Modelling Elemental Tritium Deposition, Conversion and Reemission Using Ontario Hydro’s Tritium Dispersion Code

Abstract

A mathematical model and associated computer code is being developed to assess the potential radiological impact of atmospheric releases of elemental tritium, HT, and tritium oxide, HTO, from nuclear facilities. Of the two forms of tritium under consideration, the behaviour of HT in the environment is more complex. This paper describes the theoretical basis of the Ontario Hydro Tritium Dispersion Code (OHTDC) for modelling HT deposition to soil, conversion of HT to HTO and reemission of HTO from soil. The OHTDC predictions were compared to field measured HT and HTO concentrations in air during the HT release experiments at Chalk River Nuclear Laboratories, Canada in August 1986 and June 1987, and good agreement was found. These results validate the code for radiological safety assessments of HT and HTO emissions from fusion facilities such as the International Thermonuclear Experimental Reactor (ITER) and other nuclear sites that manage tritium.