• Korean Journal of Radiology
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• 제2권2호
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• pp.87-96
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• 2001

The radiologic and clinical findings of foreign bodies in the chest of children are well recognized. Foreign bodies in adults are infrequent, however, and the radiologic findings of these unusual circumstances have rarely been described. We classified various thoracic foreign bodies into three types according to their cause: Type I, Aspiration, Type II, Trauma or Accident; Type III, Iatrogenic. This pictorial essay will illustrate the radiologic findings and consequences of thoracic foreign bodies in adults, which have rarely been described in the radiologic literature. The clinical significance of thoracic foreign bodies will be also be discussed.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.92-99
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• 2024

To minimize the cumulative radiation dose, various path-finding approaches for single agent have been proposed. However, for emergence situations such as nuclear power plant accident, these methods cannot be effectively utilized for evacuating a large number of workers because no multi-agent method is valid to conduct the mission. In this study, a novel algorithm for solving the multi-agent path-finding problem is proposed using the conflict-based search approach and the objective function redefined in terms of the cumulative radiation dose. The proposed method can find multi paths that all agents arrive at the destinations with reducing the overall radiation dose. To verify the proposed method, three problems were defined. In the single-agent problem, the objective function proposed in this study reduces the cumulative dose by 82% compared with that of the shortest distance algorithm in experiment environment of this study. It was also verified in the two multi-agent problems that multi paths with minimized the overall radiation dose, in which all agents can reach the destination without collision, can be found. The method proposed in this study will contribute to establishing evacuation plans for improving the safety of workers in radiation-related facilities.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.51-54
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• 2002

When a cold HPSI (High Pressure Safety Injection) fluid associated with an design basis accident, such as LOCA (Loss of Coolant Accident), enters the cold legs of a stagnated primary coolant loop, thermal stratification phenomena will arise due to incomplete mixing. If the stratified flow enters a reactor pressure vessel downcomer, severe thermal stresses are created in a radiation embrittled vessel wall by local overcooling. Previous thermal-mixing analyses have assumed that the thermal stratification phenomena generated in stagnated loop of a partially stagnated coolant loop are neutralized in the vessel downcomer by strong flow from unstagnated loop. On the basis of these reasons, this paper presents the thermal-mixing analysis results in order to identify the fact that the cold plume generated in the vessel downcomer due to the thermal stratification phenomena of the stagnated loop is affected by the strong flow of the unstagnated loop.

• Safety and Health at Work
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• 제8권1호
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• pp.42-48
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• 2017

Background: As one of the most frequently occurring accidents in a chemical plant, a fire accident may occur at any place where transfer or handling of combustible materials is routinely performed. Methods: In particular, a jet fire incident in a chemical plant operated under high pressure may bring severe damage. To review this event numerically, Computational Fluid Dynamics methodology was used to simulate a jet fire at a pipe of a compressor under high pressure. Results: For jet fire simulation, the Kemeleon FireEx Code was used, and results of this simulation showed that a structure and installations located within the shelter of a compressor received serious damage. Conclusion: The results confirmed that a jet fire may create a domino effect that could cause an accident aside from the secondary chemical accident.

• 한국가스학회지
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• 제19권2호
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• pp.1-4
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• 2015

본 연구는 벌크로리 이 충전중 가스누출로 인해 화재가 발생하여 주변의 식당 등 2차적인 피해를 준 가스사고에 대해 위험성평가를 DNV사의 PHAST-RISK v6.7 program을 활용하여 제트화재시 영향면적, 복사열 농도 및 피해영향거리 등 가스 누출 확산 피해범위에 대해 도출하여 충전중 가스사고를 사전에 예방하고자 한다.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2652-2660
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• 2021

The gamma-ray exposure doses in decontamination operation after a nuclear accident were evaluated with a consideration of various geometrical conditions and specific gamma-ray energies. The calculation domain is organized with three residence types and each form is divided into two kinds of geometrical arrangements. The position-wise air KERMA values were calculated with an assumption of evenly distributed gamma-ray source based on Monte Carlo radiation transport analysis using the MCNP code. The radioactivity is initially set to be unity to be multiplied by the deposition value measured in the actual accident condition. The workforce data set depending on the target object was determined by modifying the Fukushima report. The external exposure doses for decontamination workers were derived from the calculated KERMA values and the workforce analysis. These results can be used to efficiently determine the workforce required by the characteristics of the area and the structure to be decontaminated within the dose limits.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2244-2252
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• 2022

Based on GIS technologies, a decision support system (GIDSS) has been developed to remediate agricultural lands in the Bryansk region (Russia) contaminated by ¹³⁷Cs after the accident at the Chernobyl nuclear power plant. GIDSS is a multilevel system consisting of basic, information and computational layers. GIDSS allows justifying a targeted approach for the remediation of agricultural lands belonging to agricultural enterprises for the production that meets the established radiological requirements for the content of radionuclides. Evaluation of the effectiveness of alternative remediation technologies and the selection of optimal measures were carried out at the level of elementary plots using radiological criteria. The introduction of GIDSS will enable agricultural producers in the south-western districts of the Bryansk region to conduct radiation-safe agro-industrial production in radioactively contaminated areas, which will help improve the socio-economic situation of the region and return it to normal living conditions.

• Journal of Radiation Protection and Research
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• 제22권4호
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• pp.251-261
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• 1997

방사성 동위원소 등의 고준위 방사성물질을 운반하기 위한 운반용기는 국내외의 관련법규에 따라 정상수송은 물론 가상사고조건에서도 방사성물질의 누설이 발생되지 않도록 방사선차폐, 열 및 구조적 건전성이 유지되어야 한다. 운반용기의 건전성 평가는 시험모델을 이용한 시험적 방법과 전산해석 코드를 이용한 해석적 방법에 의하여 이루어지고 있다. 본 논문에서는 원자력연구소의 하나로에서 생산되는 동위원소를 동위원소 생산시설까지 이송하기 위한 HTS (Hydraulic Transfer System) 방사성 동위원소 운반용기의 안전성을 평가하였다. 방사선차폐해석, 열해석 및 구조해석을 수행한 결과 동위원소 운반용기는 정상수송조건 뿐만 아니라 가상사고조건에서도 건전성이 유지되는 것으로 나타났다.

• Journal of Radiation Protection and Research
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• 제47권1호
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• pp.30-38
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• 2022

Background: Residential areas have some factors on the external exposure of residents, who usually spend a long time in these areas. Although various survey has been carried out by the government or the research institutions after the Fukushima Daiichi Nuclear Power Plant accident, the mechanism of radiocesium inventory in the terrestrial zone has not been cleared. To better evaluate the radiation environment, this study investigated the temporal changes in air dose rate and ¹³⁷Cs inventories (Bq/m²) in residential areas and agricultural fields. Materials and Methods: Air dose rate and ¹³⁷Cs inventories were investigated in residential areas located in an evacuation zone at 5-8 km from the Fukushima Daiichi Nuclear Power Plant. From December 2014 to September 2018, the air dose rate distribution was investigated through a walking survey (backpack survey), which was conducted by operators carrying a γ-ray detector on their backs. Additionally, from December 2014 to January 2021, the ¹³⁷Cs inventories on paved and permeable grounds were also measured using a portable γ-ray detector. Results and Discussion: In the areas where decontamination was not performed, the air dose rate decreased faster in residential areas than in agricultural fields. Moreover, the ¹³⁷Cs inventory on paved surfaces decreased with time owing to the horizontal wash-off, while the ¹³⁷Cs inventory on permeable surfaces decreased dramatically owing to the decontamination activities. Conclusion: These findings suggest that the horizontal wash-off of ¹³⁷Cs on paved surfaces facilitated the air dose rate decrease in residential areas to a greater extent compared with agricultural fields, in which the air dose rate decreased because of the vertical migration of ¹³⁷Cs. Results of this study can explain the faster environmental restoration in a residential environment reported by previous studies.

• 한국정보통신학회논문지
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• 제18권7호
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• pp.1671-1680
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• 2014

원자력 발전소에서 예기치 못한 사고가 발생하거나 발전소를 해체하는 작업을 수행하는 과정에서는 방사선 물질의 유출에 대한 우려가 항상 존재한다. 유출된 방사선 물질을 제거하기위해서는 방사선의 분포에 대한 정확한 정보를 획득할 수 있는 기술이 필요하다. 그러나 방사선 물질의 직접적 취급은 매우 제한적이기 때문에 방사선과 관련된 기술의 개발은 미리 시뮬레이션을 통하여 그 가능성을 검토하여야 한다. 본 논문에서는 방사선 물질의 분포에 대한 3차원 정보를 획득할 수 있는 방사선 영상화 기술을 시뮬레이션하였다. 두 개의 가상의 1차원 방사선 센서를 이용하여 스테레오 방사선 영상을 획득하고, 스테레오 시차를 이용하여 가상의 방사선 물질에 대한 3차원 거리 정보를 획득하였다. 점과 면으로 구성된 가상의 방사선 물질에 대하여 스테레오 방사선 영상 및 3차원 정보의 획득이 가능함을 시뮬레이션하였다.