Diameter of aerosols dispersed during the plasma cutting of plutonium-contaminated metal components of MOX fuel fabrication equipment was measured. The plasma cutting is performed by workers equipped with air fed suits within the glove box dismantling facility. The aerosols are introduced into multi-stage cascade impactors, enclosed in a small glove box to prevent cross-contamination. The size distribution and the median diameter of the dispersed aerosols were obtained. The activity median aerosol diameter was found to be around 6 micrometers, with a geometric standard deviation of 2.0. Also, the trapping performance of the HEPA filter on this particulate was confirmed by conducting radiological measurements on the outer surface of HEPA filter.