Airborne release of hazardous micron-sized metallic/metal oxide particles during thermal degradation of polycarbonate surfaces contaminated by particles: Towards a phenomenological description.

The release of radioactive particles during fires is a key issue for the safety analysis of industrial nuclear facilities. Nevertheless, significant discrepancies exist between experimental measurements reported in the literature of airborne release fractions (ARF), expressed in terms of mass, and further discussions on the phenomenology of particles released from burning solid surfaces are needed. Experimental results are reported on the resuspension of metallic/metal oxide particles deposited on polycarbonate (PC) samples, representative of glove boxes used in the nuclear industry, under thermal degradation and for several particles deposit properties, i.e. equivalent volume diameter (D), density (ρ), morphology and number of mono-layer (N). A significant influence of D and ρ was identified, with a peak in ARF for diameters close to 6 μm and a decreasing ARF with increasing density. Furthermore, the particle deposit structure was identified as an influencing parameter, with ARF decreasing with increasing N up to nearly 0.3 and remaining constant above. Experimental results obtained in this study were compared with literature values to propose a phenomenological description of particles resuspension from burning PC surfaces. These findings open the way to a theoretical description of airborne release and to propose realistic surrogate to conduct large-scale fire experiments.