Computation of fission product deposition in aerosols

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] High-temperature gas-cooled reactors (HTGRs) generate carbonaceous dust during both normal operations and accidents. The dust particles can be both highly irregular and porous and have exceptionally large surface areas, making dust-facilitated fission product (FP) transport a major factor in the computation of the nuclear source term. Since the FP interactions with the dust can occur while the dust is on a surface as well as in suspension, there is a need to obtain computational and experimental results for both situations. Since the particle sizes of interest span a wide range, from nanometers to microns, and are porous with various pathways for FP interactions to occur, these computations need to include not only the continuum regime, but the transport regime as well where the particle (or pore) size is comparable to the vapor (FP) mean free path. The focus of this dissertation is on Monte Carlo computation of the condensation rate on chainlike particles and particle agglomerates in the transport regime, towards a better understanding of how aerosol geometry affects mass transport on those particles.