Characterization of simulated accident aerosols and SPARC code calculations for SPARTA pool scrubbing experiments

Pool scrubbing is a key element in LWR source term estimation. In fact a number of pathways currently identified for the most risk significant sequences involve pathway segments through water pools (e.g. a transient without scram sequence for a BWR and containment bypass for a PWR). Previous work in pool scrubbing has shown that observed decontamination factors (DFs) are very sensitive to the test conditions. The steam content of the carrier gas, pool temperature and many other parameters have a strong influence on aerosol fission product retention processes. The SPARTA experimental programme (suppression pool aerosol retention test apparatus) is under development at ENEA-CRE Cassacia laboratories to evaluate the overall DFs in a full scale facility using X-quencher and horizontal vent discharge devices. Parameter sensitivity will be established in a small scale facility (1:6 scale). The aerosol characteristics in terms of intrinsic properties and the water condensation can be checked and measured experimentally using an inertial spectrometer. This device allows the sampling of particles with sufficient resolution that overlap can be avoided. In this way, the aerodynamic size of an individual particle can be compared with its geometric size and its morphology to obtain its shape factor. (author). 1 ref., 2 figs, 2 tabs