• Analytical Science and Technology
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• v.8 no.4
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• pp.477-480
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• 1995

Isotopic-spectral method [I] was applicated for determination of carbon in silicate materials (pure silica, guartz glasses, geological probs etc.). Isotopic heterogeneous balancing of carbon in gaseous phase and solid samples was carried out at the temperature of $1500-1900^{\circ}K$. Spectroscopic measuring of isotope concentration in a balanced gas was made using the electron-vibrational band heads of CO molecules excited in HF discharge. Limits of detection of carbon concentrations appear to be $n^*10^{-6}$.

• Journal of the Korean Chemical Society
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• v.8 no.2
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• pp.39-42
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• 1964

As the bromination method with $Br_2^{82}$ for the synthesis of 5-bromouracil-$Br^{82}$ gave products with considerable impurities, e. g. uracil etc. an attempt to produce pure one by isotopic exchange method was performed. Bromide-82 ion such as $NH_4Br^{82}$ or $HBr^{82}$ undergoes no isotopic exchange with 5-bromouracil-Br. However, isotopic exchange between $NH_4Br^{82}$ and $Br_2$, and between $Br_2^{82}$ and 5-bromouracil-Br were too fast to determine the rate. The result indicated that this method can be used in the production of pure 5-bromouracil-$Br^{82}$. It was also found that the use of reducing agent to maintain $Br^{82}$ as bromide form was unnecessary on $NH_4Br^{82}$ production from reactor.

• Nuclear Engineering and Technology
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• v.1 no.1
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• pp.33-38
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• 1969

Determinations of the isotopic contents of U$^{235}$ and U$^{238}$ in ten uranium samples containing 0.72-89.70 at % U$^{235}$ were carried out in two ways utilizing high resolution Ge (Li) gamma-ray spectrometer. One method is based upon the fact that the intensity of 185.5 kev gamma-ray vary linearly with U$^{235}$ content for a given geometry. Another method applied for the direct determination of the U$^{235}$ / U$^{238}$ isotopic ratios is the precision gamma-ray spectrometric analysis of reactor irradiated uranium samples after allowing a fixed cooling time for one hour. The results obtained by both methods well agree with the values calculated from the isotopic contents of highly enriched original uranium samples measured by mass spectrometer. The precision obtained was well below 5% for most of the isotopic ratios investigated.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2761-2766
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• 2021

A method for preparing "reagent" for radioactive methyliodide vapors production using an isotopic exchange reaction has been developed. Based on the obtained data of the isotopic exchange efficiency and hydraulic resistance, white fused alumina (700-840 ㎛) was selected as the carrying agent material for "reagent" production. The radioiodine isotopic exchange dependences on such parameters as temperature, gas flow velocity, and the methyliodide concentration in it were determined. Optimal conditions have been selected to achieve 85% of the isotopic exchange rate in 1 h of the experiment. The obtained data allowed to develop an approach to the test of iodine filters for nuclear power plants and to determine their efficiency.

• Nuclear Engineering and Technology
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• v.47 no.7
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• pp.924-933
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• 2015

The correlation of the isotopic composition of uranium, plutonium, neodymium, and cesium with the burnup for high burnup pressurized water reactor fuels irradiated in nuclear power reactors has been experimentally investigated. The total burnup was determined by Nd-148 and the fractional $^{235}U$ burnup was determined by U and Pu mass spectrometric methods. The isotopic compositions of U, Pu, Nd, and Cs after their separation from the irradiated fuel samples were measured using thermal ionization mass spectrometry. The contents of these elements in the irradiated fuel were determined through an isotope dilution mass spectrometric method using $^{233}U$, $^{242}Pu$, $^{150}Nd$, and $^{133}Cs$ as spikes. The activity ratios of Cs isotopes in the fuel samples were determined using gamma-ray spectrometry. The content of each element and its isotopic compositions in the irradiated fuel were expressed by their correlation with the total and fractional burnup, burnup parameters, and the isotopic compositions of different elements. The results obtained from the experimental methods were compared with those calculated using the ORIGEN-S code.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.93-106
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• 2001

The processes and rates of groundwater recharge were studied by long-term monitoring of groundwater level and isotopic compositions of precipitation, surface water and groundwater in the Yeosu area. The isotopic compositions of surface water and groundwater were directly related to the precipitation event. It is also shown that the minimum amount of precipitation for infiltration to groundwater is about 20mm. The isotopic variations of groundwater shows that the Isotopic composition of groundwater changed by each precipitation event between June and Sep. 2000 is gradually changed without input of precipitation again. It indicates that the groundwater recharged from the upper part is mixed with the groundwater in reservoir. The infiltration rate of first precipitation event after a dry season is estimated to be 16.5% using isotopic mixing equations. It is expected that the groundwater recharge rate could be estimated more quantitavely, if the isotopic method is combined with the conservative methods.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.1-10
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• 2013

This study was performed to summarize application of ${\delta}^{13}C$, ${\delta}^{37}Cl$ and ${\delta}D$ of trichloroethylene (TCE) to studies on environmental forensic field regarding identification of TCE sources and evaluation of contribution of TCE to groundwater using data collected from literatures. ${\delta}^{13}C$, ${\delta}^{37}Cl$ and ${\delta}D$ of TCE give some information regarding sources of TCE because they show specific value according to manufacturing method. Also, TCE do not show a significant isotopic fractionation owing to adsorption and dilution. The isotopic fractionation mainly occurs by biodegradation. In addition, isotopic fractionation factor for TCE is different according to a kind of microorganism participated in biodegradation. However, the isotopic data of TCE have to be applied with chemical compositions of TCE and other hydrogeologic factors because isotopic fractionation of TCE is influenced by various factors.

• Ocean and Polar Research
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• v.38 no.4
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• pp.339-345
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• 2016

Stable water vapor isotopes have been utilized as a tracer for studying atmospheric global circulations, climate change and paleoclimate with ice cores. Recently, since laser spectroscopy has been available, water vapor isotopes can be measured more precisely and continuously. Studies of water vapor isotopes have been conducted over the world, but it is the early stage in south Korea. For vapor isotopes study, a cryogenic sampling device for water vapor isotopes has been developed. The cryogenic sampling device consists of the dewar bottle, filled with extremely low temperature material and impinger connected with a vacuum pump. Impinger stays put in the dewar bottle to change the water vapor which passes through the inside of impinger into the solid phase as ice. The fact that water vapor has not sampled completely leads to isotopic fractionation in the impinger. To minimize the isotopic fractionation during sampling water vapor, we have tested the method using a serial connection with two sets of impinger device in the laboratory. We trapped 98.02% of water vapor in the first trap and the isotopic difference of the trapped water vapor between two impinger were about 20‰ and 6‰ for hydrogen and oxygen, respectively. Considering the amount of water vapor trapped in each impinger, the isotopic differences for hydrogen and oxygen were 0.33‰ and 0.06‰, respectively, which is significantly smaller than the precision of isotopic measurements. This work can conclude that there is no significant fractionation during water vapor trapping.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.257-259
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• 2004

In this paper measurement method of uranium isotope ratio of uranium-bearing particles in swipe samples was introduced; Swipe sample screening program was proposed on the basis of studying various destructive assay and non-destructive assays. Scanning electron microscope(SEM) equipped with an energy dispersive X-ray fluorescence(XRF) system was applied to locate the deposited uranium-containing particles on the graphite support, particle's composition and size can be identified. Some isotope ratio results were compared with those of other bulk analytical methods; By measuring the same prepared sample, we got the U-particle isotopic ratio data similar to those from IAEA NWAL, indicating that our operation parameters and experimental conditions are viable and can be used for measurement of U-particle isotopic ratio from swipe samples.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.929-936
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• 2018

A basic characterization of uranium samples was performed using gamma- and X-ray spectroscopy. The studied uranium samples were eight types of certified reference materials with $^{235}U$ enrichments in the range of 1-97%, and the measurements were performed over 24 h using a high-resolution and high-purity planar germanium detector. A general peak analysis of the spectrum and the $XK_{\alpha}$ region of the uranium spectra was carried out by using HyperGam and HyperGam-U, respectively. The standard reference sources were used to calibrate the spectroscopy system. To obtain the absolute detection efficiency, an effective solid angle code, EXVol, was run for each sample. Hence, the peak activities and isotopic activities were determined, and then, the total U content and $^{234}U$, $^{235}U$, and $^{238}U$ isotopic contents were determined and compared with those of the certified reference values. A new method to determine the model age based on the ratio of the activities of $^{223}Ra$ and $^{235}U$ in the sample was studied, and the model age was compared with the known true age. In summary, the present study developed a method for basic characterization of uranium samples by nondestructive gamma-ray spectrometry in 24 h and to obtain information on the sample age.