• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2158-2165
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• 2023

Marine radioactivity monitoring is critical for taking immediate action in case of unexpected nuclear accidents at nuclear facilities located near coastal areas. Especially when the level of contamination is not predictable, mobile monitoring systems will be useful for wide-area ocean radiation survey and for determination of the level of radioactivity. Here, we used a silicon photomultiplier and a high-efficiency GAGG crystal to fabricate a compact, battery-powered gamma spectroscopy that can be used in an ocean environment. The developed spectroscopy has compact dimensions of 6.5 × 6.5× 8 cm³ and weighs 560 g. We used LoRa, a low-power wireless protocol for communication. Successful data transmission was achieved within 1.4 m water depth. The developed gamma spectroscopy was able to detect radioactivity from a ¹³⁷Cs point source (3.7 kBq) at a distance of 20 cm in water. Moreover, we demonstrated an unmanned radioactivity monitoring system in a real sea by combining unmanned surface vehicle with the developed gamma spectroscopy. A hidden ¹³⁷Cs source (3.07 MBq) was detected by the unmanned system at a distance of 3 m. After successfully testing the developed mobile spectroscopy in an ocean environment, we believe that our proposed system will be an effective solution for mobile real-time marine radioactivity monitoring.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.366-372
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• 2020

Using several accessible published data sets, we analyzed the temporal change of ¹³⁷Cs radioactivity (per unit mass of sample) in marine sediments and investigated the effect of the water content of sediment on the ¹³⁷Cs radioactivity, to understand the behavior of ¹³⁷Cs present in marine environments. The ¹³⁷Cs radioactivity in sediments decreased more slowly in the Baltic Sea (near the Chernobyl nuclear power plant) than in the ocean near the Fukushima Daiichi nuclear power plant (FDNPP). The ¹³⁷Cs radioactivity in the sediment near the FDNPP tended to increase as the water content increased, and the water content decreased at certain sampling sites near the FDNPP for several years. Additionally, the decrease in the water content contributed to 51.2% of the average ¹³⁷Cs radioactivity decrease rate for the same period. Thus, it may be necessary to monitor both the ¹³⁷Cs radioactivity and the water content for marine sediments to track the ¹³⁷Cs that was discharged from the sites of Chernobyl and Fukushima nuclear power plants where severe accidents occurred.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3199-3209
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• 2024

During the decommissioning of nuclear and particle accelerator facilities, a considerable amount of large-scale radioactive waste may be generated. Accurately defining the activation level of the waste is crucial for proper disposal. However, directly measuring the internal radioactivity distribution poses challenges. This study introduced a novel technology employing machine learning to assess the internal radioactivity distribution based on external measurements. Random radioactivity distribution within a structure were established, and the photon spectrum measured by detectors from outside the structure was simulated using the FLUKA Monte-Carlo code. Through training with spectrum data corresponding to various radioactivity distributions, an evaluation model for radioactivity using simulated data was developed by above Monte-Carlo simulation. Convolutional Neural Network and Transformer methods were utilized to establish the evaluation model. The machine learning construction involves 5425 simulation datasets, and 603 datasets, which were used to obtain the evaluated results. Preprocessing was applied to the datasets, but the evaluation model using raw spectrum data showed the best evaluation results. The estimation of the intensity and shape of the radioactivity distribution inside the structure was achieved with a relative error of 10%. Additionally, the evaluation based on the constructed model takes only a few seconds to complete the process.

• The Korean Journal of Nuclear Medicine
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• v.22 no.1
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• pp.27-31
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• 1988

In Graves' disease, changes in orbital tissue and structure are casued by inflammatory infiltation, which induces increase of capillary permeability and breakdown of blood-tissue barriers. Using the uptake of $^{99m}Tc-DTPA$ in inflammatory lesion, Eye/Brain radioactivity ratios in brain scintigraphy were evaluated in 15 normal controls and 40 Graves' patients. The results were as follows; 1) Eye/Brain radioactivity ratio was significantly higher in Graves' ophthalmopthy group than in control group (p < 0.005). 2) In Graves' ophthalmopathy, Eye/Brain radioactivity ratio was significantly higher in active (progressive) group than in inactive (non-progressive) group (p < 0.05). 3) There was no correlation between class of ATA classification of Graves' ophthalmopathy and Eye/Brain radioactivity ratio. 4) There was no correlation between Eye/Brain radioactivity ratio and serum activity of TBII. In conclusion, Eye/Brain radioactivity ratio using $^{99m}Tc-DTPA$ brain scintigraphy may be useful to determine the activity of Graves' ophthalmopathy and whether treatment of Graves' ophthalmopathy is necessary or not.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.770-780
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• 2022

In 1993 the University of Extremadura initiated the design, construction and management of the Radiological Alert Network of Extremadura (RAREx). The goal was to acquire reliable near-real-time information on the environmental radiological status in the surroundings of the Almaraz Nuclear Power Plant by measuring, mainly, the ambient dose equivalent. However, the phased development of this network has been carried out from two points of view. Firstly, there has been an increase in the number of stations comprising the network. Secondly, there has been an increase in the number of monitored parameters. As a consequence of the growth of RAREx network, large data volumes are daily generated. To face this big data paradigm, software applications have been developed and implemented in order to maintain the indispensable real-time and efficient performance of the alert network. In this paper, the description of the current status of RAREx network after 30 years of design and performance is showed. Also, the performance of the graphing software for daily assessment of the registered parameters and the automatic on real time warning notification system, which aid with the decision making process and analysis of values of possible radiological and non-radiological alterations, is briefly described in this paper.

• YAKHAK HOEJI
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• v.41 no.3
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• pp.335-344
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• 1997

The absorption, distribution and excretion of $^{14}C$ labeled YH1885 {5,6-Dimethyl-2(4-fluorophenylamino)-4-(1-methyl-1,2,3,4-tetrahydroisoquinolin-2-yl)pyrimidine hydroc hloride), a new proton pumpinhibitor, were investigated in rats after a single administration of $^{14}C$-YH1885. 1. After intravenous administration of 5mg/kg, the blood level of radioactivity declined in a biphasic fashion with the mean terminal elimination half-life of 12.4hr. 2. After oral administration of 20mg/kg, the maximum blood level of radioactirity was reached at 4.0hr in female rats. The blood level of radioactivity-time profiles in male and female rats were similar, and the absorptionof $^{14}C$-YH1885 was not affected by food. 3. Appproximately 89% and 1% of radioactivity of the total dose were excreted in feces and urine, respectively. 4. Biliary excretion of radioactivity was 47.9% of the dose. Enterohepatic circulation of radioactivity was 49.6%. 5. Radioactivity was excreted maily into feces via bile. 6. The concentration of radioactivity in most tissues reached the peak level at 4.0hr after dosing, and then declined. Autoradiograms of male rats showed that the radioactivity levlels in the fat, harder's gland, liver and G-Itract were higher than those in the other tissues and the elimination of radioactivity from fat and liver was slow. 7. Autoradiograms of a pregnant rat showed that radioactivity was transferred to mammary gland, placenta and fetus. The radioactivity level in the mammary gland was higher than that in the blood.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.108-108
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• 1995

Pharmacokinetic studies on time-course of blood levels, tissue distribution, and excretion of G009, a potential hepatoprotective agent, were performed in male rats after a single oral dose(20mg/kg) of $\^$14/C-labelled G009. The radioactivity concentrations in plasma during 0～3 hours are low, but subsequently increase to a maximum at 12 hours after dosing. $\^$14/C-G009 was well distributed to all tissue. Tissue concentration profiles of radioactivity vary among tissues on time-course after administration. G009(single oral dosage) was distributed and/or absorbed at gastric intestines and excretional organs for initial time of 0-7 hours, and distributed to most tissue at 12-24 hours. In special, the concentration of radioactivity in tiller at 48 hours were 1% of total radioactivity of $\^$14/C-G009 administered. The expired air, urinary and fecal excretion of radioactivity within 24hours after administration were 61.5%, 1.9% and 21.2% of total radioactivity of $\^$14/C-G009 administered. The biliary excretion of radioactivity in rat increased slightly for 0-6 hours after administration. The biliary excretion of radioactivity within 48hours were 1.97%.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.562-571
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• 2003

A series of factors such as sampling, pretreatment measurement, volume estimation which induces uncertainty of the calculated radioactivity in liquid effluent released from a nuclear power plant were analyzed. It is innately impossible to estimate exact error of the calculated radioactivity, since most of the input parameters are determined by a single measurement and true value of the released radioactivity cannot be known. In this paper, a systematic model to calculate uncertainty of the released liquid radioactivity was developed based upon the guidance report published by the ISO in 1993, and the model was applied to a set of hypothetical batch release conditions. As a result, the Priority of each input parameter was turned out to be (1) wastewater volume, (2) sample volume, and (3) measured radioactivity of the sample. In addition, probability distribution of the released radioactivity was simulated by Monte Carlo method combining the probability distribution of each input parameter It was shown that the radioactivity released to the environment, which has been reported as a single value, has a certain form of probability distribution.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.111-114
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• 2010

Purpose: There has been recent interest in the radioactivity uptake and image acquisition of radioactivity concentration. The degree of uptake is strongly affected by many factors containing $^{18}F$-FDG injection volume, tumor size and the density of blood glucose. Therefore, we investigated how radioactivity uptake in target influences 2D or 3D image analysis and elucidate radioactivity concentration that mediate this effect. This study will show the relationship between the radioactivity uptake and 2D,3D image acquisition on radioactivity concentration. Materials and Methods: We got image with 2D and 3D using 1994 NEMA PET phantom and GE Discovery(GE, U.S.A) STe 16 PET/CT setting the ratio of background and hot sphere's radioactivity concentration as being a standard of 1:2, 1:4, 1:8, 1:10, 1:20, and 1:30 respectively. And we set 10 minutes for CT attenuation correction and acquisition time. For the reconstruction method, we applied iteration method with twice of the iterative and twenty times subset to both 2D and 3D respectively. For analyzing the images, We set the same ROI at the center of hot sphere and the background radioactivity. We measured the radioactivity count of each part of hot sphere and background, and it was comparative analyzed. Results: The ratio of hot sphere's radioactivity density and the background radioactivity with setting ROI was 1:1.93, 1:3.86, 1:7.79, 1:8.04, 1:18.72, and 1:26.90 in 2D, and 1:1.95, 1:3.71, 1:7.10, 1:7.49, 1:15.10, and 1:23.24 in 3D. The differences of percentage were 3.50%, 3.47%, 8.12%, 8.02%, 10.58%, and 11.06% in 2D, the minimum differentiation was 3.47%, and the maximum one was 11.06%. In 3D, the difference of percentage was 3.66%, 4.80%, 8.38%, 23.92%, 23.86%, and 22.69%. Conclusion: The difference of accumulated concentrations is significantly increased following enhancement of radioactivity concentration. The change of radioactivity density in 2D image is affected by less than 3D. For those reasons, when patient is examined as follow up scan with changing the acquisition mode, scan should be conducted considering those things may affect to the quantitative analysis result and take into account these differences at reading.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.379-380
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• 2017