• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.957-964
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• 2021

Fluorine-18 used in PET/CT scans is a radioactive isotope that emits positrons, and high energy annihilation gamma rays and beta rays cause exposure to radiation workers. In this study, as part of a plan to reduce the exposure dose of radiation workers working in the Department of Nuclear Medicine, the cause of the low shielding efficiency of Apron for F-18 was identified, and the effectiveness of the Apron double-shielded with acrylic was evaluated. L-Block, Apron+acrylic, Apron, Acrylic+Apron, and Acrylic five shields are used to measure the dose, and the tendencies were compared by performing a Monte Carlo simulation. As a result, it was found that the shielding rate of Apron double shielded with acrylic was about 4 to 8% higher than that of Apron single shielded. To the extent that it does not significantly affect the user's activity, double-shielded personal protective clothing with an appropriate acrylic thickness could help reduce radiation workers' exposure.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.271-281
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• 2019

This study investigated the shielding efficiency of various types of shielding materials and measured the dose by organ using the phantom. Results of Shielding Efficiency Measurement Using Personal Radiation Meter. Among the various shielding materials, 1.1 mm RNS-TX composed of nano tungsten showed the highest shielding efficiency and 0.2 mm lead shielding showed the lowest shielding efficiency. 99mTc 30 mCi was exposed to the phantom for 120 minutes and the result of the measurement of the organs. 20.53 mSv without radiation protective clothing, 8.75 mSv when wearing 0.25 mm Pb protective clothing, 6.03 mSv when wearing 0.5 mm Pb protective clothing. 131I 2 mCi mCi was exposed to the phantom for 120 minutes and the result of the measurement of the organs. 7.71 mSv without radiation protective clothing, 4.88 mSv when wearing 0.25 mm Pb protective clothing, 2.79 mSv when wearing 0.5 mm Pb protective clothing. 18F 5 mCi was exposed to the phantom for 120 minutes and the result of the measurement of the organs. 16.39 mSv without radiation protective clothing, 15.84 mSv when wearing 0.25 mm Pb protective clothing, 12.52 mSv when wearing 0.5 mm Pb protective clothing. None of the radiation workers working in the nuclear medicine department exceeded the dose limit. However, when compared with other workers in the hospital, they showed a relatively high dose. Therefore, it is necessary to prepare measures to reduce and manage the dose of radiation workers in the nuclear medicine department through the wearing of radiation protective clothing made of lightweight, shielding material with good shielding efficiency, circulation task, task sharing, and substitution equipment such as auto dispenser.

• Journal of radiological science and technology
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• v.34 no.2
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• pp.141-147
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• 2011

We developed an alternative radiation shielding material which is economical and has high protection efficiency. We validated the material in the form of sheet to make an apron. We increased the rate of barium and mixed tourmaline into silicon to improve the flexibility and protection rate of the sheet. The results showed that the shielding effect at low radiation energy is good enough with both 5 mm and 7 mm thickness. In the future, we will perform a quantitative evaluation of the reproducibility, volumetric efficiency, and porosity in mixing the ingredients.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.449-457
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• 2023

Shielding for reducing exposure dose can make the diagnosis limited. The purpose of this study is to increase the efficiency of radiation protection and minimize the loss of image information by producing the shielding made of the water and the contrast medium which has different proportion and finding out the ideal proportion of them. Each shielding materials were made of water and water-soluble iodine contrast medium with the different proportion. The attenuation rate of absorbed dose was evaluated by the shielding materials in the plastic contents for measuring the efficiency of the radiation protection. As a result, the higher ratio of the contrast medium, the more efficient it is for radiation attenuation. The anatomical structure was observed most properly in case of the solution with 20 ml of the contrast medium and most difficultly in case of more than 60 ml of the contrast medium. In case of the signal intensity between skeleton and gas, the difference of average value had a significant as p < 0.001. Shielding with contrast medium attenuates less than the conventional shielding but in the examination for the sensitive part to radiation, it can be used to minimize the loss of the image information and reduce the exposure dose.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.770-775
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• 2014

According to ICNIRP guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields up to 300GHz, magnetic flux density which range from 3Hz to 150kHz are regulated to lower than $6.25{\mu}T$. In order to comply with its standard, OLEV(On-Line Electric Vehicle) have been designed considering EMF(Electro-Magnetic Field) reduction. However, if a current flowing in power line would be bigger for increasing power transfer efficiency, the established shield system no longer acts their role properly. In this paper, therefore, FCCL(Flexible Copper Clad Laminate) is applied to power line and pick-up devices to solve the problems. Though, the FCCL is normally utilized to insulator on circuit board, because of its high heat resistance characteristic, flexibility and thin properties, it makes effectiveness in the shielding device as well. 4 types of FCCL shielding structure are introduced to power line and pick-up devices. From the results, the FCCL which are placed in proposed positions shows maximum EMF reduction compared to the established shielding structure. Henceforth, if OLEV is applied FCCL shielding structure in practice, it will not only be more safe but also step forward to commercialization near future.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2151-2161
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• 2021

Nuclear data (ND) sensitivity and uncertainty (S/U) quantification in shielding applications is performed using deterministic and probabilistic approaches. In this paper the validation of the newly developed deterministic program package ASUSD (ADVANTG + SUSD3D) is presented. ASUSD was developed with the aim of automating the process of ND S/U while retaining the computational efficiency of the deterministic approach to ND S/U analysis. The paper includes a detailed description of each of the programs contained within ASUSD, the computational workflow and validation results. ASUSD was validated on two shielding benchmark experiments from the Shielding Integral Benchmark Archive and Database (SINBAD) - the fission relevant ASPIS Iron 88 experiment and the fusion relevant Frascati Neutron Generator (FNG) Helium Cooled Pebble Bed (HCPB) Test Blanket Module (TBM) mock-up experiment. The validation process was performed in two stages. Firstly, the Denovo discrete ordinates transport solver was validated as a standalone solver. Secondly, the ASUSD program package as a whole was validated as a ND S/U analysis tool. Both stages of the validation process yielded excellent results, with a maximum difference of 17% in final uncertainties due to ND between ASUSD and the stochastic ND S/U approach. Based on these results, ASUSD has proven to be a user friendly and computationally efficient tool for deterministic ND S/U analysis of shielding geometries.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.92-100
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• 2015

For the purpose of improving the efficiency of the radiation impact assessment of dry interim storage facilities for the spent nuclear fuel of pressurized water reactors (PWRs), radiation impact assessment was performed after the application of sensitivity assessment according to the radiation source term designation method, development of a 2-step calculation technique, and cooling time credit. The present study successively designated radiation source terms in accordance with the cask arrangement order in the shielding building, assessed sensitivity, which affects direct dose, and confirmed that the radiation dosage of the external walls of the shielding building was dominantly affected by the two columns closest to the internal walls. In addition, in the case in which shielding buildings were introduced into storage facilities, the present study established and assessed the 2-step calculation technique, which can reduce the immense computational analysis time. Consequently, results similar to those from existing calculations were derived in approximately half the analysis time. Finally, when radiation source terms were established by adding the storage period of the storage casks successively stored in the storage facilities and the cooling period of the spent nuclear fuel, the radiation dose of the external walls of the buildings was confirmed to be approximately 40% lower than the calculated values; the cooling period was established as being identical. The present study was conducted to improve the efficiency of the Monte Carlo shielding analysis method for radiation impact assessment of interim storage facilities. If reliability is improved through the assessment of more diverse cases, the results of the present study can be used for the design of storage facilities and the establishment of site boundary standards.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.129-134
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• 2019

PVC was chosen as a plastic product that can cope with lead, a radiation shielding material that is widely used in medical institutions. In addition to radiation shielding clothing, we want to evaluate whether it can be used as a medical device component and industrial shielding material in low dose areas. Commercial PVC has a density of 3.68 g/㎠ and can be positively expected sufficient shielding effect in certain radiation areas such as material flexibility and economy efficiency, and can be transformed into various forms and used as a lightweight shielding wall. The shielding performance was tested by adjusting the thickness of 5 sheets of 3mm PVC in the range of medical radiation used for clinical examination in medical institutions. Shielding performance against effective energy was evaluated based on tube radiation voltage of medical radiation. The thicker the PVC, the lower the tube voltage and the lower the effective energy, the greater the shielding effect. The shielding effect was 70% at 12mm thickness and 80kVp tube voltage. Therefore, the shielding effect of PVC material has a high dependence of thickness. In the future, continuous research is needed to make thin and light eco-friendly products while improving shielding performance.

• Advances in materials Research
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• v.3 no.2
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• pp.61-75
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• 2014

This study aimed to investigate the suitability of some concrete components for producing "high-performance heavy density concrete" using different types of aggregates that could enhances the shielding efficiency against ${\gamma}$-rays. 15 mixes were prepared using barite, magnetite, goethite and serpentine aggregates along with 10% silica fume, 20% fly ash and 30% blast furnace slag to total OPC content for each mix. The mixes were subjected to compressive strength at 7, 28 and 90 days. In some mixes, compressive strengths were also tested up to 90 days upon replacing sand with the fine portions of magnetite, barite and goethite. The mixes containing magnetite along with 10% SF reaches the highest compressive strength exceeding over M60 requirement by 14% after 28 days. Whereas, the compressive strength of concrete containing barite was very close to M60 and exceeds upon continuing for 90 days. Also, the compressive strength of high-performance concrete incorporating magnetite fine aggregate was significantly higher than that containing sand by 23%. On the other hand, concrete made with magnetite fine aggregate had higher physico-mechanical properties than that containing barite and goethite. High-performance concrete incorporating magnetite fine aggregate enhances the shielding efficiency against ${\gamma}$-rays.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.860-866
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• 2019

The lead element or its salts are good radiation shielding materials. However, their toxic effects are high. Due to less toxicity of bismuth salts, the radiation shielding properties of the bismuth salts have been investigated and compared to that of lead salts to establish them as a better alternative to radiation shielding material to the lead element or its salts. The transmission geometry was utilized to measure the mass attenuation coefficient (${\mu}/{\rho}$) of different salts containing lead and bismuth using a high-resolution HPGe detector and different energies (between 81 and 1333 keV) emitted from point sources of $^{133}Ba$, $^{57}Co$, $^{22}Na$, $^{54}Mn$, $^{137}Cs$, and $^{60}Co$. The experimental ${\mu}/{\rho}$ results are compared with the theoretical values obtained through WinXCOM program. The theoretical calculations are in good agreement with their experimental ones. The radiation protection efficiencies, mean free paths, effective atomic numbers and electron densities for the present compounds were determined. The bismuth fluoride ($BiF_3$) is found to have maximum radiation protection efficiency among the selected salts. The results showed that present salts are more effective for reducing the intensity of gamma photons at low energy region.