• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1863-1870
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• 2023

Molybdenum-99 (⁹⁹Mo) is used for preparing Technetium-99 m (^99mTc), which is the most widely used isotope in nuclear medicine. In this work, a study for ⁹⁹Mo production based on a high-power electron accelerator has been performed as an alternative approach to produce ^99mTc. In this study, Monte Carlo MCNPX2.6 code has been used to examine a novel idea of simultaneous hybrid production of ⁹⁹Mo via both photoneutron and neutron capture reactions using an electron accelerator in heavy water tank. It is expected that this conceptual design including an arrangement of metallic plates of ¹⁰⁰Mo and ⁹⁸Mo produces total activity of 97.5 Ci at the end of 20-h continuous e-beam irradiation (30 MeV, 10 mA).

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.613-623
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• 2016

Molybdenum-99 ($^{99}Mo$) is the most important isotope because its daughter isotope, technetium-99m ($^{99m}Tc$), has been the most widely used medical radioisotope for more than 50 years, accounting for > 80% of total nuclear diagnostics worldwide. In this review, radiochemical routes for the production of $^{99}Mo$, and the aspects for selecting a suitable process strategy are discussed from the historical viewpoint of $^{99}Mo$ technology developments. Most of the industrial-scale $^{99}Mo$ processes have been based on the fission of $^{235}U$. Recently, important issues have been raised for the conversion of fission $^{99}Mo$ targets from highly enriched uranium to low enriched uranium (LEU). The development of new LEU targets with higher density was requested to compensate for the loss of $^{99}Mo$ yield, caused by a significant reduction of $^{235}U$ enrichment, from the conversion. As the dramatic increment of intermediate level liquid waste is also expected from the conversion, an effective strategy to reduce the waste generation from the fission $^{99}Mo$ production is required. The mitigation of radioxenon emission from medical radioisotope production facilities is discussed in relation with the monitoring of nuclear explosions and comprehensive nuclear test ban. Lastly, the $^{99}Mo$ production process paired with the Korea Atomic Energy Research Institute's own LEU target is proposed as one of the most suitable processes for the LEU target.

• 방사성폐기물학회지
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• 제13권2호
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• pp.155-161
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• 2015

몰리브덴-99의 붕괴에 의해 생산되는 테크네튬-99m 은 방사선 진단에 중요한 역할을 담당하고 있다. 몰리브덴-99 는 주로 우라늄-235의 핵분열에 의해 생산되고 있으며, 이를 위해 고농축 우라늄 표적 또는 저농축 우라늄 표적이 연구로에서 조사된다. 현재는 고농축 우라늄의 사용에 따른 핵확산 문제를 저감하기 위해 저농축 우라늄 표적의 사용이 권장되고 있다. 본 연구는 몰리브덴-99 생산 시설의 계획 단계에서 방사성 폐기물 관리 전략을 정의하기 위하여 저농축 우라늄의 사용이 방사성 폐기물의 흐름에 미치는 영향을 분석하였다. 저농축 우라늄 표적 사용 시 우라늄 함유 폐기물의 부피가 6배 이상 증가하기 때문에 우라늄 고밀도 표적의 사용과 고온 정수압 압축법의 활용이 제안되었다.

• 한국안전학회지
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• 제12권3호
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• pp.97-105
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• 1997

Mo-99(Molybdenum) is the only source of Tc-99m(Technetium) which is most frequently used in nuclear medical diagnostics and the demand is on the increase recently. Separation and refining of Mo-99 was investigated by adsorption and desorption on alumina. At pH=0.63, adsorption isotherm of Mo was fitted by Redlich ＆ Peterson equation using the adsorption experimental data. It was found that the pore diffusion model ($D_p=1.4{\times}10^{-6}cm^2/s, K_f/=0.4 cm/s$) agreed well with batch adsorption experimental data. RTDs(Residence Time Distributions ) were measured and axial dispersion coefficients were obtained in the fixed bed absorber according to the changes of the flow rate using 0.05% -NaCl. From the adsorption experimental data, it was shown that the behavior of breakthroughs depended on flow rate. Mo recovery yield was increased as adsorption flow rate was increased and desorption flow rate was decreased.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1517-1523
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• 2020

The widely used medical isotope technetium-99 m (^99mTc) is a daughter of Molybdenum-99 (⁹⁹Mo), which is mainly produced using dedicated research reactors from the nuclear fission of uranium-235 (²³⁵U). ^99mTc has been used for several decades, which covers about 80% of the all the nuclear diagnostics procedures. Recently, the instability of the supply has become an important topic throughout the international radioisotope communities. The aging of major ⁹⁹Mo production reactors has also caused frequent shutdowns. It has triggered movements to establish new research reactors for ⁹⁹Mo production, as well as the development of various ⁹⁹Mo production technologies. In this context, a new research reactor project was launched in 2012 in Korea. At the same time, the development of fission-based ⁹⁹Mo production process was initiated by Korea Atomic Energy Research Institute (KAERI) in 2012 in order to be implemented by the new research reactor. The KAERI process is based on the caustic dissolution of plate-type LEU (low enriched uranium) dispersion targets, followed by the separation and purification using a series of columns. The development of proper waste treatment technologies for the gaseous, liquid, and solid radioactive wastes also took place. The first stage of this process development was completed in 2018. In this paper, the results of the hot test production of fission ⁹⁹Mo using HANARO, KAERI's 30 MW research reactor, was described.

• 자원리싸이클링
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• 제12권2호
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• pp.36-44
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• 2003

전구용 필라멘트 제조 공정에서 발생되는 Mo함유 폐산 내에 암모니아 가스를 취입하여 유가금속인 Mo를 암모늄테트라몰리브데이트($_3$.2NH$4MoO_3$.$H_2$O) 형태로 침전 회수하고, 여과 후 발생되는 중화 여액을 활용하기 위한 연구를 수행하였다. 암모니아 중화법을 이용한 Mo 회수공정에 있어 다양한 공정 변수들에 의한 제품의 회수율, 순도, 입도 등 특성을 평가하였으며, 그 결과로부터 Mo 염의 회수율 99.5% 이상, 순도 99.5% 이상을 확보하기 위한 최적 조업조건을 도출하였다. Bench 및 Pilot규모의 실험을 통하여 상업화 가능성을 확인하였으며, 폐산의 중화반응 후 발생된 여액은 엽면시비용 액상 복합비료의 원료로 사용 가능함을 확인하였다.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.979-986
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• 2013

Uranium metal particle dispersion plates have been proposed as targets for Molybdenum-99 (Mo-99) production to improve the radioisotope production efficiency of conventional low enriched uranium targets. In this study, uranium powder was produced by centrifugal atomization, and miniature target plates containing uranium particles in an aluminum matrix with uranium densities up to 9 $g-U/cm^3$ were fabricated. Additional heat treatment was applied to convert the uranium particles into UAlx compounds by a chemical reaction of the uranium particles and aluminum matrix. Thus, these target plates can be treated with the same alkaline dissolution process that is used for conventional $UAl_x$ dispersion targets, while increasing the uranium density in the target plates.

• 자원리싸이클링
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• 제20권5호
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• pp.40-45
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• 2011

본 연구는 전자산업용 몰리브덴 스크랩의 재활용을 위하여 수소 첨가 아르곤(Ar-H$_2$) 분위기의 진공 아크 용해(VAM)에 의한 정련 효과를 조사하였고 정련된 몰리브덴의 극미량 불순물은 글로방전 질량분석기(GDMS)를 이용하여 분석하였다. 텅스텐을 제외한 몰리브덴 내 대부분의 불순물은 Ar-H$_2$ VAM의 의하여 수 ppm 수준으로 제거되어 초기 몰리브덴 스크랩의 순도인 3N(99.95%)급에서 4N(99.995%)급으로 향상되었다. 또한 몰리브덴 내 가스 불순물인 C, N, O의 경우 초기 1290 ppm에서 Ar-H$_2$ VAM에 의해 132 ppm으로 감소함을 확인하였다. 따라서 본 연구는 플라즈마 및 전자빔 용해에 비해 경제적인 용해법인 진공 아크 용해에 의해 몰리브덴 스크랩의 재활용 가능성 및 정련효과를 확인할 수 있었다.

• 한국재료학회지
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• 제16권5호
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• pp.297-301
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• 2006

Si/Mo multilayer anode consisting of active/inactive material was prepared using rf/dc magnetron sputtering. Molybdenum acts as a buffer against the volume change of the Silicon. Multilayer deposited on RT (reversible treatment) copper foil current collector to enhance adhesion between Silicon and copper foil. Deposited Silicon was identified as an amorphous. Amorphous has a relatively open structure than crystal structure, thus prevents the lattice expansion and has many diffusion paths of Li ion. When deposited time of Silicon and Molybdenum is 30 second and 2 second respectably, electrode has more capacity and good cycle stability. A 3000 nm thick multilayer was maintained 99% of the initial capacity (1624 $mAhg^{-1}$) after 100 cycles. As the increase of the multilayer thickness (4500 nm, 6000 nm), Si/Mo mutilayer anodes show aggravation cycle stability.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.376.1-376.1
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• 2014

그래핀은 차세대 2차원 물질로서 지금까지 활발히 연구되어 왔으나 밴드갭이 없기 때문에 전자소자로서의 응용이 매우 제한적이다. 최근에 그래핀을 대체할 수 있는 물질로서 Transition Metal Dichalcogenides (TMDs)가 주목을 받고 있다. 특히, TMDs 중에서 $MoS_2$는 bulk일 때 indirect한 1.2 eV인 밴드 갭을 갖고 있으나, layer가 줄어들면서 direct한 1.8 eV인 밴드갭을 가진다. 국내외 여러 연구 그룹에서 $MoS_2$를 이용하여 제작한 Field Effect Transistor (FET)는 high-$\small{K}$ gate가 산입되지 않은 경우에 on-off ratio와 mobility가 각각 $10^6$와 약 $3cm^2/Vs$로 나타나고 있다. 이와 같이 아주 우수한 전기적, 광학적 특성을 갖는 소자 응용성을 가지고 있다. 최근까지의 연구결과들은 대부분 mechanical exfoliation method (MEM) 로 제작된 $MoS_2$ monolayer를 이용하였으나, 이 방법은 large scale 및 layer controllable에는 적합하지 않다. 본 연구에서는 대면적의 집적회로 응용에 적합한 chemical vapor deposition법을 이용하여 $MoS_2$를 성장하였다. 높은 결정성을 위해 sulphur (powder purity 99.99%)와 molybdenum trioxide(powder purity 99.9%)를 이용하고, Ar 가스 분위기에서 sulphur powder 및 molybdenum trioxide powder를 각각 $130^{\circ}C$ 및 $1000^{\circ}C$로 유지하며 $MoS_2$ 박막을 성장하였다. 성장된 $MoS_2$ 박막은 Atomic force Microscopy (AFM)을 통해 박막의 단차와 roughness을 확인하였다. 또한, X-ray Diffraction (XRD) pattern 분석으로 박막의 결정성을 확인하였으며, Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Photoluminescence (PL) 측정으로 광학적 특성을 분석하였다.