• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2919-2926
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• 2023

In this paper, rare earth element (REE)/polyester composites were designed with lanthanum oxide, gadolinium oxide, and lutetium oxide as ray shielding agents, and polyethylene terephthalate (PET) as the base. Monte Carlo simulation was carried out using FLUKA software. We found that the radiation protection performance of the composite is affected by the type and amount of REE; a higher amount of REE equated to a better radiation protection performance of the composite. When the thickness of the composite and total thickness of the REE is constant, the number of superimposed layers inside the composite does not affect its shielding performance. Compared with a single-type REE/PET composite, a mixed-type REE/PET composite has a wider range of γ-ray absorption and better radiation protection performance. When the mass ratio of PET to REE is 2:8 and different types of REE are mixed with equal mass, several 0.2 cm-thick mixed-type REE/PET composites can shield >70% of 60 and 80 KeV γ-rays.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.1031-1033
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• 2013

후쿠시마와 같은 방사선 누출 사고 시 방사선원의 위치를 찾는 일은 방사선 방호 뿐만 아니라 원전 사고의 조속하고 안전한 처리를 위해서도 중요하다. 방사선원의 3차원 위치 탐지는 기존에 방사선 탐지기의 2차원적 방사선 위치 탐지기능에 방사선원의 거리정보까지 추가 제공할 수 있어 방사선 오염원의 제거 및 제염작업에 결정적 역할을 할 수 있다. 본 연구에서는 반도체 센서에 기반한 듀얼(Dual) 방사선 탐지기를 이용한 방사선원 3차원 가시장치 개발 연구의 일환으로 방사선 센서부의 효율적 차폐체 구조설계에 관한 결과를 논하였다. 고하중의 텅스텐 또는 납 차폐체를 MCNP기반으로 최적구조로 설계함으로써 경량의 고효율 방사선원 위치탐지기 구현을 시도하였고, 이를 위해 차폐체의 구조와 두께, 그리고 콜리메이터에 형상의 다양한 변수모델에 대한 방사선 차폐시뮬레이션을 수행하였다. 본 연구의 결과는 향후 실리콘 센서기반의 소형 경량의 3차원 방사선원 탐지 및 가시화 연구에 활용될 예정이다.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.45-47
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• 2001

The function of the thermal shield(TS) is to eliminate the thermal radiation from the room temperature side to the coil temperature(4.5K) region so as to reduce the thermal load on the He refrigerator. The TS is composed of multilayer insulation(MLI) which is coated very thin aluminum on the insulating material, cryopanel which is cooled by cold gaseous He, and supports which stand the cryopanel and MLI on the room temperature part. The thermal shield for the TF coils and PF coils has been located between the coils and vacuum vessel. The thermal shielding cryopanel is cooled under 80 K by a forced flow of helium gas using cooling pipes on the cryopanel.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4181-4190
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• 2023

Nuclear power plants are subjected to various processes during decommissioning, including cutting, decontamination, disposal, and treatment. The cutting of massive bio-shields is a significant step in the decommissioning process. Cutting is performed near the target structure, and during this process, workers are exposed to potential radioactive elements. However, studies considering worker exposure management during such cutting operations are limited. Furthermore, dismantling a nuclear power plant under certain circumstances may result in the unnecessary radiation exposure of workers and an increase in secondary waste generation. In this study, a cutting scenario was formulated considering the bio-shield as a representative structure. The specifications of a standard South Korean radioactive waste disposal drum were used as the basic conditions. Additionally, we explored the hot-to-cold and cold-to-hot methods, with and without the application of polishing during decontamination. For evaluating various scenarios, different cutting time points up to 30 years after permanent shutdown were considered, and cutting speeds of 1-10nullm²/h were applied to account for the variability and uncertainty attributable to the design output and specifications. The obtained results provide fundamental guidelines for establishing cutting methods suitable for large structures.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.842-846
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• 2001

Our company produces boilers for industrial usages or power plants. The aim of this study is to investigate the flame structure, heat transfer to evaporator tube wall and NOx emission in the furnaces. Also we are to derive correct FEGT(Furnace Exit Gas Temperature) characteristic curve. When we design furnace and superheater, economizer etc. FEGT characteristic curve is very important factor for optimum design. We calculated turbulent reacting flow, heat transfer and NOx emission in furnace by using numerical modeling with the help of commercial code. Three dimensional steady state calculation is done. k-e turbulence model and equilibrium chemistry combustion model with $\beta-probability$ density function is used. To calculate radiation heat transfer discrete ordinates model is used. And we measured FEGT at several operating plants. Measurement is done by R-type thermocouple. Radiation shield is attached to the thermocouple to prevent radiation effect. Measured and calculated results show good agreement. And we could understand the flame structure and NOx formation positions in each furnaces.

• 중환자간호학회지
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• 제13권1호
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• pp.15-26
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• 2020

Purpose : This study aimed to examine factors affecting radiation protective behaviors among emergency room nurses by assessing knowledge, attitude, and environment for radiation protection. Methods : The study employed a cross-sectional design. Subjects were a convenience sample of 129 nurses working in emergency rooms of three general hospitals. Data were collected using self-report questionnaires and analyzed using t-test, ANOVA, Pearson correlation coefficients, and multiple regression. Results : The more the nurses received radiation safety education (t=2.26, p=.026), used protective gear (t=4.40, p<.001), and took health screenings (t=2.65, p=.009), the higher their levels of radiation protection behavior. There were significant relations between radiation protective behaviors and attitude (r=.27, p=.002), and radiation protective behaviors and environment for radiation protection (r=.55, p<.001). The factors affecting radiation protective behaviors were protective environment (β=.53, p<.001), protective attitude (β=.32, p<.001), and the use of protective gear (β=.24, p=.002). Conclusions : The government, hospital administrators, and radiation protection-related organization should adopt the following measures to protect emergency room nurses from radiation: research and development of shield instrument, medical examination for emergency room nurses, protocol development of radiation protection behaviors, extension of education chances of radiation protection, and encouraging the use of protective equipment.

• 한국산업정보학회논문지
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• 제7권4호
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• pp.37-45
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• 2002

본 연구에서는 다짐 성토의 밀도 및 수분을 측정하기 위해서 중성자 검출기는 2개 그리고 감마선 검출기는 5개를 사용하여 설계하였고, 또한 방사능 대비 방사선 방출수가 다른 선원에 비하여 우수한 Co-60 감마선원과 Cf-252 중성자 선원을 본 시스템에 이용하는 것이 정밀도를 향상시키기 위하여 유리하다는 것을 알 수 있었다. 특히 중성자와 감마선의 상호 반응으로 인한 간섭을 제거하기 위하여 2개의 중성자와 5개의 감마선 검출부 사이에 차폐체인 납을 각각 설치하였으며, 제시된 기준값 이하로 완전히 차폐하기 위한 최적 설계를 수행하였다. 이러한 최적 선계에 의하여 휴대용으로 사용될 본 시스템은 각 검출부 사이에 차폐체를 설치함에 따라 5.2[kg]의 무게를 경감할 수 있었고, 이는 산업 현장에서 쉽게 이동하고 간편하게 사용될 수 있을 것으로 사료된다.

• 한국방사선학회논문지
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• 제8권6호
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• pp.333-338
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• 2014

최근 의료 분야에서의 불필요한 피폭을 체계적으로 관리해야 한다는 사회적 요구 증가와 더불어 차폐의 중요성이 대두되고 있는 실정이다. 하지만 현재 상용화된 제품은 다양한 의료방사선 분야보다 세분되어 있지 않다. 이에 본 연구에서는 최적화된 차폐재의 구조를 몬테카를로 시뮬레이션을 활용하여 제시하고자 하였다. 모의 추정 결과, 유방촬영 에너지(30 kVp) 스펙트럼에 대하여 단일 차폐재의 경우 $30{\mu}mPb$, 2 mmAl에서 90% 이상의 차폐율을 확인하였고, 이중차폐 구조에서는 0.03 mmPb와 1 mmAl의 설계 시 효율적인 것으로 판단되었다. 또한, 일반촬영 에너지(80 kVp) 스펙트럼에 대해서는 $340{\mu}mPb$, 30 mmAl에서 90% 이상의 차폐율을 확인하였으며, 이중차폐 구조에서는 0.3 mmPb와 1 mmAl의 설계가 유용할 것으로 사료된다. 이러한 결과는 향후 피폭저감을 위한 맞춤형 상용화 제품 개발에 대한 기초자료로 활용될 수 있을 것으로 기대된다.

• 한국전기전자재료학회논문지
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• 제24권11호
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• pp.859-864
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• 2011

An operation temperature of $Pb(Zr,Ti)O_3$ based piezoelectric ultrasonic flowmeter was generally restricted to below 200$^{\circ}C$ due to a low depoling temperature of its ceramic material. Thus, a new designed piezoelectric ultrasonic flowmeter was fabricated in order to protect from the extremely hot fluid. Its structure is optimized by a finite element method to effectively stop heat flowing along a waveguide. Various materials such as Cu, Al, SUS were examined as a multi-plate radiation shield to enhance the performance of piezoelectric ultrasonic flowmeter. The SUS was evaluated as the most effective material to enhance the performance of piezoelectric ultrasonic flowmeter. As the number of plates of the radiation shield increased, the temperature at piezoelectric transducer away from the hot fluid was constantly decreased with a ratio of 3.12$^{\circ}C$ per the plate number.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.732-734
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• 2002

The rotor thermal analysis consists of determining the heat load to the rotor, sizing the cryogenic system, and ensuring that the HTS rotor will operate at the design goal of 30 K. The heat load to the rotor is due to heat conduction through the torque tubes, current leads, instrumentation. and radiation from the thermal shield and the end caps. Coil operating temperature is determined from the coil losses and the heat transport to the coolant. An FEM thermal conductivity model is developed to allow calculation of heat transport in HTS field coil according to the heat exchanger shape and coolant feeding method. The losses determine the size of the cryocooler.