A practical method for predicting and analyzing the consequences of ammonium nitrate explosion accidents adjacent to densely populated areas

Several catastrophic ammonium nitrate (AN) explosion accidents have been reported during the last decades. Previous studies have been mainly focused on investigating adverse effects caused by the AN explosion, while only a few systematically analyzed the consequences and impacts of AN explosions. This study collects data from three typical AN explosions (accidental explosion of the US fertilizer plant in 2013; an accidental explosion of China's Tianjin port in 2015, and a recent explosion (2020) of the Beirut port in Lebanon). The consequences of accidental explosions were analyzed by mathematical equations that further provide scientific explanations for AN explosions. Based on the explosives' properties on-site, these accidental explosions were caused by condensed phase explosives. Comparison with the conditions at the explosion site indicated that blast overpressure was the primary factor in the loss of life and damage to the building, while ground shock was a secondary factor. The severity of loss of life and building damage from explosions decreased with increasing distance. These distances could be calculated by the scaling law, which was replaced by the equivalent TNT mass of the explosive and the damage scale's overpressure boundary value. In addition, mapping the damaged area on a map helped in the visual presentation of the consequence assessment. The long-term environmental and ecological impact due to the explosions was also an important issue that could not be ignored. Overall, this study establishes a simple and easy-to-use method to rapidly predict and assess the consequences of an explosion, and provides technical guidance for future emergency response to similar large-scale accidents.

An approach to incorporate multiple forms of iodine in radiological consequence analysis

Interest is increasing in the radiological consequences of a release of aerosol and gaseous iodine, especially after the Fukushima accident and also because of new interpretations of the results of recent severe accident experiments. This work provides a brief review of the history of iodine chemistry in containment and suggests an approach to include gaseous iodine, namely in the forms of elemental iodine and organic iodide, in consequence analyses using the MACCS code. As dry deposition is an important characteristic to distinguish each chemical form of iodine when performing a consequence analysis, the mechanisms and mathematical formulas expressing dry deposition are also investigated. The proposed approach is demonstrated by performing consequence analyses with a unit release of ¹³¹I, with the resulting trends of concentration and dose for the different chemical forms of iodine presented and discussed. For the same amount of iodine release, there is a higher surface deposition of elemental iodine (I₂) because it has a higher dry deposition velocity, while the air concentration of a representative organic iodide (CH₃I) is higher due to its lower dry deposition velocity, which means a lower depletion of the air concentration. Despite elemental iodine having a lower air concentration, its higher dose coefficients for the inhalation pathway compensates for this when calculating doses. Further, inhaled doses increase when considering resuspension inhalation for extended durations of exposure. The approach proposed in this study is expected to be used flexibly to perform consequence analyses incorporating both aerosol and gaseous forms of iodine.

Case study and lessons learned from the ammonium nitrate explosion at the West Fertilizer facility

In West, Texas on April 17, 2013, a chemical storage and distribution facility caught fire followed by the explosion of around 30 tons of ammonium nitrate while the emergency responders were trying to extinguish the fire, leading to 15 fatalities and numerous buildings, businesses and homes destroyed or damaged. This incident resulted in devastating consequences for the community around the facility, and shed light on a need to improve the safety management of local small businesses similar to the West facility. As no official report on the findings of the incident has been released yet, this article first investigates the root causes of the incident, and presents a simplified consequence analysis. The article reviews the regulations applicable to this type of facility and recommended emergency response procedures to identify gaps between what happened in West and the current regulations, and discusses how the current regulations could be modified to prevent or minimize future losses. Finally, the federal response that followed the incident until the publication of this paper is summarized.

A framework for estimating the adverse health effects of contamination events in water distribution systems and its application

Intentional or accidental releases of contaminants into a water distribution system (WDS) have the potential to cause significant adverse health effects among individuals consuming water from the system. A flexible analysis framework is presented here for estimating the magnitude of such potential effects and is applied using network models for 12 actual WDSs of varying sizes. Upper bounds are developed for the magnitude of adverse effects of contamination events in WDSs and evaluated using results from the 12 systems. These bounds can be applied in cases in which little system-specific information is available. The combination of a detailed, network-specific approach and a bounding approach allows consequence assessments to be performed for systems for which varying amounts of information are available and addresses important needs of individual utilities as well as regional or national assessments. The approach used in the analysis framework allows contaminant injections at any or all network nodes and uses models that (1) account for contaminant transport in the systems, including contaminant decay, and (2) provide estimates of ingested contaminant doses for the exposed population. The approach can be easily modified as better transport or exposure models become available. The methods presented here provide the ability to quantify or bound potential adverse effects of contamination events for a wide variety of possible contaminants and WDSs, including systems without a network model.