DRAWN

DRAWN: DispeRsion Analysis of early nuclear WeapoN tests

In the ongoing NKS-B project DISARM (DISpersion of radioActivity fRom nuclear boMbs), methods are developed for description of the initial spatial distribution of radioactive matter after the detonation of a nuclear weapon. The effective spatial distribution of the stabilized mushroom cloud can be taken over by an atmospheric dispersion model which has been improved in order to comply with the description. 

The objectives of the present proposal are twofold: (1) to apply and validate the methods developed in DISARM to selected atmospheric nuclear tests in the Nevada desert in the 1950s and early 1960s, and (2) to continue the improvement of the methods describing the mushroom cloud after stabilization.
Regarding validation, we aim at selecting detonations of different yields and detonation heights. For each of the selected cases, DMI shall set up and run the non-hydrostatic Harmonie numerical weather prediction (NWP) model at high resolution using ERA5 reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF) to describe the boundary conditions. The Harmonie model will be set up on a supercomputer for a geographic domain of sufficient size to represent the dispersion of the radioactive plume. Not only a deterministic Harmonie model will be run (in the first year of DRAWN), a full Harmonie ensemble will be applied (in the second year) thereby enabling quantification of the effects of meteorological uncertainties on the dispersion patterns. Here, we shall utilize methodologies developed in the previous NKS projects MUD, AVESOME, and DISARM.
Two different descriptions of the released radioactivity will be applied, i.e. the KDFOC3 pseudo-nuclide approach described by Harvey et al. (1992), and the radionuclide-specific approach for uranium type weapons by Kraus and Foster (2014), and the resulting doses will be compared.
The predicted plumes, both deterministic and using ensemble-statistical methods, will be imported to the ARGOS nuclear decision-support system (DSS) for presentation and dose assessment, and optimum presentation for nuclear emergency management and decision making it will be considered.
As a continuation of the work initiated and carried out in the DISARM project, the updated implementation of KDFOC3 will be evaluated against the cases that are behind the formulations from the beginning. Especially, the aerosol distribution will be evaluated against the original observational data. The attempt for dynamic description of the build-up of the stabilized mushroom cloud will be assessed.
Collaboration will take place with the ongoing EU project PREDICT (imPRovements in atmospheric dispErsion moDellIng and proteCTive action strategies in case of nuclear detonation) such that there will be no duplication of efforts.