Rapid Clogging of High-Efficiency Particulate Air Filters During In-Cell Solvent Fires at Reprocessing Facilities

Recent Japanese nuclear regulations have focused on the hazards of in-cell solvent fires at reprocessing facilities. In this work, a mixture of tributyl phosphate and dodecane-based solvents was burned to generate an aerosol composed of soot and unburned solvent that was then loaded onto a high-efficiency particulate air filter simulating the ventilation system of reprocessing facilities. A radical increase of differential pressure occurred in the filters during these tests after the dodecane burned out from the solvent in a phenomenon we named as rapid clogging, likely caused by the burnout of dodecane. This relationship provides valuable insight into the establishment of new regulations for reprocessing facilities. Moreover, an analysis of the aerosol revealed an increase in unburned solvent content and aerosol particle size generated during the rapid clogging. As such, the rapid clogging may be caused by the unburned solvent release or interactions between the soot and unburned solvent vapor. Overall, this work indicates that clogging of ventilation filters during solvent fires may occur more rapidly than previously estimated.