Experiments on diffusion into the atmosphere and into the sea of discharges from nuclear installations

The Environmental Radioactivity Laboratory (Casaccia Nuclear Research Centre, Rome) and the Marine Radioactive Contamination Laboratory (Fiascherino, La Spezia) of the Italian National Nuclear Energy Commission have developed various experimental methods for studying the diffusion of pollutants in the atmosphere and in sea-water. Micrometeorological techniques have been developed to study the thermo-dynamic behaviour of the lower layer of the atmosphere (0-500 m). Various methods have also been developed for determining the diffusion coefficients in the vertical and horizontal directions. In addition, theoretical and experimental studies have been performed with the aim of evaluating the mean concentrations in the atmosphere for continuous discharges. Numerous examples of the application of these techniques are cited in the text. The Fiascherino Laboratory has performed numerous experiments on the diffusion of liquid effluents in sea-water in the Gulf of Taranto (Southern Italy), off the Trisaia Nuclear Research Centre (National Nuclear Energy Commission). The outlay necessary to collect all the various data is justified by the intention to study the capacity of the Centre to accept large nuclear installations in the future. These data have been used to calculate the limiting radiological capacity for different lengths of discharge pipe and they will also provide a means of evaluating the impact on the environment of releases from other facilities which might be constructed on the same site in the future