Ammonium Nitrate Chemistry

Bombs in Our Backyard

How would you feel about explosives packed with chemical weapons being disposed of near where you live?  This is a question facing many as the US continues to try and destroy its chemical weapons stockpile, and not surprisingly the answer is often "not in my backyard".  We have seen this yet again as the US Army struggles to find a way to dispose of old sulfur mustard munitions at the troubled Pueblo depot in Colorado.

The Chemical Weapons Convention, brought into force in 1997 and administered by the OPCW, bans the mass production and stockpiling of chemical weapons by its member states.  Importantly, it also requires that signatories destroy their existing stockpiles, which for the USA and Russia in particular has proven to be a gargantuan and on-going task.  Gone are the days when you could just dump your surplus nerve and blister agents into the sea (yes, that used to happen).

Nowadays, chemical weapons are destroyed either through high temperature incineration, or by aqueous (water-based) chemical and/or biological treatment.  Aqueous treatment options,  such as hydrolysis and neutralisation, require large and expensive processing plants, with a high degree of automation in order to protect workers.  Incineration - often with detonation of a munition's original explosive charge - is a versatile treatment alternative that mitigates some of the risks to workers.  The combustion products, however, must be dealt with, and tight controls need to be in place to ensure complete destruction of the chemical warfare agents (a research area I'm working in).  The prospect, no matter how remote, of smokestacks spewing out chemical weapons has proven to be a difficult sell to communities.

This is the bind that US Army finds itself in at Pueblo.  They have commissioned a no-expenses-spared plant in which to destroy old munitions loaded with mustard gas, but the level of operator intervention required appears to present an unacceptable risk.  Their preferred alternative of incineration, meanwhile, is being met with concern by local stakeholders.  The end result is to drag out the demilitarisation of US stockpiles, weakening diplomatic efforts to eradicate chemical weapons programs throughout the world.  Safe and prompt destruction of chemical weapons reserves is difficult, but it has to happen.