Assessment of Inhalation Dose Sensitivity by Physicochemical Properties of Airborne Particulates Containing Naturally Occurring Radioactive Materials

Title & Authors
Assessment of Inhalation Dose Sensitivity by Physicochemical Properties of Airborne Particulates Containing Naturally Occurring Radioactive Materials
Kim, Si Young; Choi, Cheol Kyu; Park, Il; Kim, Yong Geon; Choi, Won Chul; Kim, Kwang Pyo;

Abstract
Facilities processing raw materials containing naturally occurring radioactive materials (NORM) may give rise to enhanced radiation dose to workers due to chronic inhalation of airborne particulates. Internal radiation dose due to particulate inhalation varies depending on particulate properties, including size, shape, density, and absorption type. The objective of the present study was to assess inhalation dose sensitivity to physicochemical properties of airborne particulates. Committed effective doses to workers resulting from inhalation of airborne particulates were calculated based on International Commission on Radiological Protection 66 human respiratory tract model. Inhalation dose generally increased with decreasing particulate size. Committed effective doses due to inhalation of $\small{0.01{\mu}m}$ sized particulates were higher than doses due to $\small{100{\mu}m}$ sized particulates by factors of about 100 and 50 for $\small{^{238}U}$ and $\small{^{230}Th}$, respectively. Inhalation dose increased with decreasing shape factor. Shape factors of 1 and 2 resulted in dose difference by about 18 %. Inhalation dose increased with particulate mass density. Particulate mass densities of $\small{11g{\cdot}cm^{-3}}$ and $\small{0.7g{\cdot}cm^{-3}}$ resulted in dose difference by about 60 %. For $\small{^{238}U}$, inhalation doses were higher for absorption type of S, M, and F in that sequence. Committed effective dose for absorption type S of $\small{^{238}U}$ was about 9 times higher than dose for absorption F. For $\small{^{230}Th}$, inhalation doses were higher for absorption type of F, M, and S in that sequence. Committed effective dose for absorption type F of $\small{^{230}Th}$ was about 16 times higher than dose for absorption S. Consequently, use of default values for particulate properties without consideration of site specific physiochemical properties may potentially skew radiation dose estimates to unrealistic values up to 1-2 orders of magnitude. For this reason, it is highly recommended to consider site specific working materials and conditions and use the site specific particulate properties to accurately access radiation dose to workers at NORM processing facilities.
Keywords
Naturally occurring radioactive material;Human respiratory tract model;Particulate physicochemical property;Inhalation dose;Sensitivity to particulate properties;
Language
Korean
Cited by
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