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Title: Incorporating radioactive decay into charging and coagulation of multicomponent radioactive aerosols

Abstract

Compositional changes by the decay of radionuclides in radioactive aerosols can influence their charging state, coagulation frequency and size distribution throughout their atmospheric lifetime. The importance of such effects is unknown as they have not been considered in microphysical and global radioactivity transport studies to date. Here, we explore the effects of compositional changes on the charging efficiency and coagulation rates of aerosols using a set of kinetic equations that couple all relevant processes (decay, charging and coagulation) and their evolution over time. Compared to a coupled aggregation-tracer model for the prediction of the radioactive composition of particulates undergoing coagulation, our kinetic approach can provide similar results using much less central processing unit time. Altogether with other considerations, our approach is computational efficient enough to allow implementation in 3D atmospheric transport models. The decay of radionuclides and the production of decay products within radioactive aerosols may significantly affect the aerosol charging rates, and either hinder or promote the coagulation of multicomponent radioactive aerosols. Our results suggest that radiological phenomena occurring within radioactive aerosols, as well as subsequent effects on aerosol microphysics, should be considered in regional and global models to more accurately predict radioactivity transport in the atmosphere in casemore » of a nuclear plant accident.« less

Authors:
 [1];  [1];  [2]; ORCiD logo [3]
  1. Georgia Inst. of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering
  2. Georgia Inst. of Technology, Atlanta, GA (United States). School of Earth and Atmospheric Sciences, School of Chemical and Biomolecular Engineering; Foundation for Research and Technology, Patras (Greece). Inst. of Chemical Engineering Sciences; National Observatory of Athens (Greece). Inst. for Environmental Research and Sustainable Development
  3. Georgia Inst. of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1399385
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Aerosol Science
Additional Journal Information:
Journal Volume: 114; Journal Issue: C; Journal ID: ISSN 0021-8502
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; multicomponent radioactive aerosols; radioactive decay; aerosol charging; gaussian charge distributions; aerosol coagulation; radioactivity transport; nuclear plant accidents

Citation Formats

Kim, Yong-ha, Yiacoumi, Sotira, Nenes, Athanasios, and Tsouris, Costas. Incorporating radioactive decay into charging and coagulation of multicomponent radioactive aerosols. United States: N. p., 2017. Web. doi:10.1016/j.jaerosci.2017.09.024.
Kim, Yong-ha, Yiacoumi, Sotira, Nenes, Athanasios, & Tsouris, Costas. Incorporating radioactive decay into charging and coagulation of multicomponent radioactive aerosols. United States. doi:10.1016/j.jaerosci.2017.09.024.
Kim, Yong-ha, Yiacoumi, Sotira, Nenes, Athanasios, and Tsouris, Costas. 2017. "Incorporating radioactive decay into charging and coagulation of multicomponent radioactive aerosols". United States. doi:10.1016/j.jaerosci.2017.09.024.
@article{osti_1399385,
title = {Incorporating radioactive decay into charging and coagulation of multicomponent radioactive aerosols},
author = {Kim, Yong-ha and Yiacoumi, Sotira and Nenes, Athanasios and Tsouris, Costas},
abstractNote = {Compositional changes by the decay of radionuclides in radioactive aerosols can influence their charging state, coagulation frequency and size distribution throughout their atmospheric lifetime. The importance of such effects is unknown as they have not been considered in microphysical and global radioactivity transport studies to date. Here, we explore the effects of compositional changes on the charging efficiency and coagulation rates of aerosols using a set of kinetic equations that couple all relevant processes (decay, charging and coagulation) and their evolution over time. Compared to a coupled aggregation-tracer model for the prediction of the radioactive composition of particulates undergoing coagulation, our kinetic approach can provide similar results using much less central processing unit time. Altogether with other considerations, our approach is computational efficient enough to allow implementation in 3D atmospheric transport models. The decay of radionuclides and the production of decay products within radioactive aerosols may significantly affect the aerosol charging rates, and either hinder or promote the coagulation of multicomponent radioactive aerosols. Our results suggest that radiological phenomena occurring within radioactive aerosols, as well as subsequent effects on aerosol microphysics, should be considered in regional and global models to more accurately predict radioactivity transport in the atmosphere in case of a nuclear plant accident.},
doi = {10.1016/j.jaerosci.2017.09.024},
journal = {Journal of Aerosol Science},
number = C,
volume = 114,
place = {United States},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
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  • Charging and coagulation influence one another and impact the particle charge and size distributions in the atmosphere. However, few investigations to date have focused on the coagulation kinetics of atmospheric particles accumulating charge. This study presents three approaches to include mutual effects of charging and coagulation on the microphysical evolution of atmospheric particles such as radioactive particles. The first approach employs ion balance, charge balance, and a bivariate population balance model (PBM) to comprehensively calculate both charge accumulation and coagulation rates of particles. The second approach involves a much simpler description of charging, and uses a monovariate PBM and subsequentmore » effects of charge on particle coagulation. The third approach is further simplified assuming that particles instantaneously reach their steady-state charge distributions. It is found that compared to the other two approaches, the first approach can accurately predict time-dependent changes in the size and charge distributions of particles over a wide size range covering from the free molecule to continuum regimes. The other two approaches can reliably predict both charge accumulation and coagulation rates for particles larger than about 0.04 micrometers and atmospherically relevant conditions. These approaches are applied to investigate coagulation kinetics of particles accumulating charge in a radioactive neutralizer, the urban atmosphere, and an atmospheric system containing radioactive particles. Limitations of the approaches are discussed.« less
  • Charging and coagulation influence one another and impact the particle charge and size distributions in the atmosphere. However, few investigations to date have focused on the coagulation kinetics of atmospheric particles accumulating charge. This study presents three approaches to include mutual effects of charging and coagulation on the microphysical evolution of atmospheric particles such as radioactive particles. The first approach employs ion balance, charge balance, and a bivariate population balance model (PBM) to comprehensively calculate both charge accumulation and coagulation rates of particles. The second approach involves a much simpler description of charging, and uses a monovariate PBM and subsequentmore » effects of charge on particle coagulation. The third approach is further simplified assuming that particles instantaneously reach their steady-state charge distributions. It is found that compared to the other two approaches, the first approach can accurately predict time-dependent changes in the size and charge distributions of particles over a wide size range covering from the free molecule to continuum regimes. The other two approaches can reliably predict both charge accumulation and coagulation rates for particles larger than about 0.04 micrometers and atmospherically relevant conditions. Here, these approaches are applied to investigate coagulation kinetics of particles accumulating charge in a radioactive neutralizer, the urban atmosphere, and an atmospheric system containing radioactive particles. Limitations of the approaches are discussed.« less
  • The coagulation constant of nonradioactive and radioactive metallic aerosols produced by an exploding-wire technique was determined experimentally. At early stages of coagulation the coagulation constant of radioactive gold aerosols (2 to 3.5 c/g) was approximately twenty times the mean value of slightly radioactive aerosols (50 to 900 mc/ g). The values of the coagulation constant were corrected for deposition on vertical wall surfaces by means of a derived equation. Scavenging of radioactive aerosols was divided into three groups based upon the mechanism of coalescence: (l) dry particulate matter mixed with an aerosol, (2) dry particulate matter formed in the aerosolmore » atmosphere, and (3) hygroscopic and liquid particulate matter formed in the aerosol atmosphere. Brownian motion in the presence of a water vapor concentration gradient around condensing droplets was found to be the most effective scavenging mechanism for slightly radioactive aerosols.« less
  • Observational evidence of electrical forces acting significantly on small solids is present for both the modern solar system in Saturn's rings and the ancient solar system in chondritic meteorites. It is likely that grain-grain coagulation rates are affected by the distribution of charges on small grains. Plasma particle impacts and photoelectric effects can provide the charges. It appears that some charging is inevitable and that plasma grain interactions need to be evaluated to determine the size of the effect on coagulation rates. We apply the results of our previous charging work to models of the protoplanetary nebula. It is expectedmore » that the protoplanetary nebula is weakly ionized except in certain instances and locations such as: solar flares in the interior, ultraviolet radiation at the outer boundary, and during enhanced luminosity of the star. Since the grains we study are non-conducting and show strong dipole moments in flowing plasma, we modify the geometric cross sections to include the effects of flowing plasma on non-conducting grains with plasma mediated shielding. This paper provides results showing how plasma flow affects the processes involved in charging the grains--total charge and charge distribution. We calculate the modifications to the cross sections and subsequent changes in the coagulation rates.« less