• 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.

• Journal of Radiation Protection and Research
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• 제10권2호
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• pp.113-121
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• 1985

방사성폐기물 처리, 처분의 안정성 평가를 위하여 방사성 고화체에서 용출되는 $^{137}Cs$과 $^{90}Sr$의 방사능 용출율과 누적용출분율을 계측 분석하여 시멘트를 사용한 방사성 고화체에서 $Cs^+$과 $Sr^{++}$의 용출특성을 조사하였다. 모의방사성 폐액의 몰농도, 시멘트의 종류, 첨가물질 및 붕산농도 등을 변화시키면서 sodium silicate 법과 중화법으로 원주형 시멘트 고화체를 제작하였다. 여기에서 가압경수로형 원자력 발전소의 모의 농축폐액의 시멘트 고화체로부터 용출연구는 IAEA의 추천방법에 따라서 수행되었다. 실험결과는 대부분 이미 보고된 연구자료들과 잘 일치하고 있으나 수밀성 시멘트 고화체에서는 상당히 높은 방사능 용출율을 보여주고 있음으로써 방사성 폐기물 고화체에 그 사용이 적합하지 않음을 알게 된다.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2370-2378
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• 2020

Building materials contribute significantly to the indoor radon and thoron levels. Therefore, parameters that influence the exhalation rates of radon and thoron from building material need to be analyzed closely. As a preliminary study, the effects of humidity on exhalation rates were measured using a system with an accumulation chamber and RAD7 detector for Korean brick, Korean soil, and Indonesian brick. Resulting doses to a person who resides in a room constructed from the building materials were assessed by UNSCEAR method for different air exchange rates. The measurements have revealed that Korean brick exhaled the highest radon and thoron while Indonesian brick exhaled the lowest thoron. Results showed that for a typical low dense material, radon and thoron exhalation rate will increase until reached its maximum at a certain value of humidity and will remain saturated above it. Analysis on concentration and effective dose showed that radon is strongly affected by air exchange rate (ACH). This is showed by about 66 times decrease of radon dose from 0.00 h^-1 to those of 0.50 h^-1 ACH and decrease by a factor of 2 from 0.50 h^-1 to those of 0.80 h^-1. In case of thoron, the ACH doesn't have significant effects on effective dose.

• 시스템엔지니어링학술지
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• 제17권1호
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• pp.76-84
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• 2021

Radioactive waste generated from nuclear power plant decommissioning shall be strictly managed so that radioactive materials above the allowable limit are not leaked into the environment. Radioactive wastes shall be classified and treated for management based on characteristics such as the type of waste, physicochemical properties, nuclide concentration and radioactivity. Waste characterization report shall be prepared and submitted to the disposal facility operator to ensure that the treated waste is suitable for disposal. The disposal facility operator shall review the waste Characterization report and visit the nuclear power plant decommissioning site to ensure that the wastes are processed step by step according to the plan. The waste Characterization report may be used as input data to evaluate disposal facility safety. Domestic and foreign data are collected and reviewed to confirm the entire processes from waste generation to delivery. This paper proposes the method to prepare the waste Characterization report which contains data and information on waste characteristics, treatment facilities & method and packaging method & container.

• 한국수산과학회지
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• 제53권6호
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• pp.861-869
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• 2020

This study was conducted to investigate the suitability of frozen oysters as a raw material for the preparation of seafood products by measuring the concentrations of harmful microorganisms and chemicals in thawed flesh. The microbial concentrations in thawed oysters were 2.3-5.0 log CFU/g for viable cell counts, not detected (ND)-1.0 log CFU/g for coliform bacteria, and ND for Escherichia coli and pathogenic bacteria such as Staphylococcus aureus, Salmonella spp., Listeria monocytogenes, Vibrio parahaemolyticus, Enterohemorrhagic Escherichia coli (EHEC), and Clostridium perfringens. In frozen oysters, the heavy metal concentration for viable cell counts was ND-0.030 mg/kg, for lead was ND-0.393 mg/kg, and for cadmium was 0.021-0.597 mg/kg. Benzo(a)pyrene, shellfish poison (paralytic shellfish and diarrhetic shellfish poisons), and radioactivity were not detected in the thawed oysters. These results suggest that frozen oysters can be safely used as a raw material for the preparation of seafood products.

• Journal of Radiation Protection and Research
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• 제46권4호
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• pp.178-183
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• 2021

Background: This study was carried out to provide environmental transfer parameter values to estimate activity concentrations of these radionuclides in agricultural crops when direct contamination occurred. Materials and Methods: Mass interception fractions (F_Bs) and weathering half-lives (T_ws) of ¹³¹I and radiocesium were calculated using openly available monitoring data obtained after the Fukushima Daiichi Nuclear Power Plant accident. F_B is the ratio between the initial radioactivity concentration of a radionuclide retained by the edible part of the plant (Bq·kg^-1 fresh weight [FW]) and the amount of deposited radionuclide in that area (Bq·m^-2). T_w values can be calculated using activity concentrations of crops decreased with time after the initial contamination. Results and Discussion: Calculated F_B and T_w values for ¹³¹I and radiocesium were mostly obtained for leafy vegetables. The analytical results showed that there was no difference of F_Bs between ¹³¹I and radiocesium by t-test; geometric mean values for leafy vegetables cultivated under outdoor conditions were 0.058 and 0.12 m²·kg^-1 FW, respectively. Geometric mean T_w value of ¹³¹I in leafy vegetables grown under outdoor conditions was 8.6 days, and that of radiocesium was 6.6 days; there was no significant difference between T_w values of these radionuclides by Wilcoxon rank sum test. Conclusion: There was no difference between ¹³¹I and radiocesium for F_Bs and T_ws. By using these factors, we would be able to carry out a rough estimation of the activity concentrations of ¹³¹I and radiocesium in the edible part of leafy crops when a nuclear accident occurred.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.627-636
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• 2022

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO₃ solutions using antimony oxide (Sb₂O₃) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca²⁺ or Ni²⁺ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co²⁺ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol^-1.

• 방사성폐기물학회지
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• 제20권4호
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• pp.489-500
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• 2022

The decommissioning of nuclear facilities produces various types of radiologically contaminated waste. In addition, dismantlement activities, including cutting, packing, and clean-up at the facility site, result in secondary radioactive waste such as filters, resin, plastic, and clothing. Determining of the radionuclide content of this waste is an important step for the determination of a suitable management strategy including classification and disposal. In this work, we radiochemically characterized the radionuclide activities of filters used during the decommissioning of Korea Research Reactors (KRRs) 1 and 2. The results indicate that the filter samples contained mainly ³H (500-3,600 Bq·g^-1), ¹⁴C (7.5-29 Bq·g^-1), ⁵⁵Fe (1.1- 7.1 Bq·g^-1), ⁵⁹Ni (0.60-1.0 Bq·g^-1), ⁶⁰Co (0.74-70 Bq·g^-1), ⁶³Ni (0.60-94 Bq·g^-1), ⁹⁰Sr (0.25-5.0 Bq·g^-1), ¹³⁷Cs (0.64-8.7 Bq·g^-1), and ¹⁵²Eu (0.19-2.9) Bq·g^-1. In addition, the gross alpha radioactivity of the samples was measured to be between 0.32-1.1 Bq·g^-1. The radionuclide concentrations were below the concentration limit stated in the low- and intermediatelevel waste acceptance criteria of the Nuclear Safety and Security Commission, and used for the disposal of the KRRs waste drums to a repository site.

• 대한방사성의약품학회지
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• 제8권2호
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• pp.71-76
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• 2022

Indigenous diagnostic dose of ¹³¹I-labeled meta-iodobenzylguanidine ([¹³¹I]mIBG) was prepared via Cu⁺ catalyzed isotope exchange reaction generated in situ by sodium metabisulfite for imaging of neuroblastoma tumor. [¹³¹I]mIBG was produced in overall 85-90% radiochemical yield. The average amount of radioactivity of [¹³¹I]mIBG was 2164 MBq (1998-2331MBq) with an average specific activity > 1000 MBq/mg at the end of synthesis. The radiochemical purity was ≥ 99.9% after purification through Dowex-1 × 8 ion exchange resin (100-150 mesh) at the date of preparation. The stability of [¹³¹I]mIBG at concentration 480-555 MBq/mL was > 97% at 4 ℃ after 4 days. The room temperature (25 ℃) stability of [¹³¹I]mIBG was > 98% after 24 h. Biodistribution of [¹³¹I]mIBG in patient showed uptake in salivary glands, liver, spleen and excreted though urinary bladder. Neuroendocrine medicated uptake into tumor lesion and metastatic sites were noted which strongly correlate with the morphological abnormalities of patient.

• 핵의학기술
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• 제16권2호
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• pp.12-17
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• 2012

방사성 요오드 치료병실에서 나온 환의 및 시트는 본디 방사성폐기물로서 관련 규정에 따라 일반 쓰레기와 동일하게 처리해야 하지만 사정상 일정기간 보관하여 방사능을 감쇄시킨 후 재사용하게 된다. 통상 최소보관기간 산출에 표면오염도(Bq/$m^2$)를 기반으로 하는 반출기준을 적용하고 있다. 하지만 방사선측정기를 이용하여 단위 면적당 총방사능량을 구하는 방법은 측정방법에 따라 편차와 불확실성이 상당히 커진다. 본 연구에서는 '방사성폐기물 자체처분 등에 관한 규정'에서 제시하고 있는 핵종 농도(Bq/g)를 Dose Calibrator를 이용하여 직접 측정하여 최소보관기간을 구함으로써, 환의 및 시트의 정확한 재사용 주기를 산출하고자 한다. 한편 반출기준으로 산출한 최소보관기간과 비교하여 그 차이를 살펴보았다. 본원의 방사성 요오드 치료병실에서 2011년 7월부터 2012년 3월까지 I-131을 3.7 GBq (100 mCi) 이상을 사용하여 방사성 요오드 치료를 시행한 환자 31명이 사용한 환의와 시트의 방사선 오염도를 측정하여 최소보관기간을 산출하였다. 최소보관기간은 핵종 농도를 측정하여 '방사성폐기물 자체처분 등에 관한 규정'에 따라 100 Bq/g이 되는 시점과 표면오염도를 측정하여 반출기준에 따라 허용표면오염도의 1/10, 즉 4 kBq/$m^2$되는 시점을 붕괴식에 대입하여 산출하였다. 반출기준으로 산출한 최소보관기간은 침대/담요시트는 14.2일, 베개시트는 4.6일, 환의(상(上))은 63일, 환의(하(下))는 78일 이었으며, 자체처분 기준에 따른 최소보관기간은 베개시트는 18.1일, 환의(상(上))은 43일, 환의(하(下))는 62일로 산출되었다. 표면오염도와 핵종 농도의 상관관계를 분석해 본 결과 베개시트와 환의(상(上))는 상관관계가 높게 나타났으나, 환의(하)는 낮게 나타났다. 이는 베개시트와 환의는 방사성오염이 부분에 국한 되어 측정값이 일정한 반면, 환의(하(下))는 소변에 의한 방사성오염이 여러 부분에 산재되어 있어 방사선측정기의 측정값이 상대적으로 낮게 측정된 결과로 생각 된다. 실질적으로 방사성 오염도를 측정한 결과 반출기준과 자체처분 기준을 상당량 초과하는 방사능이 존재하는 것을 확인할 수 있었다. 환의와 시트의 최소보관기간 산출에는 핵종 농도를 기준으로 하는 자체처분 기준을 적용하는 것이 더 적합하다고 할 수 있다. 방사능에 오염된 환의 및 시트는 최소 60일 정도는 보관해야 성급한 재사용에 따른 불필요한 방사선피폭 및 오염 확산을 방지할 수 있을 것으로 생각된다.