• Nuclear Engineering and Technology
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• 제51권1호
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• pp.275-283
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• 2019

Rare isotope beam facilities require shielding data in early stage of their design. There is much less shielding data on neutrons from the reactions between heavy ion beams and matter than the data on neutrons produced by protons. The purpose of the present work is to produce and thus increase the amount of shielding data on neutrons generated by high-energy heavy ion beams based on the RAON in-flight fragment facility. Calculations were performed with the computational Monte Carlo codes PHITS and MCNPX. The secondary neutron source terms were evaluated at 550 MeV/u for Ca, Kr, and Sn and at 400 MeV/u for U ions on a graphite target. Source terms and attenuation lengths were obtained by fitting the ambient dose equivalent inside an ordinary concrete shield.

• 품질경영학회지
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• 제43권3호
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• pp.239-252
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• 2015

Purpose: Lead has been widely used in radiation shielding for its low price and high workability. Recently in several europe countries, use of lead was banned for environmental issues. Also lead can cause health problems like alergies. Alternative materials for lead are highly required. The purpose of this study was to propose lead free radiation shielding material. Methods: Research of radiation shielding in Korea is not easy for certain limits such as radiation materials, experimental facilities and places. The collected data through the research were simulated using MCNPX. The simulation tools used for this study were utilized Monte Carlo method. Results: we suggest new design of lead free radiation shielding material using MCNPX code comparing shielding performance of new composite materials to lead. Conclusion: This newly introduced nano-scale composite of metal and polymer makes new chance for highly lightened radiation protective garments with endurable shielding performance.

• Wind and Structures
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• 제27권6호
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• pp.439-449
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• 2018

Wind loading of a tall building built amidst a group of buildings in urban environment is always greatly affected by shielding effects. Wind tunnel tests were carried out to assess the shielding provided by a row of low-rise or medium-rise buildings upstream a square-section tall building of height-to-breadth ratio 6. Mean and dynamic wind loads on the tall building were measured at different wind incidence angles and presented as interference factors (IFs). It is found that presence of a row of upstream buildings provides significant shielding to the tall building. At normal wind incidence, the mean along-wind loads and all components of fluctuating wind loads on the tall building are always reduced by shielding. Vortex shedding seems to still occur on the upper exposed part of the tall building but the vortex excitation levels are largely reduced. The degree of shielding is found to depend on a number of arrangement parameters of the row of upstream buildings. Empirical equations are proposed to quantify the shielding effect based on the wind tunnel data.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.216-223
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• 2017

In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and $10^{th}$ value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

• 한국군사과학기술학회지
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• 제19권4호
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• pp.453-461
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• 2016

The paper represents the experimental analysis of the shock noise of medium caliber guns when a projectile is passed through the shielding material. In the study, the shielding material was constructed and tested in three separate experiments. The shielding material was not installed for medium caliber gun in Case 1. A medium caliber gun was fully covered with shielding material in Case 2, and another one was put with shielding material near muzzle in Case 3. In each experiment, the experimental data was compared with each other. Results showed the firing shielding material achieved a significant noise reduction in $90^{\circ}$ to the noise source. Case 3 is confirmed to be better effective than Case 2 in the near field. But, the noise reduction in the far field is small in quantity due to the low frequency. The paper is considered that further study is necessary for the shielding material which can absorb a low frequency noise in the future.

• Nuclear Engineering and Technology
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• 제36권1호
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• pp.1-11
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• 2004

Two approximate methods for a cosmic radiation shielding calculation in low earth orbits were developed and assessed. Those are a sectoring method and a chord-length distribution method. In order to simulate a change in cosmic radiation environments along the satellite mission trajectory, IGRF model and AP(E)-8 model were used. When the approximate methods were applied, the geometrical model of satellite structure was approximated as one-dimensional slabs, and a pre-calculated dose-depth conversion function was introduced to simplify the dose calculation process. Verification was performed with mission data of KITSAT-1 and the calculated results were also compared with detailed 3-dimensional calculation results using Monte Carlo calculation. Dose results from the approximate methods were conservatively higher than Monte Carlo results, but were lower than experimental data in total dose rate. Differences between calculation and experimental data seem to come from the AP-8 model, for which it is reported that fluxes of proton are underestimated. We confirmed that the developed approximate method can be applied to commercial satellite shielding calculations. It is also found that commercial products of semi-conductors can be damaged due to total ionizing dose under LEO radiation environment. An intensive shielding analysis should be taken into account when commercial devices are used.

• Nuclear Engineering and Technology
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• 제53권7호
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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.

• 한국산학기술학회논문지
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• 제20권2호
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• pp.321-328
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• 2019

군 통신 쉘터는 내부에 통신 및 환경장비를 탑재하여, 네트워크 중심전에서 다양한 무기체계들의 통합적인 전투력 발휘를 위해 요구되는 정보의 송/수신 기능을 실시간 보장하고 전술환경의 생존성을 극대화시키는 장비이다. 쉘터 내부에 다양한 통신용 장비가 탑재되기 때문에 외부로부터의 전자기 공격에 대한 차페 성능을 반드시 보장해야한다. 본 연구에서는 데이터 마이닝 기법(서포트 벡터 머신)과 통계적 품질관리 기법(공정능력분석)을 이용하여 군 통신용 쉘터에서 차폐성능이 안정된 지점을 탐색하는 연구를 진행하였다. 안정된 지점의 탐색을 위하여 45대 쉘터의 EMI 차폐효과 측정데이터를 활용하였다. 먼저, 차폐효과가 안정되었다고 판단할 수 있는 기준을 세우고 서포트 벡터 머신으로 해당 기준에 부합하는 측정 포인트 집단과 그 외의 집단을 분리, 이 두 집단을 분류할 수 있는 분류 하이퍼플레인을 작성하였다. 그리고 공정능력분석을 이용하여 차폐효과 측정 데이터를 분석, 공정능력지수가 높은 측정 포인트와 서포트 벡터 머신의 하이퍼플레인으로 분류한 측정 포인트를 상호 비교함으로써 분류된 측정 포인트의 타당성과 차폐효과가 안정된 정도를 분석하였다. 분석 결과, 24개의 측정포인트에서 안정된 차폐 성능을 보유하고 있음을 확인하였다.

• 한국위성정보통신학회논문지
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• 제8권3호
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• pp.20-24
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• 2013

본 논문에서는 HEMP의 개념을 소개하고, 안테나 요소의 배치 변화에 따른 방호 효율성을 분석한다. 높은 주파수의 EMP를 맥스웰 방정식을 이용하여 LOS에서 근사한다. 전자기파 감쇄의 영향을 분석하기 위하여, 차폐룸을 구성하여 측정 데이타를 얻는데 이용한다. 수신 안테나의 거리와 주파수를 변화시켜 차폐 정도를 측정한다. 기준이 되는 미국 규격문서와 측정값을 비교하고 측정방법을 간소화해본다. 차폐룸 내부를 3가지 조건으로 만들어 변화를 차폐 정도를 측정한다. 정방향 측정과 역방향 측정의 차이를 살펴보고 차폐룸 측정에 영향을 미치는 요소를 찾는다.

• Journal of Radiation Protection and Research
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• 제43권1호
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• pp.20-28
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• 2018

Background: Heat energy produced in nuclear reactors and nuclear fuel cycle facilities interactions modifies the physical properties of the shielding materials containing water content. Therefore, in the present paper, effect of the heat on shielding effectiveness of the concretes is investigated for gamma and neutron. The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors. Materials and Methods: The mass attenuation coefficients, effective atomic numbers, fast neutron removal cross-section and exposure buildup factors of ordinary and heavy concretes were investigated using NIST data of XCOM program and Geometric Progression method. Results and Discussion: The improvement in shielding effectiveness for photon and reduction in fast neutron for ordinary concrete was observed. The change in the neutron shielding effectiveness was insignificant. Conclusion: The present investigation on interaction of gamma and neutron radiation would be very useful for assessment of shielding efficiency of the concrete used in high temperature applications such as reactors.