Modeling of the Fukushima Plume

For the assessment of contamination after the accident and prediction of radioactive particle transport the Lagrangian modelling was applied. In order to describe the atmospheric processes realistically, the vertical velocity, particle dissipation and turbulence during the particle trajectory were considered. A single release of 1015 Bq of 137Cs, which occurred on March 12, 2011 from damaged Fukushima NPPwas analyzed. The initial plume height, as a result of initial vertical velocity and buoyancy, was kept to be at 2000e3000 m. The meteorological data and simulated trajectories revealed that the arrival times of particles released on 11 March, 2011 and 12 March, 2011 were different, and the particles were transported at different altitudes. It was also obvious that the jet stream affected the transport of emitted particles at upper atmospheric levels. Examples of the trajectories simulated using the Lagrangian dispersion model show (Fig. 1) that the first signs of Fukushima released radionuclides could be detected in the European countries (e.g. Island) on 20 March, 2011.