Estimating the effects of rain and snow on potential reactor accident consequences

There are several matters to be considered carefully in relation to a more realistic assessment of contamination which might result from wet deposition of radionuclides released in a nuclear accident. The use of radar data showing detailed spatial and temporal development of rain, coupled with surface wind fields, gives a better indication of when and where material released would encounter precipitation and be brought down to the ground. An understanding of the meteorological situations and dynamic movement of air aids the estimation of what processes are likely to be operative in incorporating pollutants in rainfall at ground level. The occurrence of intense rainfall is clearly revealed by radar and indicates strong convergence and possible concentrated deposition. Thus, in a real accident the radar system could be most valuable in identifying potential hot spots of deposition. (author)