Patent Publication Number: US-10325690-B2

Title: Transport arrangement

Description:
The invention relates to a transport arrangement, particularly for transporting uranium hexafluoride, comprising an inner container, preferably having at least one apron projecting beyond an end face of the inner container, an outer container, which receives the inner container, and a twist prevention device, by means of which the containers can be locked together to prevent them from twisting about their longitudinal axes. 
     Transport arrangements, particularly for transporting uranium hexafluoride, with an inner container and an outer container surrounding it can be found in WO 2013/134384 A1 or EP 2 335 251 B1, for example. 
     A generic arrangement can be found in EP 0 777 238 A1. To avoid the twisting of the inner container in relation to the outer container, the transport arrangement includes a twist prevention device in the form of a ribbon-shaped element, which is embedded into the interior wall of the outer container and which is in the shape of a semi-circle. The ends of the twist prevention device are connected to the apron of the inner container. 
     In general terms, the invention relates to a twist prevention device for containers relative to each other, in order to prevent the rotation of the containers, specifically both under normal transport conditions and under accident-related transport conditions. Such a rotation about the longitudinal axes of the containers in relation to each other particularly could occur when the inner container is only partially filled in terms of volume. This can result in a rotational momentum, especially if an impact occurs in such a manner that the center of gravity of the inner container is not located vertically above the point of impact. 
     Specifically, the invention relates to a twist prevention device for containers for the transport of uranium hexafluoride, which prevents a rotation of the inner container loaded with UF 6 , such as a 30B cylinder, relative to the outer protective packaging under the assumed normal transport conditions and accident-related transport conditions. The UF 6  in the inner container under transport conditions (solid state) is predominantly located in the lower half of the container, which is only filled to about 60% in terms of volume. Side impacts therefore may result in a rotational momentum, as the center of gravity of the inner container is not vertically above the point of impact. 
     Uranium hexafluoride typically is transported in cylinder-shaped steel containers. These containers are specified in ISO 7195 “Packaging of Uranium Hexafluoride (UF 6 ) for Transport,” and/or in ANSI N14.1 “Uranium Hexafluoride—Packaging for Transport.” During transport, these containers must fulfill the requirements of SSR-6 “Regulations for the Safe Transport of Radioactive Material” of the IAEA, as well as the requirements of international and national regulations derived from the latter. Steel containers for uranium hexafluoride with an enrichment of more than 1 weight percent uranium-235 in the uranium are surrounded by a protective container during transport, which is meant to provide compliance with the aforementioned regulations. Steel container, protective container and the contents of uranium hexafluoride form the package in the sense of the regulations. 
     In containers, which hold uranium hexafluoride with an enrichment of more than 1 weight percent, but no more than 5 weight percent, of uranium-235 in the uranium, neither the valve nor the plug may come in contact with any other component of the protective packaging or the inner container—aside from the original point of attachment—during the tests described in the following under items 1 to 3. 
     The following tests must be conducted on one and the same package: 
     1. A drop test from a height depending on the weight of the package (for example, 1.2 m for a weight of the package of up to 5,000 kg) onto an unyielding target. 
     2. A drop from 9 m height onto an unyielding target. 
     3. A drop from 1 m height onto a steel cylinder with a diameter of 150 mm and a minimum length of 200 mm. 
     To protect the valve, it is known that a valve protector is integrated into the protective packaging, such as can be found in EP 2 335 251 B1. However, this only provides effective protection to the extent that the valve remains in the 12-o&#39;clock position during and after the aforementioned test conditions. The valve could hit the valve protector if the inner container rotates. 
     Across from the valve, a plug is arranged in the 6-o&#39;clock position. A metal pan is welded onto the corresponding place in the protective packaging, which creates sufficient room for relative movement of plug and protective packaging to avoid any contact between plug and protective packaging. However, this safety characteristic only is effective if the plug remains in the 6-o&#39;clock position. If the inner container were to rotate, no sufficient room would be available for relative movements between plug and protective container to protect the plug from coming into contact with the protective container. 
     Currently used protective packages for inner containers for transporting UF 6  are the designs UX-30, MST-30 and COG-OP-30B. Of these, only the design MST-30 comprises twist prevention (approval number J/159/AF-96 (Ver. 2)). 
     The twist prevention of the design MST-30 consists of a bent flat bar, which on one side is attached to the flange of the lower shell of the protective package via a hinge and which comprises a welded-on pin on the other side, which engages with one of the two boreholes in the apron of the 30B cylinder. As the boreholes are arranged at the 3-o&#39;clock and 9-o&#39;clock positions in the apron of the 30B cylinder, the cylinder must be turned 30° to be able to insert the pin into the borehole. As the cylinder is always stored and handled with its valve in the 12-o&#39;clock position, this turning of the cylinder (which has a weight of 3,000 kg when loaded) is associated with great effort and potential hazards for the operators. 
     The object underlying the present invention is to further develop an arrangement of the type described above in such a manner that it provides twist prevention in a simple design. According to an additional aspect of the invention, it will provide the option of determining whether the twist prevention is in its effective position without elaborate monitoring measures. 
     The twist prevention device according to the invention is intended to prevent rotational movements of the inner container potentially resulting from the mechanical stress under transport and accident-related conditions. It is intended to facilitate the secure and economical operation while requiring little maintenance. It should be operable by a single person without tools. 
     One or more of the aforementioned aspects are achieved in the invention by the arrangement of the type described above, wherein the twist prevention device comprises: 
     a locking element that is axially adjustable in a first receptacle and in that receptacle&#39;s longitudinal direction, 
     a second receptacle that rotatably receives the first receptacle and is fixedly connected to one of the containers, and 
     a handle that extends from the first receptacle and is radially guided by the second receptacle transversely or perpendicular to the second receptacle&#39;s longitudinal axis, the pivoting movement of said handle being convertible via the first receptacle into the axial adjustment of the locking element for engagement in the other container or disengagement therefrom. 
     In particular, the design is such that the twist prevention device extends from the outer container, which preferably consists of two shells joined together in one plane. 
     Preferably, the invention comprises a first receptacle that includes a hollow cylinder shape with at least one helical opening in axial direction, that is, in its longitudinal direction, wherein said opening is penetrated by at least one protrusion extending from the locking element, wherein the protrusion engages with a recess extending in the longitudinal direction of the second receptacle. This guarantees that the locking element, which preferably is designed as a stud, can be moved axially during a rotational movement of the first receptacle, and that the locking element thereby sufficiently engages with—or, respectively, can be removed from—the other container, in particular the inner container, preferably with/from its apron. 
     In the further development of the invention, it is provided that the second receptacle comprises a second opening extending radially, which is penetrated by the handle extending from the first receptacle. The second opening is located in a plane extending perpendicularly to the longitudinal axis of the second receptacle and preferably extends over an arc length π. 
     The handle can easily be swiveled, wherein the resulting synchronous movement of the first receptacle (as a sleeve), the penetration of the at least one helical opening in the first receptacle by the stud extending from the locking element (as a locating pin), and the stud&#39;s engaging with the longitudinal opening (as a groove) cause the locking element in the second receptacle to axially adjust itself to the first and second receptacle. The swiveling movement of the handle and the corresponding axial adjustment of the locking element can be performed by a single person without additional tools. 
     In particular, the design provides two helical first openings in the longitudinal direction of the first receptacle, wherein protrusions extending from the locking element engage with each of the first openings like an adjusting pin. 
     In a noteworthy further development of the invention, an arrangement of the type described above—in which the outer container, that is, the protective packaging, consists of two shells that are joined when properly surrounding the inner container—is designed such that the handle can be positioned in a locking position and in an unlocking position, wherein the shells are joined in the locking position of the handle, such that the outer container properly surrounds the inner container, and wherein the shells are positioned at a distance from each other in the area of the handle when the same is in the unlocking position. This last scenario means that the outer container—that is, the shells—cannot be properly closed and the transport unit therefore cannot be used. 
     To implement such a safety measure, the invention in particular provides two support elements for the handle, which extend from one of the shells, wherein the handle can brace against—or, respectively, rest upon—one of these support elements in the handle&#39;s unlocking or locking position, and a counter element associated with one of the support elements, said counter element extending from the respective other shell, wherein the distance between the counter element and the associated support element is smaller than the effective extent of the handle between these two elements when the outer container is properly enclosing the inner container. 
     This way, it is ensured that it is impossible to close the outer container when the handle rests upon the support element in which the locking element is engaged with the inner container, because the necessary distance between support element and counter element, which facilitates the proper closure of the outer container, cannot be achieved due to the handle being positioned between these two elements; this is the case because, as mentioned previously, the gap between the support element and the counter element is smaller than the effective extent of the handle between these two elements during proper closure. 
     However, if the handle braces against the support element, which is not associated with the counter element, it is possible to close the outer container. Thereby, it can be ensured in simple fashion that the outer container can only be closed when the outer container is locked to the inner container, that is, when the proper twist prevention is guaranteed. 
    
    
     
       Additional details, advantages and characteristics of the invention follow not only from the claims and the characteristics contained in the same—on their own and/or in combination—but also from the preferable exemplary embodiments described in the following and in the drawings. 
       These show: 
         FIG. 1  A container 
         FIG. 2  A perspective diagram of a twist prevention device 
         FIG. 3  A front view of the twist prevention device according to  FIG. 2   
         FIG. 4  A sectional view along the line A-A in  FIG. 3   
         FIG. 5  A schematic diagram of a container in horizontal view 
         FIG. 6  A longitudinal view through the twist prevention device according to  FIG. 2   
         FIG. 7  A sectional view along the line B-B in  FIG. 6   
         FIG. 8  A sectional view along the line C-C in  FIG. 6   
         FIG. 9  The twist prevention device according to  FIGS. 6 to 8  in the position locking the inner and outer containers of the container 
     
    
    
     The drawings show schematic diagrams of a transport arrangement with a twist prevention device, which safeguards an inner container  10  and a protective packaging to be described as outer container  12  with regards to twisting, such that the inner container  10  is prevented from twisting or rotating relative to the outer container  12 , thus precluding damages to components of the inner container  10  such as a valve or plug. In this context, the twist prevention device works both under normal transport conditions and under accident-related conditions, such that even an impact of the outer container  12  outside of the 6-o&#39;clock position would not lead to a rotation. 
       FIGS. 1 and 5  show schematic diagrams of the inner container  10  receiving or containing specifically uranium hexafluoride and of the outer container  12 , which consists of two shells  14 ,  16 , which, in the assembled state of the outer container  12 , specifically are joined in a plane that extends horizontally. 
     As can be seen in the horizontal sectional view in  FIG. 5 , the inner container  10  comprises aprons  18 ,  20 , which protrude from the front sides  22 ,  24  of the inner container  10 . In the exemplary embodiment, two twist prevention devices  26 ,  28 , which extend from the lower shell  16 , engage with the apron  18  shown on the right in  FIG. 5  when the device is in transport position, in order to preclude a rotation of the unit comprising the inner container  10  and the outer container  12  about their longitudinal axis  15  relative to each other. 
     The diagrams show that the twist prevention device  26 ,  28  includes a locking element, which in the exemplary embodiment is designed as stud  30 , which is axially moveable in an inner sleeve  32  comprising a hollow cylinder shape. The sleeve  32  can be described as a first receptacle, which is rotatably received by a second receptacle  34 , which in turn is fixedly connected with the lower shell  16  of the outer container  12 . The second receptacle  34 , which also comprises a hollow cylinder geometry in the exemplary embodiment, extends from a bracket  36 , which is connected with the lower shell  16 . 
     A handle  38  extends from the first receptacle  32 , said handle having a bar shape, although the inventive teaching is not limited to this embodiment. The handle  38 , which is referred to as a grip in the following, penetrates a radially extending opening  40  in the second receptacle  34  or sleeve, which may comprise an arc length of  7 E. The opening  40  therefore extends in a plane, which transversely or perpendicularly crosses the longitudinal axis  31  of the twist prevention device  26 ,  28  and thereby the longitudinal axis both of the inner sleeve  32  and of the outer sleeve  34 . 
     As illustrated in the cross-sectional view of  FIG. 8 , protrusions such as the locating pins  42 ,  44  extend from the stud  30 , which protrude diametrically opposite from the outer surface of the stud  30 . The locating pins  42 ,  44  penetrate helical openings  46 ,  47  extending in the axial direction of the first receptacle or inner sleeve  32 , in order to engage with recesses extending in the axial direction of the second receptacle or sleeve  34 , such as grooves  48 ,  50 . 
     Due to the helical openings  46 ,  47  in the first receptacle  32  and the penetration of these openings by the radially protruding protrusions or locating pins  42 ,  44  of the stud  30  and the engagement of these pins with the axially extending recesses such as grooves  48 ,  50  in the inner surface of the second receptacle  34 , an axial adjustment of the stud  30  only occurs if the first receptacle  32  is swiveled via the grip  38 . The rotational movement of the first receptacle  32  thereby is transformed into an axial adjustment of the stud  30 . The rotational movement shifts the locating pins  42 ,  44  along the axial grooves  48 ,  50 , in order to lock—or, respectively, release—the lower shell  16  to/from the inner container  10 . A locking position is shown schematically in the upper image in  FIG. 5 , as is the unlocking position in the lower image of the same drawing. 
     Thus, the possibility is created of achieving an axial movement of the locking element  30 , which is designed as a stud in the exemplary embodiment, by a rotational movement of the grip  38 , without interrupting the edge surrounding the lower shell  16 , which serves as a seal against splashing water. This is shown schematically in  FIG. 1 . 
     The operation of the twist prevention device—only rotational movement, low torque, no additional tools necessary—is very user-friendly. The inner container  10  can be loaded into and/or removed from the protective packaging, that is, into/out of the lower shell  16  of the outer container  12 , in its storage position, without needing to be turned. 
     However, another advantage results from the inventive teaching. Namely, it is impossible to join the upper shell  14  to the lower shell  16  when the twist prevention device is unlocked, as will be explained by means of  FIGS. 2 and 9 . 
     The invention includes two support elements or supports  52 ,  54  extending from the lower shell  16 , which are arranged on opposite sides of the twist prevention device and are connected with the bracket  36  in the exemplary embodiment. The surfaces of the supports  52 ,  54  are positioned in a plane, which extends parallel to the position of the grip  38  in its respective end position, as is shown schematically in the drawings. 
     The support  54  is associated with a counter element or counter support  56 , which extends from the upper shell  14 . When the lower shell  16  is joined to the upper shell  14 , the distance between the support  54  and the counter support  56  is smaller than the effective extent of the handle between the lower and upper shells  14 ,  16 , that is, the diameter of the grip  38  in the exemplary embodiment. 
     The counter support  56  is associated with the support  54 , upon which the grip  38  rests when the stud  30  is not engaged with the apron  18  but instead is in its unlocked position. If one attempts to close the outer container  12  in this position, that is, to join the upper and lower shells  14 ,  16 , the shells  14 ,  16  could not be properly joined, as the grip  38  would be located between the support  54  and the counter support  56 . 
     In the locked position, that is, when the stud  30  engages with the apron  18 , which results in the desired locking between inner container  10  and upper shell  16 , the grip is located on the support  52 , such that the lower and upper shell  14 ,  16  can be properly joined, as the support  54  and counter support  56  can be aligned sufficiently; this is due to the fact that the grip  38  is not located in the gap  58 . Thus, the upper shell  14  can be set exactly on top of the lower shell  16  and the latches of lower and upper shell  14 ,  16  can be properly closed. 
     The inventive twist prevention device guarantees that protective elements of the inner container  10  that are positioned inside the outer container  12 —that is, inside the protective packaging—can maintain their function under normal conditions and accident-related transport conditions, and that they will not be rendered ineffective by a rotation of the inner container  10  and that such a rotation cannot lead to components of the inner container  10  being damaged. The twist prevention device is designed such that a closing of the protective packaging—that is, of the outer container  12 —is impossible insofar as the twist prevention device does not properly lock the inner and outer containers  10 ,  12 . Therefore, any transport only is possible with a properly locked twist prevention device. 
     Regarding the dimensions and materials of the twist prevention device, the following must be noted. 
     The preferred material for the components is stainless steel. 
     The locking element  30 —that is, the stud—may have a length of 60 to 95 mm and a diameter of 40 to 60 mm. The diameter of the first receptacle  32 —that is, the first sleeve—is adjusted accordingly, which means that the diameter can be between 50 and 75 mm. The length should be between 60 and 95 mm, wherein a wall thickness between 4 and 10 mm is preferable. 
     The second receptacle, or sleeve  34 , correspondingly should have a diameter of 65 to 90 mm and a length of 60 to 95 mm. The wall thickness may be between 4 and 8 mm. 
     Regarding the axially extending grooves  48 ,  50 , it must be noted that their width should be between 5 and 10 mm and their depth between 2 and 5 mm. 
     The helical passage or opening  46 ,  47  should have a width of 5 to 15 mm.