KR20210141967A - Assembly comprising packaging for storage of radioactive material and its support system - Google Patents

Abstract

The invention relates to an assembly (100) comprising a packaging (1) for storage of radioactive material and a support system (3) thereof, comprising a radiation screen (20) for thermal protection of the ground, The screen is formed between the second side 30 of the screen and the lower end of the packaging 4 and a zone 32 for circulation of air for ground cooling defined below the first side 28 of the screen. and at least one or more air passages 24 providing communication between zones 34 for circulation of air for cooling the ocean of packaging being used. The support system 3 comprises elements 36 for supporting the bottom of the packaging, each projecting from the second side 30 of the radiation screen 20 and extending through the region 34, and 3) comprises a bearing element protruding from the region 32 .

Description

Assembly comprising packaging for storage of radioactive material and its support system

FIELD OF THE INVENTION The present invention relates to the field of packaging for the storage of radioactive materials such as drummed radioactive waste, nuclear fuel assemblies, and the like.

More specifically, the present invention relates to a support system that provides an interface between the bottom of the package and the ground of a storage site in a vertical storage position with such a package. It relates to the formed assembly.

In general, packages are stored in a vertical position in a storage area, also referred to as a storage hall or building.

These packages are usually placed directly on the ground of a storage building, meaning that the bottom of the package is in direct contact with the ground. As a result, the portion of the ground facing the bottom of the package may reach high temperatures that may exceed average and maximum tolerated ground temperatures of the ground.

One object (one object) of the present invention, the bottom of the package and the storage building in the storage configuration of the package (a storage configuration of the package) in order to lower the average and maximum allowable temperature of the ground in contact with the package To provide an assembly comprising a package for storage of radioactive materials and a support system thereof, arranged between the ground of a storage building.

In order to lower the average and maximum allowable temperature of the ground in contact with the package, one object of the present invention is the bottom of the package and the storage building in a storage configuration of the package. It is to provide an assembly including a package for storage of radioactive materials and a support system thereof, arranged between the ground of a storage building.

According to the invention, a support system has a first, lower face, and a second, upper face opposite the first face. a radiation shield for protection, the radiation shield having a ground cooling air circulation zone formed below the first face of the radiation shield and a second face of the radiation shield at least one air passage ensuring communication between the package bottom cooling air circulation zone formed between the second face and the package bottom; It includes a central part provided.

Further, the support system further comprises a plurality of spaced bottom package support elements, each support element projecting from the second side of the radiation shield and in contact with the bottom package. It extends through the bottom package cooling air circulation zone.

And, the support system further includes a plurality of bearing elements projecting from the first side of the radiation shield into the ground cooling air circulation zone.

The present invention therefore makes it possible first of all to reduce the average and maximum temperature of the part of the ground where the radiation shield comes into contact with the assembly by means of a support system that limits the radiation of the package towards the ground. In addition to this radiation shielding, the support system can cool the ground by air being sucked into a ground cooling air circulation zone formed below the first face of the radiative shield. and this suction is performed radially from the outside to the inside until the air has passed through the central air passage(s). The air is then discharged through the cooling air circulation area at the bottom of the package.

In other words, the present invention provides a simple method of limiting the temperature rise of the ground and the bottom of the package by combining the effects of heat shielding and natural convection cooling.

The present invention, alone or in combination, may provide for implementing one of the following optional features.

The central part of the radiation shield to which each air passage is restricted has a first diameter D1 smaller than the largest transverse dimension D2 of the package so as to satisfy the following relationship.

D1 < 0,5 . D2

These dimensions combine both thermal shielding and natural convection cooling effects to further improve the cooling efficiency of the bottom of the package and the ground.

wherein said at least one air passage has a cumulative air circulation area S1, the package in the storage configuration being orthogonal to the ground and radiation shield and has a longitudinal central axis centered with respect thereto. The package has a surface area S2 (surface area S2) projected onto the ground along the longitudinal central axis, and the areas S1 and S2 satisfy the following relationship.

S1 < 0,25 . S2

Once again, this design combines the effects of both thermal shielding and natural convective cooling, contributing to improved cooling effectiveness at the bottom of the package and at the ground level.

The support element and bearing element at the bottom of the package form two by two legs passing through the heat protective radiation shield.

This is advantageous in that it results in a simple design. Each leg is preferably made of one piece, except when a heat insulation layer is incorporated at its end in contact with the bottom of the package. Alternatively, the support element and the bearing element at the bottom of the package may be configured as independent elements, and may or may not be aligned in pairs along the longitudinal central axis direction of the package in the storage configuration.

In this storage configuration, the support system includes a liner supported at the periphery of the radiation shield, the liner defining an air suction channel around the package.

This liner promotes natural convective cooling and provides a chimney effect to the air in the cooling air circulation zone below the package.

The bearing element and/or the support element are oriented radially or substantially radially with respect to the central longitudinal axis of the package, and the support system is also centered thereon.

This function provides better circulation of fresh air in the air passage(s) as well as better discharge of the heated air passed through the air passage(s). That is, the bearing and support elements limit the physical barriers to air circulation in the support system that are created by the presence of these elements.

The bearing element and/or the support element are arranged radially outwardly with respect to the central portion of the radiation shield.

This prevents direct heat conduction between the ground and the hottest part of the bottom of the package, the center, and limits the overall size of the center of the radiation shield including the air passage(s). .

The radiation shield is equipped with a plurality of mechanical reinforcement elements interconnecting at least some of the underlying supporting and/or bearing elements.

The mechanical reinforcing element has a central connecting member and radially internal ends interconnected with each other, the plurality of air passages being bounded radially inwardly around the central connecting member, (delimited), each air passage is circumferentially bounded by a directly and consecutive mechanical reinforcing element.

Each mechanically reinforcing element is secured at its radially external end to one of the bearing elements and/or to one of the lower support elements.

The assembly comprises attachment means for reversibly attaching the support system to the package, the attachment means preferably comprising a lifting trunnion provided on the package ( Includes fixing elements for cooperating with lifting trunnions.

This allows the package to be secured to the support system and thus the entire assembly in the storage building can be moved when the package is handled vertically, eliminating the need to move the package and support system separately. When the package is placed on the support system, the latter is preferably attached to the trunnion of the package.

Each support element has a contact end with the bottom of the package in the form of an insulating layer.

This makes it possible to reduce the heat conduction through the support element in contact with the bottom of the package, and to limit the deterioration of the bottom of the package by this same support element.

Finally, one object of the present invention is a method for storing packages belonging to the assembly described above, arranged on the ground so that the package bottom cooling air circulation zone appears. and placing the package on the support system.

Additional advantages and features of the present invention will become apparent from the following non-limiting detailed description.

The present invention makes it possible first of all to reduce the average and maximum temperature of the portion of the ground where the radiation shield is abutted against the assembly by means of a support system that limits the radiation of the package towards the ground.

The present invention provides a simple method of limiting the temperature rise of the ground and the bottom of the package by combining the effects of heat shielding and natural convection cooling.

The description will be made as follows with reference to the accompanying drawings.
1 shows an axial longitudinal section of an assembly 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 is a cross-sectional view taken along line III-III of FIG. 1 .
FIG. 4 shows a view of another preferred embodiment of the assembly as in FIG. 1 .
5 shows a plan view of a radiation shield mounted to an assembly according to another embodiment.
6 shows a plan view of a radiation shield according to another embodiment.
7 shows a perspective view of a support system on which an assembly according to another preferred embodiment of the present invention is mounted.
Fig. 8 shows a partial perspective view of the support system shown in Fig. 7;
Fig. 9 shows a bottom view of the support system shown in Figs. 7 and 8;
10 shows a schematic diagram of a reversible mechanical connection between a package and its support system.

1 to 3 , an assembly 100 according to a preferred embodiment of the present invention comprises a package 1 for storage of radioactive material and a support system on the ground level 5 of a storage building 7 . An assembly comprising (3) is shown.

The package 1 is presented in a vertical storage position in which the longitudinal central axis 2 is oriented vertically, ie perpendicular to the ground surface 5 .

In general, the package comprises a removable lid 6 along a height direction 8 parallel to a longitudinal central axis 2 and a package bottom 4 opposite. In addition to the lower end 4 and the lid 6 spaced from each other along the axis 2 , the package 1 comprises a side body 10 extending with respect to this axis 2 . The bottom 4 and the lid 6 delimit axially the housing cavity 12 in which a radioactive material (not shown) is received.

The assembly 100 also includes a support system 3 positioned between the package bottom 4 and the ground 5 in the storage configuration of the package as shown in FIG. 1 . This support system 3 may be a system movable on the ground 5 or a system fixed to the ground 5 . The latter case is advantageous in meeting the seismic constraint.

The support system 3 comprises a radiation shield 20 for thermal protection of the ground. This shield 20 is in the form of a plate, and the geometry is identical to or homothetic with the bottom of the package 4 . Here, the radiation shield 20 has an overall disc shape about a central longitudinal axis 2 of the package, and the axis 2 is a longitudinal central axis of the system 3 and the assembly 100 . also applies to

The shield 20 is centered on the axis 2 and has a central portion 22 whose diameter D1 is smaller than the outer diameter D2 of the package-side body. The ratio between the two diameters D1 and D2 is preferably less than 0.5. The outer diameter D3 of the shield 20 is greater than or equal to the outer diameter D2 of the package-side body, and the ratio of D3 and D2 is preferably between 1 and 1.3.

The previously discussed central portion 22 corresponds to the portion of the shield 20 in which one or more air passages 24 are made. In this preferred embodiment, a single air passage 24 is provided which is circular and centered on the axis 2 . This passage 24 has a diameter D4 that creates a surface area S1. It is also preferred that the projected surface area S2 of the package on the ground surface 5 along the axis 2 has a ratio between S1 and S2 of less than 0.25. The projected surface area S2 may also correspond to the projected surface area of the package on the radiation shield 20 along the axis 2 , without taking into account the openings formed by the air passages 24 .

The shield 20 has a lower first face 28 and a second face 30 opposite the upper first face. An air passage 24 connects these two faces 28 , 30 . The lower first surface 28 is positioned parallel to and at a distance from the ground surface 5 , so that the ground cooling air zone circulation 32 between the first surface 28 and the ground surface 5 . is axially delimited. Similarly, the upper second side 30 is positioned parallel from the package bottom 4 and at a distance from the package bottom 4 to cool the bottom of the package between the package bottom 4 and the second side 30 . It delimits an air circulation zone 34 axially. The air passages 24 ensure communication between the two sections 32 , 34 respectively open radially outwardly.

The support system 3 also comprises a plurality of support elements 36 for the package bottom spaced apart from each other in the zone 34 . Such support elements 36 are provided, for example, in four, although other numbers may nevertheless be employed without departing from the scope of the present invention. Each support element 36 also projects vertically from the second face 30 of the shield 20 and extends upwardly through the region 34 until it contacts the package bottom 4 . As best seen in FIG. 3 , each support element 36 has a radius with respect to the axis 2 of the package, for better channel air circulation within the package bottom cooling air circulation zone 34 . oriented radially or substantially radially. Furthermore, this support element 36 is arranged radially outwardly with respect to the central portion 22 of the shield 20 . In the upper contact end bearing on the package bottom 4 , each support element 36 incorporates a thermal insulation layer to limit direct heat transfer from the bottom 4 to the ground 7 . good.

In a similar manner, the support system 3 comprises a plurality of bearing elements 38 on the ground 5 spaced from each other in a zone 32 . Such bearing elements 38 are provided, for example, in four pieces, although other numbers may nevertheless be employed without departing from the scope of the invention. Each support element 38 also projects vertically from the first face 28 of the shield 20 and extends downwardly through the section 32 until it contacts the ground surface 5 . The contact may be direct, or a thermal insulation layer may be interposed between the bearing element and the ground. Optionally, the bearing element 38 may be connected to a plate at its lower end and then contact the ground to further even out the temperature. In practice, such a plate makes it possible to limit the risk of hot spots on the ground against which the bearing element 38 abuts.

As can best be seen in FIG. 2 , each support element 38 is radially or generally with respect to the axis 2 , for better channel air circulation within the ground cooling air circulation zone 32 . oriented substantially radially. Furthermore, this bearing element 38 is arranged radially outwardly with respect to the central portion 22 of the shield 20 .

Within this preferred embodiment, support elements 36 and bearing elements 38 are brought together in 2X2 to form legs 40 passing through radiation shield 20 and between package bottom 40 and ground surface 5 . extends perpendicular to the

According to this preferred embodiment, fresh outside air flows radially inward towards passageway 24 and is drawn into zone 32 where channels are formed between legs 40 . During this circulation, the air cools the ground (5) so that the temperature drops, and this decrease limits the heat radiation provided by the radiation shield (20) disposed between the package bottom (4) and the ground (5). enhanced by the effect of limiting heat radiation. After passing through passage 240 , air circulates radially outward and enters region 34 where channels are formed by legs 40 . This air circulation occurs by natural convection. In addition, this air circulation in zone 34 contributes to cooling of the package bottom 4 surrounded by this same moving air.

To further enhance the suction effect by natural convection, the support system 3 may include, at the surface of the shield 20 , a liner 46 surrounding the side body 10 of the package. This liner 46 can be seen in FIG. 4 and has a cylindrical shape here. Together with the side body 10 , the liner 46 forms an annular air intake channel 48 around the package. This liner 46 is centered on the axis 2 and conforms to the shape of the side body 10 , and has a length greater than the height of the support element 36 at the bottom of the package, ie greater than the height of the section 34 . It may extend over its length.

Preferably, the length of this liner 46 is less than one quarter of the total length of such a package in a storage configuration. Optionally, the liner 46 may not have a cylindrical shape, but may still assume a conical shape about the axis 2 and widening towards the top of the package. This solution is particularly preferred if the ratio between the aforementioned diameters D3 and D2 tends towards 1.

The support system may also include an annular radiation protection ring, at the outer surface of the liner 46 , the height of which is at least greater than the height of the support element 36 at the bottom of the package. In addition to its radiation protection role, this ring may extend over all or a portion of the height of the liner 46, and may also be externally It may be possible to insulate the liner 46 against the

In the previously described mode, the radiation shield 20 has a single circular air passageway therethrough. However, several passages 24 may be provided within the central portion 22 of the shield 20 , such as several circular passages 24 uniformly distributed with respect to the axis 2 as shown in FIG. 5 . . According to another possible embodiment shown in FIG. 6 , the air passage 24 may correspond to angular sectors of rings, separated from each other by a ligament 50 of material.

Referring now to FIGS. 7 to 9 , there is shown a support structure 3 according to another preferred embodiment of the present invention. In this embodiment, six legs 40 are provided, all evenly distributed radially with respect to axis 2 . These legs may directly support the ground, or they may be coated with an insulating layer 52 to form an interface with the ground.

Furthermore, the radiation shield 20 is made by alternately forming angular shield sectors 54 and mechanical reinforcement elements 56 . More specifically, the angular sector 54 is a ring section, while a mechanical reinforcement element 56 is disposed at the interface between two directly successive ring sections 54 for fixing the ring sections. It is a radially oriented beam.

The beams 56 also serve to connect the legs 40 as each of the legs 40 is secured to the radially outer end of one of the beams.

On the other hand, at its radially inner end, each beam 56 is fixed to a central connecting member 58 which forms an integral part of the shield 20 , which member 58 has an axis 2 ) is centered on That is, the air passages 24 are distributed in a manner similar to that shown in the shield of FIG. 6 , each radially inward by a central member 58 , radially outward by a ring section 54 , and 2 It is circumferentially delimited by the radially inner end of the directly continuous beam 56 .

FIG. 10 schematically shows the steps of a method for storing a package 1 in a building 7 , aimed at disposing this package on a support system 3 already placed on the ground 5 . In this regard, it should be noted that for storage of the package 1 , the package 1 is released from its shock-absorbing cover which is normally mounted to the axial end of the package 1 when transported.

The simple fact of placing the package 1 on the system 3 makes the package bottom cooling air circulation zone 34 appear. Once placed, the package 1 is temporarily fixed to the support system 3 so that both objects can move simultaneously during handling operations performed during storage in the building 7 . have.

To achieve this connection between the package 1 and the system 3 , the system 3 is a reversible attachment comprising a fastening element 64 for clamping the trunnion 62 of the package. attachment means) can be mounted.

Of course, various changes may be made by those skilled in the art of the present invention described herein by way of non-limiting example and in accordance with the scope defined by the appended claims. In particular, different preferred embodiments can be combined with each other.

Claims (13)

a package (1) for storing radioactive materials and a support system (3) arranged between the bottom (4) of the package and the ground (5) of a storage building (7) in a storage configuration of said package,
The support system (3) comprises a radiation shield (20) for thermal protection from the ground, having a lower first face (28) and an upper second face (30) opposite the first face, The radiation shield 20 includes a ground cooling air circulation zone 32 formed below the first surface 28 of the radiation shield and between the second surface 30 of the radiation shield and the package bottom 4 . characterized in that it comprises a central portion (22) provided with at least one air passage (24) ensuring communication between the package bottom cooling air circulation regions (34) formed in the
The support system (3) further comprises a plurality of spaced-apart bottom package support elements (36), each support element (3) protruding from the second face (30) of the radiation shield (20) for the package. extending through the cooling air circulation section (34) for the package bottom (4) to come into contact with the bottom (4);
The support system (3) also comprises a plurality of bearing elements (38) projecting from the first surface (28) of the radiation shield (20) into the ground cooling air circulation region (32). The method of claim 1,
The central portion 22 of the radiation shield surrounding each air passage 24 has a first diameter D1 less than the maximum transverse dimension D2 of the package 1 , with the relationship D1 < 0,5 . Assembly, characterized in that it satisfies D2. 3. The method according to claim 1 or 2,
Said at least one air passage (24) has a cumulative air circulation surface area (S1), said package (1) in said storage configuration being perpendicular to said ground (5) and said radiation shield (20) and said radiation shield (20) ), the package has a surface area S2 projected onto the ground surface 5 along the longitudinal central axis 2, the area S1 and the area S2 having the following relation S1 < 0,25 . Assemblies that satisfy S2. 4. The method according to any one of claims 1 to 3,
Assembly characterized in that the support element (36) and/or the bearing element (38) at the bottom of the package form a 2X2 leg (40) passing through the radiation shield (20) for thermal protection. 5. The method according to any one of claims 1 to 4,
In the storage configuration, the support system (3) comprises a liner (46) supported on the surface of the radiation shield (20), the liner forming an air intake channel (48) around the package (1). assembly, characterized in that. 6. The method according to any one of claims 1 to 5,
The bearing element 38 and/or the support element 36 are oriented radially or generally radially with respect to the longitudinal central axis 2 of the package, and also the longitudinal center in the support system 3 . Assembly characterized in that the axis (2) is the center. 7. The method according to any one of claims 1 to 6,
Assembly characterized in that the bearing element (38) and/or the support element (36) are arranged radially outward with respect to the central portion (22) of the radiation shield (20). 8. The method according to any one of claims 1 to 7,
Assembly characterized in that the radiation shield is provided with a plurality of mechanically reinforcing elements (56) interconnecting at least some of the lower support elements (36) and/or the bearing elements (36). 9. The method according to any one of claims 1 to 8,
The mechanically reinforcing element (56) has radially inner ends connected to each other at a central connecting member (58), around the central connecting member (58) the plurality of air passages (24) are bounded in a radially inward direction; Assembly characterized in that each air passage (24) is circumferentially bounded by two directly successive mechanical reinforcement elements (56). 10. The method according to claim 8 or 9,
Assembly characterized in that each said mechanically reinforcing element (56) is fixed at its radially outer end to one of said bearing elements (38) and/or to one of said support elements (36) of said package bottom (4). . 11. The method according to any one of claims 1 to 10,
attachment means for reversibly attaching the support system (3) to the package (1), the attachment means preferably cooperating with a lifting trunnion (62) provided on the package (1) Assembly characterized in that it comprises a fastening element (64) for fastening. 12. The method according to any one of claims 1 to 11,
Assembly according to claim 1, wherein each support element (36) has an end in contact with the bottom of the package in the form of an insulating layer. 13. A method for storing the package (1) belonging to the assembly (100) according to any one of the preceding claims, comprising:
disposing the package (1) on the support system (3) placed on the ground (5) in order to cool the bottom (4) of the package so that the zone (34) for air circulation appears A method comprising:

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