Investigations and Modeling of Tritium Reemission from Soil

Although the process of tritium reemission from soils after HT or HTO deposition is principally understood, the prediction of initial values and time courses of reemission rates on the basis of readily available data is still insufficient, especially when high time resolutions are required. Theoretical and experimental investigations discussed here show that for a yet limited number of environmental conditions good model performance is reached. In the case of evaporation conditions the initial reemission rate after HT deposition can be coupled to the evaporation rate, when the tritium profile in soil is of exponential shape, characterized by a mean scaling length. After HTO deposition the ideal profile can be described by an error function with a scaling length about 1/3 of that of the HT case. Hence, the initial reemission rate is 3 times higher. Time courses can be modeled by a diffusion approach applying the same diffusion coefficient as for the deposition process.