending in a given angular sector, centered on the longitudinal axis of the package.
• the structure 26 comprises a reinforcing metal reinforcement 30, extending in the longitudinal direction, preferably over the entire length of the structure 26. It is married by a block 32 made of lead or one of its alloys, cast on the frame 30 and embedding it, so that the frame 30 is entirely covered laterally by the lead.
• the armature 30 is equipped with a plurality of retaining elements 34, provided to retain the cast block 34 in the longitudinal direction.
• the retaining elements 34 are holes through the frame metal, the latter being preferably made of steel, for example black steel or stainless steel.
• the two elements 34, 36 nested one inside the other thus together form a mechanical connection 38 between the block 32 and the armature 30, preventing the relative displacement of these two entities relative to one another, according to the longitudinal direction.
• the surface of the holes 34 corresponds to about 20 to 60% of the surface of the armature, and preferably to 40% thereof. It is noted that this percentage is given by considering the surface of the frame as being the surface of the elements that compose it, and not the sum of the two opposite surfaces of each of these elements.
• This value range makes it possible to obtain a good hold of the lead block 32 with respect to the armature 30, because of the number and size of the mechanical links 38 that it generates.
• this interval is adapted to provide a rapid casting of lead all around and inside the frame, since the liquid lead actually borrows holes 34 during casting to penetrate any closed areas of the frame 30, before solidifying in these same holes 34.
• the metal armature 30 takes for example the form of a hollow beam defining an inner side wall 40 delimiting a recess extending in the longitudinal direction, and an outer side wall 42, each of these surfaces 40, 42 being marryed by the lead block 32, preferably over their entire length also corresponding substantially to the length of the lead block 32.
• the beam 30 has the cross-sectional shape of a parallelogram, so that the lead block 32, traversing each of the four sides of the parallelogram using the portions 36, has an outer ring 44 embracing the outer surface 42 of the beam all around the periphery thereof, and an inner portion 46 conforming to the inner surface 40 also all around it.
• the armature 30 also comprises a central element 50 of identical length to the parallelogram, which, in cross section, connects the two vertices furthest from this parallelogram. Therefore, the inner portion 46 of the block 32 takes the form of two sub-blocks of triangular section integral with each other thanks to the lead portions 36 passing through the holes 34 made on the central element 50.
• this central element 50 forming diagonal is not mandatory, as shown by the alternative embodiment shown in FIG. 5, in which only the parallelogram constitutes the armature 30.
• any other shape than the parallelogram could be employed, of open or closed cross section, without departing from the scope of the invention, and as is also shown in Figures 5a and 5b respectively showing a frame 30 of substantially circular cross section and a frame 30 of substantially U-shaped cross-section, each embedded in a lead block 32.
• the reinforcement metal reinforcement 30 is completely embedded or almost in the cast block 32, in that it is covered laterally by the lead all over its periphery. , ie more apparent from the outside, laterally 360 °.
• the end edges of the armature 30 remain visible from the outside thereof, as visible at the upper end of the structure 26 shown in FIG.
• Block 32 is manufactured by casting lead or one of its alloys into a mold in which the reinforcing metal reinforcement 30 has been previously put in place. It is therefore the shape of the mold that imposes the external shape of the block 32. In this regard, it comprises, on its outer ring 44, a first radially outer recess 54, extending tangentially. Thus, on the relevant flank of the block 32, one can successively perceive, radially from the outside to the inside, said tangential recess 54, followed by a recess 55.
• the radially outer recess 54 of any structure 26 be housed in the radially outer recess 57 of the structure directly adjacent in the tangential direction T, as shown in Figure 2.
• the radially inner recess 56 of this structure is housed in the radially inner recess 55 of the structure directly adjacent in the tangential direction T. It is then preferably that the tangential extent of the overlaps between the recesses 54, 56 facing two by two, and preferably in contact, is sufficiently large to limit of satisfactorily the risk of gamma-ray leakage between protective structures 26.
• the profile 60 houses the block 32 embedding the armature 30, having a shape open in the circumferential direction T, in cross section. This opening allows the prior introduction of the block 32 in the profile 60, by relative circumferential displacement of the two elements.
• the profile 60 has two opposite flanks spaced radially and circumferentially moving, these two flanks being interconnected at one of their ends by a radial element shaped to fit the recess 54 and the recess 55 of the block. 32 housed in the profile.
• the block marries each of the two flanks.
• each block 32 preferably machined after casting of the lead on the frame, is introduced into a profile 60 by the circumferential opening provided for this purpose, by moving the block in the direction circumferential T, until its detachment 54 and its recess 55 come to marry the radial joining element of the profile 60.
• Each profile 60, thus equipped with its protective structure 26, is then placed around the inner ferrule 22, with the radial element matching the recess 56 and the recess 57 of the block 32 housed in the profile 60 adjacent, as shown in Figure 7.
• a substantially radial displacement of the profile 60 equipped with its protective structure 26 is conceivable, as shown schematically by the arrow of the same figure.
• This procedure progressively covers the inner ferrule 22 progressing in the circumferential direction T, and is repeated until the inner ferrule 22 is entirely laterally covered by structures 26.
• the outer shell of the lateral body 14 is disposed around the structures 26 housed in the profiles 60, with preferably an earlier step consisting of joining together circumferentially adjacent profiles, for example by welding on any their length, which preferably corresponds substantially to the length of the block 32 and the armature 30.
• the longitudinal welding is preferably carried out between the radially outer side of a profile 60, and the radial element of junction belonging to profile 60 directly consecutive.
• the reinforcing metal reinforcements 30 each having a cross section in the form of zigzags.
• the number and pattern of zigzags can be chosen according to the needs encountered. It may for example be a repetition of a wave-shaped pattern, slot, or V, as is respectively shown in Figures 8a, 8b, 8c.
• FIG. 9 there is shown another alternative embodiment for the structure 26, the difference with those described above residing again in the form of the reinforcing metal reinforcement 130. Indeed, even if that could be achieved, it has more holes as retaining elements of the cast lead block 32, but instead incorporates projections 134 provided for example on planar elements 170 of the metal frame. More specifically, these planar elements 170, extending from one end to the other of the structure 26 in the X direction, take for example the shape of a cross in cross section, projections 134 in the form of pions oriented transversely projecting on either side of each branch of the cross, as shown in Figure 9.
• the shape, the number and the dimensions of the protrusions can be adapted according to the needs and constraints encountered, as the bearing structure of these protrusions.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Ceramic Engineering (AREA)
• Metallurgy (AREA)
• Measurement Of Radiation (AREA)
• Buffer Packaging (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Monitoring And Testing Of Nuclear Reactors (AREA)
• Packages (AREA)
• Vibration Dampers (AREA)

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• 2007
  • 2007-03-21 FR FR0753965A patent/FR2914104B1/fr active Active
• 2008
  • 2008-03-18 JP JP2009554016A patent/JP5629466B2/ja active Active
  • 2008-03-18 US US12/532,075 patent/US20100183110A1/en not_active Abandoned
  • 2008-03-18 EP EP08717925A patent/EP2140459B1/de active Active
  • 2008-03-18 ES ES08717925T patent/ES2394383T3/es active Active
  • 2008-03-18 CN CN2008800088937A patent/CN101652817B/zh not_active Expired - Fee Related
  • 2008-03-18 WO PCT/EP2008/053191 patent/WO2008125409A1/fr not_active Ceased
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