The Organisation for the Prohibition of Chemical Weapons (OPCW) have now begun their work in Syria. Their first task will be to visit the sites declared by the Syrian Government and verify that the chemical weapons, precursor chemicals - used in their manufacture and chemical weapon production and filling facilities present at each site match what has been declared by Syria. Once this has been done, their next task will be to oversee the inactivation of the production and filling facilities. This can be achieved by the removal of key components, the insertion of blanking plates to seal off key pipes or vessels and the use of tamperproof seals to prevent the facilities from being reactivated. Under the terms of the CWC all these facilities will eventually have to be destroyed in accordance with procedures set down in the treaty.

The next step in the process will be to develop and agree on a plan for the destruction of all of the declared items. The inactivated production and filling plants will need to be decontaminated, to remove any traces of chemical agents, dismantled and the individual components destroyed in a safe and effective manner. All the associated buildings and facilities will also have to be destroyed.

The declared chemical weapons will consist of filled chemical munitions of various types - some of which may also contain explosives, bulk stocks of chemical agents, unfilled chemical munitions and stocks of the key precursor chemicals used to make the chemical agents. Each of these will pose a different destruction problem and it is likely that a range of technical solutions will be needed to achieve their safe destruction in an environmentally acceptable manner.

In drawing up this plan, a key decision will be whether to move all of the chemical weapons to a single location for destruction or undertake their destruction at the individual sites. Moving them to a single location would enable the use of larger, non-mobile, equipment with increased destruction capacity, capability and efficiency. The safe transportation of chemical filled munitions and bulk chemical agents, however, is a complex process, requiring very careful planning and specialised equipment. The current situation on the ground in Syria may make this a particularly difficult operation. The alternative would be to undertake the destruction process at each of the declared sites. For this to be achieved, in an acceptable timeframe, it will be necessary to use mobile destruction facilities. A number of these have been developed and used in different parts of the world. Their major disadvantage is that they normally have a limited capacity and are manpower intensive. Depending on the number of sites involved, several systems would probably be needed if destruction is to be achieved within the desired timescale.

In reality a mixture of these two options may provide the optimum solution. Unfilled chemical munitions, for example, can be destroyed relatively easily using techniques such as crushing or cutting up with oxyacetylene torches. Their destruction at each declared location should, therefore, not pose any particular problems. Although some of the precursor chemicals are very corrosive and hazardous they are not highly toxic. Their safe transport by road or sea, in normal circumstances, would not be significantly different from that involved in the routine movement of other hazardous industrial chemicals. Their movement to a single location either in country or, with the agreement of the OPCW, out of country for destruction may prove the most practical option.

The safe destruction of the filled chemical munitions and bulk chemical agents will be more difficult. Filled chemical munitions can be stored either without their explosive components fitted or complete with their explosive components. Clearly, the destruction of munitions that are explosively configured, ready for immediate use, poses additional destruction problems. The traditional approach to dealing with a filled chemical munition is to separate the chemical agent from the munition and any explosives present. This, by its nature, is a hazardous operation, ideally undertaken in facilities that protect the operator from blast or accidental exposure and prevent the risk of release of chemical agent to the environment. Once the various components have been separated they can be safely destroyed using a range of well established techniques. Any explosive contents can either be destroyed in a specially designed furnace or by open air detonation. The munition cases can be destroyed by heating, in a specially designed metal parts furnace at 500 – 600C, for sufficient time to destroy any residual chemical agent and ensure that the metal components are no longer useable. After removal from the furnace they can, where necessary, undergo further treatment, for example by mechanical crushing, to ensure their complete destruction.

The recovered chemical agents can be destroyed along with the bulk chemical agents. Two well proven technologies for carrying out this final step are incineration and chemical breakdown. Both techniques have their advantages and disadvantages. Incineration has been shown to be highly effective but does require an incinerator specifically designed for this purpose and fitted with a pollution abatement system to ensure that hazardous combustion products present in the exhaust gases from the furnace are removed before they are released to the atmosphere. Incineration systems designed for the destruction of chemical weapons are complex, fixed site, installations and primarily designed for installation at a single location. While mobile incineration systems have been developed they tend to have a limited capacity and although described as transportable are not easily moved from site to site. Chemical breakdown, by what is known as hydrolysis, is also a well established technique. The principal downside of this technique is that the waste products need some form of secondary treatment before they can be released to the environment. Once again portable units for undertaking this process have been developed but they again tend to have a much more limited capacity than a larger fixed site-based system.

In recent years alternative approaches to the need to first disassemble chemical munitions into their individual components have been developed. These mainly involve the use of explosive containment chambers in which the chemical munitions are either destroyed using added explosives or high temperature. The containment vessels are designed to withstand the force of an exploding chemical munition and any resulting gases can be treated before they are released to the atmosphere. Their principal downside is that they are very large, heavy items, not easily transportable and can only treat small numbers of munitions each day. They do, however, eliminate the need for the hazardous disassembly step. While such systems would be suitable for use in Syria they are not available off the shelf and only a small number are currently operating in different parts of the world. The timescale involved with obtaining such a system and the limited rate of destruction may, therefore, rule out its use in Syria.

Overall the complexity of the destruction process and the time required to complete it will be dependent on the amounts of each category of chemical weapons present in Syria and the number of sites involved. Clearly, the larger the number of filled chemical weapons the more complex and time consuming the destruction process will be. The final solution to destroying Syria’s chemical munitions, in a safe and environmentally effective manner, will, therefore, require very careful planning and will almost certainly require a significant period of time to establish the necessary capability and complete the operation.