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6. Spatial Uncertainty in Modeling Inhalation Exposure to Volatile Organic Compounds in Response to the Application of Consumer Spray Products

Author

Jung, Yerin, Kim, Yoonsub, Seol, Hwi-Soo, Lee, Jong-Hyeon, and Kwon, Jung-Hwan

Subjects
Earth Sciences, Atmospheric Sciences, Aerosols, Inhalation Exposure, Mass Spectrometry, Uncertainty, Volatile Organic Compounds, micro environmental modeling, volatile organic compounds, inhalation exposure, spray product, proton transfer reaction mass spectrometry, Toxicology
Abstract

(1) Background: Mathematical exposure modeling of volatile organic compounds (VOCs) in consumer spray products mostly assumes instantaneous mixing in a room. This well-mixed assumption may result in the uncertainty of exposure estimation in terms of spatial resolution. As the inhalation exposure to chemicals from consumer spray products may depend on the spatial heterogeneity, the degree of uncertainty of a well-mixed assumption should be evaluated under specific exposure scenarios. (2) Methods: A room for simulation was divided into eight compartments to simulate inhalation exposure to an ethanol trigger and a propellant product. Real-time measurements of the atmospheric concentration in a room-sized chamber by proton transfer reaction mass spectrometry were compared with mathematical modeling to evaluate the non-homogeneous distribution of chemicals after their application. (3) Results: The well-mixed model overestimated short-term exposure, particularly under the trigger spray scenario. The uncertainty regarding the different chemical proportions in the trigger did not significantly vary in this study. (4) Conclusions: Inhalation exposure to aerosol generating sprays should consider the spatial uncertainty in terms of the estimation of short-term exposure.

Published
2021

48. Evaluation of SMUT Properties according to Nb Content in the Pickling Process of Nuclear Fuel Cladding Tube

Author

Lee Jin-hang, Young Jun Lee, Jong Han Moon, Lee， Jong-Hyeon, and Jong Won Hong

Subjects
Cladding (metalworking), Materials science, Nuclear fuel, Zirconium alloy, Alloy, Metallurgy, engineering.material, chemistry.chemical_compound, Hydrofluoric acid, chemistry, Nitric acid, Pickling, engineering, General Materials Science, Particle size
Abstract

Currently, the Korean nuclear industry uses ZIRLO as material for nuclear fuel cladding(zirconium alloy). KEPCO Nuclear Fuel is in the process of developing a HANA alloy to enable domestic production of cladding. Cladding manufacture involves multistage heat treatments and pickling processes, the latter of which is vital for the removal of defects and impurities on the cladding surface. SMUT that forms on the cladding surface during such pickling process is a source of surface defects during heat treatment and post-treatment processes if not removed. This study analyzes ZIRLO, HANA-4, and HANA-6 alloy claddings to extensively study the SEM/EDS, XRD, and particle size characteristics of SMUT, which are second phase particles that are formed on the cladding surface during pickling processes. Using the analysis results, this study observes SMUT formation characteristics according to Nb concentration in Zr alloys during the washing process following the pickling process. In addition, this study observes SMUT removal characteristics on cladding surfaces according to concentrations of nitric acid and hydrofluoric acid in the acid solution.

Published
2019

49. Effect of AlF3 on Zr Electrorefining Process in Chloride-Fluoride Mixed Salts for the Treatment of Cladding Hull Wastes

Author

Lee， Jong-Hyeon, Deok Yoon Kang, Chang Hwa Lee, and Sung-Jai Lee

Subjects
Materials science, Renewable Energy, Sustainability and the Environment, Scanning electron microscope, Inorganic chemistry, Alloy, Management, Monitoring, Policy and Law, engineering.material, Chloride, chemistry.chemical_compound, Fuel Technology, Nuclear Energy and Engineering, X-ray photoelectron spectroscopy, chemistry, medicine, engineering, Cyclic voltammetry, Molten salt, Waste Management and Disposal, Fluoride, medicine.drug, Electrowinning
Abstract

Zr electrorefining is demonstrated herein using Zirlo tubes in a chloride-fluoride mixed molten salt in the presence of AlF3. Cyclic voltammetry reveals a monotonic shift in the onset of metal reduction kinetics towards positive potential and an increase in intensity of the additional peaks associated with Zr-Al alloy formation with increasing AlF3 concentration. Unlike the galvanostatic deposition mode, a radial plate-type Zr growth is evident at the top surface of the salt during Zr electrorefining at a constant potential of −1.2 V. The diameter of the plate-type Zr deposit gradually increases with increasing AlF3 concentration. Scanning electron microscopy–energy-dispersive Xray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses for the plate-type Zr deposit show that trace amount of Al is incorporated as Zr-Al alloys with different chemical compositions between the top and bottom surface of the deposit. Addition of AlF3 is effective in lowering the residual salt content in the deposit and in improving the current efficiency for Zr recovery.

Published
2019

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