• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.77-83
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• 2021

The purpose of the study is to evaluate the effect on medical application and convergence for the efficient disaster responses in the massive radiological events by comparison of two types of survey-meters(hand held survey-meter and transportable portal monitor). In the simulated radiation disaster drill, twelve participants randomly wore a personal protective equipments (PPE) with twelve check source. We measured participants to detect five real radioactive sources of the twelve check sources, using two types of survey meters. The primary outcome was the measuring time. The secondary outcome was the sensitivity and specificity of the detection of the real radioactive source. The average time by the hand held survey meter was 231.9 ± 116.6 seconds, and the time by transportable portal monitor was statistically shorter 8.690 ± 1.667 seconds. There was no difference in the sensitivity and specificity between two survey meters. The transportable portal monitor survey meter was considered to have medical application and play an important role in radiological disasters.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.2
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• pp.107-115
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• 2023

Cobalt can be released into the natural environment as industrial waste from the alloying industry and as acid mine drainage, and it is also a radionuclide (⁶⁰Co) that constitutes high-level radioactive waste. Smectite is a mineral that can be useful for adsorption and isolation of this element. In this study, Cheto-type montmorillonite (Cheto-MM), which is the source clays of The Clay Mineral Society (CMS) and already well-characterized, was used. The effect of the adsorption site affected by the presence of interlayer water on the adsorption of cobalt before and after dehydration by heating was evaluated and the adsorption mechanism of cobalt on Cheto-MM was studied by applying adsorption kinetics and adsorption isotherm models. The results showed that the adsorption characteristics changed with dehydration and subsequent shrinkage, and cobalt was found to be adsorbed at the edge of Cheto-MM for about 38% and adsorbed at the interlayer site for about 62%, suggesting that the cobalt adsorption of Cheto-MM is significantly influenced by the interlayer. By applying the adsorption kinetic models, the cobalt adsorption kinetics of Cheto-MM is explained by a pseudo-second-order model, and the concentration-dependent adsorption was best described by the Langmuir isotherm adsorption model. This study provides basic knowledge on the adsorption characteristic of cobalt on montmorillonite with different adsorption sites and is expected to be useful in predicting the adsorption behavior of smectite in high-level radioactive waste disposal sites in the future.

• The Korean Journal of Nuclear Medicine Technology
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• v.28 no.1
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• pp.57-69
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• 2024

Purpose: Quantitative analysis through count measurement in nuclear medicine planar images is limited by analysis techniques that are useful for obtaining various clinical information or by organ overlap or artifacts in actual clinical practice. On the other hand, the use of SPECT tomography images is quantitative analysis using volume rather than planar, which is not only free from problems such as projection overlap, but also has excellent quantitative accuracy. In the use of developing SPECT quantitative analysis technology, this study aims to compare the accuracy of quantitative analysis between ROI of the conventional planar images and VOI of the SPECT tomographic images in evaluating the count change happened by the volume change of the source. Materials and Methods: A ^99mTcO₄^- source(200.17 MBq) was filled with sterilized water in the syringe to create a phantom with an inner diameter volume of 60 cc, and a planar image and a SPECT image were obtained by reducing the volume by 15 cc (25%) respectively. ROI and VOI(threshold: 1~45%, 5% interval) were set for each image obtained to estimate true count and measure the total count, and compared with the preseted volumetric change rate(%). Results: When volume changes of 25%, 50%, and 75% occurred in the initial volume of 60 cc(100%) of the phantom, the average count changes of the measured planar image were 26.8%, 53.2%, 77.5%, and the average count changes of the SPECT image were 24.4%, 50.9%, and 76.8%. In this case, the VOI size(cm³) set showed an average change rate of 25.4%, 51.1%, and 76.6%. The highest threshold value for the accuracy of radioactive concentration by VOI size (average error -1.03%) was 35%, and the VOI size of the same threshold had an error of -17.1% on average compared to the actual volume. Conclusion: On average, the count-based volumetric change rate in nuclear medicine images was able to track changes more accurately using VOI than ROI, but there was no significant difference with relatively similar value. However, the accuracy of radioactive concentration according to individual VOI sizes did not match, but it is considered that a relatively accurate quantitative analysis can be expected when the size of VOI is set smaller than the actual volume.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.431-438
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• 2016

Recently, Both rapid economic growth and high-quality native finishing materials demand in buildings such as local infrastructure facilities and cultural facilities have increased along with local quarries. So, increasing local quarries and environmental pollution occurred in quarries get the eyes to damaged area of the surroundings. As an example, carcinogen such as solid formed to fixing asbestos and dust have damaged to local resident. Especially, Radon gas released from asbestos can exist everywhere on earth, released soil and rock as radioactive substances, can be caused lung cancer followed by a smoking. When pollution source to indoor air quality that lacking ventilation rate of the residential building moved in a cycle, human responses such as headache, dizziness, etc. get appear, so on it threatened resident's physical condition. Thus, we need to urgent attention to reduction harmful substance. In the case of radon gas of the pollution source to indoor air quality in housing, it has characteristic that keep on going through half-life released from source, we need to control radon gas source than source removal. We set on vermiculite addition ratio to 10% which has harmful substances adsorption performance, proceed experiment to basalt waste rock addition ratio 50, 60, 70, 80(%). The result of an experiment, based on 'KS F 4035, precast terrazzo', we can be obtainable in the best terrazzo at basalt waste rock addition ratio 70%.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.53-61
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• 2013

Objectives: It is certain that Radioactive iodine thyroid uptake(RAIU) rate should be measured with the standard counts considering the thyroid gland depth in enlarged thyroid patients for the variation from geometric factors. The purpose of this paper is to consider the effects of geometric factors according to detector to source distance and the effective thyroid depth on RAIU rate with experiment test. Materials and Methods: I-131 370 kBq ($10{\mu}Ci$) point source was measured by Captus-3000 thyroid uptake system (Capintec, NJ, USA) with a change Detector-Source Distance from 20 cm to 30 cm at an interval of 1 cm. And we changed the Neck phantom surface-Source Depth in the phantom with 1 cm, 2 cm, 5 cm using the neck phantom in order to reproduce the effective thyroid depth. Results: Every experimental group follows power curve as inverse square curve ($$R2{\geq_-}0.915$$). The average count rates in the case not using a phantom and the every case applied the effective thyroid depth using a phantom was not identical each other. There was significant fluctuations upon the effective thyroid depths applied the effective thyroid depth above 1 cm in $364.4 keV{\pm}10%$ energy ROI (p<0.01). There was not significant difference between the count rates of 1 cm and 2 cm in $364.4keV{\pm}20%$ and $637.1keV{\pm}6.2%$ (p=0.354, p=0.397). In assumed RAIU rate from regression equation, $364.4keV{\pm}20%$ was lower difference than $364.4keV{\pm}10%$ as 6.42% and 5.09% per 1 cm. Every change of count rate upon depth appears decreased line on Linear Regression, but the case of $284.3keV{\pm}10%$ increased only. And also, The graphs of coefficient of variation upon depth increased as straight line on every experimental group. Conclusion: The result appears that application of $364.4keV{\pm}20%$ energy ROI is more suitable for reducing error from the effective thyroid depth. And also, we can estimate the error of 20 cm should be highly reduced than 30 cm for Inverse Square Law. Therefore, If there is not information of the thyroid depth, it is considered that the error from thyroid depth can reduce through set up energy ROIs for $364.4keV{\pm}20%$, and increase Detector-Source Distances.

• Analytical Science and Technology
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• v.21 no.6
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• pp.474-479
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• 2008

Radioactivity of naturally occurring radioactive nuclides (NORN) such as $^{226}Ra$, $^{228}Ac$ and $^{40}K$ were investigated for surface sediments collected from Ordos, Alashan, Taklimakan deserts and Loess plateau regions in China. By a Gamma-ray spectrometry, specific activity (SA) and SA ratio (SAR) of the NORN were determined for each source region of Asian dust. Characterization of the source regions of Asian dust was performed with the SA and SAR values. SA of $^{226}Ra$ in the three desert regions have almost same values in the range of mean value 17.9~21.9 Bq/kg, however, the SA in Loess Plateau has much higher values in the mean value of 35 Bq/Kg. SA of $^{228}Ac$ in the Ordos and Alashan desert regions have almost same values in the range of mean value 27.1~27.2 Bq/kg, and those in Taklimakan desert and Loess Plateau were 31.7 and 49.0 Bq/kg, respectively. In case of 40K, the SA in all regions have similar values in the range of 636~943 Bq/kg. The mean SAR value of $^{226}Ra/^{228}Ac$ in four source regions was almost same in the range of 0.708-0.721. It is shown that relationship between $^{226}Ra$ and $^{228}Ac$ is clearly presented in the source regions. The mean SAR values of $^{226}Ra/^{40}K$, $^{228}Ac/^{40}K$ are 0.0209-0.056, 0.0287-0.0773, respectively.

• Nuclear Engineering and Technology
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• v.46 no.4
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• pp.547-556
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• 2014

Korea expects a shortage in storage capacity for spent fuels at reactor sites. Therefore, a need for more metal and/or concrete casks for storage systems is anticipated for either the reactor site or away from the reactor for interim storage. For the purpose of interim storage and transportation, a dual purpose metal cask that can load 21 spent fuel assemblies is being developed by Korea Radioactive Waste Management Corporation (KRMC) in Korea. At first the gamma and neutron flux for the design basis fuel were determined assuming in-core environment (the temperature, pressure, etc. of the moderator, boron, cladding, $UO_2$ pellets) in which the design basis fuel is loaded, as input data. The evaluation simulated burnup up to 45,000 MWD/MTU and decay during ten years of cooling using the SAS2H/OGIGEN-S module of the SCALE5.1 system. The results from the source term evaluation were used as input data for the final shielding evaluation utilizing the MCNP Code, which yielded the effective dose rate. The design of the cask is based on the safety requirements for normal storage conditions under 10 CFR Part 72. A radiation shielding analysis of the metal storage cask optimized for loading 21 design basis fuels was performed for two cases; one for a single cask and the other for a $2{\times}10$ cask array. For the single cask, dose rates at the external surface of the metal cask, 1m and 2m away from the cask surface, were evaluated. For the $2{\times}10$ cask array, dose rates at the center point of the array and at the center of the casks' height were evaluated. The results of the shielding analysis for the single cask show that dose rates were considerably higher at the lower side (from the bottom of the cask to the bottom of the neutron shielding) of the cask, at over 2mSv/hr at the external surface of the cask. However, this is not considered to be a significant issue since additional shielding will be installed at the storage facility. The shielding analysis results for the $2{\times}10$ cask array showed exponential decrease with distance off the sources. The controlled area boundary was calculated to be approximately 280m from the array, with a dose rate of 25mrem/yr. Actual dose rates within the controlled area boundary will be lower than 25mrem/yr, due to the decay of radioactivity of spent fuel in storage.

• Journal of Radiation Protection and Research
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• v.26 no.4
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• pp.393-398
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• 2001

The non-combustible RI wastes disposed of in hospital every year emit ${\gamma}$-ray or ${\beta}$-ray but their activities are very low to the extent of background. Development of more simple methods is needed because the conventional detection methods are so ineffective and complex. In this study, to solve this problem, detection method using efficiency curve for ${\gamma}$-ray emitting radioactive wastes measurement is proposed and experimental detection efficiency equation is also determined through HPGe's standard specimen measurement. For ${\beta}$-emitting radioisotopes detection, new measurement method using detection efficiency estimated by Monte Carlo simulation and SBD measurements is also proposed. According to the results of this paper, the unknown activity of low-level radioactive wastes without LSC requiring the preparation of standard sample and measurement for standard source detection efficiency could be determined efficiently and simply about ${\pm}17%$ in errors by using the theoretical detection efficiency and the SBD measurement result.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.347-356
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• 2010

Bauxite is a main raw material for the production of alumina and aluminum hydroxide in the processing plant of KC company. It is a NORM (Naturally Occurring Radioactive Materials), and its waste, red mud, is a TENORM (Technologically Enhanced Naturally Occurring Radioactive Materials). The purpose of the geochemical and mineralogical investigations of the bedrock and soils in and around the plant, a large NORM source, was to provide basic data for measuring the radiation dose and protecting from radioactive hazards. Soils were mixtures of minerals derived from the country rock (quartz, feldspar, mica, kaolin, gibbsite, and sepiolite) and bauxite (hematite, boehmite, and calcite) of open-air storage. Average U and Th contents of the soil samples were 4.7 ppm and 23 ppm, respectively, indicating somewhat Th anomaly. The average concentrations of radionuclides are $^{40}K$ 100~1,433 Bq/kg, $^{226}Ra$ anomaly in the red mud open-air storage. Soil external hazard indices range from 0.10 to 1.66 with an average of 0.63. Although most of the indices are below 1.0 that is a regulation value, those of 4 samples of total 41 soil samples exceed 1.0, requiring further detailed investigation.

• Journal of Welding and Joining
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• v.27 no.1
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• pp.65-70
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• 2009

Ir-192 radiation sealed sources are widely employed to the therapeutic applications as well as the non-destructive testing. Production of Ir-192 sources requires a delicate but robust welding technique because it is employed in a high radioactive working environment. A GTA(Gas Tungsten Arc) welding technique is currently well established for this purpose. However, this welding method requires a frequent replacement of the electrode, which results in the delay of the production to take a preparatory action such as to isolate the radiation sources from the working place before getting access to the welding machine. Hence, a resistance welding technique is considered as an alternative method of the GTA welding technique. The advantages of resistance welding are high welding speed and high-rate production. Also it has very long life of electrode comparing to GTA welding. In this study, the resistance welding system and proper welding conditions were established for sealing Ir-192 source capsule. As a results of various experiments, it showed that electrode displacement can be employed as a indicator to predict welding quality. We proposed two mathematical models(linear and curvilinear) to estimate electrode displacement with process parameters such as applied force, welding current and welding time by using regression analysis method. Predicting results of both linear and curvilinear model were relatively good agreement with experiment.