Evaluation of Radiation Consequences of Releases in Accidents with Spills of Liquid Radioactive Materials in Areas with Forced Ventilation

This report focuses on assessment of radiation consequences of releases in accidents with spills of liquid radioactive materials in areas with forced ventilation. During the study, characteristic dependences between parameters of liquid radioactive materials and air exchange in areas with forced ventilation and associated radiation consequences were determined. The proposed approach is based on the theory of non-stationary heat and mass transfer in surface evaporation of liquid heated below the boiling temperature. The physical model includes: liquid radioactive material, steam-aerosol radioactive mixture, air of forced ventilation, airborne filters, and floor of the emergency area. The key aspects of the model are evaporation of liquid material, its removal with exhaust ventilation and partial trapping on airborne filters. It is considered that the steam-aerosol radioactive mixture is released to the environment after filters. The advantage of this model is the possibility to determine integral release of radionuclides to the environment and activity concentration of air in the emergency area at any moment after beginning of the accident, effective dose received by an adult during 14 days for a wide range of input thermodynamic and geometrical parameters, different operating modes of the ventilation system and different productivities of the filtering system. Results from assessment of radiation consequences for the selected accident are presented and the associated effect of filtering systems is analyzed.