Studies on Collection Performance of HEPA Filter against Pu Aerosols

Decontamination Factors (DFs) of HEPA filter were measured against 239Pu oxide aerosols. Collection performance of HEPA filter media was investigated using monodisperse NaCl aerosols at various air flow face velocities. From the penetration curves the most penetrating particle size, MPPS, and the maximum penetration, Pmax, were obtained in each face velocity. The MPPSs at 0.8-11cm s-1 flow were not found in 0.3μm size range but in 0.1-0.15μm size range. The reciprocal of Pmax, which means the minimum of decontamination factor, DFmin, linearly increased with decreasing face velocity in a logarithmic paper. Experimental DFs against Pu aerosols in the MPPS range were nearly equal to the DFmin, and the others were always larger than the DFmin. This means that there are no differences between Pu and NaCl aerosols in terms of filtration. The DFmin estimated from the nonradioactive test aerosols is important for evaluating the performance of HEPA filters in the radiation protection field.