• Journal of Korean Society for Atmospheric Environment
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• v.24 no.5
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• pp.538-550
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• 2008

Radon is an invisible, odorless, and radioactive gas. It is formed by the disintegration of radium, which is a decay product of uranium. Some amounts of radon gas and its products are present ubiquitously in the soil, water, and air. Particularly high radon levels occur in regions of high uranium content. Although radon is permeable into indoor environment not only through geological features (bed rock and permeability) but also through the construction materials and underground water, the radiation from the geological features is generally main exposure factor. So there can be a problem in a certain space such as the underground and/or relatively poor ventilation condition. In this study, a GIS technique was used in order to investigate spatial distribution of radon measured from sub- way stations of 1 thru 8 in Seoul, Korea in 1991, 1998, 2001, and 2006. Spatial analysis was applied to reproduce the radon distribution. We utilized spatial analysis techniques such as inverse distance weighted averaging (IDW) and kriging techniques which are widely used to relate between different spatial points. To validate the results from the analyses, the jackknife technique for an uncertainty test was performed. When the number of measuring sites was less than 100 and also when the number of omitted sites increased, the kriging technique was better than IDW. On the other hand, when the number of sites was over 100, IDW technique was better than kriging technique. Thus the selection of analytical tool was affected sensitives by the analysis based on the number of measuring sites.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.165-171
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• 2009

Resins were synthesized by mixing 1-aza-15-crown-5 macrocyclic ligand attached to styrene (2th petroleum in 4th class hazardous materials) and divinylbenzene (DVB) copolymer with crosslinkage of 1%, 2%, 8%, and 16% by substitution reaction. The characteristic of these resins was confirmed by content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, dielectric constant of solvent and crosslinkage on adsorption of metal ion by the synthetic resin adsorbent were investigated. The metal ion showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in an increasing order of uranium $(UO_2^{2+})$ > lead $(Pb^{2+})$ > chromium $(Cr^{3+})$ ion. The adsorption was in the order of 1%, 2%, 8%, and 16% crosslinkage resin and adsorption of resin decreased in proportion to the order of dielectric constant of solvents.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1638-1649
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• 2019

Top soil samples across the state of Kuwait numering ninety were collected and analysed using gamma-ray spectrometry, to evaluate the elemental concentration of $^{238}U$, $^{232}Th$ and $^{40}K$ and their depletion/enrichment. Results of elemental concentration ranges from 0.48 to 2.61 mg/kg, 0.87-5.23 mg/kg, and 0.24-2.23%, with a mean values of 1.39 mg/kg, 3.47 mg/kg, and 1.18%, for the $^{238}U$, $^{232}Th$ and $^{40}K$, respectively. Further analysis was conducted amongst the five identified soil types, i.e. Aquisalids (S1), Calcigypsids (S2), Petrocalcids (S3), Petrogypsids (S4), and torripsamment (S5). The highest radioactivity concentrations from both uranium and thorium were recorded in the S2 (Calcigypsids) soil, with a value of 1.71 (mg/kg) and 4.45 (mg/kg), respectively. Minimum and maximum values of $^{40}K$ are 1.1(%) and 1.27(%) and is prevalent in Aquisalids (S1) and Petrocalcids (S3) soil types, respectively. Ratios of elemental concentration for $^{232}Th/^{238}U$, $^{40}K/^{238}U$, $^{40}K/^{232}Th$ across the soil types are 2.53, 0.09 and 0.03, with a correlation coefficient of 0.92, 0.34, and 0.38, respectively. A progressively higher $^{232}Th/^{238}U$ ratio is observed moving south-wards, indicating lower $^{238}U$ content in soils from the south relative to the northern part. Overall results indicate Kuwait to be relatively an area with low level of natural radioactivity.

• Analytical Science and Technology
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• v.22 no.1
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• pp.92-100
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• 2009

Azacrown resins were synthesized by mixing 1-aza-12-crown-4 macrocyclic ligand into styrene (2th petroleum in 4th class hazardous materials) divinylbenzene (DVB) copolymer with crosslinkage of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, crosslinkage of resins and dielectric constant of solvent on adsorption of metal ions by resin adsorbent were investigated. Metal ions showed a great adsorption over pH 3 and adsorption equilibrium of metal ions was about two hours. In addition, adsorptive selectivity of metals on the resin in ethanol solvent was increased in the order of ${UO_2}^{2+}$ > $Ca^{2+}$ > $Sm^{3+}$ ion and adsorption of uranium ion was decreased with increase of crosslinkage such as 1%, 2%, 5% and 10% and was inversely proportional to the order of dielectric constant of solvents.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.236-244
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• 2005

Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common feature is the potential hazard associated with their radioactivity and the need to manage them in such a way as to protect the human environment. The geological disposal is regarded as the most reasonable and effective way to safely disposal high-level radioactive wastes in the world. The conceptual model of geological disposal in China is based on a multi-barrier system that combines an isolating geological environment with an engineered barrier system. The buffer is one of the main engineered barriers for HLW repository. The buffer material is expected to maintain its low water permeability, self-sealing property, radio nuclides adsorption and retardation property, thermal conductivity, chemical buffering property, overpack supporting property, stress buffering property over a long period of time. Benotite is selected as the main content of buffer material that can satisfy above. GMZ deposit is selected as the candidate supplier for Chinese buffer material of High Level Radioactive waste repository. This paper presents geological features of GMZ deposit and basic property of GMZ Na bentonite. GMZ bentonite deposit is a super large scale deposits with high content of Montmorillonite (about $75\%$) and GMZ-l, which is Na-bentonite produced from GMZ deposit is selected as reference material for Chinese buffer material study.

• Korean Journal of Materials Research
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• v.10 no.2
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• pp.166-170
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• 2000

Nuclear fuel $UO_{2+x}$ power was produced from concentrated $UF_6$ by the DCP(Dry Conversion Process). The characterstics of $UO_{2+x}$ powder, prepared with respect to steam flowing conditions and temperature variations in a rotary kiln reactor, have been investigated with a uranium analyzer, water vapor measurement, and SEM. Fluorine content of the powder could be reduced to 8ppm. The moisture content was found to be optimized.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.264-269
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• 2001

Large amounts of orange juice are produced in Japan every yea.. Accompanied by the production of orange juice, large amount of juice residues are also generated in nearly the same amounts with juice. Although, at present, some of these residues are marketed as a feed for cattle after drying and mixing with lime, the marketing price is lower than its production cost and the difference is paid by the consumers as a part of the price of orange juice. In the present work, we developed new innovative use of orange juice residue, a biomass waste, as adsorption gel for removing toxic heavy metals such as lead. arsenic, selenium and so on as well as radioactive elements such as uranium and thorium from environments. The major components of orange juice residue are cellulose. hemicellulose and pectin, which are converted into pectic. acid, an acidic polysaccharide, by means of saponification with concentrated sodium hydroxide solution. In the previous work, we found that crosslinked pectic acid gel strongly an selectively adsorbs lead over other metals such as zinc an copper. On the other hand. it is well known that polysaccharides such as cellulose can be easily phosphorylated and that phosphorylated polysaccharides have high affinity to uranium and thorium as well as some trivalent metals such as ferric iron and aluminum. Taking account of the noticeable characteristics of these polysaccharides, 2 types of adsorption gels were prepared from orange juice residue: one is the gel which was prepared by saponificating the residue followed by crosslinking with epichlorohydrin and another is that prepared by crosslinking the residue followed by phosphorylation. The former gel exhibited excellent adsorptive separation behavior for lead away from zinc owing to high content of pectic acid while the latter gel exhibited that for uranium and thorium. Both types of adsorption gels exhibited high affinity to ferric iron, which enables selective and strong adsorption for some toxic oxo-anions of arsenic (V and III), . selenium and so on via iron loaded on these gels. These results demonstrate that biomass wastes such as orange juice residue can be effectively utilized fer the purpose of removing toxic heavy or radioactive metals existing in trace or small amounts in environments.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.1
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• pp.12-20
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• 2010

Metamictization and color change in zircons from Cambodia and Tanzania were investigated. Elements analysis to detect radioactivity of elements such as U and Th, and spectroscopic analysis using UV-VIS and Fourier transform infrared spectroscopy were performed. According to the UV-VIS spectroscopic analysis, it was perceived that many and high intense absorption peaks appeared in blue and colorless zircons, while less and low intense absorption peaks appeared in uranium contained green and yellow zircons. It was found that those stones have made progress to the metamictization. After heat treatment, we could detect opposite results. As the results of FTIR spectroscopy analysis, in the metamict green and yellow zircon, it is showed that 3-phonon combination mode bands of $[SiO_4]^{4-}$ internal vibration in the region of 3100~3400 $cm^{-1}$ are broad and some of them disappear. However, the disappeared bands are observed again due to restored crystal lattice by the heat treatment. Also, $U^{4+}$ peaks that can detect the uranium content in zircon appears at near 4800 $cm^{-1}$ in the green and yellow samples. From this investigation, we could observe the metamictization effect and color change in uranium-bearing zircon by heat treatment using spectroscopic analysis.

• Nuclear Engineering and Technology
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• v.29 no.4
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• pp.299-309
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• 1997

The neutronic feasibility of typical Korean three-loop 900MWe class PWR core loaded with mixed oxide fuels for both annual and 18-month cycle strategies has been investigated as a means for spent fuel management. For this study, a method of determining equivalent plutonium content was developed under the equivalence concept which gives the same cycle length as uranium fuel. Optimal plutonium zoning within the MOX assembly was also designed with the aim of minimizing the peak md power. Conceptual core designs hate hen developed for equilibrium cycle with the following variations: annual and 18-month cycle, 1/3 and full MOX loading schemes, and typical and high moderation lattice. The analysis of key core physics parameters shows that in all cases considered satisfactory core designs seem to be feasible, though addition of control rod system and change in Technical Specification for soluble boron concentration are required for full MOX loading in order to meet the current design requirements.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.344-349
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• 2005

Neutron count rate measurements to assay fissile content of uranium powder have been carried out in a neutron counter. The induced fission neutrons by Cf-252 neutron source are counted as the variation of fissile material in fuel material. The measured counts are compared with equivalent results obtained from calculation. It shows that the measured neutron counts versus quantity of $UO_2$ powder enrichment agreed reasonably well with the calculated values.