Ionizer induced 220Rn decay product removal in confined environment: Continuous vs. instantaneous source

This paper presents an experimental approach to evaluate the effectiveness of unipolar ionizers in indoor environment for the removal of thoron (220Rn) daughter products. Both continuous and instantaneous source conditions were simulated during these experiments. Activity and aerosol related parameters were measured for these experiments and results were interpreted. Activity concentration was found to be reduced by a factor 6.6 and 34 for continuous and instantaneous source conditions, respectively. The particle size dependency of mitigation of particles using ionizer is also discussed. The effect of ionizer on activity size distribution has been directly measured for the first time. The ionizer induced changes in particle size distributions were coupled to Dose Reduction Factor (DRF) model and significant DRF values were obtained for both source conditions. This study discusses open issues which are important for establishing ionizer induced radioactivity mitigation as a technology application.