Modeling Thermomechanical Failure and Entrainment of Structural and Geological Materials into a Nuclear Fireball

Understanding how the fireball from a nuclear detonation interacts with its environment is essential to predicting the post-detonation environment, including fallout composition and form. Realistic scenarios for nuclear events inevitably involve complex environments, such as urban settings, however the majority of data informing fallout processes come from environments devoid of relevant buildings or other structures. This paper summarizes recent developments in simulations of above-ground nuclear explosions as part of a broader effort to better characterize conditions within a fireball that may influence the chemical evolution of bomb materials and other materials entrained from the local explosion environment. We discuss our recent improvements in modeling of the coupling of radiation transport and mechanical deformation, as well as the transition from intact materials (e.g., rock, concrete, etc.) into airborne particulates. The entrainment process is particularly important to our investigations because entrained materials are a predominant influence on the chemistry and form of resultant fallout.