Computation of Fission Product Condensation on Chainlike Aerosols and Agglomerates—II: Role of Energy and Mass Dependence of Molecules

Abstract

Although aerosols in some postaccident nuclear environments can be nonspherical, chainlike, or agglomerates, there have been limited investigations of the rate processes (such as coagulation, evaporation, condensation, and deposition) involving such particles. In a previous investigation, the understandings of condensation and evaporation on such particles were expanded through use of a one-speed approximation for modeling vapor (or fission product) molecular transport, and the present paper extends that work to energy- and mass-dependent transport of vapor molecules within the context of the linear Boltzmann equation via the Monte Carlo particle transport method for rigid sphere molecules. The results are benchmarked against available numerical results and experimental data for a single sphere, and it is found again that the normalized condensation rate has only a weak dependence on the molecular mass ratio (vapor to background) and that the one-speed approximation is quite good. Results are reported for a range of chainlike and agglomerate aerosols.