A protective and disposable intervention envelope shaped tent

Abstract

 A protective and disposable intervention envelope shaped tent (3), in particular for intervention on contaminated objects, said tent being leak tight and comprising at least a first (20) flexible flat sheet and a second (21) flexible flat sheet, said tent further comprises at least one first mechanically resistant and re-usable closure member (22) having a first and a second part (23), said first part being attached to said first sheet and said second part (24) being attached to said second sheet, said first closure member being provided to attach and detach said first (20) and second (21) flexible sheet to each other, said tent further comprising at least one second leak tight and re-usable closure member (25,26) comprising a first flap (25) connected in a leak tight manner to said first sheet (20) and a second flap (26) connected in a leak tight manner to said second sheet (21), said first and second flap being provided to be leak-tightly attached to each other by a leak tight seal and being applied in such a manner that said first and second closure members extend substantially parallel to each other and so as to overlap said first mechanical closure member when said first and second flaps and sheets are attached to each other.

Description

[0001] The present invention relates to a protective and disposable intervention envelope shaped tent, in particular for intervention on contaminated objects, said tent being leak tight and comprising at least a first flexible flat sheet and a second flexible flat sheet. In particular, the present invention relates to a protective tent which is suitable for intervention on contaminated objects such as nuclear radiated objects or objects contaminated by bacteria or viruses. The present invention also relates to a method for testing the leak-tightness of nuclear enclosures and to a method for storing the protection tent after its lifecycle.

[0002] When dismantling nuclear installations, such as for instance, mixed oxide ('MOX') and other Plutonium-bearing fuel rod production lines, one of the main issues is that of dismantling enclosures the interior of which has become contaminated with radioactive materials, without releasing this radioactive contamination. Several methods have been proposed for dismantling nuclear contaminated enclosures. So for example glove boxes are used, as this type of enclosures is the most widely used, but of course other types of nuclear enclosures can be used for this purpose.

[0003] Firstly, it must be considered whether the glove box is to be dismantled in the building where it was in operation or whether it will be moved elsewhere. In the latter case, the glove box will be packed and transported. This transport has the risk of contamination release during packing, loading, transport and unloading of the glove box. Furthermore, the transport of glove boxes with very large dimensions may be difficult, or even not possible.

[0004] Due to these transportation drawbacks, dismantling a glove box outside its operation building has usually only been considered when an existing hot cell, suitable for processing the glove box, has already been made available.

[0005] When the nuclear enclosure or glove box is however to be dismantled within the facility where it has been operated, whether it is in the same room or another room inside the same building, three different methods have been proposed : dismantling the glove box in an alpha-tight cell, in a cutting box or in a protective tent.

[0006] With the first method, the glove box is transported to a dismantling alpha-tight cell located inside the operation facility. The alpha-tight cell contains all cutting equipment necessary to perform the necessary dismantling operations under leak-tightness towards the external environment. Actuation of the dismantling tools is performed by operators who are standing inside the alpha-tight cell. These operators are equipped with special leak tight clothes and respiratory devices that enable them to operate in the inner environment of the leak tight room. Entrance and exit of the operators are foreseen through adapted airlocks. The removal of the waste pieces resulting from the cutting operations is realised by using waste drums connected to the tight cell.

[0007] If the glove box is to be dismantled in a cutting box located inside the operation facility, the glove box is firstly transported to the cutting box. A cutting box is a dedicated glove box containing cutting equipment for realising the dismantling operations while remaining isolated from the external environment. Like a glove box, the cutting box is equipped with glove ports and windows and is maintained at an under pressure by its own ventilation system. Actuation of the dismantling tools is performed by operators who are standing outside the cutting box. These operators are equipped with equipment and monitoring devices similar to those worn while operating on a glove box. Entrance to the cutting box where the glove box to be dismantled is placed, occurs by using a conventional bag -in technique, with however very large bags. The latter technique enables to maintain the confinement of the enclosure while introducing equipment or other material. To this purpose the equipment or the material is placed in a bag on which opening side there is provided an O-ring. The latter is than fixed inside a groove applied on a periphery of an access port of the enclosure in such a manner as to overlap a further bag already present on the access port and closing the latter. For entering the equipment or the material the latter is pulled with the bag inside the enclosure. Once the equipment or the material is inside, the access port is closed by the bag in which the equipment or the material was stored.

[0008] The removal of the waste pieces resulting from the cutting operation is ensured by waste drums docked to the cutting box. Optionally, light master-slave arms and tongs can be used on the cutting box in order to extend the working range and reduce the exposure of the operator to radiation. Comparable safety and containment issues are met when performing heavy maintenance on contaminated process enclosures.

[0009] In order to address the drawbacks of hot cells, alpha-tight cells and cutting boxes, the technique of protective tent has been proposed, for instance in the German patent application with publication number DE 4030186, or in the papers "Dismantling Techniques for Plutonium-Contaminated Glove-boxes : Experience from First Year of Decommissioning", R. BAUMANN, P. FABER, 6th International Symposium of Radioactive & Decommissioning Wastes, Kontec 2003, Berlin, Germany, March 2003; "Strategy for Decommissioning of Glove-Boxes in the Belgonucleaire Dessel Mox Fuel Fabrication Plant", A. VANDERGHEYNST, JM. CUCHET, 11th International Conference on Environmental Remediation and Radioactive Waste Management, ICEM'07, September 2-6, 2007, Bruges, Belgium, and "An evolutionary Approach for the Decommissioning of the Glove Boxes in the Belgonucleaire Dessel Plant", A. VANDERGHEYNST, JM. CUCHET, SFEN International Conference "Decommissioning Challenges: an Industrial Reality", September 28 to October 2, 2008, Avignon, France.

[0010] According to this technique, the glove box is transported to a protective tent located inside the glove box operation facility, or the protective tent is erected in situ around the glove box. The protective tent is disposable and comprises a flexible, leak tight envelope tailored to the shape and dimensions of the glove box to be dismantled and attached to an outer metallic support to prevent from collapsing when under pressurized. Like a glove box, the protective tent may be equipped with gloves, glove ports and windows and maintained at an under pressure by its own ventilation system. What is understood within the context of the present invention by "under pressure", is a pressure significantly lower than that of the surrounding atmosphere. The tent may contain cutting equipment (saws, nibblers, ...) for performing dismantling operations in isolation from the external environment. Actuation of the dismantling tools is performed by operators who are standing outside the dismantling tent. These operators may be equipped with equipment and monitoring devices similar to those used while operating a process glove box. Waste resulting from the cutting operations may be evacuated by conventional bag-out techniques through access ports or to waste drums docked to the protective tent in a leak tight manner. A bag-out technique being similar to a bag-in technique with the difference however that now material is brought out the glove box rather than brought in.

[0011] After dismantling, the protective tent is disposed off as secondary waste. To limit the amount of secondary waste, the envelope is made of thin wall resistant plane sheets welded to each other to provide structural resistance and leak-tightness. After use, this envelope is discarded, therefore it can be wrapped and further shredded into small pieces or packed in drums for conditioning at a later stage. Gloves or glove ports, windows and other mechanical and electrical tools are attached in a leak tight way to the envelope. To prevent from incidental contamination release in case of mechanical damage to the envelope with the dismantled parts or dismantling tools, the envelope is maintained under significant nominal under pressure (100-200Pa) with respect to the atmospheric pressure. The envelope's resistance is tested (for instance to twice the operational under pressure) and ventilation is performed at appropriate flows to keep under pressure even in case of significant mechanical damage (e.g. 60 m³/h).

[0012] When implementing this approach, it is of prime importance for safety purpose to prevent from weak or defective welds between adjacent sheets of the envelope. To achieve welds of good quality, tents are prefabricated according to quality control programs and heavy welding machines with process control are used in specialised manufacturing workshops. Overall tightness and resistance to accidental under pressure are tested on the final product before delivery to the dismantling plants.

[0013] Within the context of dismantling glove boxes, what is understood as "leak tight" is not absolute gas-tightness, but dust and aerosol containment which can be achieved, provided that the enclosure is kept at an under pressure in the range of 100-200 Pa with respect to atmospheric pressure and the air-tightness is in the order of magnitude of 0.1 % volume/hour.

[0014] However, in order to be able to introduce the glove box into the envelope on the dismantling works, the envelope has to be open at first and then closed and the leak-tightness measured again once the contaminated glove box is inside.

[0015] If the glove box has a complex shape, it will be necessary to give a complex shape to the leak tight envelope too and therefore to join adjacent flexible sheets at intersecting angles, while ensuring their leak-tightness. Moreover, if the glove box has large dimensions, it will be necessary to tailor the leak tight envelope in different parts for purpose of manufacturing and transportation in non-contaminated conditions and ultimate disposal once the interior of this envelope has been irreversibly contaminated.

[0016] It is an object of the invention to provide a protective and disposable intervention envelope shaped tent which is re-usable, as far as not contaminated, and which can be easily mounted and demounted.

[0017] For this purpose a protective and disposable intervention envelope shaped tent according to the present invention is characterised in that said tent further comprises at least one first mechanically resistant and re-usable closure member having a first and a second part, said first part being attached to said first sheet and said second part being attached to said second sheet, said first closure member being provided to attach and detach said first and second flexible sheet to each other, said tent further comprising at least one second leak tight and re-usable closure member comprising a first flap connected in a leak tight manner to said first sheet and a second flap connected in a leak tight manner to said second sheet, said first and second flap being provided to be leak-tightly attached to each other by a leak tight seal and being applied in such a manner that said first and second closure members extend substantially parallel to each other so as to overlap said first mechanical closure member when said first and second flaps and sheets are attached to each other. As the tent is built up of flexible flat sheets, the mounting of it is realised by assembling the different flexible flat sheets to each other. For this purpose use is made of the first mechanical closure member, the first and second parts of which are attached to each other such as to attach the sheets together. The presence of the flaps, which are leak-tightly attached to the sheet, provides a leak tight attachment of the sheets to each other, since the flaps are leak tight attached to each other. As moreover the flaps overlap the first mechanical closure member, any leakage which would have crossed the first closure member would be retained by the flaps, thereby providing a reliable leak tight tent.

[0018] A first preferred embodiment of a protective and disposable intervention envelope shaped tent is characterised in that when said tent is in a mounted state said first and second closure member extend in a substantially horizontal direction. This is for example the case when the tent is formed by a base structure and a hood structure which are connected to each other by a horizontally extending first and second closure member.

[0019] A second preferred embodiment of a protective and disposable intervention envelope shaped tent is characterised in that said first respectively second part of said first closure member are attached at a lateral border of said first respectively said second sheet, said tent further comprises at least a third flexible flat sheet, said first closure member further comprising a third respectively a fourth part attached to a transversal edge of said first or second sheet respectively a transversal edge of said third sheet and provided to attach and detach either said first or second flexible sheet to said third sheet by means of said third and fourth, said second closure member comprising a third respectively a fourth flap connected in a leak tight manner to said transversal edge of said third sheet respectively said first or second sheet, said first, second, third and fourth flap being provided to be leak-tightly attached to each other by a leak tight seal applied on said first, second, third and fourth flap, said first, second and third sheets being each time positioned adjacent to each other, in such a manner as to have a combination of at least one substantially horizontally and at least one substantially vertically extending first and second closure member when said tent is in a mounted state. This enables to build up a tent with a more complex geometrical shape as use can be made of vertically and horizontally juxtaposition of a plurality of sheets assembled to each other by using the first and second closure members.

[0020] A third preferred embodiment of a protective and disposable intervention envelope shaped tent is characterised in that said flaps extend beyond a surface over which their respective sheet, to which they are attached, extends. In such a manner T or other shaped juxtapositions of the first, second, third a fourth parts of the first closure member can be used. Indeed, as the flaps extend beyond the surface of their respective sheet, an overlap is also possible beyond the surface of the adjacent sheets, which improves the leak-tightness of the tent.

[0021] A fourth preferred embodiment of a protective and disposable intervention envelope shaped tent is characterised in that said tent further comprises a plurality of third mechanically resistant and re-usable closure members, each third closure member comprising a first closure element connected to said first sheet and a second closure element connected to said second sheet, said first and second closure element being complementary to each other so as to form, when in closed state, an additional attachment of said first and second flexible sheets and to bridge said at least one first mechanical closure member when the latter is in closed state. The use of a third closure member enables to improve the attachment of the sheets among them. As the third closure member bridges the first closure member a possible defect of the first closure member will be compensated by the third closure member.

[0022] The invention will now be described in more details with reference to the annexed drawings. In the drawings:

figure 1 shows a protective and disposable intervention envelope shaped tent covering a glove box to be dismantled;

figure 2 is a cross sectional view along the line II - II' of a protective and disposable intervention envelope shaped tent covering a glove box to be dismantled;

figure 3 shows a detail of the first, second and third closure member;

figures 4a and b show a detail of a section of the protective and disposable intervention envelope shaped tent illustrating vertically and horizontally applied first, second and third closure members;

figures 5a, b and c show a cross sectional view of a detail of the first, second and third closure members;

figure 6a shows a protective tent having a rectangular parallelepiped geometry and figure 6b a multiple rectangular parallelepiped geometry;

figure 7 illustrates the method to test the leak-tightness of the protective tent;

figures 8 and 9 illustrate the dismantling and storage of a tent;

figure 10 illustrates a secondary tube for storing the tent to be shredded; and

figure 11 illustrates how a tent is stored in a drum after dismantling.

[0023] The drawings are only schematic. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes only. Furthermore, same reference signs refer to a same or an analogous element.

[0024] Figure 1 shows the protective and disposable intervention envelope shaped tent 1 according to the present invention and covering a glove box 2 (showed in dotted lines) to be dismantled. For the sake of clarity the present invention will be described related to the example as a protective tent for dismantling a glove box. It will however be clear that the invention is not limited to this example and that the tent can be used for intervention on all kind of contaminated objects. The protective tent 1 comprises a leak tight envelope 3 for creating a leak tight environment, which is necessary because the risk of contamination is minimised during interventions inside the glove box. The leak-tightness of the protective tent is ensured by the use of leak tight closure members which provide a leak tight seal between the different sheets 20 and 21 forming the envelope shaped tent.

[0025] The envelope is upheld by straps 5 applied on a metallic support 6 forming an outer metallic frame. The support provides a structural, multi-purpose backbone to the tent. The support 6 can be reused after the contaminated envelope has been discarded.

[0026] The protective tent 1 comprises a leak tight port 7 e.g. airlocks, which allow transporting materials in and/or out of the envelope shaped tent without breaching its leak-tightness. Also, devices (not shown) needed for assistance during manipulations such as equipment, tools, electrical power outlets, monitoring devices, incident fighting equipment, a robotic arm, for example for remote controlled operation or ventilation pipes etc. can be brought into the leak tight tent in a leak tight manner. Actuation of the dismantling tools is performed by operators who are standing outside the protective tent. These operators may be equipped with tools and monitoring devices similar to those used while operating a process glove box. Further, a waste container 8 is coupled to the leak tight tent in a leak tight manner for the evacuation of waste, e.g. resulting from a dismantling operation.

[0027] The protective tent 1 also preferably comprises at least one leak tight window 9 allowing for light to penetrate into the tent and to see inside the tent. The protective tent further comprises at least one glove port 11 applied in the material of which the tent is made. For example, one or more gloves, e.g. one or more pairs of gloves, are attached to the glove ports in a leak tight manner to enable manual acts inside the envelope.

[0028] The protective tent 1 further preferably comprises at least one ventilation piping 50, as shown in figure 8, connected to a ventilation system (not shown) to enable ventilation and the creation of a vacuum inside the envelope 3. What is understood within the context of the present invention by "vacuum" is pressure which is in particular 100 to 200 Pa lower than that of the surrounding atmosphere. Ventilation is typically performed at appropriate flows e.g. 60 m³/h to minimise the release of nuclear contamination even in case of significant mechanical damage. The tent is typically maintained under vacuum (100-200 Pa) to further prevent incidental release of contamination in case of mechanical damage to the tent 3 caused by e.g. the dismantled parts or the dismantling equipment. Prior to dismantling the glove box, the envelope's resistance is preferably tested by applying a stronger vacuum, e.g. twice the operational vacuum. What is understood by "resistance" is structural resistance of the tent and the welding or seams between the constituent flexible sheets, efforts due to vacuum and other operational efforts originating from the operator handling parts and actuating tools after the tent has been attached to the metallic support 6.

[0029] The envelope is typically made of flexible canvas material, such as woven or non-woven polymeric flexible sheets, for example woven polyethersulfone (PES) foil. The flexible sheets may be coated on one or both sides, e.g. with polyvinylchloride (PVC), which provides structural resistance and facilitates the welding and/or gluing of the sheets during manufacturing of the envelope.

[0030] Figure 2 shows a cross-section through the tent of figure 1. The envelope comprises a first 20 and a second 21 flexible flat sheet, which are attached to each other. For the sake of clarity, a tent comprising only two sheets is illustrated, but it will be clear that the invention is not limited to tents of which the envelope is made of only two sheets and that a plurality of sheets can be used to form the tent. In the shown example the first sheet forms the bottom part of the tent, whereas the second sheet forms the upper part of the tent.

[0031] To enable the attachment of the different sheets, forming the envelope, at least one first mechanically resistant and re-usable closure member 22 is provided. By mechanically resistant there is meant a closure member that is resistant against a force of at least 50N. By re-usable there is generally meant that the closure member must enable a plurality of attachments and dissociations of the first and second sheet.

[0032] As illustrated in figure 3, the first closure member 22 comprises a first 23 and a second 24 part. The first part 23 is attached to the first sheet 20, whereas the second part is attached to the second sheet 21. In the example shown in figure 3, the first closure member is formed by a zip fastener which is preferably stitched on the sheet. Alternatively a hook and loop attachment member such as a Velcro (®) could be used. Instead of stitching the first closure member on the sheet, a gluing of the first and second part to the respective sheets could be done. The first and the second part of the first closure member are complementary to each other in such a manner as to enable attachment of the first 20 and the second sheet 21 to each other. So, when the first closure member is formed by a zip fastener it will be sufficient to close the latter for attaching the first and the second sheet to each other. The first closure member is preferably applied along a lateral and/or a transversal border of the sheet.

[0033] The first closure member however only provides a mechanical resistant and re-usable closure member for attaching the first and second sheet to each other. The first closure member is re-usable because it enables to open and close it several times by handling for example the zip fastener or the loop and hook attachment member.

[0034] To provide the leak-tightness to the attachment between the sheets forming the envelope, there is provided at least one second leak tight and re-usable closure member. The latter comprises a first flap 25 connected in a leak tight manner to the first sheet 20 and a second flap 26 connected in a leak tight manner to the second sheet 21. The connection in a leak tight manner of the flaps to the sheets is for example realised by welding or gluing the flaps to their respective sheet. To apply the flap on a sheet, an edge 27, 28 of the flap is welded or glued offset the part of the sheet where the first closure members 23, 24 are applied. Preferably the flaps extend substantially in parallel to the first closure member and to each other. The first 25 and the second 26 flaps are further provided to be leak-tightly attached to each other by a leak tight seal, preferably applied along their further edges 29 and 30.

[0035] So, once the first and second part of the first closure member 22 are attached to each other the first flap 25 and the second flap 26 are brought together so as to overlap the first closure member. The flaps are thereafter welded or glued together, preferably along their edges 29 and 30. The flaps are preferably made of Polyvinylchloride. In such a manner a leak tight closure between the first and second sheet is obtained.

[0036] As further illustrated in figure 3, the envelope is further provided with a plurality of third closure members 31 which are mechanically resistant and re-usable. Each third closure member 31 comprises a first closure element 31-1 connected to the first sheet 20 and a second closure element 31-2 connected to the second sheet 21. The first and the second closure element are complementary to each other so as to form, when in a closed state, an additional attachment of the first and second flexible sheets. The third closure members each time bridge the first mechanical closure member 22 when both are in closed state. The third closure member is for example formed by a buckle the elements of which are clipsed together. The third closure members are applied in the space covered by the second closure member so as not to affect the leak tightness. The first and second closure elements are preferably stitched on the sheet to which they are applied. The presence of the third closure members improves the mechanical attachment between the first and second sheet. Once the first and second part of the first closure member are attached to each other, the third closure members are brought in their closed state and consequently the second closure members are brought in their closed state.

[0037] Figure 4a and b illustrate the attachment of three and four different sheets to each other by means of the closure members. In the embodiment of figure 4a, a third sheet 32 is attached to the first 20 and to the second 21 sheet. For the attachment of the first 20 and the third 32 sheet with the second sheet 21, the first closure member 22, the second flaps 25 and 26 and the third 31 closure member extend in a substantially horizontal direction, whereas for the attachment of the first 20 and the third sheet 32 the closure members extend in a substantially vertical direction.

[0038] As can be seen in figure 4b, the first 23, respectively the second 24, part of the first closure member 22 are attached to a lateral border of all the sheets and extend in a substantially horizontal direction. In order to enable the attachment of the first 20 and third 32 sheet, and of the fourth 33 and the fifth 34 sheet to each other, the first closure number further comprises a third 35, respectively a fourth 36 part attached to a transversal border of the first 20 and third 32 sheet, respectively to a transversal of the fourth 33 and fifth 34 sheet. Analogous to the first and second part of the first closure member, the third 35 and fourth 36 parts are provided to attach and detach the first and the third and the and the fourth and the fifth sheet to each other in a transversal direction. The third and fourth part of the first closure member are, analogous to the first and second part, preferably either stitched on or glued to their respective sheet and are formed by a zip fastener or a loop and hook attachment member.

[0039] The second closure member further comprises a third 37 respectively a fourth 38 flap connected in a leak tight manner to the first 20 and third 32 sheet, respectively of the fourth 33 and fifth 34 sheet. The flaps extend along a transversal edge of the sheets to which they are applied. Preferably, the flaps extend beyond the surface over which their respective sheet, to which they are attached, extends. As will be described hereinafter this will enable a leak tight attachment over the corner pieces of the different sheets attached to each other for forming the tent.

[0040] The third 37 and the fourth 38 flaps are, just like the first and the second flap, provided to be leak-tightly attached to each other by a leak tight seal. As is further illustrated in the figures 3 and 4a and b, the third, fourth and fifth sheets are also preferably provided with the third closure members 31, which extend in a substantially horizontal as well as in a vertical direction.

[0041] In order to assemble the first 20, second 21 and third 32 sheet as illustrated in figure 4a, the first and second sheet are for example first attached to each other by bringing the first part 23 of the first closure member on the first sheet and the second part 24 of the first closure member on the second sheet 21 towards each other. Then the first and second parts of the first closure member are attached to each other, thereby attaching the first and second sheet to each other. Thereafter the third sheet 32 is placed next to the first and second sheet in such a manner that the first part 23 of the first closure member on the third sheet extends next to the second part 24 of the first closure member on the second sheet 21. Thereafter the first and second parts are attached to each other for example by activating the zip fastener, as illustrated in figure 5a. The attachment of the third sheet to the second sheet has caused the third 35 and fourth 36 part of the first closure member to extend next to each other, thereby enabling to attach them to each other so that the third 32 and first 20 sheets are now attached to each other. Thereafter, if present, the third closure members 31 are closed in order to improve the attachment between the first, the second and third sheets, as shown in figure 5b.

[0042] Once the sheets are mechanically attached to each other, the flaps of the second closure member will be attached together, as shown in all the figures 5. It is for example started by bringing the third 37 and the fourth 38 flap towards each other so that their respective edges 40 and 41 contact each other. A welding is then for example applied along the edges 40 and 41. If the third and fourth flaps extend beyond the transversal edges of the first and third sheet, the applied welding also extends beyond those edges so that the flaps are welded over their total length. In the section extending beyond the transversal edge of the first and third sheet, the flaps are even welded on both their lateral edges on their transversal edges so as to obtain closed sealing over the whole peripheral of the flaps.

[0043] Thereafter the first flap 25 of the third sheet 32 and the second flap of the second sheet 21 are brought together so that their edges contact each other. A welding is then applied along the edge 29 of the first flap 25 of the third sheet 32 and that section of the second flap 26 of the second sheet 21 which extends in parallel with the latter first flap. Again the welding extends over the whole length of the considered flap section. Thereafter the first 25 flap of the first sheet 20 and the second flap 26 of the second sheet are welded together in a similar way as the one of the third and second sheet. The sections of the third 37 and the fourth 38 flap which extend over the first 25 and 26 second flap of the first, third and second sheet are then welded together by applying for example a welding between an upper edge of the first flap 25 of the third sheet and the fourth flap and a lower edge section of the first flap of the third sheet and the fourth flap. Another welding is then applied between the latter lower edge section and an edge section of the first and second flap of the first and second sheet. Finally the transversal edges of the first and second flaps are welded together. In such of manner a leak tight closure is obtained. Any leakage which could arise through the first closure member would remain trapped in the volume delimited by the flaps. As the latter are welded over the lateral and transversal edges, a leak tight enclosure is obtained, which avoids any leakage out of the envelope to reach the outside world.

[0044] The connection between the four sheets illustrated in figure 4b is realised in an analogous manner as the one which has been described with respect to figure 4a and will therefore not be described in more detail. The leak tight closure member of the protective tent of the present invention could also comprise other closure members. For example, other types of first mechanical closure members could be used such as pressure buttons. They could alternatively be attached by stapling or riveting.

[0045] Figures 6a and b show a large protective tent provided for dismantling a large or a complex glove box which is not transportable. The tent 3 comprises a plurality of adjacently applied flexible sheets. Depending on the possibility to dress the envelope parts, one or more flexible sheets 21 are provided at the bottom of the tent. As an example, the dividing of an extra-long envelope into two normally long envelope parts facilitates the fabrication and transportation, the erection around a long and not transportable glove box, as well as the ultimate disposal by successive wrapping and shredding.

[0046] Figure 6a shows a protective tent 1 has a rectangular parallelepiped geometry. Hence, the protective tent 1 of the present invention can cover a wide variety of shapes and sizes and can be tailed to complex shapes, so as to cover glove boxes of large or complex shape. This is possible because the flexible sheets whereof the envelope 3 is made can be attached to each other in a leak tight way by the leak tight closures members as described here before.

[0047] Figure 6b shows a protective tent 1 having a multiple rectangular parallelepiped geometry, i.e. an arrangement of more than one parallelepiped geometry. Again, leak-tightness of this complex shaped tent is achieved because the flexible sheets of the envelope 3 can be attached to each other in a leak tight way by the leak tight closure members.

[0048] In order to cope with complex sizes and shapes, the closure members may comprise an arrangement of straight or curved segments. One straight or curved segment is positioned next to another straight or curved segment whereby the last one abuts to the first one, so as to provide a continuous leak tight closure.

[0049] Figure 7 illustrates a method for testing the leak-tightness of the envelope once assembled. Since preserving the leak-tightness of the protective tent is very important, leak-tightness is typically measured preferably after mounting and further more at several occasions during its lifetime. For example, leak-tightness is measured after a glove box has been introduced into the tent. In order to be able to introduce the glove box into the tent 1 for dismantling purposes, the envelope has to be opened at first, and then closed and the teak-tightness measured again once the contaminated glove box is inside. Before proceeding with dismantling the glove box within the envelope, it will normally be necessary to test the leak-tightness of the latter. Before measuring the leak-tightness of such an envelope, the air and other gases are pumped out of the envelope until a predetermined vacuum has been reached. Then the envelope is hermetically sealed by sealing all entries to the envelope. However, this method may not be accurate enough to evaluate the leak-tightness of such a nuclear enclosure. Acceptable leak rates of such enclosures, in particular for dismantling glove boxes, lie typically in the order of magnitude of a few 10^-3 Pa. There are several sources of errors in such leak-tightness tests, such as the relationship between temperature and pressure, the eventual flexibility of the enclosure walls, etc...

[0050] Leak tightness is also assessed after manufacturing the envelope shaped tent. To achieve quality seams between adjacent sheets of the tent (either between different edges of one folded sheet or between edges of different sheets), tents are prefabricated - preferably as parallepipeds - thereby applying quality insurance programs. Heavy welding machines with process control (e.g. high frequency or resistance welding machined) are used in specialised manufacturing workshops for applying the welding on the flaps applied on the sheets. Overall tightness under normal conditions and overall resistance to accidental conditions are tested on the final product before delivery to the dismantling works, to demonstrate the reliability of the welding. These tests are performed by putting the empty and non contaminated envelope under normal and accidental vacuum (for instance, twice the normal vacuum). The tightness is measured using the method of pressure increase.

[0051] The method for testing the leak-tightness of the intervention tent of the present invention, comprises the steps of:

a) closing any access gate to the tent in order to tight envelope 3 around the glove box 2;

b) providing an outer disposable 45 around the tent 1. Preferably some distance is left open between the envelope 3 and the outer disposal 45;

c) providing via an inlet 46 a tracer gas at a predetermined concentration into the envelope 3; and

d) measuring leakage of the tracer gas in the space between the envelope 3 and the enclosure 45.

[0052] A leakage of the envelope 3 can be determined by measuring either an air flow coming out of the envelope or concentration of tracer gas in the outer disposable enclosure 45. The tracer gas is for example chosen from CO₂, SF₆ or refrigerant gases.

[0053] As in the case of the nuclear enclosure according to the prior art, this detection and/or measurement may be carried out using a tracer gas sensor connected to a ventilation system of the tent. Advantageously, in order also to improve the accuracy of the tracer gas sensing, and to prevent radioactive blow-out from the enclosure, the inside of the envelope also presents a vacuum with respect to the outer world. The leak-tightness of the enclosure is measured by the concentration of gas within the nuclear enclosure, which is a straightforward measurement applying a common tracer gas sensor within the enclosure. By applying a vacuum, the leakage of radioactive substance from the envelope is prevented. Moreover, this also contributes to the accuracy of the method, as the tracer gas leaked into the envelope is prevented from re-exiting it and measurement errors are thus reduced. Advantageously, the total gas pressure in the outer enclosure 45 may be lower than the total gas pressure outside the outer enclosure. This reduces the risk of the test gas escaping from the outer enclosure, which is particularly beneficial when the tracer gas is not entirely innocuous. Thus, testing the leak-tightness with a vacuum in the outer enclosure is a measure for safe and accurate performance. Indeed, gases and substances carried by gasses, such as hazardous substances, are prevented from escaping the enclosure by providing a vacuum inside its leak tight envelope, which also contributes to more accurate gas measurements.

[0054] After having introduced the contaminated glove box in the tent and made the tent envelope tight again by welding or gluing the flaps attached to the adjacent sheets, the leak-tightness has to be checked again for safety purpose. To avoid risks of contaminating the envelope at this stage on an irreversible way, if the method of pressure increase is used on the envelope, checking the leak-tightness will be preferably performed with one tracing gas method, according to ISO 10648-2 method. As helium is too fluid for this level of leak rate, other tracing gases will be considered, such as CO₂, SF₆ and refrigerant gases (Freon-like gases). The use of these gasses is subject to international restrictive regulations because of their toxicity for human beings and their impact on the environment. A temporary envelope is preferably built around the protective tent envelope and specially the re-usable joints to limit the used quantity of tracing gas. A cascade of vacuum (P _{glove box} < p _tent envelope < P _{temporary envelope} < P workshop) will be temporarily organised with the respective ventilation and filtration systems so as to avoid contaminating the envelope too early and to protect the operator against too early incidental contamination of the envelope and against inhalation of the toxic tracing gas. Leaking rate of the tent envelope will be assessed, by measuring air flow and tracing gas concentrations in test enclosure, tent envelope and glove box, according to formulas given in the standard ISO 10648-2.

[0055] Provided that this temporary envelope is large enough to receive operators, and that an appropriate ventilation and filtration is foreseen, this latter envelope can also be used as an additional nuclear containment system ("third barrier") to limit spreading of contamination in the workshops in case of an incidental contamination during the dismantling or maintenance works (e.g. pinhole in a glove).

[0056] One the tent according to the present invention has been built up by attaching the different sheets to each other using the closure members, and once the leak-tightness has been tested, the tent can be used for interventions on contaminated objects. As the closure members are all re-usable, it is possible to demount the tent, in as far as the tent has not been contaminated during the intervention, which occurred inside the tent. For this purpose, the flaps are opened by for example cutting away the applied welds or the applied glue stripes. In such a manner access is provided again to the first and if present, also the third closure members, which can be opened. The flaps initially have a sufficient width of for example 50 cm in order to enable several uses including a mounting and demounting of the tent.

[0057] Although the tent can be used several times for intervention on contaminated objects, at one time during its lifetime the tent will reach the end of its lifecycle, either because the tent is damaged or broken because the tent is too much contaminated. When the tent has reached its end of life, the latter has to be discarded and stored in a safe manner. Preferably before the tent is discarded, the inner walls of the envelope are coated with a spray in order to have contaminated particles adhering as much as possible to the inner wall of the envelope. In such a manner a secondary nuclear or other contaminated waste is obtained. In view of the fact that the material of which the envelope is made is combustible and may comprise halogens, it can be stored in a drum. For the latter purpose, the envelope has to be folded up so as to enable storage in the drum. Depending on the dimension of the envelope the envelope can either be directly stored inside the drum, or after having been cut into smaller pieces.

[0058] Figure 8 illustrates the different steps of a method for storing the protective and disposable intervention envelope 3 according to the present invention. In order to avoid contaminated air or gases to reach the outer atmosphere, the envelope 3 is connected via its outlet 50 to an air pumping device (not shown). The envelope is detached from its support structure and falls down on the ground due to gravity. The air pumping device remains attached to the outlet 50 while detaching the envelope and also when the envelope falls on the ground.

[0059] By falling on the ground, the envelope collapses as if to say and can be folded together to obtain a packed up structure. Also during this folding up, the pumping device remains active. The folded up envelope is thereafter wrapped in order to form a wrapped envelope, whilst still continuing to pump air and gases out of the inner body of the envelope. Once the envelope is wrapped up, the pumping device is disconnected from the envelope and the latter is thereafter shifted inside a primary tube 53. Once the envelope is inside the primary tube, the latter is sealed by applying seals 51 and 52 on both ends of the primary tube. The primary tube is preferably made of polyvinylchloride (PVC).

[0060] When the envelope comprises a larger structure as illustrated in figure 9, where an envelope made of three sections is illustrated, each section is connected to the pumping device. The sections are, before being folded, separated from each other by applying a cutting through the flaps and opening the first and if necessary the third closure members. In such a manner the sections can be dealt with separately as if they were individual envelopes.

[0061] Once each envelope is enclosed in the primary tube 53, the envelope and its sealed primary tube 53 are shifted inside a secondary tube 56. The secondary tube 56, as illustrated in figure 10, is preferably made of polyurethane and provided at its entrance opening with an O-ring 54. This enables to attach the secondary tube and its content to a glove box input where the envelope and the primary and secondary tubes can be discarded. The use of an O-ring enables a substantially leak-free connection of the secondary tube to the glove box. Once the envelope has been discarded in the glove box, the discarded envelope can be stored in a drum in a similar manner as used for other contaminated objects.

[0062] Figure 11 illustrates a similar method as the one described with figure 10. The method of figure 11 distinguishes over the one of figure 10 in that no secondary tube is used. The envelope wrapped into the primary tube is directly stored into the drum 57.

Claims

1. A protective and disposable intervention envelope shaped tent (3) , in particular for intervention on contaminated objects, said tent being leak tight and comprising at least a first (20) flexible flat sheet and a second (21) flexible flat sheet, characterised in that said tent further comprises at least one first mechanically resistant and re-usable closure member (22) having a first and a second part (23), said first part being attached to said first sheet and said second part (24) being attached to said second sheet, said first closure member being provided to attach and detach said first (20) and second (21) flexible sheet to each other, said tent further comprising at least one second leak tight and re-usable closure member (25,26) comprising a first flap (25) connected in a leak tight manner to said first sheet (20) and a second flap (26) connected in a leak tight manner to said second sheet (21), said first and second flap being provided to be leak-tightly attached to each other by a leak tight seal and being applied in such a manner that said first and second closure members extend substantially parallel to each other so as to overlap said first mechanical closure member when said first and second flaps and sheets are attached to each other.

2. The protective and disposable intervention envelope shaped tent as claimed in claim 1, characterised in that when said tent is in a mounted state said first and second closure member extend in a substantially horizontal direction.

3. The protective and disposable intervention envelope shaped tent as claimed in claim 1, characterised in that when said tent is in a mounted state said first and second closure member extend in a substantially vertical direction.

4. The protective and disposable intervention envelope shaped tent as claimed in claim 1, characterised in that said first respectively second part of said first closure member being attached at a lateral border of said first respectively said second sheet, said tent further comprises at least a third flexible flat sheet, said first closure member further comprising a third respectively a fourth part attached to a transversal edge of said first or second sheet respectively a transversal edge of said third sheet and provided to attach and detach either said first (20) or second (29) flexible sheet to said third sheet by means of said third and fourth part, said second closure member comprising a third(37) respectively a fourth (38)flap connected in a leak tight manner to said transversal edge of a third sheet respectively said first or second sheet, said first, second, third and fourth flap being provided to be leak-tightly attached to each other by a leak tight seal applied on said first second, third and fourth flap, said first second and third sheets being each time positioned adjacent to each other in such a manner as to have a combination of at least one substantially horizontally and at least one substantially vertically extending first and second closure member when said tent is in a mounted state.

5. The protective and disposable intervention envelope shaped tent as claimed in any one of the claims 1 to 4, characterised in that said flaps extend beyond a surface over which their respective sheet to which they are attached extends.

6. The protective and disposable intervention envelope shaped tent as claimed in any one of the claims 1 to 5, characterised in that said leak tight seal is formed by a welding applied on the flaps.

7. The protective and disposable intervention envelope shaped tent as claimed in anyone of the claims 1 to 4 , characterised in that each sheet has at least a first and at least a second sheet edge situated at opposite sides of said sheets, said first part of said first mechanical closure member being applied along said first sheet edge of said first sheet and said second part of said first mechanical closure member being applied along said second sheet edge said first and second part being complementary to each other so that said first part of said first mechanical closure member of one said sheets forms an attachable and detachable liaison with said second part of said first mechanical closure member of a sheet adjacent to said one sheet.

8. The protective and disposable intervention envelope shaped tent as claimed in any one of the claims 1 to 7, characterised in that said first closure member is formed by a zipper or a hook and loop attachment member.

9. The protective and disposable intervention envelope shaped tent as claimed in any one of the claims 1 to 8, characterised in that said tent further comprises a plurality of third mechanically resistant and re-usable closure members, each third closure member comprising a first closure element connected to said first sheet and a second closure element connected to said second sheet, said first and second closure element being complementary to each other so as to form, when in closed state, an additional attachment of said first and second flexible sheets and to bridge said at least one first mechanical closure member when the latter is in closed state.

10. The protective and disposable intervention envelope shaped tent as claimed in claim 9, characterised in that said third closure member is formed by buckles applied at regular distances of each other along an edge of said sheet.

11. The tent according to any one of the claims 1 to 10, further comprising a metallic support for holding said envelope.

12. A method for testing the leak-tightness of the protective and disposable intervention envelope shaped tent according to any one of the claims 1 to 11, comprising the steps of :

a) closing said intervention envelope shaped tent by using said closure members;

b) providing an outer disposable enclosure around said envelope;

c) providing a tracer gas at a predetermined concentration between said outer disposable enclosure and said envelope shaped tent; and

d) measuring leakage of said tracer gas into said envelope shaped tent.

13. The method according to claim 12 wherein step a) further comprises the steps of:

i) closing said at least one first mechanical closure member respectively said at least one first and fourth mechanical closure member; and

ii) closing said at least one second leak tight closure member respectively said at least one second and fifth leak tight closure member; and

iii) closing said plurality of third back-up closure members respectively said plurality of third and sixth back-up closure members.

14. The method according to claim 12 or 13 wherein leakage of said envelope is assessed by measuring air flow or a concentration of said tracing gas in said outer disposable enclosure, envelope or glove box.

15. The method according to any one of the claims 12 to 13, wherein said tracer gas (80) is chosen from CO₂, SF₆ or refrigerant gases.

16. A method for storing said protective and disposable intervention envelope shaped tent as claimed in any one of the claims 1 to 15 , characterised in that said envelope is connected with an air pumping device, said envelope being folded while air inside said envelope is pumped out by said pumping device, said folded envelope being thereafter wrapped in order to form a wrapped envelope, which envelope is thereafter disconnected from said pumping device and thereafter shifted inside a primary tube, said primary tube being sealed and thereafter stored in a secondary tube or a drum.

17. The method as claimed in claim 16, characterised in that before being wrapped said tent is divided into tent segments by separating said sheets by cutting away a section of said flaps.

Drawing