• Analytical Science and Technology
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• v.13 no.6
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• pp.743-750
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• 2000

For the ${\gamma}$-ray spectrometry analysis of radium and radon in environmental samples, plastic Marinelli beakers have been usually used. But, there are two problems; one is the increment of background by adsorption of airborne radon daughters on the plastic beaker, and other is the incompleteness of radioactive equilibrium by the loss of gaseous radon produced during the radioactive equilibrium process. In order to solve these problems, we made aluminium counting container, and investigated its characteristics. We investigated radioactive equilibrium process using the aluminium container. We found that both solid and liquid samples reached at radioactive equilibrium state in the aluminium container without loss of gaseous radon. By the use of the aluminium container, we established radon and radium analysis method of solid and liquid samples using gamma-ray spectrometry.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.2
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• pp.171-183
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• 2022

The parent and daughter nuclides in a radioactive decay chain arrive at secular equilibrium once they have a large half-life difference. The characteristics of this equilibrium state can be used to estimate the production time of nuclear materials. In this study, a mathematical model and algorithm that can be applied to radio-chronometry using the radioactive equilibrium relationship were investigated, reviewed, and implemented. A Bateman equation that can analyze the decay of radioactive materials over time was used for the mathematical model. To obtain a differential-based solution of the Bateman equation, an algebraic numerical solution approach and two different matrix exponential functions (Moral and Levy) were implemented. The obtained result was compared with those of commonly used algorithms, such as the Chebyshev rational approximation method and WISE Uranium. The experimental analysis confirmed the similarity of the results. However, the Moral method led to an increasing calculation uncertainty once there was a branching decay, so this aspect must be improved. The time period corresponding to the production of nuclear materials or nuclear activity can be estimated using the proposed algorithm when uranium or its daughter nuclides are included in the target materials for nuclear forensics.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.3935-3939
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• 2023

The paper presents the results of a study of radioactive noble gases and from decay products in the atmosphere of the reactor hall of the research nuclear reactor IVV-2M. The distribution of short-lived ⁸⁸Rb and ¹³⁸Cs activity by sizes of aerosol particles was measured in the range of 0.5-1000 nm. It is shown that radioactive aerosols are characterized by three main modes with AMTD 2-3 nm, 7-15 nm and 400 nm. About 70% of aerosol activity is due to ⁸⁸Rb. The equilibrium factor between ⁸⁸Kr and ⁸⁸Rb is 0.2 ± 0.1. The total concentration of aerosols particles was measured using an aerosol diffusion spectrometer. The value of unattached fraction of radioactive aerosols in the atmosphere of reactor hall IVV2M was f = 0.15-0.25 at the average total aerosol particles concentration from 20,000 cm³ to 53,000 cm³.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2006.11a
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• pp.301-301
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• 2006

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2006.06a
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• pp.193-193
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• 2006

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.335-336
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• 2018

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.105-114
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• 2004

This study investigated the thermal behavior of the nuclear graphite waste generated from the decommissioning of the Korean nuclear research reactor, The first part study investigated the decomposition rate of the nuclear graphite waste up to $1000^{\circ}C$ under various oxygen partial pressures using a thermo-gravimetric analyzer (TGA). Tested graphite waste sample not easily destroyed in the oxygen-deficient condition. However, the gas-solid oxidation reaction was found to be very effective in the presence of oxygen. No significant amount of the product of incomplete combustion was formed even in the limited oxygen concentration of 4% $O_2$. The influence of temperature and oxygen partial pressure was evaluated by the theoretical model analysis of the thermo-gravimetric data. The activation energy and the reaction order of graphite oxidation were evaluated as 128 kJ/mole and 1.1, respectively. The second part of this study investigated the behavior of radioactive elements under graphite oxidation atmosphere using thermodynamic equilibrium model. $^{22}Na$, $^{134}Cs$ and $^{137}Cs$ were found be the semi-volatile elements. Since volatile uranium species can be formulated at high temperatures above $1050^{\circ}C$, the temperature of incinerator furnace should be minimized. Other corrosion/activation products, fission products and uranium were found to be the non-volatile species.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1489-1497
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• 2003

Aerosol charge neutralizers with various radioactive sources have been used to apply an equilibrium charge distribution to aerosols of unknown charge distribution. However, the performance of aerosol charge neutralizers is not well known, especially for highly charged particles. Measurements of highly charged particles are needed in air cleaning devices, e.g. electrostatic precipitator, bag filter with a pre-charger, and electrical cyclone. In this study, the particle charging characteristics of two different aerosol charge neutralizers were experimentally investigated for singly charged monodisperse particles and highly charged polydisperse particles. One has radioactive source of $^{85}$ Kr (beta source, 2 mCi) and the other has $^{210}$ Po (alpha source, 0,5 mCi). The air flow rate passing through each aerosol charge neutralizer was changed from 0.2 to 2.5 L/min. The results show that the charge distribution of singly charged monodisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer is well agreed with the Boltzmann equilibrium charge distribution at an air flow rate of 0.3 L/min, However, it deviates from the equilibrium charge distribution when the air flow rates are 0.6, 1,0, and 1,5 L/min, On the other hands, the effect of air flow rate is insignificant for the $^{210}$ Po aerosol charge neutralizer. The non-equilibrium character in charge distribution of highly charged polydisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer greatly depends on the air flow rate, however it is insensitive to the air flow rate for the $^{210}$ Po aerosol charge neutralizer.

• Journal of Radiation Protection and Research
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• v.29 no.1
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• pp.1-8
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• 2004

Diphosil, a new version of the organic-inorganic composite resin developed by ANL has a structure of the chelating diphosphonic acid groups grafted to a silica support. To apply Diphosil for the treatment of liquid radioactive waste from nuclear power plants, the adsorption equilibrium and column experiments were carried out for the main radionuclides, $^{137}Cs\;and\;^{60}Co$, in the liquid radwaste stream. Through the adsorption equilibrium experiments, the removal efficiencies of $^{137}Cs\;and\;^{60}Co$, and the effects of non-radioactive ions on the removal efficiency have been measured in various conditions using radiotracers. The breakthrough curves for the tested tracers were obtained from the laboratory scale column tests using the simulated liquid radioactive waste. In addition, the removal capacity of Diphosil is compared with that of Amberlite IRN 77 resin, generally used in nuclear power plants.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.3
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• pp.207-213
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• 2010

The effect of temperature on swelling pressure was observed with a Korean domestic Ca-bentonite which has been considered as a potential buffer material in the engineering barrier of a high level radioactive waste (HLW) disposal system. The Ca-bentonite was compacted to a dry density of 1.6 g/$cm^3$, and then de-ionized water was supplied into it with a constant pressure of 0.69 MPa. The equilibrium swelling pressures were measured with different temperatures of $25^{\circ}C$, $30^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$, $60^{\circ}C$, $70^{\circ}C$, respectively. The Ca-bentonite showed a sufficiently high swelling pressure of 5.3 MPa at room temperatures. Then it was clearly showed that the equilibrium swelling pressure was decreased with an increase of temperature. Interestingly, there were some differences in temperature effect on the equilibrium swelling pressure when the environmental temperature is increasing or decreasing. For further clarifying the swelling behaviour of a Korea domestic Ca-bentonite, the change of a compaction level, and the composition variation of a supplied water would be needed to use in conceptual design of HLW disposal system.