Decontamination factor of air filter against 198Au aerosol particles

DF (decontamination factor) of two types of air filter was investigated against 198Au aerosol particles with AMAD (activity median aerodynamic diameter) = 1.2 μm and σg (geometric standard deviation) = 2.0. One of the filters, SO filter, is HEPA (high efficiency particulate air) filter media with 46 mmφ, and the other is HE-40T (cellulose-glass fiber filter for dust sampling) filter media with 40 mmφ. DF of the SO filter was found to be over 5 x 104 at air flow rate of 1 l/min. And DF of HE-40 T filter was determined to be 94±4 at the same airflow rate. In the multistage HE-40 T filter system, DF decreased at each succeeding stage. It was confirmed by numerical simulation that the decrease of DF was not inconsistent with the decrease of collection performance in each successive filter. It was also confirmed that DF could be predicted by the numerical simulaiton, if particle penetration function of filter and size distribution function of radioactive aerosol particles were known. (author)