DISARM

DISARM: DISpersion of radioActivity fRom nuclear boMbs

The current geopolitical situation indicates that there is an increased risk for use of weapons of mass destruction such as nuclear weapons. Detonation of nuclear bombs implies atmospheric dispersion of radioactivity posing a risk to the public at longer distances from the detonation. Thus, there is a need for developing new, or improving existing, prediction model tools for such events aiming at enhanced civil protection. Accordingly, the overall intention with the DISARM project is to improve the capability to predict the atmospheric dispersion of radioactivity from detonation of nuclear bombs of different yields.
The envisioned model system will describe the initial spatial distribution of radioactive matter when stabilization has occurred around ten minutes after detonation. This effective initial spatial distribution will be taken over by an operational atmospheric dispersion model, which will have to be further developed in order to comply with such description.
The first version will be based on existing descriptions, e.g. the KDFOC3 approach by Harvey et al. (1992) in combination with the source strengths described by Kraus and Foster (2014), and using parameters which are observed in the field. It needs further to be considered if calculation of the effective initial distribution should ideally take place as a pre-processor implemented on the supercomputer at the national meteorological service or in the nuclear decision support system (DSS) in use.
The system should preferably be able to accept NATO CBRN messaging according to e.g. the ATP-45 standard. Algorithms converting the information contained in these messages to the inputs are needed for the atmospheric dispersion models. This may include merging and co-processing of multiple observation reports.
The description of the initial phase can be improved, e.g. by incorporating dependences on meteorological parameters and arriving at better descriptions of particle size distributions. Here, recent work by Arthur et al. (2021) on the early dynamics of the nuclear cloud may be of interest; however, this approach does not take into account the fireball ground hit.
The previous NKS-B projects MUD and AVESOME have demonstrated that inherent case-dependent meteorological uncertainties play a significant role for the atmospheric dispersion model results. As for nuclear power plants, uncertainties of the source term description are expected to dominate; however, as the meteorological uncertainties influence the transport pathway they may well have significant impact on emergency preparedness far from the detonation. In DISARM, methods will be developed and applied to quantify the meteorological uncertainties of the predicted plumes.