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
  • 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 invention relates to a container for transporting or storing radioactive materials, such as fuel elements from nuclear reactors, which may or may not incorporate fissile materials.
• Existing containers intended for the storage or transport of radioactive materials comprise a hollow body, of generally cylindrical or parallelepiped shape.
• This hollow body is usually provided with anti-shock devices, in particular at its ends, and gripping devices such as ears or trunnions. It internally delimits a closed cavity used to house radioactive materials. More specifically, the radioactive materials are generally received in a set of receptacles, called “basket” or “internal arrangement”, designed to conform to the cavity delimited by the hollow body.
• the hollow body of the container has, at least at one of its ends, an opening allowing access to the cavity.
• a closing device such as a bolted cover.
• These sealing means generally comprise one or more flexible or metallic seals.
• the body of the container can in particular comprise an outer metallic ferrule and an inner metallic ferrule between which a neutron absorbing material is placed.
• the ends of the two metal ferrules are welded respectively to a metal bottom plate and to a solid metal flange delimiting the abovementioned opening.
• a container intended for the storage or the transport of radioactive materials one defines as “containment enclosure" the whole of the elements which delimit the closed cavity where are housed the radioactive materials and their receptacles in conditions of storage or transport, and which are likely to be in direct contact with the particles that can be emitted by said materials.
• the containment includes said body, the closure device thereof, as well as the sealing means which are interposed between the body and its closure device. All of these elements then have sufficient mechanical strength to preserve the confinement, in the event of accidental impact.
• the confinement enclosure comprises the internal metal shell, the flange and the bottom of said body, the closure device and the sealing means ensuring the interface between the flange and the closure device.
• the impact energy produced by an accidental impact is then absorbed by the deformation of the outer metallic shell of the body and of the neutron absorbing material, which makes it possible to preserve the tightness of the inner metallic ferrule, forming the most fragile part of the enclosure.
• the other elements of the containment have sufficient mechanical strength to preserve the containment in the event of accidental impact.
• the containers should be designed to prevent as much as possible from loosening in 1 atmosphere of particles from radioactive materials, for example in the form of gaseous particles or aerosols.
• a container capable of receiving fissile radioactive material must be designed to prevent an uncontrolled multiplication of the neutrons emitted by these materials. Otherwise, runaway chain reaction could have serious consequences for people near the container. Indeed, these would be exposed to radiation due to neutrons then emitted almost instantaneously and in very large quantities.
• preventing the risk of criticality is based in particular on the design of receptacles designed to receive fissile material inside the containers.
• these receptacles must have excellent mechanical strength in order to limit in all circumstances the deterioration of the arrangement of fissile materials, capable of amplifying the multiplication of neutrons, in particular following an accident such as a fall of the container.
• the quality of the confinement remains dependent on the tightness ensured by this single enclosure, in particular at the level of the body of the container.
• the definition of the internal arrangements of the container must always take into account the penetration of water into the container to prevent the risk of criticality.
• the subject of the invention is precisely a container for transporting or storing radioactive materials, the original design of which allows it, in a particularly simple manner, to have two complete containment enclosures placed one inside the other, ensuring the complete redundancy of the containment and, consequently, by not taking into account the penetration of water into the container when defining the internal arrangements thereof aimed at preventing the risk of criticality in the event of an accident.
• a container for transporting or storing radioactive materials comprising a body having at least one end flange delimiting an opening, a cover for closing said opening of the body. , first sealing means interposed between the cover and said body end flange, and first means for fixing the cover to said body end flange, capable of compressing the first sealing means, so that at least one internal part of the body, the cover and the first sealing means together form an external confinement enclosure, said container being characterized in that said end flange of the body comprises, inside the external confinement enclosure, at least a first shoulder capable of serving as a support for an end flange of a container, delimiting a container opening, a stopper being provided for closing said opening of the container, second sealing means being interposed between the stopper and the end flange of the container, and second fixing means being provided for compressing the second sealing means between the stopper and the container end flange, so that the container, the stopper and the second sealing means together form a removable interior
• the second fixing means then comprise a ring capable of being supported on one face of the stopper facing the cover, and members for fixing the ring on a third shoulder formed in the body end flange.
• the second fixing means comprise members for fixing the plug to the second shoulder formed in the end flange of the body.
• third sealing means are interposed between the plug and the second shoulder formed in the end flange of the body.
• Fourth sealing means can also be interposed between an outer peripheral surface of the end flange of the container and an inner peripheral surface of the end flange of the body.
• the container has a sealed bottom opposite its end flange.
• the cover and at least said internal part of the body are advantageously made of a material chosen from the group comprising cast irons, iron alloys, stainless steels and carbon steels.
• the plug and the container are advantageously made of a material chosen from the group comprising stainless steels, carbon steels, aluminum and aluminum alloys.
• the wall of the container has a thickness preferably between 0.3 cm and 5 cm.
• FIG. 1 is a vertical half section which schematically represents a part of a container for transporting or storing radioactive materials according to a first embodiment of the invention
• FIG. 2 is a vertical sectional view showing on a larger scale a part of the container of Figure 1;
• FIG. 3 is a sectional view comparable to Figure 2 illustrating another embodiment of one invention
• - Figure 4 is a sectional view comparable to Figure 1 illustrating yet another embodiment of the invention.
• FIG. 1 represents a part of a container according to a first embodiment of the invention.
• the container comprises a main body 10 consisting of a thick ferrule made for example of cast iron, iron alloy, carbon steel or stainless steel.
• the shape of the main body 10, for example cylindrical or parallelepiped, depends on the radioactive materials which it is desired to be able to place in the container.
• the main body 10 is hollow and internally delimits a cavity 11. This cavity is closed at one of its ends by a thick bottom 10a which is an integral part of the body 10 (in the case where the body 10 is made of steel, the bottom 10a can in particular be welded inside the shell).
• This opening of the body 10 is intended to be closed by a cover 12. More specifically, the cover 12 is provided to be fixed on the end face 13 (FIG. 2) of the flange 10b, by first fixing means such as screws 14. The cover 12 thus obtains the closure of the opening delimited by the end flange 10b of the body 10.
• the cover 12 can be made of the same materials as the body 10.
• First sealing means are interposed between the faces facing the cover 12 and the body 10, so that the assembly formed by the body 10 and the cover 12 forms an external confinement enclosure for the container.
• first sealing means comprise at least one annular seal such as a flexible elastic seal or a metal seal placed at the interface between the body and the cover.
• these first sealing means comprise two concentric seals 16 (that is to say parallel to each other) , received in grooves machined on the face of the cover 12 facing the body 10, so as to be in sealed contact with the end face 13 of the flange 10b of the body 10, on which the cover is fixed.
• the external confinement enclosure thus formed is entirely doubled by a separate internal confinement enclosure, placed removably in the external confinement enclosure of the container.
• the removable internal confinement enclosure comprises a container 18 intended to be placed inside the cavity 11 delimited by the main body 10.
• the container 18 comprises a metallic ferrule of tubular or parallelepiped shape (depending on the shape of the body 10) , closed by a welded bottom 18a, at its end intended to be turned towards the bottom 10a of the body 10.
• the container 18 is produced, by for example, stainless steel, carbon steel, aluminum, or aluminum alloy.
• the opposite end of the container 18 includes an end flange 18b defining an opening. This end flange 18b extends outwards, so as to be able to bear against a first shoulder 20 machined inside the end flange 10b of the body 10.
• the interior confinement enclosure of the container illustrated in FIGS. 1 and 2 further comprises a closure cap 22, designed to seal the opening defined by the end flange 18b of the container 18.
• This cap 22 is produced in the same materials as the container 18. It has a flange 22a at the periphery which bears on the end face of the flange 18b of the container 18.
• Second sealing means are interposed between the flange 22a of the stopper and the end flange 18b of the container.
• the second sealing means comprise at least one annular seal such as a flexible elastic seal or a metal seal.
• the second sealing means comprise two concentric seals 24 housed in grooves machined on the underside of the flange 22a of the plug 22, so as to be in abutment sealed on the end face of the flange 18b of the container 18.
• the flange 22a of the plug 22 is also supported, by its underside, on a second shoulder 26 machined inside the end flange 10b of the body 10 of the container.
• second fixing means are provided, arranged so as to apply a constant compressive force between the flange 22a of the stopper and the flange 18b of the container, to ensure the sealing of the seals 24 and therefore of the enclosure of internal containment of the container.
• the second fixing means also ensure the fixing of the stopper 22 on the flange 10b of the body 10 of the container, and they also apply a compressive force between the flange 22a of the stopper and the shoulder 26.
• the second fixing means comprise a ring 28 fixed, by fixing members 30 such as screws, on a third shoulder 32 machined in the end flange 10b of the body 10.
• the lower face of the ring 28 is in abutment on the upper face of the flange 22a of the stopper 22. Consequently, the stopper 22 is kept in sealed abutment against the end face of the flange 18b of the container 18.
• the seals 24 are thus compressed, so that the container 18, the plug 22 and these second sealing means together form the removable internal confinement enclosure of the container.
• third sealing means are provided between the underside of the flange 22a of the plug 22 and the second shoulder 26 formed in the end flange 10b of the body 10.
• These sealing means comprise advantageously at least one annular seal 33 such as a flexible elastic seal or a metal seal, received in a groove machined in the plug 22, so as to be in leaktight contact against the shoulder 26.
• fourth sealing means are interposed between the outer peripheral surface of the flange 18b of the container 18 and the inner peripheral surface of the end flange 10b of the body 10, between the shoulders 20 and 26.
• These fourth sealing means comprise at least one annular seal such as a flexible elastic seal or a metal seal.
• the fourth sealing means comprise two seals 36 housed in annular grooves machined on the external peripheral surface of the flange 18b, so as to be in sealed support on the inner peripheral surface of the end flange 10b of the body 10, between the shoulders 20 and 26.
• the fourth sealing means constituted by the seals 36 in FIG. 2 have the function of preventing the infiltration of contaminated water into the space between the container 18 and the body 10 of the container, in particular when loading underwater combustible elements inside the container 18, after having removed the cover 12 and the plug 22.
• a passage 38 passes through the cover 12, in the direction of its thickness, to open out between the seals 16 on the underside of the cover.
• a passage 40 passes through the plug 22, in the direction of its thickness, and opens out between the seals 24, on the underside of this plug.
• a passage 42 passes radially through the end flange 10b of the body 10, to open out between the cover 12 and the plug 22, for example above the shoulder 32.
• the passage 38 can be connected to an external leak detection installation, to control the tightness of the seals 16.
• the passage 40 can be connected to an external leak detection installation, to control the sealing of the seals 24, before the fitting of the cover 12.
• the passage 42 makes it possible to control the space between the cover 12 and the plug 22, and in particular the seal 33 when it exists.
• the passage 42 also makes it possible to take a sample or to inject a neutral gas into said space, according to techniques known to those skilled in the art.
• FIG 3 there is shown schematically a second embodiment of the invention.
• This embodiment essentially differs from the previous one by the nature of the fixing means used to tighten the plug 22 both on the end face of the flange 18b of the container 18 and on the shoulder 26 machined in the end flange 10b of the body 10.
• the ring 28 is eliminated and the diameter of the plug 22 as well as the width of the shoulder 26 are increased.
• the plug 22 is directly fixed to the end flange 18b of the container 18, by means of fixing members such as screws. In this case, two options are possible.
• the shoulders 26 and 32 are eliminated and the thickness of the flange 18b is increased.
• FIG. 4 Another embodiment of the invention, illustrated in FIG. 4, essentially differs from the embodiments described above by the container body structure. Indeed, instead of being made up of a thick monobloc ferrule, the body of the container in this case has a multilayer structure. More specifically, the container body, designated in this case by the reference 10 ′, comprises an interior metallic ferrule 44, an exterior metallic ferrule 46, as well as an intermediate filling material 48.
• the interior metallic ferrules 44 and exterior 46 are made for example of cast iron, iron alloy, stainless steel or carbon steel.
• the filling material 48 is a softer material, such as lead, capable of stopping gamma radiation, or a material of the plaster, resin or other type, capable of absorbing neutrons and ensuring thermal insulation, or else a mixture of these materials.
• the inner 44 and outer 46 ferrules are welded to a metal flange forming the end flange 10b 'of the body 10' of the container.
• the flange 10b ' is made of the same material as the ferrules 44 and 46. It is machined on its end face as well as on its inner periphery, in the same manner as in the embodiments described above in order to be able to receive the cover. 12, the plug 22 and the ring 28 when it exists.
• the inner ferrule 44 and the outer ferrule 46 are closed in a sealed manner, respectively, by an inner bottom 52 and an outer bottom 54.
• the bottoms 52 and 54 are welded to the ferrules 44 and 46 respectively.
• the material 48 is also present between the bottoms 52 and 54.
• the outer containment of the container is constituted by the inner ferrule 44 provided with its bottom 52, the end flange 10b 'of the body 10', the cover 12 and the seals sealing rings 16 located at the interface between the end face of the flange 10b 'and the face opposite the cover 12.
• the container comprises two separate confinement enclosures, placed one inside the other.
• This arrangement ensures redundant containment of radioactive materials and makes it possible to prevent any penetration of water inside the container, even in the event of severe accident situations such as a fall of the container or a fire. Consequently, the dimensioning of the structures internal to the container as well as the quantities of neutron-absorbing poisons integrated in these structures can be appreciably reduced compared to the containers. existing. This is reflected in particular by a significant reduction in the cost of designing and manufacturing such a container.
• the installation of the internal confinement enclosure is carried out in such a way that the installation of the components of this enclosure can be done with great ease.
• the container 18 is placed or wedged by simple compression between the peripheral part of the plug 22 and the shoulder 20 machined internally in the end flange 10b of the body of the container.
• This characteristic makes it possible to set up the container 18 filled with radioactive materials and devoid of its cap 22, inside the body of the container using gripping and remote handling means. This operation is completed when the flange 18b of the container 18 comes to bear on the shoulder 20. In other words, no clamping means such as screws are used at this stage. The personnel performing this operation is thus protected from contamination and radiation from the radioactive materials housed in the container 18.
• the following operation of placing the plug 22 on the upper face of the flange 18b of the container 18 and on the shoulder 26 is also a simple operation which can also be carried out remotely. Consequently, no presence of personnel in the vicinity of the container 18 is necessary until the latter is sealed.
• the intervention personnel then performs either the fixing of the ring 28 on the end flange 10b of the body 10 using the screws 30, or directly the fixing of the plug 22 on this flange or on the flange 18b of the container , for example using screws such as screws 30 ', the container 18 is already closed. The personnel is therefore well protected against internal contamination and radiation by the thickness of the plug 22 and the sealing means constituted by the seals 24.
• the container 18 can be easily dismantled. It suffices either to remove the clamping ring 28 and the plug 22, or to directly disassemble the latter. The container 18 can then be easily removed from the body of the container by any suitable gripping means, since it is simply supported on the shoulder 20.
• the plug 22 is then replaced or not.
• the container no longer contains any of the elements of the internal confinement enclosure. It can then transport larger quantities of less active or less fissile materials.
• the ease of dismantling and the mode of installation of the container 18 also make it possible, conversely, to strengthen the protection against radiation emitted outside the container.
• the container 18 and possibly the plug 22 can be replaced by a container and a plug of different thicknesses, suitable for the transport of other radioactive materials.
• a container 18 of greater thickness has been shown in broken lines in FIG. 1.
• the thickness of the wall of the container 18 is generally between 0.3 cm and 5 cm.
• the embodiments described with reference to the figures make it possible to reduce the dimensions of the recesses machined in the end flange 10b of the container body, in order to receive the components of the internal confinement enclosure.
• the flange 18b of the container 18 is simply compressed between the plug 22 and the shoulder 20 of the body 10, without any means of tightening at this level, such as that screws which would require sufficient space for their implantation through the flange 18b and the shoulder 20. Consequently, the width of the flange 18b and that of the shoulder 20 can be reduced to a minimum, as illustrated the figures.
• the aforementioned characteristic makes it possible to reduce the widths and the outside diameters of the shoulders as much as 26 and 32 intended to receive respectively the plug 22 and possibly the ring 28 associated with the screws 30, in the embodiments described with reference to the figures.

Applications Claiming Priority (3)

Publications (1)

Family

ID=8847346

Family Applications (1)

Country Status (10)

Families Citing this family (12)

Family Cites Families (8)

• 2000
  • 2000-02-24 FR FR0002314A patent/FR2805655B1/fr not_active Expired - Fee Related
• 2001
  • 2001-02-23 AR ARP010100850A patent/AR029473A1/es unknown
  • 2001-02-23 BR BR0108665-0A patent/BR0108665A/pt not_active Application Discontinuation
  • 2001-02-23 JP JP2001562715A patent/JP2003524786A/ja not_active Withdrawn
  • 2001-02-23 WO PCT/FR2001/000534 patent/WO2001063621A1/fr not_active Application Discontinuation
  • 2001-02-23 CA CA002399262A patent/CA2399262A1/fr not_active Abandoned
  • 2001-02-23 CZ CZ20022845A patent/CZ20022845A3/cs unknown
  • 2001-02-23 EP EP01909884A patent/EP1258009A1/de not_active Withdrawn
  • 2001-02-23 KR KR1020027011058A patent/KR20030011776A/ko not_active Application Discontinuation
  • 2001-02-23 US US10/204,774 patent/US20030010938A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events