• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.46-51
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• 1998

토륨핵연료를 이용한 플루토늄 소모에 대한 연구를 목적으로 조직된 IAEA CRP(Coordinated Research Program) 업무의 일환으로, 농축우라늄 및 플루토늄을 seed로한 토륨핵연료를 국내의 900MWe 가압경수로에 이용하였을 경우에 플루토늄을 비롯한 heavy isotope의 원소량 변화, 사용 후 핵연료로부터의 방사능 준위, 노심의 반응도 특성을 분석하여 혼합핵연료 노심과 비교하였다. (Th+Pu)O$_2$,는 혼합핵연료 보다 플루토늄의 소모량이 약 2.4배 많으며, fissile 플루토늄 원소의 존재비율은 10% 정도 더 감소하는 것으로 나타나 플루토늄 소모의 특성이 유리하고 핵비확산 성격이 강한 것으로 나타났다 사용후 핵연료의 방사능은, 핵연료가 노심에서 바로 인출된 시점에서 는 (Th+Pu)O$_2$,가 가장 낮으나, 그 이후로는 (Th+Pu)O$_2$와 혼합핵연료의 방사능은 비슷한 반면, (Th+U)O$_2$,의 방사능이 가장 낮은 것으로 나타나 장기적으로는 (Th+U)O$_2$가 가장 유리하다. 대략적인 전환비는 (Th+Pu)O$_2$노심이 약 0.56, (Th+U)O$_2$ 노심은 약 0.63, 혼합핵연료 노심은 약 0.61 정도로 추정되었다. 토륨핵연료의 연소도에 따른 반응도 변화, 가돌리니아봉의 중성자 횹수 성질 및 반응도 특성 등 노심특성은 seed 물질의 특성과 함량에 따라 좌우되는 것으로 나타났다.

• Membrane Journal
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• v.9 no.2
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• pp.132-139
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• 1999

Solid scintillation proximity membranes were prepared for measuring the amount of radioactivity in laboratories contaminated by the radionuclide of $^3H$-cortisol. The membranes, consisting of polysulfone as a polymer matrix and cerium activated yttrium silicate as a fluor, were used to monitor the amount of radioactivity without the aid of a scintillation cocktail required for the conventional wipe test. The test results of the cocktail-free wipe test showed that the prepared membranes were efficient to monitor radionuclide-contaminated areas with the good counting ability as well as with the decrease of overall production of radioactive waste. On the other hand, solvent treatment of the prepared membranes could induce a significant variation of membrane morphology, but the counting efficiency of the solvent-treated membranes was not improved than that of the untreated one.

• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.130-136
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• 1985

The activity measurement of a solution of $^{133}Ba$ which is an electron capture nuclide was carried out by the ${\beta}-{\gamma}$ coincidence method. The counting rates at the ${\beta}-,\;{\gamma}-$, and coincidence-channels were measured using a $4{\pi}$ proportional counter and two NaI(Tl) scintillation detectors. The specific activity of the solution calculated by the efficiency extrapolation was $(1151.01{\pm}2.99)kBqg^{-1}$ at the reference time(00h UT, 03-15-84). According to an international comparison of activity measurements organized by the Bureau International des Poids et Mesures, this result showed the difference of 0.94% to the mean value derived from the comparison.

• Journal of Radiation Protection and Research
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• v.29 no.4
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• pp.231-236
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• 2004

An imaging plate(IP) detector, a two-dimensional digital radiation detector that can acquire image of radioactivity distribution in a sample, has been applied in many fields; for industrial radiography, medical diagnosis, X-ray diffraction test, etc. In this study, the possibility of IP detector to be used lot measuring radioactivity of sample is explored using its high sensitivity, higher spatial resolution, wider dynamic range and screen uniformity for several kinds radiations. First, the IP detector is applied to measure the surface uniformity for area source. Surface uniformity is measured rapidly and nondestructively by measuring the radioactivity distribution of common standard area source$(^{241}Am)$. Next, the IP is employed to study the possibility of measuring an extremely low-level activity of environmental sample. For this study the screen uniformity, shield effect of background radiation, linear dynamic range and fading effect of the IP detector is investigated. The potato, banana, radish and carrot samples are chosen to measure ultra low-level activity of $^{40}K$ isotope. The efficiency calibration of IP detector is carried out using the standard source.

• Journal of Radiation Protection and Research
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• v.34 no.3
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• pp.115-120
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• 2009

Since 1990s, some events - detection of a dirty bomb in a Russian nation park in 1995, 9/11 terrorist attack to WTC in 2001, discovery of Al-Qaeda's experimentation to build a dirty bomb in 2003 etc - have showed that nuclear or radiological terrorism relating to radioactive materials (hereinafter "radioactive materials" is referred to as "nuclear material, nuclear spent fuel and radioactive source") is not incredible but serious and credible threat. Thus, to respond to the new threat, the international community has not only strengthened security and physical protection of radioactive materials but also established prevention of and response to illicit trafficking of radioactive materials. In this regard, our government has enacted or revised the national regulatory framework with a view to improving security of radioactive materials and joined the international convention or agreement to meet this international trend. For the purpose of prevention of nuclear/radiological terrorism, this paper reviews physical characteristics of nuclear material and existing detection instruments used for prevention of illicit trafficking. Finally, national detection regime against nuclear/radiological terrorism based on paths of the smuggled radioactive materials to terrorist's target building/area, national topography and road networks, and defence-in-depth concept is suggested in this paper. This study should contribute to protect people's health, safety and environment from nuclear/radiological terrorism.

• 한국해양학회지
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• v.30 no.4
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• pp.288-301
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• 1995

Rates of the sedimentation and particle mixing have been estimated by applying uranium-series disequilibrium techniques to three sediment cores collected from the korea Deep Ocean Study (KODOS) site between the clarion and Clipperton Fracture Zones (CCFZ) of the Equatorial Pacific. Sedimentation rates based on the profiles of excess /SUP 230/Th activity and /SUP 230/ Th/SUB xs//SUP 232/ Th activity ratios at the southeastern part of the study area were estimated to be in the order of a few millimeters per thousand year, while at the northwestern part a factor of ten lower. Excess activities of /SUP 230/Th and /SUP 230/Th ratios showed intervals of constant values in the upper part of the sediment cores, probably generated by biological particle mixing. A "two-box" advection-diffusion steady state mixing model was employed in order to estimate particle mixing rates in the upper and the lower layers, based on the distribution profiles of excess /SUP 210/Pb activities. Particle mixing coefficients were estimated to be in the order of 10$^1$ cm$^2$/y in the upper layer and 10/SUP -1/-10/SUP 0/ cm$^2$/y in the lower layer.

• The Korean Journal of Nuclear Medicine
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• v.33 no.6
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• pp.519-526
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• 1999

Purpose: This study was designed to evaluate the usefulness of a technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3) single photon emission computed tomography (SPECT) performed on transplanted kidney. Materials and Methods: Thirty renal transplant patients were included in this study. Planar scan was performed for 30 minutes using 555 MBq Tc-99m MAG3. A post-voiding SPECT scan was acquired on the third, seventh, fourteenth and twenty eighth day after transplantation. Results: SPECT scan showed interpretable image quality in 26 of 30 patients (86.7%) and 84 in 120 scans (70%). Fourteen of 26 patients with interpretable SPECT image showed decreased or increased radioactivity, but only 5 had abnormal findings on the planar scan. Focal SPECT defects were seen in allografts with normal function (n=3), acute tubular necrosis (n=3), and acute rejection (n=2). The defects are thought to reflect focally underperfused renal parenchyme or, in normal allografts, an artifact from uneven radioactivity distribution. Four of 10 patients with renal arterial variation showed focally decreased radioactivity and SPECT helped guide funker studies that confirmed the exact cause. Five of 10 patients with acute tubular necrosis or acute rejection showed focally decreased radioactivity, but its relation to the patients' clinical course was not clear. Focally increased radioactivity was observed in 5 allografts with normal function and 1 with double ureter in which local clearance delay was observed. Conclusion: Tc-99m MAG3 SPECT renal scan can detect additional focal abnormalities compared to planar scan. Further study is necessary to elucidate the exact clinical significance of the SPECT findings.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.59-66
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• 2013

Purpose: Recently, there is an increase of the number of hospitals using auto dispenser to reduce occupational radiation exposure when drawing up of the $^{18}F-FDG$ dose (5.18 MBq/kg) in a syringe from the dramatic high activity of $^{18}F-FDG$ multidose vial. The aim of this study is to confirm that using auto dispenser actually reduces the radiation exposure for technologists. Also we analyzed the reproducibility of auto dispenser to find optimized dispensing method for the device. Materials and Methods: We conducted three experiments. Comparison of radiation exposure on chest and hands: The chest and hands exposure dose received by technologists during the injection were measured by electronic personal dosimeter (EPD) and ring TLD respectively. Reproducibility of dispensed volume: We draw up the normal saline into 5 and 2 mL syringe using auto dispenser by changing the volume from 1 to 15 mm for 5 times in the same setting of the volume. The weight of 5 normal saline dispensed from the device at same volume was measured using micro balance and calculated standard deviation and coefficient of variation. Reproducibility of dispensed radioactivity: We dispensed 362.6 $MBq{\pm}10%$ of $^{18}F-FDG$ in 5 and 2 mL syringes from the multidose vial of different specific activity. In the same setting of volume, we repeated dispensing for 4 times and compared standard deviation and coefficient of variation of radioactivity between 5 syringes. Results: There was significant difference in the average of chest exposure dose according to the dispensing methods (P<0.05). Also, when dispensing $^{18}F-FDG$ in manual method, exposure dose was 11.5 times higher in right hand and 4.8 times higher in left hand than in auto method. In the result of reproducibility of dispensed volume, standard deviation and coefficient of variation shows decline as the dispensing volume increases. As a result of reproducibility of dispensed radioactivity, standard deviation and coefficient of variation increases as the specific activity increases. Conclusion: We approved that the occupational radiation exposure dose of technologists were reduced when dispensing $^{18}F-FDG$ using auto dose dispenser. Secondly, using small syringes helps to increase reproducibility of auto dose dispense. And also, if you lower the specific activity of $^{18}F-FDG$ in multidose vial below 915-1,020 MBq/mL, you can use auto dispenser more effectively keeping the coefficient of variation lower than 10%.

• Journal of the Korean Society of Radiology
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• v.9 no.6
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• pp.357-362
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• 2015

This study was to evaluate the usefulness through the comparison of patients group and healthy control group by acquiring a variety of functional parameters index from time-activity curves of salivary gland scan using 99mTc-pertechnetate. From December 2014 to February 2015, had the targets of 30 patients with dry mouth and 10 people in healthy control group underwent the salivary gland scan. After intravenous injection of 370 MBq of 99mTc-pertechnetate, Vitamin C powder stimulation was administerd orally at 20 min and then 10 minutes were taken scan. The method of quantitative analysis was as follows, the time-activity curve was drawn after the parotid gland and submandible gland were prescribed as a region of interest, a variety of function parameters index was obtained in each position of the curve, and the patients group and the control group were compared. As for the methods applied in comparison and measurement, uptake ratio (UR), time at maximum counts (Tmax), time at minimum counts (Tmin), maximum accumulation (MA), accumulation velocity, maximum secretion (MS), maximum stimulation secretion (MSS), and secretion velocity (SV) were used. In the comparison of functional parameters index of patient group and normal group, the healthy normal group showed significant difference compared to the patient group in all indices except for the minimum radioactivity time (Tmin), and also in terms of variation over time the normal group showed significant difference compared to the patient group (p<0.05). Consequently, it was considered that the quantitative analysis that used a variety of function parameters index would be useful for evaluating the function of the salivary glands of the patients with dry mouth as an objective and standardized information.

• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.531-538
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• 2017

Agricultural products produced in the agricultural area around the nuclear power plant are radioactive contamination, which can cause radioactive contamination to the human body. The purpose of this study was to investigate the limit of the radioactivity concentration $^{90}Sr$ for the internal exposure dose evaluation by ingesting the agricultural products collected around the nuclear power plant. The results of the gamma-isotope element analysis were freshly <0.0166-0.0336 Bq / kg for all samples and for artificial radionuclides not detected, and fresh <0.00586-0.0421 Bq / kg for Chinese cabbage, The freshness was 0.106 Bq / kg, and the freshness was 0.0114-0.0901 Bq / kg. 0.0177%, 0.0222%, 0.0376% and 0.00243%, respectively, for Chinese cabbages and large roots, which is lower than the legal standard value of $1mSv/yr{\cdot}man%$. It is considered that the formulas need to be broadly evaluated for the foods consumed by children and adults, taking into consideration the age of the food and the diet