Atmospheric dispersion and deposition (continuation)

The meteorological factors are subject to marked spatial and temporal variations. They are not independent, but related with each other in many ways. In Riskmap, for each NPP the atmospheric dispersion of the released radioactive cloud was simulated using the meteorological conditions of the climatically representative year 1995.

For a total of 88 accident times at different times of the year and the day during the year 1995, the dispersion and deposition of Cs-137 has been calculated according to the respective actual meteorological conditions (during 10 days). The area for which the calculations have been performed includes Europe and the eastern Atlantic, and vertically the whole troposphere and the lower stratosphere.

The deposition was calculated for a coarse and a fine grid (see table) in order to obtain a better resolution in the more densely populated parts of Europe, an area where also the majority of the NPPs are found. The deposition near the source (within one grid distance of the NPP under consideration) is not described well (dilution over the whole grid cell).