• Journal of Radiation Protection and Research
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• 제28권4호
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• pp.299-309
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• 2003

동적 섭식경로모델 DYNACON을 개선하여 원자력시설의 사고시 환경으로 누출된 방사성물질에 의한 가축의 공기 흡입과 토양 섭취에 따른 축산물의 오염 영향을 고찰하였다. 이들 두 오염경로에 대한 수학적 모델은 고려되는 모든 축산물에 대해 수립되었지만 결과에 대한 상세 고찰은 우유에 국한하였다. 젖소의 공기 흡입과 토양 섭취는 방사성물질의 환경 누출이 목초가 성장하지 않는 비방목 기간에 일어나는 경우에 우유의 중요한 오염경로가 될 수 있다는 사실을 알 수 있었다. 비방목 기간동안 방사성물질이 환경으로 누출되는_경우 초기에는 공기 흡입이 토양 섭취에 의한 영향보다 높으나, 시간이 경과할수록 토양 섭취가 우유의 오염에 있어서 지배적 영향을 미쳤다. 이러한 현상은 전반적으로 지상으로 상대적으로 많은 침적을 일어나게 하는 누출기간 중 강우가 있는 경우에 보다 뚜렷하였다. $^{137}Cs$과 $^{90}Sr$의 경우와 달리 $^{131}I$은 누출기간 중 강우에 거의 영향을 받지 않았다. 방목기간에 방사성물질이 환경으로 누출되는 경우 누출기간 중 강우의 유무에 관계없이 공기 흡입에 의한 우유의 오염 영향은 무시 가능한 수준이었다.

• Journal of Nuclear Fuel Cycle and Waste Technology
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• 제1권1호
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• pp.49-55
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• 2013

To characterize quantitatively the transport of $^{99}Tc$ and the global fallout ($^{137}Cs$, $^{90}Sr$, and $^{239+240}Pu$) for soils in Korea, the transport parameters of a convective-dispersion model, apparent migration velocity, and apparent dispersion coefficient were estimated from the vertical depth profiles of the radionuclides in soils. The vertical profiles of $^{99}Tc$ were measured from a pot experiment for paddy soil that had been sampled from a rice-field around the Gyeongju radioactive waste repository in Korea, and the vertical depth distributions of the global fallout $^{137}Cs$, $^{90}Sr$, and $^{239+240}Pu$ were measured from the soil samples that were taken from local areas in Korea. The front edge of the $^{99}Tc$ profiles reached a depth of about 12 cm in 138 days, indicating a faster movement than the fallout radionuclides. A weak adsorption of $^{99}Tc$ on the soil particles by the formation of Tc(VII) and a high water infiltration velocity seemed to have controlled the migration of $^{99}Tc$. The apparent migration velocity and dispersion coefficient of $^{99}Tc$ for the disturbed paddy soil were 2.88 cm/y and 6.3 $cm^2/y$, respectively. The majority of the global fallout $^{137}Cs$, $^{90}Sr$, and $^{239+240}Pu$ were found in the top 20 cm of the soils even after a transport of about 30 years. The transport parameters for the global fallout radionuclides were 0.01-0.1cm/y ($^{137}Cs$), 0.09-0.13cm/y ($^{90}Sr$), and 0.09-0.18cm/y ($^{239+240}Pu$) for the apparent migration velocity: 0.21-1.09 $cm^2/y$ ($^{137}Cs$), 0.12-0.7$cm^2/y$ ($^{90}Sr$), and 0.09-0.36$cm^2/y$ ($^{239+240}Pu$) for the apparent dispersion coefficient.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.10-13
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• 2016

In this study, we developed a new volume reduction technique for cesium contaminated soil by magnetic separation. Cs in soil is mainly adsorbed on clay which is the smallest particle constituent in the soil, especially on paramagnetic 2:1 type clay minerals which strongly adsorb and fix Cs. Thus selective separation of 2:1 type clay with a superconducting magnet could enable to reduce the volume of Cs contaminated soil. The 2:1 type clay particles exist in various particle sizes in the soil, which leads that magnetic force and Cs adsorption quantity depend on their particle size. Accordingly, we examined magnetic separation conditions for efficient separation of 2:1 type clay considering their particle size distribution. First, the separation rate of 2:1 type clay for each particle size was calculated by particle trajectory simulation, because magnetic separation rate largely depends on the objective size. According to the calculation, 73 and 89 % of 2:1 type clay could be separated at 2 and 7 T, respectively. Moreover we calculated dose reduction rate on the basis of the result of particle trajectory simulation. It was indicated that 17 and 51 % of dose reduction would be possible at 2 and 7 T, respectively. The difference of dose reduction rate at 2 T and 7 T was found to be separated a fine particle. It was shown that magnetic separation considering particle size distribution would contribute to the volume reduction of contaminated soil.

• Journal of Radiation Protection and Research
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• 제46권4호
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• pp.194-203
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• 2021

Background: Surface soil radiation monitoring around nuclear facilities is important to classify and characterize the contaminated areas. A scanning and direct measurement technique can survey the sites rapidly before starting sampling analysis. Materials and Methods: Regarding this, we test and suggest a measurement technique for gross alpha/beta and ⁹⁰Sr activities in surface soil based on a mobile ZnS(Ag)/PVT (polyvinyltoluene) array and a handheld PVT rod, respectively. To detect ⁹⁰Sr selectively in soil mixed with naturally occurring radioactive materials, chosen energy channel counts from the multichannel analyzers were used instead of whole channel counts. Soil samples contaminated with exempt liquid ⁹⁰Sr with 1 Bq·g^-1, 3 Bq·g^-1, and 10 Bq·g^-1 were prepared and hardened by flocculation. Results and Discussion: The mobile ZnS(Ag)/PVT array could discriminate gross alpha, gross beta, and gamma radiation by the different pulse-shaped signal features of each sensor material. If the array is deployed on a vehicle, the scan minimum detectable concentration (MDC) range will be about 0.11-0.17 Bq·g^-1 at 18 km·h^-1 speed, highly sensitive to actual sites. The handheld PVT rod with 12 mm (Φ) × 20 mm (H) size can directly measure ⁹⁰Sr selectively if channels on which energies are from 1,470 and 2,279 keV are gated, minimizing crossdetection of other radionuclides. These methods were verified by measuring soil samples fabricated with homogeneous ⁹⁰Sr concentrations, showing static MDC of 2.16 Bq·g^-1 at a measurement time of 300 seconds. Conclusion: Based on the results, comprehensive procedures using these detectors are suggested to optimize soil sites survey.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.271-272
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• 2005

• International journal of advanced smart convergence
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• 제4권1호
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• pp.93-98
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• 2015

Recently, Radon has been gotten attention for problems of Nuclear Generating Station and a variety of nuclear. It is naturally arises that is accumulated in the interior through the soil with radioactive materials. People exposed to indoor a Radon increase the high risks of lung cancer. The data are consisted of regional Country, The Location, Average Radon pCi/L, Geo Mean and Geo S.D etc. The research is experimented using E-M algorithm. The research result appears to make a division of soil distance, regional and cluster. It requires in effort to minimize exposure to people who live in areas with high radon levels. A country must apprise to people about Radon risk and needs to work out measures plan.

• Journal of Radiation Protection and Research
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• 제41권4호
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• pp.418-423
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• 2016

Background: This work was to get information about $^{90}Sr$ contamination of the environment by using soil and moss from selected areas in Jeju Island, Korea. Materials and Methods: The activities of $^{90}Sr$ in soil and moss samples were investigated at nine locations of Jeju island, Korea. The soil samples have been collected at 4 sites of Jeju island during June to August of 2013, analyzed for vertical distribution of $^{90}Sr$ activities. The moss samples have been collected at 5 sites of Jeju island during November of 2011 to June of 2012, and analyzed for radioactive $^{90}Sr$. Results and Discussion: The $^{90}Sr$ vertical concentrations in the investigated soil samples were 2.77 to $18.24Bq{\cdot}kg^{-1}$ in eastern part, 1.69 to $18.27Bq{\cdot}kg^{-1}$ in northern part, 3.76 to $13.46Bq{\cdot}kg^{-1}$ in the western part and 1.09 to $8.70Bq{\cdot}kg^{-1}$ in the southern part of the Mt. Halla in Jeju island, respectively. Activities of $^{90}Sr$ show the highest value at the surface soil and decrease with depth. The activity concentration measured was in the range of 79.6 to $363Bq{\cdot}kg^{-1}$ -dry moss. Conclusion: This material is expected to be basis reference for survey of environmental radioactivity in Jeju Island.

• 방사성폐기물학회지
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• 제15권4호
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• pp.369-380
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• 2017

중 저준위방사성폐기물 표층처분시설 인간침입시나리오의 '평가/해석에 대한 불확실성'의 관리를 위해 GENII를 이용한 평가결과를 오염토양에 대한 방사선영향평가를 위해 개발된 RESRAD를 이용하여 검증하였다. 중저준위방사성폐기물 표층처분시설의 인간침입시나리오로 시추후거주시나리오를 선정하여 각 코드의 현상 모사에서 발생하는 한계점을 파악하고 동일한 입력데이터 조건에서 두 코드의 평가결과를 비교분석함으로써 모델링의 불확실성을 분석하였다. 평가결과 각 코드에서 일부 핵종의 거동모사에 대한 차이는 있었으나 폐쇄후관리기간 이후 선량평가 결과 모든 피폭경로에 대한 경향이 유사함을 확인하였다. 또한 RESRAD에서 확인한 선량평가 결과를 바탕으로 입력인자에 대한 민감도 분석을 수행하고 주요입력인자를 도출하였다. 이를 통해 모델링 결과 및 입력인자에 대한 불확실성을 분석하고 안전성평가 결과에 대한 신뢰성을 확인하였다. 본 연구의 결과는 중저준위방사성폐기물 처분시설의 Safety Case 구축에 활용될 수 있다.

• 분석과학
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• 제15권1호
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• pp.20-25
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• 2002

추출크로마토그래피와 액체섬광계수기를 이용하여 기존의 방사성 스트론튬 분석법 단점을 해결하는 신속하고 신뢰성 있는 $^{89}Sr$ 과 $^{90}Sr$ 분석법을 개발하였다. 옥살산 공침혹은 양이온 교환수지로 방해원소를 제거한 후 Sr-spec 컬럼을 사용하여 스트론튬만을 순수분리한 후, 액체섬광계수기를 사용하여 $^{89}Sr$에서 방출하는 첼렌코프광을 측정하였고 spectrum unfolding 방법으로 $^{90}Sr$을 정량하였다. 본 연구에서 개발된 방사성 스트론튬 분석법을 환경 표준시료 (IAEA-375, Soil) 및 액체 폐기물시료에 적용하여 분석법의 유효성을 검증하였다.

• Journal of Radiation Protection and Research
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• 제45권1호
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• pp.16-25
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• 2020

Background: To investigate radiological effects on biota, it is necessary to assess radiation dose for flora and fauna living in a terrestrial ecosystem. This paper presents a dynamic model to assess radioactivity concentration and radiation dose of terrestrial flora and fauna after a nuclear accident. Materials and Methods: Litter, organic soil, mineral soil, trees, wild crops, herbivores, omnivores, and carnivores are considered the major components of a terrestrial ecosystem. The model considers the physicochemical and biological processes of interception, weathering, decomposition of litter, percolation, root uptake, leaching, radioactive decay, and biological loss of animals. The predictive capability of the model was investigated by comparison of its predictions with field data for biota measured in the Fukushima forest area after the Fukushima nuclear accident. Results and Discussion: The predicted radioactive cesium inventories for trees agreed well with those for evergreens and deciduous trees sampled in the Fukushima area. The predicted temporal radioactivity concentrations for animals were within the range of the measured radioactivity concentrations of deer, wild boars, and black bears. The radiation dose for the animals were, for the whole simulation time, estimated to be much smaller than the lower limit (0.1 mGy·d^-1) of the derived consideration reference level given by the International Commission on Radiological Protection for terrestrial flora and fauna. This suggested that the radiation effect of the accident on the biota in the Fukushima forest would be insignificant. Conclusion: The present dynamic model can be used effectively to investigate the radiological risk to terrestrial ecosystems following a nuclear accident.