The performance of aerosol filters of class S with air of high humidity passing through

It is known from the literature that even in specified normal operation of ventilation systems in nuclear facilities, air streams of high humidity may induce filter failure due to cracking or breaking of the filter medium, which results in an irreversable, significant deterioration of the filter efficiency. For investigating the failure mechanisms, the differential pressures and damaging mechanisms in the filters affected by high air humidity and the underlying physical phenomena have been studied. The results obtained reveal the causes of many failures reported and have been taken as a basis for defining remedial measures or engineered measures for improving filter resistance against high air humidity. Empirical models have been established for simulating instationary flows in ventilation systems and for studying the time-related differential pressure patterns in filters under conditions of high air humidity. (orig./BBR)