GB2238298A - Packaging dangerous material - Google Patents

Abstract

Packaging for dangerous material, e.g. radioactive items or waste, comprises an external container (14), which may be an ISO container, and an internal cage (20) for receiving enclosures, e.g. 200 litre drums, shock absorbing means (e.g. 11) being placed between the external container (14) and the cage (20). The shock absorbing means may be large rubber tubes placed along the vertices of the internal container, and abutting longitudinal stiffening ribs of the external container, or springs ((26), Fig. 3, not shown) which can be levered out of the retaining position. <IMAGE>

Description

Packaging for transportation of dangerous material The present invention relates to packaging for transporting dangerous materials for example to packaging meeting the safety norms prescribed by the International Atomic Energy Agency (IAEA) for the transportation of radioactive materials of type B, published in the safety collection Series 6 (edition 1985).

When large radioactive contaminated items or large amounts of alpha-contaminated waste must be transported, the packaging presently existing (known as packaging of type B) is not suitable, as it can only hold items of small sizes.

A transportation of items of large size is subjected to special authorisations, which are not easy delivered by the competent Authorities.

Preferred embodiments of the present invention provide packaging meeting the norms prescribed by the IAEA and allowing the transportation of items of large size and of alpha-contaminated waste.

The proposed packaging comprises an external container, in which is arranged an internal cage, able to receive an enclosure, such as a drum, and is characterized in that between the external container and the internal cage, shock absorbing means are placed, which allows when a fall or drop occured, to lag the shock waves between the external container and the internal cage, and to lower the maximum acceleration to which the container is exposed.

According to an embodiment of the invention, the packaging is made of a container having an external structure formed of thick metal sheets and of an internal cage fastened to said structure b means of shock absorbing devices, such as springs, fenders, or others, whereby the internal cage incorporates the enclosures which ensure that the materials to be transported are tightly confined.

According to an advantageous embodiment of the invention, the thick metal sheets of the external container are made of allied aluminium and are welded together with an electron beam; the metal sheets are preferably grids or ribbed sheets.

According to a preferred embodiment of the invention, the shock absorbers are fenders, which substantially surrounds the longitudinal ribs of the cage, or the shock absorbers are springs placed at regular intervals along the longitudinal ribs of the cage.

Embodiments of the invention will now be described, by way of example, with reference to the enclosed drawings, in which: Fig 1 a perspective view of a packaging according to the invention, placed on a truck; Fig 2 a cross section of a packaging when dropped on one of its ribs; Fig 3 a partial cross section of the packaging showing one embodiment of shock absorbing means; Fig 3A an enlargement of a part of figure 3; Fig 4 a partial cross section of the packaging showing another embodiment of shock absorbing means.

The perspective view of figure 1 shows the packaging 10 placed on a truck 12. The exterior container 14 having the dimensions of a 20 feet ISO container is formed of metal sheets 16 and beams 18 forming grids.

Within the container 14 an internal cage 20 is placed, which is adapted for the transportation of 200 liter drums.

This cage 20 is formed of tubular steel sections having dimensions of 40 x 20 x 2 mm, welded together to form frames, reinforced by St Andreas crosses, formed of tubular bars welded to the frames.

According to the invention the longitudinal ribs of the internal cage 20 are provided at given intervals with anchoring means 24 for the shock absorbers 11. These means 24 are also fixed to the internal corners of the external container 14.

For the introduction and the removal of the internal cage 20 from the container, inflatable means are used to support the case. On removal inflatable cushions (not shown) are placed under the cage1 then inflated and thus supports the weight of the internal cage. Then the shock absorbers 11 are disconnected from the internal side of the external container 14, and the cage is removed by using a table 30, provided with rollers, and being adaptable in height.

The internal cage is designed to contain enclosures 22 of predetermined dimensions, in function of material to be transported. When 200 liter drums are considered the enclosures will for instance have the form of cylinders, having on top covers which can be firmly screw-bolted and which comprise a double seam allowing the measuring of the tightness. Each cylinder can contain two drums and sixteen cylinders can be placed in the cage (eight rows of each two cylinders), so that a total of 32 drums can be transported in the container.

If wished the cylinders can be additionally attached, for instance bolted to clamps, which are welded to the internal cage. When it is necessary to delimit the radiation dose of the personal in charge of the handling, a protection wrapper made from steel or lead can be placed around each enclosure 22.

Figure 2 shows the packaging 10, its longitudinal ribs 15 which are machined and extruded to improve the absorption of the energy developed by a fall on the ground of the packaging 10,and shock absorbing 11 means placed along the ribs 15.

The external container 14 is made with thick aluminium alloy sheets of large dimensions, produced with a high level of quality assurance as required for military and space applications.

In vie to optimize the weight of the structure, the aluminium sheets are in this example of the type 2017 or 5083 and are machined and ribbed to form a planking supported b a square shaped pattern of beams. The spacing of the lattice of the beams, generally between 150 to 420 mm, is depending of the energy to be absorbed by each part of the structure during a fall of the packaging on the ground. The energy is deduced from the norms prescribed b IAEA.

The metal sheet thickness is choosen on an economic basis, taking into account the price of the aluminium, the material removed during machining and the cost of electron beam welding. This welding process is choosen as it limits the heat development and affects in a minimal way the characteristics of the metal.

The longitudinal ribs of the external structure of the container 14 are machined and extruded, thus forming weak parts of the structure, which will be locally distorted during a fall on the ground from a height of 9 m on one of its ribs.

When the rib is collapsed, part of the energy is absorbed and the contact force with the ground can be spread out over a larger part of the structure.

The shock absorbing means 11 suspend and/or support the internal cage 20 within the container 14 during transportation. During handling (loading and unloading) the shock absorbing means 11 are freed from the internal cage 20 allowing thus the removal or introduction of the internal cage from or into the container 14.

Figure 3 shows an embodiment of shock absorbing means and in particular the upper end of a spring 26 fixed to a rod 32 hold in a housing 34 formed by a strap 36 attached to the cage 20. This rod 32 extends over the length of the cage and has a partly flat surface 33 so that it can be removed from the housing 34 by revolving it over 90 . Such a rotation can be carried out by a lever connected to the rod 32 at the outer end of the cage 20. The lower end of the spring 26 is fixed between two reinforcing straps 38 of the external structure of the container 14 and a pin 40 passes to the straps and is fixed on them.

Before freeing the rod 32, a system of inflatable cushions is placed under the cage 20 and then inflated to support the cage. Lever means 42 fixed on the internal surface of the container, near the rod 32 are operated from the outer end of the container. The rod 32 and the lever 42 are connected by a bar 44. By rotating clock-wise the lever 42 motion is transmitted to the rod 32 and the springs 26 thus freeing the cage for removal out of the container.

The absorbing means protect the enclosure 22 during accidents and absorb the static and other stresses suffered by the internal cage, whatever be the material to be transported and the type of enclosure used. It becomes thus possible to transport a variety of materials and enclosures, without that the structure should be calculated and tested each time.

During a fall from a height of 9 m the springs vibrate according to their own frequency, comprised between 5 and 10 Hertz. The -shock absorbing means delay the stress on the internal case and cut down the maximum acceleration to which the external container will be subjected. The shock absorbing means allow thus a better energy absorption with the time.

Moreover as the impact of the container with the undeformable ground takes place at a very high frequency (higher than 1000 Hertz), the shock absorbing means will have a very high absorption factor and protects the internal cage 20 from the accelerations suffered by the packaging during the impact.

When springs are used, the are placed along the longitudinal ribs of the container 14 . Preferably they will be hot processed windings made from an iron-nickel alloy with very high elastic characteristics (80 kg/mm ). Spring ends will have an hook form, so that they can work under compression and under traction. In the example, 13 springs will be placed along each longitudinal rib, so that the internal case will be protected by 52 springs.

According to another embodiment of the invention the shock absorbing means are rubber fenders, for instance of the type used for berthing ships. The fenders proposed are large cylindrical tubes able when compressed to develop a reaction force of several tenths of tons.

Figure 4 shows the external container 14 and the internal cage 20. The internal longitudinal ribs of the container 14 are rounded off and provided with a metallic plate 50 corresponding in shape to the fender 51. The fender 51 is fixe-d to the container 14 by means of nuts 52 and screws 53.

Inside the fender 51 a bar 54 stretches out to the full length of the internal cage 20. The fender is also placed on the full length of the cage but in a discontinuous way, for instance in parts of 50 cm.

During transportation the fender is put under tensile force so that it takes slightly an elliptical form with its long axis parallel to the axis of the nut 52. To this end the cage 20 comprises near each of its longitudinal ribs a rod 55 having at regular intervals (corresponding to the discontinuities of the fender 51) hooks 56, which can revolve round the rod 55 and engage or disengage the bar 54. When the hooks 56 engage the bar 54, the fender can be put under tensile force by screwing up the screws 53.

Each hook 56 can revolve round the rod 55 by means of a lever 58 attached to the case 20 and a bar 57, connecting the lever 58 with the hook 56. To engage or disengage the bar 54 from the hook 56, the bar 54 has a partly flat surface and can be operated in a similar way as described in the preceding example for the rod 32 shown in figure 3A.

For the introduction and the removal of the cage 20, the bar 54 is disengaged by revolving the hooks 56 and the screws 53 are unscrewed to release the tensile force from the fender 51. Afterwards the cage can be handled as in the preceding example with the help of inflatable cushions and a trolley.

Fenders 51 placed along the four longitudinal ribs of the container 14 conrer a maximal protection, During a fall of the container the fenders 51 under tensile force will distort and will be compressed, they will take an elliptical form with its small nxis parallel to the axis of te nut 52. After complete deformation of the fenders they will still absorb the choc by compression of the rubber structural material. It has been demonstrated that by using fenders specially manufactured for shock absorption, with an outside diameter of 25 cm and an inside diameter of 12,5 Cm the reaction force of the fender reaches 66 tons per meter of lender, when the outer dimensions of the flattened tube after compression reaches 14,9 Cm.

As distinct front the existing containers according to the state of the art, the enclosure according to the invention is not in direct contact with the outer container, but is separated from it, well protected and can be easily interchanged. The doors of the container made also from alloyed aluminium are secured with bolts, they can withstand high shocks without damage for the enclosure.

The packaging according to the invention allows to lighten the structure of the outer container due to the cutting down of the acceleration and the absorption during impact. Various configurations of the internal cage and of the enclosures are possible without the need for modification of the structure or the outer container and the absorbing means.

It is clear that the invention is not limited to the examples described and that many variations can be considered by the man skilled in the art. For instance the fixation of the springs or fenders and their engagement or disengagement can be made by various different. ways.

Claims (10)

1. Packaging for dangerous material, comprising an external container (14) and an internal cage (20) for receiving enclosures (22) characterized in that between the external container (14) and the internal cage (20) shock absorbing means (11) are placed, allowing in the event of the fall of the packaging, to lag the shock waves between the external container (14) and the internal cage (20) and to lower the maximum acceleration to which the container (14) is exposed.

2. Packaging according to claim 1, characterized in that the external container (14) is manufactered from thick alloyed aluminium sheets of large dimensions, which are machined and ribbed to form a planking supported b a square shaped pattern of beams (18).

3. Packaging according to claim 2, characterized in that the machined sheets are welded together b using the electron beam process.

4. Packaging according to claim 1, characterized in that the internal cage (20) is made from tubular steel sections, welded together to form frames and reinforced by St Andreas crosses.

Packaging according to one or more of the preceding claims, characterized in that the shock absorbing means (11) are placed along the internal longitudinal ribs of the external container (14).

6. Packaging according to claim 5, characterized in that the shock absorbing means are springs (26), placed at regular intervals along the longitudinal ribs, and are fixed between the external container (14) and the internal cage (20).

7. Packaging according to claim 5, characterized in that the shock absorbing means are fenders (51), made of rubber hollow tubes, placed along the longitudinal ribs over substantially the total length of the ribs.

8. Packaging according to claim 5, characterized in that the shock absorbing means are provided with locking means allowing to keep the internal cage (20) in place during transportation and to disengage the internal cage during the handling operations.

9. Packaging according to claim 8, characterized in that the locking means comprise a rod placed in a housing attached to the internal cage, which rod can be removed from the housing by a rotation, actuated from outside the cage with the help of a lever.

10. Packaging for dangerous material, substantially as hereinbefore described with reference to the accompanying drawings.