• Title, Summary, Keyword: 내부피폭

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Internal Dose Assessment of Worker by Radioactive Aerosol Generated During Mechanical Cutting of Radioactive Concrete (원전 방사성 콘크리트 기계적 절단의 방사성 에어로졸에 대한 작업자 내부피폭선량 평가)

  • Park, Jihye;Yang, Wonseok;Chae, Nakkyu;Lee, Minho;Choi, Sungyeol
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.18 no.2
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    • pp.157-167
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    • 2020
  • Removing radioactive concrete is crucial in the decommissioning of nuclear power plants. However, this process generates radioactive aerosols, exposing workers to radiation. Although large amounts of radioactive concrete are generated during decommissioning, studies on the internal exposure of workers to radioactive aerosols generated from the cutting of radioactive concrete are very limited. In this study, therefore, we calculate the internal radiation doses of workers exposed to radioactive aerosols during activities such as drilling and cutting of radioactive concrete, using previous research data. The electrical-mobility-equivalent diameter measured in a previous study was converted to aerodynamic diameter using the Newton-Raphson method. Furthermore, the specific activity of each nuclide in radioactive concrete 10 years after nuclear power plants are shut down was calculated using the ORIGEN code. Eventually, we calculated the committed effective dose for each nuclide using the IMBA software. The maximum effective dose of 152Eu constituted 83.09% of the total dose; moreover, the five highest-ranked elements (152Eu, 154Eu, 60Co, 239Pu, 55Fe) constituted 99.63%. Therefore, we postulate that these major elements could be measured first for rapid radiation exposure management of workers involved in decommissioning of nuclear power plants, even if all radioactive elements in concrete are not considered.

Influence of the Monitoring Interval and Intake Pattern for the Evaluation of Intake (내부피폭 감시주기 및 섭취형태가 방사성핵종 섭취량 평가에 미치는 영향)

  • Jong-Il Lee;Tae-Young Lee;Si-Young Chang;Jai-Ki Lee
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.2 no.1
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    • pp.53-59
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    • 2004
  • A variety of factors such as the pattern of intake (acute or chronic), monitoring interval and the characteristics of the radionuclides could have a significant influence on the estimates for the intake and internal dose. The relative differences of the assessed intakes based on the assumption of an acute intake to that of a chronic intake were evaluated by using the predicted bioassay quantity in the whole body or organs for an acute and chronic intake through the inhalation of $^{125}$ I, $^{137}$ C, $^{235}$ U with the AMAD of 1 ${\mu}{\textrm}{m}$ and 5 ${\mu}{\textrm}{m}$ for the monitoring intervals of 7, 14, 30, 60, 90, 120, 180, 360 days, respectively, The relative difference of the assessed intakes based on the intake pattern is affected by the monitoring interval, radionuclide and absorption type, but the particle size has little influence on the difference of the assessed intakes based on the intake pattern. The maximum monitoring interval, which is defined as the monitoring interval that the relative difference of the assessed intakes based on the assumption of an acute intake to that of a chronic intake is less than 10%, is 60 d for $^{125}$ I with Type F, 180 d for $^{137}$ C with Type F, 90 d for $^{235}$ U with Type M, and 360 d for $^{235}$ U with Type S. It was concluded that an intake pattern has little influence on the estimates of the assessed intake in the case where the monitoring interval is shorter than the maximum monitoring interval for each radionuclide.

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A Study on the Verification and Improvement to Locate and Determine the Radioactive Contamination Using a Whole Body Counter (전신계측기를 이용한 원전종사자 방사성오염 위치확인과 내부방사능 측정개선에 관한 연구)

  • Kim, Hee-Geun;Kong, Tae-Young
    • Journal of Radiation Protection and Research
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    • v.34 no.1
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    • pp.37-42
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    • 2009
  • Whole body counters (WBCs) are used to monitor radiation workers for internal contamination of radionuclides at domestic nuclear power plants (NPPs). A WBC is a scintillation detector using sodium iodide (NaI) and provides the identification of inhaled radionuclide and the measurement of its internal radioactivity in a short time. However, it is often possible to estimate external contamination as internal contamination due to radionuclides attached to the skin of radiation workers and this leads to an excessively conservative estimation of radioactive contamination. In this study, several experiments using a WBC and the Korean humanoid phantom were performed to suggest the more systematic method of discrimination between external and internal contamination. Furthermore, a WBC geometry experiment was conducted to suggest the optimal WBC geometry in consideration of deposited areas inside the body for dominant radionuclides at NPPs. The procedure of measurement and estimation of internal radioactivity for radiation workers at NPPs was improved on the basis of experimental results. Thus, it is expected to prevent from estimating internal exposure dose conservatively owing to the application of accurate whole body counting program to NPPs.

Practical Radiation Safety Control: (I) Application of Annual Limit on Intake and Derived Air Concentration (방사선안전관리 실무: (I) 연간섭취한도와 유도공기중농도의 적용)

  • Kim, Hyun Kee
    • Journal of Radiation Protection and Research
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    • v.38 no.4
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    • pp.234-236
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    • 2013
  • Some of radioactive contamination is unavoidable in the facilities using the unsealed radioactive material. The primary purpose of radioactive contamination control in the workplace with contamination concern is the effects from the potential intake of radioactive material into the body. This paper provides procedures to estimate the level of internal exposure for the worker based on the conservative assumptions and simple calculations. They consist of two processes; to calculate air concentration of radioactive material and annual intake by inhalation with contaminated air and to compare each of them to Derived Air Concentration and Annual Limit on Intake mentioned in the related notification. The procedures are applicable to make a decision on practical requirements for monitoring air contamination and internal exposure of worker as follows; needs for measurement of air contamination and internal exposure and acquisition of information on the design of the ventilation system.

Analysis of Air Activation in PET Cyclotron Facility (PET 사이클로트론 시설의 공기 방사화 분석)

  • Jang, Dong-Gun;Kang, Sesik;Kim, Changsoo;Kim, Junghoon
    • Journal of the Korean Society of Radiology
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    • v.10 no.7
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    • pp.489-494
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    • 2016
  • Nuclear reaction which occurs in the cyclotron generate unnecessary neutrons. The results of this happening can radioactivate surrounding materials and radioactive materials cause radiation exposure. When people take radioactive air, it makes internal exposure. The purpose of this study was to analyze the radioactive air inside of the ultra-compact 16.5 MeV cyclotron in operation. As a result of study, the radio activation occurred by compact cyclotron generates a very low internal exposure to workers. Comparing the radioactivity from radioactive nuclide with legal standard, that was under reference value. However, it could be at risk for internal exposure in case of higher energy cyclotron. Therefore, legal standard is needed for ventilation equipment of radiation facilities.

Assessment of Inhalation Dose Sensitivity by Physicochemical Properties of Airborne Particulates Containing Naturally Occurring Radioactive Materials (천연방사성물질을 함유한 공기 중 부유입자 흡입 시 입자의 물리화학적 특성에 따른 호흡방사선량 민감도 평가)

  • Kim, Si Young;Choi, Cheol Kyu;Park, Il;Kim, Yong Geon;Choi, Won Chul;Kim, Kwang Pyo
    • Journal of Radiation Protection and Research
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    • v.40 no.4
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    • pp.216-222
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    • 2015
  • 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 $0.01{\mu}m$ sized particulates were higher than doses due to $100{\mu}m$ sized particulates by factors of about 100 and 50 for $^{238}U$ and $^{230}Th$, 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 $11g{\cdot}cm^{-3}$ and $0.7g{\cdot}cm^{-3}$ resulted in dose difference by about 60 %. For $^{238}U$, inhalation doses were higher for absorption type of S, M, and F in that sequence. Committed effective dose for absorption type S of $^{238}U$ was about 9 times higher than dose for absorption F. For $^{230}Th$, inhalation doses were higher for absorption type of F, M, and S in that sequence. Committed effective dose for absorption type F of $^{230}Th$ 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.