• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.147-159
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• 2024

Plutonium-238 has always been considered as the one of the promising radioisotopes for space nuclear power supply, which has long half-life, low radiation protection level, high power density, and stable fuel form at high temperatures. The industrial-scale production of ²³⁸Pu mainly depends on irradiating solid ²³⁷NpO₂ target in high flux reactors, however the production process faces problems such as large fission loss and high requirements for product quality control. In this paper, a conceptual design study of producing ²³⁸Pu in a multi-purpose high flux reactor was evaluated and analyzed, which includes a sensitivity analysis on ²³⁸Pu production and a further study on the irradiation scheme. It demonstrated that the target structure and its location in the reactor, as well as the operation scheme has an impact on ²³⁸Pu amount and product quality. Furthermore, the production efficiency could be improved by optimizing target material concentration, target locations in the core and reflector. This work provides technical support for irradiation production of ²³⁸Pu in high flux reactors.

• Journal of Radiation Protection and Research
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• v.49 no.1
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• pp.19-28
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• 2024

Background: This study aims to analyze radiation safety management and regulatory perceptions, focusing on companies that must report radiation sources. The intent is to reduce the gap between regulation measures and addressing real concerns while improving practical safety management measures and regulations for all stakeholders. Materials and Methods: Radiation safety officers at a total of 244 reporting companies using radiation generators (79.8%) and sealed radioisotopes (15.1%) were surveyed using a questionnaire. Results and Discussion: The perception that regulation is stronger than the actual risk of the radiation source used was 3.47 points (out of 5 points), indicating a score above average. The most important factors and considerations were education and training (48%) as a human factor, safety devices of the radiation source (71.3%) as a hazardous material factor, the use of radiation (50.8%) as an organizational environment, and the radiation effect of nearby facilities (67.2%) as a physical environment. Radiation safety management educational experience (F= 5.030, p< 0.01), the group with high subjective knowledge (t= 6.017, p< 0.001), and the group with high objective knowledge (t= 1.989, p< 0.05) was found to be better at radiation safety management. Conclusion: It is necessary to standardize the educational experience regarding radiation safety management because each staff member has individual differences in educational experience. It is necessary to provide more information on how to solve radiation accidents via educational content. Applying radiation safety regulations based on the factors that significantly affect radiation safety management shown in this survey will help improve safety.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.3996-4001
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• 2023

The High-flux Advanced Neutron Application Reactor (HANARO) produces radioisotopes (RIs) (¹³¹I, ¹⁹²Ir, etc.) through neutron irradiation on various RI production targets. Among them, ¹⁷⁷Lu and ¹⁶⁶Ho are particularly promising owing to their theranostic characteristics that facilitate simultaneous diagnosis and treatment. Prior to neutron irradiation, evaluating the nuclear heating of the RI production target is essential for ensuring the thermal-hydraulic safety of HANARO. In this study, the feasibility of producing ¹⁷⁷Lu and ¹⁶⁶Ho using irradiation holes of HANARO was investigated in terms of thermal-hydraulic safety. The nuclear heating rates of the RI production target by prompt and delayed radiation were calculated using MCNP6. The calculated nuclear heating rates were used as an input parameter in COMSOL Multiphysics to obtain the temperature distribution in an irradiation hole. The degree of temperature increase of the ¹⁷⁷Lu and ¹⁶⁶Ho production targets satisfied the safety criteria of HANARO. The nuclear heating rates and temperature distribution obtained through the in silico study are expected to provide valuable insight into the production of ¹⁷⁷Lu and ¹⁶⁶Ho using HANARO.

• Journal of Radiation Industry
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• v.17 no.4
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• pp.417-425
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• 2023

Lutetium(¹⁷⁷Lu), with its theranostic properties, is one of the most widely used radioisotopes and has a large share of the radiopharmaceutical market due to its many applications and targeted therapeutic research using lutetium-based radiopharmaceuticals. However, lutetium-based radiopharmaceuticals currently approved by the US Food and Drug Administration (FDA) are limited to the indications of gastrointestinal cancer, pancreatic neuroendocrine cancer and metastatic castration-resistant prostate cancer. To overcome these limitations, we aimed to demonstrate the feasibility of expanding the use of lutetium-based radiopharmaceuticals by verifying the availability and therapeutic efficacy of lutetium produced in a research reactor(HANARO). In this study, we confirmed the therapeutic efficacy of lutetium by using cancer cells from different types of cancer. In addition, we selected cancer biomarkers based on characteristics common to various cancer cells and compared and evaluated the therapeutic efficacy of lutetium by regulating the expression of target genes. The results showed that modulation of cancer biomarker gene expression resulted in higher therapeutic efficacy compared to lutetium alone. In conclusion, this study verified the potential use and therapeutic efficacy of lutetium based on the production of a research reactor (HANARO), providing fundamental evidence for the development of lutetium-based radiopharmaceuticals and the expansion of their indications.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2050-2056
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• 2024

Handling of radioisotopes may cause external and internal contamination to occupational workers while using radiation for medical purposes. This research aims to monitor the internal hazard of occupational workers who handle ¹³¹I. Two methods are used: in vivo or direct method and in vitro or indirect method. The in vivo or direct method was performed by assessing thyroid intake with a thyroid uptake monitoring machine. The in vitro or indirect method was performed by assessing urine samples with the help of a gamma-ray spectroscopy practice using a High-Purity Germanium (HPGe) Detector. In this study, fifty-nine thyroid counts and fifty-nine urine samples were collected from seven occupational workers who were in charge of ¹³¹I at the National Institute of Nuclear Medicine and Allied Sciences (NINMAS), Dhaka. The result showed that the average annual effective dose of seven workforces from thyroid counts were 0.0208 mSv/y, 0.0180 mSv/y, 0.0135 mSv/y, 0.0169 m Sv/y, 0.0072 mSv/y, 0.0181 mSv/y, 0.0164 mSv/y and in urine samples 0.0832 mSv/y, 0.0770 mSv/y, 0.0732 mSv/y, 0.0693 mSv/y, 0.0715 mSv/y, 0.0662 mSv/y, 0.0708 mSv/y.The total annual effective dose (in vivo and in vitro method) was found among seven workers in average 0.1039 mSv/y, 0.0950 mSv/y, 0.0868 mSv/y, 0.0862 mSv/y, 0.0787 mSv/y, 0.0843 mSv/y, 0.0872 mSv/y. Following the rules of the International Commission on Radiological Protection (ICRP), the annual limit of effective dose for occupational exposure is 20 mSv per year and the finding values from this research work are lesser than this safety boundary.

• Journal of Radiation Protection and Research
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• v.41 no.1
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• pp.31-39
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• 2016

Background: It is necessary to consider the overall countermeasure for analysis of nuclear activities according to the increase of the nuclear facilities like nuclear power and reprocessing plants in the neighboring countries including China, Taiwan, North Korea, Japan and South Korea. South Korea and comprehensive nuclear-test-ban treaty organization (CTBTO) are now operating the monitoring instruments to detect radionuclides released into the air. It is important to estimate the origin of radionuclides measured using the detection technology as well as the monitoring analysis in aspects of investigation and security of the nuclear activities in neighboring countries. Materials and methods: A three-dimensional forward/backward trajectory model has been developed to estimate the origin of radionuclides for a covert nuclear activity. The developed trajectory model was composed of forward and backward modules to track the particle positions using finite difference method. Results and discussion: A three-dimensional trajectory model was validated using the measured data at Chernobyl accident. The calculated results showed a good agreement by using the high concentration measurements and the locations where was near a release point. The three-dimensional trajectory model had some uncertainty according to the release time, release height and time interval of the trajectory at each release points. An atmospheric dispersion model called long-range accident dose assessment system (LADAS), based on the fields of regards (FOR) technique, was applied to reduce the uncertainties of the trajectory model and to improve the detective technology for estimating the radioisotopes emission area. Conclusion: The detective technology developed in this study can evaluate in release area and origin for covert nuclear activities based on measured radioisotopes at monitoring stations, and it might play critical tool to improve the ability of the nuclear safety field.

• The Korean Journal of Nuclear Medicine
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• v.8 no.1_2
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• pp.57-62
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• 1974

이 논문(論文)은 1973년(年) ICSH주최로 열린 panel에서 적혈구파괴(赤血球破壞) 장소(場所)를 결정(決定)하기 위한 생체(生體) 체표계측법(醫表計測法)의 표준화(標準化)에 관(關)한 토론(討論) 결과(結果)를 초록(抄錄)한 것이다. 체표계측(體表計測)은 체외(體外)에서 계측기(計測器)를 이용(利用)하여 각(各) 장기(臟器)에서의 방사표지물질(放射標識物質)의 분포(分布) 및 시간경과(時間經過)에 따른 변화(變化)를 측정(測定)하는 것으로서 $^{51}Cr$를 사용(使用)하여 적혈구수명(赤血球壽命)을 측정(測定)할 때 간(肝), 비(脾), 심장(心臟)의 방사능(放射能)을 계측(計測)한다. 이 방법(方法)은 각(各) 장기(臟器)에서의 적혈구파괴(赤血球破壞)의 정도(程度)를 예측할 수 있다. 특(特)히 용혈성(溶血性) 빈혈환자(貧血患者)에서 비장적출(脾臟摘出) 여부를 결정(決定)하는데 도움이 된다. 이 panel에서는 주(主)로 오차(誤差)의 원인(原因)이 되는 여러가지 요인(要因)에 대(對)하여 토론(討論)하였으며 일반적으로 다음과 같은 것에 의견(意見)의 일치(一致)를 보았다. 즉(卽) 비장(脾臟)의 위치(位置)는 $^{99m}Tc$로 비주사(脾走査)를 실시하여 결정(決定)하는것이 좋고, $^{51}Cr$은 체중(體重) 1kg당 $1.5{\mu}Ci$를 사용하여, 계측기(計測器)는 NaI crystal(직경이 5cm이상, 두께가 3.75cm이상)의 scintillation doctor를 사용하고, 계측(計測)은 $^{51}Cr$로 표지(標識)된 적혈구(赤血球) 주입후(注入後) 15분(分) 이후(以後)에 하고 다음날 계측(計測)한 후(後) 2주(週) 동안에 적어도 6번 계측(計測)한다. Data 처리는 excess count법(法)과 비(脾)와 간(肝)의 비(比)로서하는 것이 좋다.定値)에 차이(差異)가 있어 그 결과(結果)의 해석(解釋) 및 비교(比較) 검토(檢討)에 적지않은 난점(難點)이 생겨 표준화(標準化)된 공통적(共通的)인 방법(方法)의 사용(使用)이 중요(重要)하다는 사실(事實)이 인식(認識)되게 되었다. 1966년(年) 호주(濠洲)의 Sydney에서 개최(開催)되었든 제11차(第11次) 국제혈액학회(國際血學會)때 열린 제4차(第4次) International Committee for Standardization in Haematology(ICSH)에서 Diagnostic Applications of Radioisotopes in Haematology에 관(關)한 expert panel을 갖을것을 의결(議決)하여 다음과 같은 12명(名)의 위원(委員)이 결정(決定)되었으며 위원회(委員會)의 의장(議長)에 Dr. Szur, 총무(總務)에 Dr. Glass가 각각(各各) 선임(選任)되었다. 그간(間) 1967년(年) 영경(英京) London에서 첫 회합(會合)이 있은후(後) New York, Vienna(IAEA후원(後援)) Brthesda(NIH후원(後援))에서 전문위원회(專門委員會)를 갖고 적혈구수명측정법(赤血球壽命測定法)에 관(關)한 의견(意見)의 일치(一致)를 보았다. ICSH와 국제혈액학회(國際血學會)에서는 이번에 결정(決定)된 적혈구수명측정법(赤血球壽命測定法)을 널리 소개(紹介)하며, 측정법(測定法)과 얻어진 결과(結果)의 해석(解釋)에 표준화(標準化)를 기(期)할 목적(目的)으로 이에 연관성(聯關性)있는 전문지(專門誌)에 게재(揭載)할 것을 요청(要請) 받었기에 이에 전문(全文)을 소개(紹介)하는 바이다. 이들은 방사성(放射性) chromium 법(法)의 모든 세부적(細部的)인 면(面)을 표준화(標準化)하고 있으며 그간(間) 가장 논란(論難)의 대상(對象)이 되었던, $^{51}Cr$-표지방법(標識方法)에 있어서의 세가지 변법(變法),

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.213-219
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• 2013

Currently, about 35 cyclotrons have been operating in South Korea. Most of them are mainly used for the synthesis of radiopharmaceuticals such as $^{18}FDG$, which is a cancer tracer for nuclear medicine. Highly enriched $H_2{^{18}}O$ containing up to 98% of $^{18}O/O$ isotope ratio is used as the target for $^{18}F$ production. The price of the highly enriched $H_2{^{18}}O$ ranges 60~70 USD/g, and all of them have been imported from foreign country in spite of the very expensive price. The target (enriched $H_2{^{18}}O$) is non-radioactive before the proton beam irradiation. But, the post-irradiation target (used $H_2{^{18}}O$) must be managed following the National Radiation Safety Regulations, because it turns into radioactive by the radioactivation of the impurities within the target. Recently, nevertheless of the fast increasing amount of used $H_2{^{18}}O$ in accordance with the increasing number of nuclear medicine cases, any activation analysis on the used $H_2{^{18}}O$ have been conducted yet in Korea. In this research, activation analysis have been conducted to confirm the specific radioactivity(Bq/g) of each radioisotopes within the used $H_2{^{18}}O$. The analysis have been done on the 3 of 20g samples collected from the used $H_2{^{18}}O$ storages at different cyclotron centers. Based on the results, it was confirmed that the "used $H_2{^{18}}O$" contains gamma emitters such as $^{56}Co$, $^{57}Co$, $^{58}Co$, and $^{54}Mn$ as well as the considerable amount of beta emitter $^3H$. It was also confirmed that the only one sample contained over exemption level of gamma emitters while the specific activity of tritium was lower than the exemption level in all samples. The specific activity of radioisotopes were measured different levels in the samples depending on the elapsed time after irradiation. Further study on the activation of the "used $H_2{^{18}}O$" is definitely necessary, nevertheless the as-is results of this research must be useful in establishing a rational "used $H_2{^{18}}O$" management protocol.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.25-29
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• 2013

Purpose: In this study, we evaluated the accuracy of CT-based attenuation correction (AC) under the conventional CT protocol (140 kVp, on average 50-60 keV) by comparing the SPECT image qualities of different energy of radioisotopes, $^{201}Tl,\;^{99m}Tc$ and $^{131}I$. Materials and Methods: Using a cylindrical phantom, three different SPECT scans of $^{201}Tl$ (70 keV, 55.5 MBq), $^{99m}Tc$ (140 keV, 281.2 MBq) and $^{131}I$ (364 keV, 96.2 MBq) were performed. The CT image was obtained with 140 kVp and 2.5 mA in GE Hawkeye 4. The OSEM reconstruction algorithm was performed with 2 iterations and 10 subsets. The experiments were performed in the 4 different conditions; non-AC and non-scatter correction (SC), only AC, only SC, AC and SC in terms of uniformity and center to peripheral ratio (CPR). Results: The uniformity was calculated from the uniform whole region in the reconstructed images. For $^{201}Tl$ and $^{99m}Tc$, the uniformities were improved by about 10-20% AC was applied, but these were decreased by about 2% as SC was applied. The uniformity of $^{131}I$ was slightly increased as both AC and SC were applied. The CPR of the reconstructed image was close to one, when AC was applied for $^{201}Tl$ and $^{99m}Tc$ scans and $^{131}I$ was distant from 1 and that is only AC. Conclusion: The image uniformity improved by AC on low energy likely to $^{201}Tl$ and $^{99m}Tc$. However, image uniformity of high energy such as $^{131}I$ was improved, when both AC and SC was applied.

• Analytical Science and Technology
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• v.18 no.1
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• pp.5-12
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• 2005

It has been established that soft error of high precision electronic circuits can be induced by alpha particles emitted from the naturally occurring radioactive impurities such as U, and Th. As the electronic circuits have recently become lower dimension and higher density, these alpha-particle emitting radioactive impurities have to be strictly controlled. The aim of this study is to develop of NAA (Neutron Activation Analysis) and gamma-spectrometry to improve the analytical sensitivity and precision of U and Th. A new NAA method has been established using the HTS (Hydrulic transfer system) irradiation facility which has been used to produce radioisotopes for industries and medicines instead of the PTS (pneumatic transfer system) irradiation facility which has been used in general NAA. When the ultratrace impurities have to be analyzed by NAA, background gamma-ray spectra induced from $^{222}Rn$ and its progenies in air is serious problem. This unstable background has been eliminated or stabilized by the use of a nitrogen purging system. Ultra trace amounts of U (0.1 ng/g) and Th (0.01 ng/g) in high purity silica used for EMC could be analyzed by the use of HTS-NAA and low background gamma-spectrometry.