The simulation developed in September 2011 by a team at CEREA, Ecole des Ponts  was performed with a specific version of the numerical atmospheric chemistry and transport model Polyphemus/Polair3D. The parametrisations used for the transport and physical removal of the radionuclides are described in [1,2,3,4].

The magnitude of activity concentration field is uncertain and could be significantly different from the actual one. In particular, the source term remains uncertain. Therefore, these results should be seen as preliminary and they are likely to be revised as new information become available to better constrain the source term and when radionuclides data can be used to evaluate the model simulation results.

http://cerea.enpc.fr/en/fukushima.html  http://www.enpc.fr/english/research/cerea.htm