An approach to the nuclear aerosol source term assessment in an HCDA of LMFBR

A calculational model was developed for estimating the amount of fragmented fuel particles released from the closure head of reactor vessel following a fuel coolant interaction in an HCDA of LMFBR. Sample calculations were performed to determine the relative importance of the various complex physical processes involved in this phenomena. The followings became clear through this investigation: 1) the dimension, shape of bubbles and the contents of noncondensable gas have much influence on the vapor condensation rate. 2) the effect of the mass of the smallest diameter particles is predominant among others for aerosol release. In order to verify the behavior of bubbles, experimental studies are under way. Underwater experiments have been completed and the changes in the shape and velocity of the bubbles rising in a pool were investigated. A small scale sodium test will be started in the near future