• Title/Summary/Keyword: Radioactive plume

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Applying a big data analysis to evaluate the suitability of shelter locations for the evacuation of residents in case of radiological emergencies

  • Jin Sik Choi;Jae Wook Kim;Han Young Joo;Joo Hyun Moon
    • Nuclear Engineering and Technology
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    • v.55 no.1
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    • pp.261-269
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    • 2023
  • During a nuclear power plant (NPP) accident, radioactive material may be released into the surrounding environment in the form of a radioactive plume. The behavior of the radioactive plume is influenced by meteorological factors such as wind direction and speed. If the residents are evacuated to a shelter in the direction of the flow of the radioactive plume, the radiation exposure of the residents may increase, contrary to the purpose of the evacuation. To avoid such an undesirable outcome, this paper applies a big data analysis to evaluate the suitability of the shelter locations near 5 NPPs in the Republic of Korea in terms of the seasonal wind direction frequency in those areas. To this end, the wind data measured around the NPPs from 2016 to 2020 were analyzed to derive the seasonal wind direction frequency using a big data analysis. These analyses results were then used to determine how many shelters around NPPs locate in areas with prevailing wind direction per season. Then, suggestions were made on the direction for residents not to evacuate, if possible, that is, the prevailing seasonal wind directions for 5 NPPs, depending on the season in which the accident occurs.

Analysis of Radiation Exposure from Nuclear Reactor Accident in Complex Terrain (산악지형에서의 원자력발전소 사고시의 피폭해석)

  • Moon Hee Han;Sung Ki Chae;Moon Hyun Chun
    • Nuclear Engineering and Technology
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    • v.17 no.3
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    • pp.216-223
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    • 1985
  • The Gaussian plume model is widely used to calculate the concentrations of gaseous radioactive effluents in the atmosphere. This model assumes that the terrain is flat, so that the dispersion coefficients which are the most important parameters in this model must be compensated in complex terrain such as in Korea. In this study the compensation of vertical dispersion coefficient in two dimensional x-z plane has been accomplished by comparing the Gaussian plume model with numerical model. The results show that the concentractions of radioactive effluents over complex terrain are more dilluted than those expected over flat terrain.

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An Approximation Method for the Estimation of Exposed dose due to Gamma - rays from Radioactive Materials dispersed to the Atmoshere (대기로 확산된 방사성물질로부터 방출되는 감마선에 의한 피폭선량을 계산하기 위한 근사화 방법)

  • Kim, T.W.;Park, C.M.;Ro, S.G.
    • Journal of Radiation Protection and Research
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    • v.15 no.2
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    • pp.51-56
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    • 1990
  • The dispersing model of radioactive plume in the atmosphere was assumed to form finite ellipseshaped volumes rather than a single plume and gamma absorbed doses from the plume were computed using the proposed model. The results obtained were compared with those computed by the Gaussian plume and the circular approximation models. The results computed by the proposed ellipse-shaped approximation model were close to those by the Gaussian plume model. and more accurate than those by the circular approximation model. The computing time for the proposed approximation model was one fortieth of that for the Gaussian plume model.

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A Study on the Diffusion of Gaseous Radioactive Effluents Based on the Statistical Method (통계적 방법을 이용한 방사성 물질의 대기 확산 평가)

  • Na, Man-Gyun;Lee, Goung-Jin
    • Journal of Radiation Protection and Research
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    • v.23 no.4
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    • pp.251-257
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    • 1998
  • A diffusion model of radioactive gaseous effluents is improved to apply for domestic nuclear power plants. Up to now, XOQDOQ computer code package developed by U. S NRC has been used for the assessment of radioactive plume dispersion by normal operation of domestic nuclear power plants. XOQDOQ adopts the straight-line Gaussian plume model which was basically derived for the plane terrain. However, since there are so many mountains in Korea, the several shortcomings of XOQDOQ are improved to consider the complex terrain effects. In this work, wind direction change is considered by modifying the wind rose frequency using meteorological data of the local weather stations. In addition, an effective height correction model, a plume reduction model due to plume penetration into mountain, and a wet deposition model are adopted for more realistic assessments. The proposed methodology is implemented in Yongkwang nuclear power plants, and can be used for other domestic nuclear power plants.

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A Study on the Oceanic Diffusion of Liquid Radioactive Effluents based on the Statistical Method (통계적 방법을 이용한 방사성 물질의 해양 확산 평가)

  • Kim, Soong-Pyung;Lee, Goung-Jin
    • Journal of Radiation Protection and Research
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    • v.23 no.1
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    • pp.1-6
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    • 1998
  • A diffusion model of radioactive liquid effluents is developed and applied for YGN NPP's site, based on the Gaussian plume type model. Due to the complexity of oceanic diffusion characteristics of YGN site, a simple and reliable statistical model based on Reg. Guide 1.113 is developed. Also, a computer code package to calculate dilution factors as a function of plant operation conditions and pathway of radioactive materials. A liquid effluents diffusion model is developed by dividing the diffusion range into two categories, i. e, a near field mixing region and a far field mixing region. In the near field, the initial mixing is affected by a buoyance force, a high initial turbulence and momentum which is characterized by a plant operation condition and environmental conditions. The far field mixing is similar to gaseous effluents diffusion. So, beyond the near field region, wellknown Gaussian plume model was adopted. A different area averages of Gaussian plume equation was taken for each radioactive exposure pathway. As a result, we can get different dilution factors for different pathways. Results shows that present dilution factors used for YGN ODCM is too much overestimated compared with dilution factors calculated with the developed model.

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Data Assimilation Techniques Applied to Estimate the Dispersion of the Pollutant in the Atmosphere (자료동화기술을 이용한 대기중 오염물질 확산평가)

  • 한문희;정효준;김은한;서경석;황원태;이선미
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.06a
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    • pp.368-376
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    • 2004
  • The estimation of the diffusion coefficients of the Gaussian plume model and the release rate by assimilation of tracer-gas measurements on Younggwang site was tested. Diffusion coefficients were modified by linear programming of both the measurements and the simulated using the Gaussian plume model. The application of the modified diffusion coefficients improved the prediction ability of the Gaussian plume model on both 3 km and 8 km arc lines. And, the release rate of tracer gas was estimated using least squares method. The optimal source rate was estimated by minimizing the errors between the measured concentrations and the computed ones by the Gaussian plume model. The obtained release rate showed a good agreement with the real release rate of the Younggwang experiment in 24%.

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Analysis of wind field data surrounding nuclear power plants to improve the effectiveness of public protective measures

  • Jin Sik Choi;Jae Wook Kim;Han Young Joo;Jeong Yeon Lee;Chae Hyun Lee;Joo Hyun Moon
    • Nuclear Engineering and Technology
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    • v.55 no.10
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    • pp.3599-3616
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    • 2023
  • After a nuclear power plant (NPP) accident, it would be helpful to predict the movement of the radioactive plume emitted from the NPP as accurately as possible to protect the nearby population. Radioactive plumes are mainly affected by wind direction and speed. Since it is difficult to identify the wind direction and speed immediately after the accident, a good understanding of the historical wind data could save many lives and ensure smoother evacuation procedures. In this study, wind data for the past 10 years are analyzed for the five NPPs in the Republic of Korea (ROK). The analyzed data include wind direction and wind speed from 2012 to 2021. In particular, the characteristics of the wind field blowing from the NPPs to the nearest densely populated regions are examined. Finally, suggestions to improve evacuation plans are made.

Uncertainty Evaluation of the Estimated Release Rate for the Atmospheric Pollutant Using Monte Carlo Method (Monte Carlo 방법을 이용한 대기오염 배출률 예측의 불확실성 평가)

  • Jeong, Hyo-Joon;Kim, Eun-Han;Suh, Kyung-Suk;Hwang, Won-Tae;Han, Moon-Hee
    • Journal of Environmental Science International
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    • v.15 no.4
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    • pp.319-324
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    • 2006
  • Release rate is one of the important items for the environmental impact assessment caused by radioactive materials in case of an accidental release from the nuclear facilities. In this study, the uncertainty of the estimated release rate is evaluated using Monte Carlo method. Gaussian plume model and linear programming are used for estimating the release rate of a source material. Tracer experiment is performed at the Yeoung-Kwang nuclear site to understand the dispersion characteristics. The optimized release rate was 1.56 times rather than the released source as a result of the linear programming to minimize the sum of square errors between the observed concentrations of the experiment and the calculated ones using Gaussian plume model. In the mean time, 95% confidence interval of the estimated release rate was from 1.41 to 2.53 times compared with the released rate as a result of the Monte Carlo simulation considering input variations of the Gaussian plume model. We confirm that this kind of the uncertainty evaluation for the source rate can support decision making appropriately in case of the radiological emergencies.

Population Dose Assessment for Radiation Emergency in Complex Terrain (복잡 지형에서의 주민선량 계산)

  • Yoon, Yea-Chang;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
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    • v.12 no.2
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    • pp.28-36
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    • 1987
  • Gaussian plume model is used to assess environmental dose for abnormal radioactive release in nuclear facility, but there has a problem to use it for complex terrain. In this report, MATTEW and WIND04 Codes which had been verified were used to calculate wind field in the complex terrain. Under the base of these codes principle, wind fields were obtained from the calculation of the finite difference approximation for advection-diffusion equations which satisfy the mass-conservative law. Particle concentrations and external doses were calculated by using PIC model which approximate the particle to radioactive cloud, and atmospheric diffusion of the particles from the random walk method. The results show that the adjusted wind fields and the distributions of the exposure dose vary with the topography of the complex terrain.

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A Study on Transport and Dispersion of Chemical Agent According to Lagrangian Puff and Particle Models in NBC_RAMS (화생방 보고관리 및 모델링 S/W 시스템(NBC_RAMS)의 라그랑지안 퍼프 및 입자 모델에 따른 화학작용제 이송·확산 분석)

  • Hyeyun Ku;Jiyun Seo;Hyunwoo Nam
    • Journal of the Korea Institute of Military Science and Technology
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    • v.26 no.1
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    • pp.102-112
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    • 2023
  • This research mainly focuses on the transport and dispersion of chemical agent plume according to the Lagrangian Puff Model and Lagrangian Particle Model of NBC_RAMS(Nuclear, Biological, Chemical Reporting And Modeling S/W System). NBC_RAMS was developed with the purposes of estimating the fate of Chemical, Biological, and Radioactive(CBR) agent plumes and evaluating damages in the Republic of Korea. First, it calculates the local weather pattern, i.e. wind speed, wind direction, and temperature, by considering the effects of land uses and topography. The plume behaviors are calculated by adopting the Lagrangian Puff Model(LPFM) or Lagrangian Particle Model(LPTM). In this research, we assumed a virtual chemical agent exposure event in a stable atmospheric condition during the summer season. The plume behaviors were estimated by both LPFM and LPTM on the used area(urbanized and dry area) and the agricultural land. The higher heat flux in the used area led to stronger winds and further downward movement moving of the chemical agent than the farmland. The lateral dispersion of the chemical plume was emphasized in the Lagrangian Puff Model because it adopted Gaussian distribution.