Seminar: Yong-ha Kim, Ph.D., School of Civil and Environmental Engineering, Georgia Institute of Technology



The College of the Coast & Environment presents

Yong-ha Kim, Ph.D.

School of Civil and Environmental Engineering

Georgia Institute of Technology

Monday, Sept. 11, 2017

11 a.m.

Dalton J. Woods Auditorium


Topic:  Radioactivity Transport: From Microphysics to Global Transport

Human health and environmental risk assessments from radiation exposure, after a nuclear plant accident or a deliberate explosion of a radiological dispersion device, are based on theoretical predictions of atmospheric dispersion of radionuclides. Because of large discrepancies between theory and observations after nuclear accidents, however, improving predictive modeling of radioactivity transport is a top priority. In general, it is assumed that the microphysical processes of atmospheric particles containing radionuclides are independent of electrostatic surface interactions. Radioactive decay of radionuclides, however, may induce significant surface charging; therefore, electrostatic particle-surface interactions should be included in predictive models of radioactivity transport to reduce uncertainty in radiation risk assessments.
This presentation will be focused on experimental and modeling investigations of radioactivity-induced charging and subsequent charge effects on radioactivity transport. These investigations include (i) assessment of air ionization by radionuclides, (ii) verification of radioactivity-induced charging mechanisms, (iii) evaluation of radioactivity-induced charging effects on the microphysics of radioactive particles, (iv) development of a theoretical framework to couple the charging effects with the microphysical behavior of radioactive particles, and (v) simulation of global transport of multicomponent radioactive aerosols released during the Fukushima accident. Results of these investigations suggest that radioactivity-induced charging may change the production and growth rates of radioactive aerosols, and this change significantly influences the transport and distribution of airborne radionuclides. Examples will be given to demonstrate that the theoretical framework developed in this research can be applied to various environmental systems involving radioactive materials.

Dr. Yong-ha Kim is currently a postdoctoral fellow in the School of Civil and Environmental Engineering at the Georgia Institute of Technology from where he received his Ph.D. degree in 2016. He obtained his BS and MS degrees in Environmental Engineering from the Jeju National University and Seoul National University, South Korea, respectively. His research interests cover atmospheric and water systems, in which colloid and surface science can play a major role, and include: colloidal phenomena (e.g., surface charging and electrosorption), contaminant transport in environmental systems, radiation effects on environmental systems, radiation dosimetry and indoor air quality modeling, and application of neutron imaging to environmental processes. He received a Radiological Worker Training II at the Oak Ridge National Laboratory (ORNL), which allows him to perform experiments using radioactive materials and neutron beams at ORNL. He has published 10 refereed journal papers and holds 2 patents.