First Responder Safety in the Event of a Dirty Bomb Detonation in Urban Environment

Abstract

The malevolent dispersion of radioactive material, with the aim of contaminating people and the environment, is considered a credible terroristic threat. This article analyzes a hypothetical Dirty Bomb detonation in an urban area, estimating the radiological consequences to the involved population and to first responders. The dispersion of radioactive material is simulated using the HOTSPOT code, considering the explosion of devices containing (alternatively) 60Co, 137Cs, 192Ir, 238Pu or 241Am sources, frequently used in medical or industrial settings. Each source is evaluated separately. The resulting ground deposition is used to calculate the effective dose received by first responders in two different scenarios. Based on the dispersed radionuclide, the influence of the use of personal protective respirators is analyzed. Confirming previous published results, this article illustrates that the radioactive material is diluted by the detonation, resulting in relatively low doses to the general public. However, the emergency workers’ stay time in the most contaminated area must be carefully planned, in order to limit the received dose. Due to the general fear of radiation, extensive psychological effects are expected in the public, irrespective of the evaluated radiation dose.

Emergency Management in the Event of Radiological Dispersion in an Urban Environment

“…Based on the results, the authors determine the various countermeasures to adopt, as a function of distance from the source, and the actions to take to reduce risk factors for the population and the first responders. This study demonstrates, as do other studies in the literature [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ], that wind and weather parameters remain key factors in assessing the dilution of radioactive materials, especially when in the evaluation it is possible to take into account the real geometry of the urban context considered. This means that the representation of the scenario obtained considering these variables affects the actions that need to be taken for the protection of the population and the first responders under emergency management plans.…”

“…Two distinct detonations of a Co-60 with different activities were performed: a medium activity source, having 10 GBq activity (as in the case of the real discovery), and a high activity source, charged with the activity of 1.5 × 10 5 GBq (that can be thought as the value the activity would have had if manufactured several decades earlier, or simply as the value of a high activity source used for teletherapy [ 10 ]). The projection model of the fragments due to the explosion was built in analogy with what is reported in the Hotspot software manual, with an initial blast for 5 s, assuming the entire release of the activity of the radiological source distributed along the vertical axis at a level of about 150 m from the ground.…”

“…The nuclear materials and the data used for the simulations, except for the meteorological situation, are taken from this real case. Then cases with higher activity were analyzed both to increase the level of complexity of the scenarios and in continuity with previous studies about these topics [ 10 ]. Several software simulations were performed to test the model capabilities, focusing on the differences in scenarios generated by different radiological sources, at a given weather condition; three of them are reported in this work to compare the outcomes in terms of the dispersions originating from a fire and from an RDD.…”

“…Several computer code simulations are performed by verifying the possibility of structuring detailed analyses regarding the dispersion of radionuclides in urban areas and verifying the possible countermeasures that can be implemented to reduce the impact in terms of dose on the population and on rescuers [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ].…”