FR2778238A1 - Chemical or biological warfare munition destruction process - Google Patents

Abstract

A chemical or biological warfare munition destruction process employs a power laser for munition perforation and dispersion charge initiation within an explosion resistant, sealed chamber. Destruction of a munition, comprising a toxic agent charge and a pyrotechnic dispersion charge, within an explosion resistant, hermetic, closed chamber is carried out by a cycle of (a) using a first power laser beam to pierce an opening in the munition for access to the dispersion charge; (b) using a second power laser beam to heat the pyrotechnic dispersion charge until it reacts; and, after bursting of the munition; (c) purging effluents from the chamber and emptying solid debris for carrying out another cycle. An Independent claim is also included for an installation for carrying out the above process, comprising an explosion resistant chamber equipped with inlet and emptying lock chambers, windows for laser beam passage, a power laser and a system for focusing or defocusing the beam and for directing the beam onto different zones of the munition.

Description

The present invention is in the field of ammunition containing

  toxic chemical or bacteriological agents. Its purpose is to propose a method and an installation for destroying such ammunition5 which are satisfactory for the safety of personnel

and the environment.

  It relates more particularly to the destruction of such munitions from the battlefields where they are found, after firing, but which have not worked for various reasons. These munitions have a

  very great pyrotechnic danger since it is reasonable to think that the initiation pyrotechnic chain is in the operational position and can operate under the effect of even low stresses.

  The pyrotechnic danger is coupled with a toxic danger.

  The manipulation by personnel of this ammunition is prohibited and the use of advanced process automation, based on remote handling, is required to

fact.

  These ammunition, of the shell head type, include in different envelopes, generally metallic: - a charge of toxic agent, - a pyrotechnic charge of dispersion, - an initiation system which initiates the operation of the pyrotechnic charge of dispersion and causes the munition to burst and disperse

the toxic agent.

  The initiation system is for example of the type

impact or proximity rocket.

  Chemical toxic agents are among those known as "combat gases" and are characterized by their suffocating, vesicant, hemotoxic or neurotoxic action. Bacteriological toxic agents are much less known, but microbial or viral strains

are used.

  By destruction of ammunition we mean the destruction of containers and contents:

  say the destruction of the pyrotechnic charge of dispersion, the destruction (or detoxification) of the

  charge of toxic agent and finally the destruction of the envelopes which contain these charges and of the structure of the ammunition so that they can be scrapped or recycled after decontamination.

  The methods consisting in placing relay charges on the munition to initiate the operation of the pyrotechnic charge for dispersion, in appropriate installations, such as the method described in patent FR 2 704 640, are difficult to envisage since they are little or not suitable for the setting

telemanipulation work.

  Methods using armored furnaces to heat the munition until the pyrotechnic charge of dispersion disperses are also known. If these methods lend themselves well to automation, they have the disadvantages of being implemented in complex and heavy installations and of being very energy-consuming. Indeed the material of the furnace and the shield loses its mechanical properties when hot, the device must be largely oversized to resist detonations and it will take a lot of energy to heat it. For example, patent WO 96/12157 describes an oven containing a detonation enclosure in which the ammunition to be destroyed is placed, which is thus indirectly heated until it bursts. The process of the present invention, compatible with advanced automation, aims to resolve these

  problems while presenting satisfactory conditions of use for the safety of personnel and the environment.

  According to the present invention, the method of destroying ammunition, placed in a sealed and explosion-proof closed enclosure, said ammunition comprising at least one charge of toxic agent and one pyrotechnic charge of dispersion, the reaction of which is initiated, is such that the cycle following operations is carried out: - a first beam of a power laser pierces an opening in the ammunition to access the charge of dispersion, - a second beam of a power laser heats the pyrotechnic charge of dispersion until its reaction, - after bursting of the ammunition the enclosure is purged of effluents and emptied of solid debris for the

another cycle.

  The first laser beam cuts into the munition an opening of sufficient size, section greater than 0.5 cm2 approximately but less than 8 cm2 approximately and for example between 1 and 4 cm2 approximately. This opening exposes a portion of the pyrotechnic charge or at least a portion of the envelope surrounding said charge according to the

configuration of the ammunition.

  During the heating by the second laser beam, the temperature of the pyrotechnic charge of dispersion increases, when it reaches its point of auto ignition, the pyrotechnic charge reacts by a more or less lively combustion, a deflagration or a detonation. We will use the term explosion to designate these different types of reaction.

  which can take place according to the degree of confinement.

  This reaction bursts the ammunition and disperses the toxic agent. The effluents thus released and the solid debris are then sent to additional installations for treatment: these installations include ovens for pyrolysis under vacuum or reduced pressure or molten metal baths, or

  any other detoxification and treatment facility.

  Preferably, it is the beam emission from the same power laser which is used for the first two steps of the method. The laser beam is focused for piercing the ammunition, then the laser beam is defocused for heating the pyrotechnic charge of dispersion. By using a defocused beam we manage to heat, and this quite quickly, a large surface of the pyrotechnic charge to obtain a certain reaction of the charge, whereas if the heating is too punctual the reaction can be a simple combustion of the pyrotechnic charge . Advantageously, the second laser beam may be intermittent, which allows the heat to be distributed over a larger surface and prevents overheating.

very punctual.

  When the laser used in this process is a Neodymium YAG laser, its beam is guided towards the ammunition by an optical fiber, at least for the phase

of heating.

  Preferably, the first two steps are carried out under vacuum or under an atmosphere of neutral gas, for example nitrogen. This procedure avoids the formation, especially during the second stage, of combustible or detonating gas mixtures which would severely stress the installation. This process, conducive to automation, allows the destruction of ammunition under conditions satisfactory to operators and the environment. In addition it solves the problems posed. Since the explosion-proof enclosure is not heated, it does not require oversizing to take account of the reduction in the mechanical properties of the materials when the temperature increases. Only the pyrotechnic charge of dispersion, possibly with its envelope being heated, by the laser beam consumption

energy is very reduced.

  The installation for implementing the process of the invention comprises: - an explosion-resistant enclosure, this enclosure is sealed in a sealed manner by airlocks for entry and emptying, - means for evacuating and / or admit an inert gas, - windows for the passage of laser beams, - a power laser, as well as means for focusing or defocusing the beam and directing and aiming it at different zones of the munition, - remote handling means, appropriate automata and monitoring equipment.

  An operation cycle includes the following steps:

  -: introduction into the enclosure of the munition to be destroyed, closing of the airlock, establishment of the vacuum or atmosphere of inert gas, - mobile aiming of the focused laser beam for piercing the opening, then heating of the charge pyrotechnic by the defocused beam, - after bursting of the munition sweeping off the gaseous effluents and emptying of the liquid residues and solid debris by the emptying airlock; these residues are automatically directed to the additional detoxification installations, - the emptying airlock is closed, the intake airlock is

  open for the completion of a new cycle.

  For example with a C02 laser of 5 kW of power

  sance, a square opening of 20mm square is drilled in about one minute in the steel casing or in

  melting of the ammunition to a thickness of about 10mm.

  Heating the pyrotechnic charge through this 4cm2 opening, until it reacts, requires

about 1 minute.

Claims (9)

Claims   1. A method of destroying ammunition placed in a closed, leaktight and explosion-resistant enclosure, said ammunition comprising a charge of toxic agent and a pyrotechnic charge of dispersion, the reaction of which is initiated, characterized in that the following cycle of operations is carried out: - a first beam of a power laser pierces an opening in the munition to access the dispersion charge, - a second beam of a power laser heats the pyrotechnic dispersion charge until it reacts, - after the munition bursts, the enclosure is purged of effluents and emptied of solid debris to the completion of another cycle.   2. Method according to claim 1 characterized in that it is the beam emission of the same power laser which is used for the first two stages: the beam is focused for drilling, then the beam is defocused for heating the pyrotechnic charge of dispersion.   3. Method according to claim 1 or 2 characterized in that the opening made in the munition to a section greater than 0.5cm2.   4. Method according to claim 3 characterized in that the opening made in the munition has a section between 1 and 4 cm2.   5. Method according to claim 1 or 2 characterized in   that the second laser beam is intermittent.   6. Method according to one of the preceding claims   characterized in that the laser beam is produced by a YAG neodymium laser.   7. Method according to claim 5 or 6 characterized in that the beam is guided by an optical fiber.   8. Method according to one of claims 1 to 7   characterized in that the operations of the first two steps are done under vacuum.   9. Method according to one of claims 1 to 7   characterized in that the operations of the first two   steps are carried out under an atmosphere of neutral gases.   O10. Installation for the destruction of ammunition comprising a charge of toxic agent and a pyrotechnic charge of dispersion, installation comprising an explosion-resistant enclosure, closed in leaktight manner by entry and drain locks, characterized in that it comprises: windows for the passage of laser beams, - a power laser, as well as means for focusing or defocusing the beam and directing and pointing it at different areas of the ammunition.