Studies of HTO washout and deposition in the vicinity of emission source

Russian Federal Nuclear Center, VNIIEF, Mira Prospect 37, 607190 Sarov, Nizhegorodsky Region, Russia

Abstract

There are presented in the report research results of HTO wash-out and the model of HTO atmosphere concentration in the vicinity of a long-term HT and HTO emission source. The site of the scavenging experiments was around a 30 m emission source. The sampling arcs were chosen at 150-300 m from the base of the source to minimize dry deposition on the precipitation collectors. To study dependence of scavenging of tritium on raindrops characteristics, an optical device was constructed and used to measure the distribution of the drop radii and velocities during the period of experiment. The wash-out model, used for assessments, takes into account dispersion, deposition and re-emission. Soil surface is considered as secondary area source. Primary source is characterized as a source of infinite duration and permanent strength. Ingress of HTO to soil from primary source is occurred due to both dry and wet deposition. The model of HTO wet deposition is taken into account kinetics of HTO exchange between vapor and liquid phase with parameters such as rain drop spectra, rain intensity, condensation-evaporation on drop's interface Ingress of HT in soil is only due to HT dry deposition. Gauss type formulae for permanent emission source is used to calculate HTO atmosphere concentration. Averaged real meteorological data are used as input parameters for modeling.