Self-Acting Formation of an ANFO Similar Type of Explosive under Fire Conditions: A Case Study

Abstract

On 2 October 2003 in Saint-Romain-en-Jarez (France) a fire in a farm building triggered an explosion in which 26 people were injured. Police investigation, based solely on an analysis of the effects and on general engineering knowledge, showed that the explosion was caused by an uncontrollably generated mixture of ammonium nitrate (AN) and molten plastic crates which formed an explosive mixture similar to ammonium nitrate fuel oil (ANFO). This is the only commonly known example of an ammonium nitrate blast taking place at its end user destination. Is such an explanation of the incident plausible and could a similar blast possibly happen anywhere else? The experimental results support this thesis of French investigators but raise further doubts. Laboratory reconstruction of the self-acting process of generating the explosive material confirmed the investigators’ report. However, other materials at the incident site could have influenced the final outcome too. The lab-recreated explosion of a mixture of AN and molten plastic partially confirmed the report’s thesis.

Explosion Risks during Firefighting Operations in Storage Rooms and the Transport of Ammonium Nitrate-Based Fertilizers

“…In the laboratory of the Lodz University of Technology, a series of tests were carried out to determine the explosive potential of AN with PP and PE in the adopted proportions of 20% and 50%. A more detailed analysis is presented in the first article in the series [10], and the following articles present an analysis of threats to other popular polymers, such as nylon or polyvinyl chloride [11,12]. Figures 2-4 show the DSC analysis results for the tested AN and PP mixtures.…”

“…2-4 show that AN + 20% PP is the most explosive configuration, where during the sample decomposition a rapid release of 1310 kJ/kg of energy is emitted in an exothermic reaction. The important information is, however, that for each of the case studies, as well as for the other polymers [10][11][12], the nature of the decomposition changed from endothermic-for pure AN-to exothermic for mixtures with polymers or dusts. Moreover, this decomposition was often violent and resulted in the release of significant amounts of heat into the environment.…”

“…The conducted laboratory tests are to provide initial research material to estimate the time that-in certain conditions-is at the rescuers' disposal between the fire occurrence and the potential spontaneous formation of an explosive in the fire environment. This may increase the safety of rescuers and bystanders in the event of fires in facilities containing polyethylene, polypropylene [10], polyurethane [11], or other polymers, such as polyamides, polyvinyl chloride, polystyrene, poly(methyl methacrylate) [12], dusts of organic origin [28], silicon dioxide [29], and even soybean oil [30], as well as other components which have the potential to generate-in an uncontrolled manner-an explosive similar to ANFO. This similarity is based not only on the analogous chemical structure of the given organic substance in the mixture, but also on the comparable course of the decomposition reaction.…”

“…A series of thermal analyses of mixtures of AN with PP and PE were carried out [10][11][12]. Such a choice was influenced by the aforementioned accident in Saint-Romain-en-Jarez, where French investigators pointed to the direct contact of molten PE boxes with stored AN as the reason for the ANFO-analogous material creation.…”

Formation of an Ammonium Nitrate Fuel Oil Similar Type of Explosive under Fire Conditions: Materials Based on Selected Polymers (PUR)

“…From our point of view, examining such a combination is important due to the significant probability of the formation of mixtures containing PUR or polyisocyanurate (PIR) as well as AN in farm buildings or warehouses where fertilizers are stored. This article is an evaluation of our two previous publications [3,4]-initially based on the real incident in the French province of Loire in 2003 [5]-which discuss the explosive potential of mixtures containing polymers and AN. One can easily imagine a situation where crushed polyurethane foam-e.g., from sandwich panels, mounting foams or upholstered furniture and mattresses-stored in farm utility rooms, has access to collective packaging with AN-based fertilizers or their scattered remains, constituting a potentially explosive material.…”