WO2002077563A1

WO2002077563A1 - A method and apparatus for neutralising an explosive device

Info

Publication number: WO2002077563A1
Application number: PCT/GB2002/000625
Authority: WO
Inventors: John Robert French
Original assignee: J R French Limited
Priority date: 2001-03-23
Filing date: 2002-02-15
Publication date: 2002-10-03

Abstract

A method of neutralising an explosive device (12) having a detonator (14), includes the step of enclosing the detonator (14) within a space (26) defined at least in part by a thermally insulating barrier (16). It also includes the step of refrigerating the space (26) to cool the detonator (14) to less than its minimum operative temperature. Cooling the detonator (14) below the minimum operative temperature reduces the detonation capability of the detonator (14) such that it is incapable of detonating the explosive device (12). The explosive device (12) is thereby neutralised.

Description

A METHOD AND APPARATUS FOR NEUTRALISING AN EXPLOSIVE DEVICE

The invention relates to a method of neutralising an explosive device, and to an apparatus capable of carrying out the method.

The term "explosive device" used herein includes, but is not limited to, landmines, booby traps and other explosive ordnance that includes one or more detonators.

There is an unending requirement for disposal of explosive devices. This requirement is made by civilian organisations, such as charities, that face the task of clearing e.g. landmines remaining after an armed conflict. Other organisations also sometimes have similar needs.

At the present time explosive devices, in particular landmines, are most commonly disposed of by detonation. Although this is intended to neutralise the devices (i.e. render them safe to handle) the practice is hazardous, both to personnel and machinery.

Detonation also damages the area surrounding an explosive device. For example, detonating a landmine often leaves a crater in the ground that requires subsequent repair.

The detonation of explosive devices can sometimes worsen the disposal problem. It is known, for example, for some landmines to suffer incomplete detonation such that fragments of undetonated ordnance result. The need to dispose of multiple fragments may be more time-consuming and hazardous than disposing of single, intact mines. Such fragments may in addition exist unnoticed in e.g. a crater awaiting repair. Furthermore some kinds of bomb are intended, on detonation, to disperse several armed bomblets over a wide area. The bomblets are in some instances designed to create as much craterous damage as possible. Consequently they present a particularly acute disposal problem.

It is also known to attempt to destroy or neutralise an explosive device by first of all removing the explosive device from the area in which it is located. Such a method involves transferring the explosive device into an explosion resistant container.

A problem with this known method is that there is a risk of explosion of the device during transfer to the container. In addition, particularly with large explosive devices, it is virtually impossible to ensure that the container is explosion proof, so that an explosive device located within the container may still be hazardous to personnel and machinery.

There is therefore a need for a method and apparatus that facilitate and improve the safety of explosives disposal.

According to a first aspect of the invention there is provided a method of neutralising in situ an explosive device having a detonator, the method including the steps of:

(i) enclosing the detonator in situ within a space defined, at least in part, by a thermally insulating barrier; and

(ii) refrigerating the space to cool the detonator to less than its minimum operative temperature.

Cooling the detonator to less than its minimum operative temperature reduces the detonation capability of the detonator such that it is incapable of detonating the explosive device. The explosive device is thereby neutralised.

Enclosing the detonator within a space defined, at least in part, by a thermally insulating barrier improves the efficiency of the refrigeration step because it helps to ensure that, during the refrigeration step, heat is absorbed from the detonator rather than from the surrounding environment such as air in the vicinity of the device.

The thermally insulating barrier enables the detonator to be refrigerated in situ. By means of the present invention therefore it is not necessary to move the explosive device in order to neutralise the device. This eliminates the risk that the explosive device will explode due to movement of the device.

The thermal barrier means that the detonator may be cooled regardless of the ambient temperature of the surroundings.

The step of refrigerating the space preferably includes adding a fluid cryogen to the space substantially to immerse the detonator therein.

Conveniently the step (i) of enclosing the detonator includes the step of enclosing a substantial portion of the explosive device; and the step (ii) of refrigerating the space includes cooling of the said substantial portion of the device. Cooling or freezing of the explosive material of the device in this way has advantages in reducing the risk of detonation of the explosive material by compression. This is because in the case of certain explosive materials the rate of compression needed to cause detonation increases in dependence on the temperature to which the material is cooled. The fluid cryogen may be selected for example from liquefied Nitrogen, liquefied Oxygen, mixtures thereof and cryogenic slushes. Other cryogenic fluids, including some gases, are useable within the scope of the invention.

In a preferred embodiment of the invention, the method includes the further step of:

(iii) disuniting parts of the explosive device from one another while the detonator remains cooled.

This ensures that the detonator cannot detonate the explosive device in the event that its temperature increases above the minimum operative temperature.

The step of disuniting parts of the explosive device may include drilling the explosive device. For example, it may include drilling the detonator from the explosive device.

In other embodiments of the invention, the step of disuniting parts of the device may include one or more of: (a) sawing the device;

(b) crushing the device;

(c) hammering the device;

(d) shooting the device;

(e) grinding the device; and (f) deploying a high pressure water slug toward the device.

The method may include the step of immersing the device in a further fluid while the detonator remains cooled. The further fluid may be, or include, a foam. While the detonator remains cooled, an image of the explosive device may optionally be recorded and/or generated.

The method preferably includes the step of steadying the explosive device after the step (ii) of cooling the detonator. This enables the explosive device to be held in position while parts of the explosive device are disunited, or images of the device are recorded or generated.

Preferably, when the explosive device includes a plurality of detonators, the method includes the step of enclosing the plurality of detonators and cooling them below the minimum operative temperature.

In a particularly preferred embodiment of the invention, the step of enclosing the detonator includes enclosing the explosive device. This cools the explosives of the explosive device as well as the, or each, detonator.

Cooling the explosive material is an additional safety measure to ensure that the explosive device is neutralised. Cooling the, or each, detonator may not in some cases be sufficient to cool the explosives because of the generally poor heat conductivity of explosive materials. Reducing the temperature of the explosives therefore makes it relatively more difficult for the explosive device to detonate.

The step of enclosing the, or each, detonator may include the sub-step of moving the thermally insulating barrier, preferably on a robot arm. This enables the positioning of the thermally insulating barrier to be performed from a remote position whilst allowing the or each detonator to be enclosed in situ, and therefore improves the safety of personnel performing the method. The step of disuniting parts of the explosive device may include moving a tool relative to the explosive device. In preferred embodiments of the invention, it includes moving the tool on a robot arm.

In order to add a fluid cryogen to the space, fluid cryogen is preferably caused to flow from a reservoir thereof via one or more conduits and one or more outlets that open into the interior of the space.

This step may additionally include the sub-step of opening a valve in a said conduit or an outlet, to permit flow of the fluid cryogen.

According to a second aspect of the invention, there is provided an apparatus for neutralising in situ an explosive device, comprising: (i) a thermally insulating barrier that is positionable to define, at least in part, a space enclosing a detonator of a said explosive device in situ;

(ii) a reservoir of fluid cryogen;

(iii) an outlet, for fluid cryogen, that opens into the said space; and (iv) a conduit, for fluid cryogen, that permits flow of the cryogen from the reservoir to the interior of the space substantially to immerse the detonator therein, when the detonator is enclosed by the barrier, and thereby cool the detonator to less than its minimum operative temperature.

The apparatus preferably includes one or more tools for disuniting parts of the explosive device while the detonator is cooled.

The, or each, tool may be a drill, a saw, a jackhammer, a gun or a crushing device, a grinding device, a high pressure water slug or a high pressure air jet. The apparatus preferably includes one or more stabilizer members for holding the explosive device in position after the detonator is cooled.

The thermally insulating barrier may be positionable to define, at least in part, a space enclosing a plurality of detonators of an explosive device.

In particularly preferred embodiments, the thermally insulating barrier is positionable to define, at least in part, a space enclosing the explosive device. The provision of such a barrier enables the apparatus to be used to cool the explosives of the explosive device as well as the, or each, detonator.

The apparatus may include a robot arm for positioning the barrier relative to an explosive device.

The apparatus may additionally include a second robot arm for moving the, o each, tool relative to the explosive device while the detonator is cooled.

Alternatively the, or each, tool may be interchangeable with the barrier on the first robot arm.

The use of the or each robot arm ensures that the in situ neutralisation of an explosive device may be carried out with minimum risk of harm to personnel.

Preferred embodiments of the invention will now be described, by way of non-limiting examples, with reference to the accompanying figures in which:

Figure 1 shows an apparatus for carrying out a method of neutralising an explosive device according to an embodiment of the invention; Figure 2 shows an apparatus for disuniting parts of an explosive device while a detonator of the device is cooled;

Figure 3 shows an apparatus for carrying out a method of neutralising an explosive device according to another embodiment of the invention;

Figure 4 shows a nozzle arrangement for use in the apparatus for Figure 3;

Figure 5 shows another apparatus for disuniting parts of an explosive device while a detonator of the device is cooled; and

Figure 6 shows a yet further apparatus for disuniting parts of an explosive device while a detonator of the device is cooled.

A method of neutralising an explosive device 12 in situ, having a detonator 14, according to an embodiment of the invention, will now be described with reference to the apparatus 10 shown in Figure 1.

The apparatus 10 includes a thermally insulating barrier 16, a distribution nozzle 18, a hose 20 and a pressurised reservoir 22 containing a fluid cryogen 24 such as liquefied Nitrogen.

The barrier 16 in the embodiment shown is a rectangular box-like member that defines a hollow interior space 26. The space 26 is open on one side 28 enabling the barrier 16 to be positioned over the detonator 14 of an explosive device 12.

The barrier 16 may of course be of a different shape to that shown. Examples of possible shapes are described herein in relation to Figure 3. The distribution nozzle 18 opens into the interior of the space 26, and is connected to the reservoir 22 by the hose 20.

In use, the barrier 16 is positioned to enclose the detonator 14 within the space 26 as shown in Figure 1. The space 26 is then refrigerated and the detonator 14 is cooled below a minimum operative temperature.

The space 26 is refrigerated by opening a valve 32 on the distribution nozzle 18 to permit the fluid cryogen 24 to flow into the space 26, substantially immersing the detonator 14 therein.

Upon contact with the detonator 14, the fluid cryogen 24 absorbs heat energy from the detonator 14 and thereby reduces the temperature of the detonator 14.

The barrier 16, enclosing the detonator 14, reduces the amount of heat energy that the fluid cryogen 24 can absorb from surrounding air. The barrier 16 therefore enables the detonator 14 to be cooled relatively more quickly than if there was no barrier 16.

The cryogenic agent 24 is applied until the detonator 14 is cooled below its minimum operative temperature.

When the detonator 14 is cooled below its minimum operative temperature, the detonating capability of the detonator 14 is inhibited such that it cannot detonate the explosive device 12. The explosive device 12 is thereby neutralised. While the detonator 14 remains cooled, the parts of the explosive device 12 may be disunited from one another. This eliminates the risk of detonating the explosive device 12 when the temperature of the detonator 14 increases above the minimum operative value.

As shown in Figure 2, a rotating grinding tool 34 may be used to disunite parts of the explosive device 12 from one another while the detonator 14 remains cooled.

In the arrangement shown in Figure 2, the explosive device 12 is stabilized and held in position by stabilizer plates 36 (only one shown) while the rotating grinding tool 34 destroys the explosive device 12. The rotating grinding tool 34 may be moved across the explosive device 12 in contact therewith, or brought down onto the explosive device 12.

In another embodiment of the invention, the parts of the explosive device 12 may be disunited using a drill. For example, a drill may be used to drill the detonator 14 from the explosive device 12.

In yet further embodiments, parts of the explosive device 12 may be disunited by using one or more of a hydraulic crushing device, a hammer, a foam explosive dispenser, a high pressure water slug, a shotgun, and/or a high pressure air jet.

Before, or rather when, disuniting parts of the explosive device 14, the explosive device 12 may be immersed in a further fluid while the detonator 14 is cooled.

In some embodiments, the further fluid may be a foam. A method of neutralising an explosive device 12 having a plurality of detonators 14, according to another embodiment of the invention, will now be described with reference to the apparatus 35 shown in Figure 3.

The apparatus 35 shown in Figure 3 includes a thermally insulating barrier 36, a plurality of distribution nozzles 38, a robot arm 40 and a pressurised reservoir 42 containing a fluid cryogen 44 such as liquid Nitrogen.

The barrier 36 is provided at one end of the robot arm 40 and in the embodiment shown includes a rectangular box-like member that defines a hollow interior space 46. The space 46 is open along one side 37 enabling the barrier 36 to be positioned so as to enclose an explosive device 12 within the space 46. Of course the barrier 36 need not take the precise form of a rectangular box. Any of a range of barrier designs, including but not limited to hollow cylinders, spheroids and pyramids are useable.

Each of the plurality of distribution nozzles 38 opens into the interior of space 46 and is connected by means of a conduit (not shown) to the reservoir 42.

In use, the barrier 36 is positioned to enclose the explosive device 12 within the space 46 by moving the robot arm 40. The provision of the robot arm 40 enables a controller to control movement of the barrier 36 from a remote position.

The space 46 is then refrigerated and the detonators 14 are cooled below a minimum operative temperature. The explosives of the explosive device 12 are also cooled as a result. The space 46 is refrigerated by opening a valve (not shown but of per se conventional design) on each of the distribution nozzles 38 to permit the fluid cryogen 44 to flow into the space 46 and immerse the explosive device 12 therein.

When the fluid cryogen 44 contacts the explosive device 12, it absorbs heat energy from substantially the whole surface of the explosive device 12, and not just the detonators 14. The fluid cryogen 44 thereby cools the explosives of the explosive device 12 as well as the detonators 14.

The distribution nozzles 38 are arranged around the periphery of the space 46 (Figure 4) to ensure that the fluid cryogen 44 contacts all surfaces of the explosive device 12. This is because explosive materials are generally poor conductors of heat. Application of the cryogenic fluid to one surface of the explosive device 12 may not therefore be sufficient to cool the explosives.

The fluid cryogen 44 is applied until each of the detonators 14 is cooled below the minimum operative temperature.

Cooling the explosives, as well as the detonators 14, is a safety feature to ensure that the explosive device is neutralised. The generally low heat conductivity of explosive materials means that it is relatively much more difficult to detonate cooled explosives.

While each of the detonators 14 remains cooled, parts of the explosive device 12 may be disunited from one another.

Parts of the explosive device 12 may be disunited using a tool such as the rotating grinder 34 shown in Figure 2. They may also be disunited using one or more of a drill, a hydraulic crushing device, a hammer, a foam explosive dispenser, a high pressure water slug, a high pressure air jet and/or a shotgun.

Figure 5 shows a drill 48 provided on a robot arm 50 that may be used to disunite parts of an explosive device 12 while the detonator(s) (not shown) remain cooled. The robot arm 50 also includes a pair of stabilizer plates 52,54 for steadying the explosive device 12 while parts of the explosive device 12 are drilled.

The robot arm 50 can be used to move the drill 48 and the stabilizer plates 52,54 relative to the explosive device 12, and in some embodiments may be the same arm as the robot arm 40 used to move the barrier 36.

In other embodiments, the drill 48 may be replaced on the robot arm 50 by a grinder, a shotgun, a hammer 56 (Figure 6), a foam explosive dispenser, a camera or a high a high pressure water slug dispenser and/or a high pressure air jet nozzle.

Claims

1. A method of neutralising in situ an explosive device having a detonator, the method including the steps of: (i) enclosing the detonator in situ within a space defined, at least in part, by a thermally insulating barrier; and

2. A method according to Claim 1 wherein the step of refrigerating the space includes adding a fluid cryogen to the space substantially to immerse the detonator therein.

3. A method according to Claim 1 or Claim 2 wherein the step (i) of enclosing the detonator includes the step of enclosing a substantial portion of the explosive device; and wherein the step (ii) of refrigerating the space includes cooling of the said substantial portion of the device.

4. A method according to Claim 2 wherein the cryogen is selected from liquefied Nitrogen, liquefied Oxygen, mixtures thereof and cryogenic slushes.

5. A method according to any preceding claim including the further step of: (iii) disuniting parts of the explosive device from one another while the detonator remains cooled.

6. A method according to Claims 5 wherein the step of disuniting parts of the explosive device includes drilling the explosive device.

7. A method according to Claim 6 including drilling the detonator from the explosive device.

8. An apparatus for neutralising in situ an explosive device, comprising: (i) a thermally insulating barrier that is positionable to define, at least in part, a space enclosing a detonator of a said explosive device in situ; (ii) a reservoir of fluid cryogen;

9. A method according to any preceding claim including the step of immersing the device in a further fluid while the detonator remains cooled.

10. A method according to Claim 9 wherein the further fluid is a foam.

11. A method according to any preceding claim including the step of recording and/or generating an image of the explosive device while the detonator remains cooled.

12. A method according to any preceding claim including the step of steadying the explosive device after the step (ii) of cooling the device.

13. A method according to any preceding claim including the steps of enclosing and cooling a plurality of detonators of the explosive device.

14. A method according to any preceding claim wherein the step of enclosing the detonator includes enclosing the explosive device.

15. A method according to any preceding claim wherein the step of enclosing the, or a said, detonator includes the sub-step of moving the thermally insulating barrier on a robot arm.

16. A method according to Claim 4 or any claim dependent therefrom, wherein the step of disuniting parts of the explosive device includes moving a tool relative to the explosive device.

17. A method according to Claim 16 including moving the tool on a robot arm.

18. A method according to Claim 2 or any claim dependent therefrom wherein the step of adding a fluid cryogen to the space includes causing fluid cryogen to flow from a reservoir thereof via one or more conduits and one or more outlets that open into the interior of the space.

19. A method according to Claim 18 including the sub-step of opening a valve in a said conduit or an outlet, to permit flow of the fluid cryogen.

20. A method generally as herein described with reference to and/or as illustrated in the accompanying drawings.

21. An apparatus for neutralising in situ an explosive device comprising: (i) a thermally insulating barrier that is positionable to define, at least in part, a space enclosing a detonator of a said explosive device in situ; (ii) a reservoir of fluid cryogen; (iii) an outlet, for fluid cryogen, that opens into said space; and (iv) a conduit, for fluid cryogen, that permits flow of the cryogen from the reservoir to the interior of the space to substantially immerse the detonator therein, when the detonator is enclosed by the barrier, and thereby cool the detonator to less than its minimum operative temperature.

22. An apparatus as claimed in Claim 21 further including one or more tools for disuniting parts of the explosive device while the detonator remains cooled.

23. An apparatus as claimed in Claim 22 wherein the, or each, tool is one of a drill, a saw, a jackhammer, a gun, a crushing device, a grinding device, a high pressure water slig or a high pressure air jet.

24. An apparatus as claimed in any of Claims 21 to 23 further including one or more stabilizer plates.

25. An apparatus as claimed in any of Claims 21 to 24 wherein the thermally insulating barrier is positionable to define, at least in part, a space enclosing a plurality of detonators of an explosive device.

26. An apparatus as claimed in any of Claims 21 to 25 wherein the thermally insulating barrier is positionable to define, at least in part, a space enclosing the explosive device as well as the, or each, detonator.

27. An apparatus as claimed in any of Claims 21 to 26 further including a robot arm for positioning the barrier.

28. An apparatus as claimed in Claim 27 when dependent from at least Claims 22 and 23 further including a second robot arm for moving the, or each, tool relative to the explosive device.

29. An apparatus as claimed in Claim 27 when dependent from at least Claims 22 and 23 wherein the, or each, tool is interchangeable with the barrier on the robot arm.

30. An apparatus generally as herein described with reference to and/or as illustrated in the accompanying drawings.