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Determinations of the Exposure Rate Using a NaI(Tl) Detector of the Environmental Radiation Monitor
Young-Yong Ji,Wanno Lee,Sang-Do Choi,Kun Ho Chung,Mun Ja Kang,Geun-Sik Choi 한국방사성폐기물학회 2013 방사성폐기물학회지 Vol.11 No.3
NaI(Tl) 섬광검출기로 측정한 에너지 스펙트럼으로부터 공간 감마 선량률을 계산하기 위하여 에너지밴드 방법과 G-factor 방법의 결과를 비교 검토하였다. 먼저 한국원자력연구원 내 운영 중인 환경방사선감시기 EFRD 3300에 장착된 3“ΦX3” NaI(Tl) 검출기의 G-factor를 MCNP 모델링을 통하여 입사 방사선의 방향에 따라 각각 구하였으며, 이로부터 계산된 선량률과 에너지밴드 방법으로 계산된 결과의 차이를 비교 검토함으로써 EFRD 3300에 적용 가능한 최적의 G-factor 값을 유도하였다. 그리고 EFRD 3300 방사선감시기가 운영되고 있는 지역 주변에 위치한 HPIC 방사선감시기의 선량률과 비교 검토를 수행하였으며, 3“ΦX3” NaI(Tl) 검출기 기반의 EFRD 3300에서 7.7 μR/h의 측정값을 얻어 약 3 μR/h 정도의 차이를 보였다. 일반적으로 HPIC 방사선감시기는 고에너지 우주방사선량도 측정할 수 있는 것으로 알려져 있으므로, 이 차이는 3“ΦX3” NaI 계측기로 측정되지 못하는 고에너지 영역의 우주방사선에 의한 영향으로 평가할 수 있었다.
Kim, Hyuncheol,Jung, Yoonhee,Lee, Wanno,Choi, Guen-Sik,Chung, Kun Ho,Kang, Mun Ja The Korean Association for Radiation Protection 2016 방사선방어학회지 Vol.41 No.4
Background: Liquid scintillation counters (LSCs) are commonly used as an analytical method for detecting $^{222}Rn$ in groundwater because they involve a simple sample pretreatment and allow high throughout with an autosampler. The Quantulus 1220 is the best-selling LSC in Korea, but its production was stopped. Recently, a new type of LSC, the 300SL, was introduced. In this study, the 300SL was compared with the Quantulus 1220 in order to evaluate the ability of each apparatus to detect $^{222}Rn$ in groundwater. Materials and Methods: The Quantulus 1220 and 300SL were used to detect the presence of $^{222}Rn$. Radon gas was extracted from a groundwater sample using a water-immiscible cocktail in a LSC vial. The optimal analytical conditions for each LSC were determined using a $^{222}Rn$ calibration source prepared with a $^{226}Ra$ source. Results and Discussion: The optimal pulse shape analysis level for alpha and beta separation was 80 for the Quantulus 1220, and the corresponding pulse length index was 12 in the 300SL. The counting efficiency of the Quantulus 1220 for alpha emissions was similar to that of the 300SL, but the background count rate of the Quantulus 1220 was 10 times lower than that of the 300SL. The minimum detectable activity of the Quantulus 1220 was $0.08Bq{\cdot}L^{-1}$, while that of the 300SL was $0.20Bq{\cdot}L^{-1}$. The analytical results regarding $^{222}Rn$ in groundwater were less than 10% different between these LSCs. Conclusion: The 300SL is an LSC that is comparable to the Quantulus 1220 for detecting $^{222}Rn$ in groundwater. Both LSCs can be applied to determine the levels of $^{222}Rn$ in groundwater under the management of the Ministry of Environment.
Photocatalytic enhancement of cesium removal by Prussian blue-deposited TiO<sub>2</sub>
Kim, Hyuncheol,Kim, Minsun,Kim, Wooyul,Lee, Wanno,Kim, Soonhyun Elsevier 2018 Journal of hazardous materials Vol.357 No.-
<P><B>Abstract</B></P> <P>After the Fukushima nuclear accident, tremendous efforts were made to treat radiocesium, radiostrontium, and other radioactive materials. For the first time, we demonstrate that a TiO<SUB>2</SUB> photocatalyst can significantly enhance Cs adsorption by Prussian blue-deposited TiO<SUB>2</SUB> (PB/TiO<SUB>2</SUB>) under UV irradiation. In this study, we synthesized PB/TiO<SUB>2</SUB> using the photodeposition method. After the Cs ions were adsorbed on the PB/TiO<SUB>2</SUB> in darkness, we then exposed the PB/TiO<SUB>2</SUB> to UV light irradiation. This resulted in a further increase in Cs ion adsorption of more than 10 times the amount adsorbed in darkness. This photocatalytic-enhanced adsorption of Cs ions was not observed on PB mixed with SiO<SUB>2</SUB>, nor under visible light irradiation. We investigated the effects of PB concentration, PB/TiO<SUB>2</SUB> concentration, and gas purging on both dark and photocatalytic-enhanced adsorption of Cs ions by PB/TiO<SUB>2</SUB>. Based on the results, we suggest that the photocatalytic-enhanced adsorption of Cs ions on PB/TiO<SUB>2</SUB> is due to photocatalytic reduction of PB, which leads to additional adsorption of Cs ions. The change in solution color before and after the reaction, and the change in solution pH in the dark and during UV irradiation strongly support this suggestion. The photocatalytic-enhanced adsorption of Cs ions was equivalent during radioactive <SUP>137</SUP>Cs removal, indicating important applications for pollutant removal from contaminated water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Prussian blue (PB)-deposited TiO<SUB>2</SUB> was synthesized using the photodeposition method. </LI> <LI> TiO<SUB>2</SUB> photocatalysts greatly enhance Cs adsorption by PB/TiO<SUB>2</SUB> under UV irradiation. </LI> <LI> Photocatalytic-enhanced Cs adsorption is due to photocatalytic reduction of PB. </LI> <LI> Photocatalysts can be used for radioactive <SUP>137</SUP>Cs removal from contaminated water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
김창종(Chang-Jong Kim),임충섭(Chung-seop Lim),이완로(Wanno Lee),장미(Mee Jang),지영용(Young-Yong Ji),정근호(Kun-Ho Chung),강문자(Mun-Ja Kang) 한국식품과학회 2015 한국식품과학회지 Vol.47 No.6
본 연구는 국내에서 유통되는 수산물에 대한 방사능 농도 조사 결과를 바탕으로 평상시 수산물의 방사능 농도에 대한 기초자료 생산을 목표로 수행되었으며, 그 과정에서 사고 상황에 맞는 신속한 분석 방법과 최소검출가능농도 설정에 대해 고찰하였다. 국민건강통계의 섭취빈도를 참고로 하여 수산물 시료의 종류를 결정하였고, 전처리 과정을 간소화하여 <SUP>40</SUP>K, <SUP>137</SUP>Cs, <SUP>134</SUP>Cs, <SUP>131</SUP>I의 방사능 농도를 분석하였다. 그 결과 40K는 21.9-3050 Bq/kg의 방사능 농도 범위를 나타내었으며, 인공방사성 핵종인 <SUP>137</SUP>Cs, <SUP>134</SUP>Cs, <SUP>131</SUP>I의 방사능 농도는 최소검출가능농도 이하였다. 따라서, 2013년부터 2015년까지 조사한 국내 유통 수산물에 대해서는 후쿠시마 사고의 영향이 없는 것으로 판단할 수 있으며, 선량적인 측면에서 역시 분석한 핵종에 의한 추가적인 방사선 피폭 영향이 없다고 볼 수 있다. 최소검출가능농도의 경우 <SUP>137</SUP>Cs 0.140-1.97, <SUP>134</SUP>Cs 0.0900-1.89, <SUP>131</SUP><SUP></SUP>I 0.124-1.94 Bq/kg의 범위를 나타내었으며, 시료량 및 <SUP>40</SUP>K의 농도에 최소검출가능농도 변동을 확인할 수 있었다. 측정시간, <SUP>40</SUP>K의 농도, 검출기 종류 등의 인자에 따른 최소검출가능농도 설정에 관한 논의가 추후 필요할 것으로 판단된다. Samples of fishery products were tested for radioactivity by using the intake frequency data from Korea Health Statistics. The radioactivity of <SUP>40</SUP>K, <SUP>137</SUP>Cs, <SUP>134</SUP>Cs, and <SUP>131</SUP>I was analyzed using gamma spectrometry with a simplified sample pre-treatment procedure. The radioactivity range for <SUP>40</SUP>K was 21.9-3050 Bq/kg, whereas the radioactivities of <SUP>137</SUP>Cs, <SUP>134</SUP>Cs, and 131I were under minimum detectable activity which were in the range of 0.140-1.97, 0.0900-1.89 and 0.124-1.94 Bq/kg, respectively, for the three species. The results suggest that the Fukushima accident did not have a significant impact on domestic fishery products, which were analyzed during the period from 2013 to 2015. Additionally, there seemed to be no significant impact of additional exposure dose by the analyzed radionuclides.
환경방사선감시기의 NaI(Tl) 검출기를 이용한 조사선량률 결정방법
지영용,이완로,최상도,정근호,강문자,최근식,Ji, Young-Yong,Lee, Wanno,Choi, Sang-Do,Chung, Kun Ho,Kang, Mun Ja,Choi, Geun-Sik 한국방사성폐기물학회 2013 방사성폐기물학회지 Vol.11 No.3
The energy band and the G-factor method were compared to determine the exposure rate from the measured spectrum using a NaI(Tl) scintillation detector. First, G-factors of a 3"${\Phi}X3$" NaI(Tl) detector mounted to a EFRD 3300, which means the environmental radiation monitor, in Korea Atomic Energy Research Institute (KAERI) were calculated for several directions of incident photons through the MCNP modeling, and the optimum G-factor applicable to that monitor was then determined by comparing the results both the energy band method and the G-factor method. The results for these spectrometric determinations were also compared with the dose rate from a HPIC radiation monitor around a EFRD 3300. The measured value at the EFRD 3300 based on a 3"${\Phi}X3$" NaI(Tl) detector was $7.7{\mu}R/h$ and its difference was shown about $3{\mu}R/h$, when compared with the results from a HPIC radiation moditor. Since a HPIC is known to be able to measure cosmic rays with the relatively high energy, the difference between them was caused by cosmic rays which were not detected in a 3"${\Phi}X3$" NaI(Tl) detector.