How to destroy chemical weapons

The recent news that Syrian President Bashar al-Assad is willing to accede to the international Chemical Weapons Convention (CWC) has raised the question: How might one actually go about eliminating Syria’s chemical munitions?

The CWC entered into force in 1997. Seven CWC member countries have declared existing chemical weapons stockpiles—Albania, India, Iraq, Libya, Russia, South Korea, and the United States. Three of these—Albania, India, and South Korea—completed stockpile destruction in the last few years. Three more—Libya, Russia, and the US—expect to complete their destruction programs over the next decade. And Iraq, which joined the convention in 2009, is planning the destruction of its chemical weapons equipment and agents left from the 1991 Gulf War.

There are essentially three broad categories of destruction approaches, all used successfully in the above programs. These approaches can be mixed and matched, depending on the type, size, quantity, and condition of the agents, munitions, and containers.

Incineration.The initial destruction technology used by the United States—which began operating its first prototype facility on Johnston Atoll in the Pacific Ocean in 1990—involves burning chemical agents and munitions in high-temperature furnaces. Individual munitions such as rockets and artillery shells, likely similar to what has been used in Syria, are dismantled and drained of their liquid agents on a robotic disassembly line. The liquid agent is captured in holding tanks and then moved to a liquid furnace. Should the munitions include explosives or propellant, these are separated and burned in an explosives furnace, armored to withstand blasts. A metal parts furnace is used to burn any remaining residue of agent left in the metal containers and weapon shells A fourth “dunnage” furnace was designed to burn all other materials—wood pallets, plastics, fiberglass cases—but in practice, these potentially contaminated materials are fed through the metal parts furnace as well.

Tons of gaseous effluents from this process are then scrubbed by multiple wet and dry filters and released into the atmosphere through a tall smokestack; alarms notify workers if any agent is accidently released out the smokestack.

Neutralization.The preferred process of Russia and four American states has been a wet chemistry approach, typically called neutralization or hydrolysis. This requires that the chemical weapons container or weapon be drained; its liquid agent is placed in a mixing tank with hot water or a caustic reagent such as sodium hydroxide, or with both. Russia introduces its reagent directly into its large aerial bombs, allowing the chemical process to operate directly in the bomb for a month or more. The chemical reaction destroys the toxicity of the agent and the liquid effluent can then be further processed in a second stage, using either a liquid industrial incinerator or a bioremediation process similar to sewage treatment. The metal parts of weapons are processed in a metal parts furnace.

Explosive destruction systems. In a third option, countries seeking to destroy chemical weapons  detonate or neutralize each weapon in a closed “bang box,” a heavy reactor designed to blow up or treat chemically each individual weapon in a contained and safe manner, capturing and treating all gas, liquid, and solid toxic effluents. This process is being used by the Japanese now to destroy the hundreds of thousands of abandoned Japanese chemical weapons being excavated at multiple sites around China; it is also used to treat unexploded ordnance, both chemical and conventional, unearthed in Europe after the world wars. It will also be used as a complementary treatment process in the United States for some weapons.

There are a variety of other possible treatments for destroying chemical weapons, including steam reactors, plasma reactors, and super-critical water oxidation reactors. The basic approach to chemical weapons destruction is typically conditioned on safety, public health, local preferences, cost, and schedule. In fact, the CWC mandates that such demilitarization programs be based primarily on the protection of public health, the environment, and workers. Ocean dumping, burial, and open burning are prohibited, even though these were common practice decades ago.

It will be difficult to predict the best destruction options for Syria until more specific details of its program are known: how many sites, how many weapons, what types of agents, the amount of precursor chemicals, and the condition of the stockpiles. The good news is that the governmental and private sectors of the United States, Russia, Germany, Japan, and other countries have many years of experience that can help guide the project. The bad news? It will be a long-term, expensive operation.