(185b) Why Do Devastating Ammonium Nitrate Detonations Still Occur: Lesson Still Not Learned in Beirut, Tianjin and West Texas

Ammonium nitrate (AN) is widely used as a nitrogen fertilizer and as an additive when manufacturing explosives. It can be found naturally as a mineral and is produced by reacting anhydrous ammonia with nitric acid and dried to form small beads/prills. While extremely stable under most conditions, this widely used fertilizer is also commonly stored in bulk quantities posing a risk if not properly protected against large fires. Despite knowing such risks, ammonium nitrate explosions have continued to occur in recent years.

Last year in Beirut, Lebanon, 2,750 tons of ammonium nitrate was stored unsafely in a warehouse. A fire broke out in the warehouse and started a series of events that lead to the detonation of the hazardously stored ammonium nitrate. The city of Beirut was shaken by the detonation and severe damage was observed throughout the city. Dreadfully, this incident has similarities to the Tianjin explosion in China which occurred in August 2015 and the explosion in West, Texas in the USA, in April 2013. All these events involved the “unique” set of conditions necessary to turn the relatively stable oxidizer Ammonium Nitrate into a detonating explosive. This presentation will discuss these unique set of conditions common to each incident.

In addition, advanced blast techniques were used to determine the quantity of ammonium nitrate that likely detonated during each of these blasts. These techniques included near field blast effects (e.g., the resulting crater left by the blast) as well as the far-field blast damage resulting in the neighboring community. Results showed that the detonation of AN in Lebanon was the largest of the three in terms of blast damage approaching levels up to 1,000 tons of TNT, where Tianjin was estimated to be equivalent to approximately 300 tons TNT. This paper will address lessons learned to hopefully avoid such incidents in the future.