• Journal of Radiation Industry
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• v.6 no.1
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• pp.1-9
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• 2012

In spite of colossal efforts taken for safe handling and storage of radioactive waste, the uncontrolled release of radiocesium ($^{137}Cs$ and $^{134}Cs$ isotopes) into the natural environment is inevitable. $^{137}Cs$ is of particular concern because of its long half-life, ability to transfer into biota through food chains, as well as its great mobility, bioavailability, and chemical and ecophysiological similarity with potassium. Radiocesium is released anthropogenically into the environment. Mushrooms are known for their ability to accumulate radionuclides, particularly radiocesium, which is heterogeneously distributed in the individual parts of mushrooms, and it is found that mushrooms are a hyper-accumulator of radiocesium from their environment than other vegetation. Mushrooms play a major role in the mobilization, accumulation, and translocation of cesium, i.e., decontamination of soils (mycoextraction) polluted with cesium radioisotopes, and this capacity appears to be a relevant bioindicator of cesium contamination in the environment. Moreover, the extension of mycelium into the soil makes the use of mushrooms as bioindicators of radiocesium possible. This paper reviews the potential of mushrooms in the accumulation of radiocesium from the environment, and dissertates the salient features to support the employment of mushrooms in environmental biomonitoring as a sensitive bioindicator of radiocesium contamination.

• Journal of Radiation Protection and Research
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• v.46 no.4
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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.

• Journal of Radiation Protection and Research
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• v.44 no.4
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• pp.128-148
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• 2019

Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

• Environmental Engineering Research
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• v.11 no.2
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• pp.106-125
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• 2006

Cesium and strontium are two important fission products and the removal/speciation of these two cations with several inorganic/bio-materials is an interesting topic to discuss. It is to be noted that inorganic materials are found to be fairly effective and efficient in the removal/speciation of these cations. Moreover, these solids are to be found promising as they show fairly good radiation and temperature stability. Hence, they play an important role in the radioactive waste management studies. However, various studies reveal that in addition to inorganic materials various biosorbents can also be employed in the removal/speciation of these ions. But the radiation and temperature stability of these bio-sorbents and dead biomasses are still the topic lying among the researchers to be investigated.

• Mycobiology
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• v.32 no.3
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• pp.110-114
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• 2004

Mycobiota including Alternaria alternata, Fusarium verticillioides and Aspergillus pulverulents were tested for their ability to uptake radiocobalt(Co-60) and radiocesium(Cs-137) from radionuclide containing medium. A. alternata was the most efficient fungal species for uptake of radioisotopes, followed by A. pulverulents, whereas F. verticilliodies came in the last rank. The conditions of radioisotope uptake were optimized such as the form of the fungal organism either spores or mycelium, inoculum age and pH of growing medium. Furthermore the total pigments of the tested fungi were extracted and tested for their ability to bind with radioisotope, where melanin of A. alternata produced about 60% for radioisotope uptake out of total added radioisotope radioactivity. Moreover, transmission electron microscopic examination of radioisotope exposed spores showed high precipitation of melanin granules in the spore wall and within the cell as comparing to untreated spores.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.407-416
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• 2018

This study presents a novel complete solution starting with a synthesis of silica modified with potassium-nickel hexacyanoferrate and ethanolamine (SiEA-KNiFe) sorbent through radiocesium sorption in different process configurations and moving on to the vitrification of the spent sorbent, using the sol-gel method. The experimental data for deionized water solution, as well as seawater solution, correlates strongly with the Langmuir isotherm model. Moreover, the study also presents a method for spent sorbent solidification in the glass matrix. The cesium leaching test confirmed that spent sorbent can be stably bound in the glass matrix after radionuclide removal.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.229-238
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• 2016

This study evaluated potential application of illite, which is produced at Yeongdong area in Korea, to remove radiocesium released to environmental system through severe nuclear accidents. The Yeongdong illite was formed by metamorphose of micaceous schist in hydrothermal condition, and composed of quartz, illite, and albite. Sorption distribution coefficient ($K_d$) of cesium by the Yeongdong illite was higher than the $K_d$ values for other clay minerals. It may be affected by preferential adsorption of cesium to Frayed Edge Sites (FES) on illite. Nonlinear isotherm models were suitable to describe the sorption processes for the Yeongdong illite. Its max. single layer capacity was $250,000{\mu}g\;kg^{-1}$ for cesium. Therefore, the Yeongdong illite could be an efficient and economic sorbent to prevent dispersion of radiocesium, and apply for remediation.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.531-532
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• 2018

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.960-966
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• 2021

A technical approach to design and carry out an experiment to determine the uptake of selected radionuclides in site-specific conditions in Kuwait was developed and successfully executed for developing a radioecological decision support system. The radionuclides from soil-to-plant transfer factors have been obtained for leafy and non-leafy vegetables, and root crops cultivated in Kuwait. Two types of vegetated soils were selected and spiked with high concentrations of three relatively short-lived selected radionuclides (⁸⁵Sr, ¹³⁴Cs, and ¹³³Ba). The highest strontium and barium transfer factors were found in the order: leafy vegetables > root crops > non-leafy vegetables. The approximate range of radiocesium transfer factor was found to be low in all plant groups and was comparable to those reported elsewhere in different soil types of temperate and tropical environments. A strong negative correlation between the obtained transfer factors and the distribution coefficient of the radionuclide in soil was found. It is recommended to adopt the newly derived parameters for the sensitive areas in Kuwait and other Gulf countries instead of using the generic parameters, whenever dose calculation codes are used. This will help to more accurately assess and predict the end results of the committed effective dose equivalent through ingestion pathway.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.339-340
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• 2018