This edition of the 100LL coincides with the 20th anniversary of an ammonium nitrate explosion at a fertilizer plant near Toulouse, France — the 10th largest property damage loss in the history of the energy industry; as well as the 100th anniversary of an ammonium nitrate explosion in Oppau, Germany, which resulted in over 500 fatalities. Tragically, since the publication of our 2020 edition, a major ammonium nitrate explosion occurred in the Port of Beirut, Lebanon, in August 2020. The incident resulted in massive, dispersed property damage and over 200 fatalities.
With each new loss, the general public, regulators, and other stakeholders increase their focus on the measures that organizations that manufacture, transport, and store ammonium nitrate are taking to prevent such incidents from reoccurring. Although the loss events outlined in this report span more than a century, there are a number of common themes that emerge, and an indication of either a failure to learn the lessons, or to ensure that any learnings stand the test of time.
Ammonium nitrate is used primarily in the manufacture of fertilizers, and is also a main component of some explosives. It is a white, crystalline solid which is stable under normal conditions but explosive if exposed to shock or subjected to high temperatures. Ammonium nitrate is hygroscopic — that is, if improperly stored, it readily absorbs moisture from the air to cake, or solidify into larger masses, which further increases the confinement and the severity of any explosion.
Oppau, Germany, September 1921
Two consecutive explosions occurred in a silo containing approximately 4,500 metric tons of ammonium nitrate compound fertilizer, causing more than 500 fatalities and damaging approximately 700 homes. A number of changes had occurred which modified the chemical’s behavior to make it more explosive. Further compounding the dangerous situation, at the time, it was routine practice to use dynamite to deal with caking. A lack of hazard awareness, and ineffective change management during the manufacturing process, alongside unsafe storage, and proximity to urban areas, were key contributory factors that led to the catastrophic loss.
Toulouse, France, September 2001
There was a major explosion measuring 3.4 on the Richter scale involving 400 metric tons of off-specification ammonium nitrate in a temporary storage, which led to 30 fatalities, approximately 3,000 injuries, as well as substantial damage to neighboring properties. It is understood that a number of mixed grades of waste containing ammonium nitrate (for both fertilizer and explosives) were combined, without a full appreciation of the hazards these materials posed. This accident scenario was not included in the safety case report for this plant, and one of the key learnings from this event was the requirement to improve the risk governance process. There was a significant update of Seveso II, and later refinements in the Seveso III directive, to include the identification of off-specification and downgraded ammonium nitrate compounds as regulated substances.
Beirut, Lebanon, August 2020
This explosion, in a non-industrial setting, involved 2,750 metric tons of ammonium nitrate that was seized from a ship at port, and stored for six years in a nearby warehouse ¬ near fireworks and other hazardous materials ¬ while a dispute over ownership of the cargo was being resolved. The explosion caused over 200 fatalities, injured 6,000 people, and made nearly 300,000 homeless.
The ammonium nitrate was reported to have been stored in large sacks stacked on top of each other, with large rips in the bags, in a humid environment. A fire was reported to have broken out in the warehouse, initially igniting the fireworks, before reaching the ammonium nitrate stockpile.
Hazard perception and awareness. In each of the incidents listed above, work practices indicated an unsafe level of risk tolerance, or a lack of awareness of the hazards associated with ammonium nitrate.
Storage and handling. Given the inherent characteristics of the ammonium nitrate material, storage conditions are crucial to the safety and stability of the product. This includes the use of non-combustible materials, anti-caking additives, adequate ventilation, and provision of sprinklers.
Proximity to urban areas. The impact of each of the incidents above was intensified by the proximity of residential areas to the storage site. In a number of historical cases, land use planning had allowed urban development without an accurate understanding of the worst credible scenario at the storage facility. In the case of Beirut, the hazardous material was brought into a densely populated area and left for a number of years.
Following the Beirut incident, the Marsh Specialty risk engineering team published a paper detailing best practices and lessons learned for handling ammonium nitrate.