STUDY ON MODELS FOR MEAN DIAMETER OF AEROSOL-PARTICLE FOR ANALYSIS OFRADIONUCLIDE BEHAVIOR INSIDE CONTAINMENT

When high enthalpy liquid is discharged into a containment, thermal fr agmentation is a dominant mechanism for the dispersion of liquid into droplets. The current method for aerosol size estimation in the SMART code used for CANDU containment analysis, however; results in too smal l aerosol diameter because it considers only aerodynamic atomization w ith very fast discharging velocity. The smaller the aerosol diameter t he less is the effect of aerosol removal mechanisms. Therefore, the am ount of aerosol released into environment for some of the containment isolation failure cases and the resulting dose values are very conserv ative. Among several models to predict the drop diameter for a high en thalpy liquid jet, an appropriate model (Koestel, Gido and Lamkin mode l) has been selected for aerosol size calculation and incorporated in SMART code. This updated SMART code has been assessed for WALE (Water Aerosol Leakage Experiments)for the code verification. The calculated aerosol amount released into environment is still significantly higher than the experimental value but much lower compared to those predicte d by non-updated (original) SMART code. Some of CANDU DBAs (Design Bas is Accidents) have been analyzed by using updated and original SMART c odes. The comparison of the results shows that the amount of each radi onuclide isotope released into outer atmosphere is significantly reduc ed with the updated SMART code. Copyright (C) 1996 Elsevier Science Lt d