• Korean Chemical Engineering Research
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• 제52권3호
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• pp.279-288
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• 2014

원자력발전은 국가의 안정적인 에너지 공급원 및 저탄소 발생 에너지원으로써 기능을 해왔으나, 원자력발전에 필수적으로 발생하는 사용후핵연료 축적이라는 큰 숙제를 안고 있다. 이를 해결하기 위한 방법 중의 하나가 파이로프로세싱과 소듐냉각고속로를 연계한 사용후핵연료의 재활용이다. 용융염 전해공정을 이용하는 파이로프로세싱은 사용후핵연료에 존재하는 장 반감기 고독성 원소와 고방열 핵종을 분리하여 고준위 폐기물을 줄이면서도 고속로의 원료물질을 공급하고, 소듐냉각고속로에서는 이를 이용하여 전력을 생산한 후 다시 그 사용후핵연료를 파이로프로세싱에서 원료물질로 가공하는 개념이다. 파이로프로세싱의 전단부에 해당하는 전해환원 공정은 산화물 형태의 사용후핵연료를 금속으로 전환시켜 후속 공정인 전해정련공정에 금속을 공급하는 역할을 한다. 파이로프로세싱을 위한 전해환원 공정의 상용화를 위해서는 고용량, 고효율의 시스템 개발이 요구되므로 양극과 음극에서 공정 속도의 영향을 미치는 인자를 연구하였다.

• 한국세라믹학회지
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• 제32권4호
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• pp.471-481
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• 1995

Unirradiated UO2 pellets were pulverized by oxidation in air at 40$0^{\circ}C$, and the oxidized powders were reduced in H2 and CO atmospheres at $600^{\circ}C$. During the oxidation of UO2 at 40$0^{\circ}C$, intergranular cracks which caused the spallation were mainly developed by the volume contraction due to the formation of intermediate phase (U4O9 or U3O7). As oxidation proceeded, U3O8 finally formed. As the oxidation/reduction cycles were repeated, the powder surface became coarser, specific surface area was increased and average particle size was decreased. The sintered densities of the powder were increased by the oxidation/reduction cycle due to the characteristic changes of the powder.

• Nuclear Engineering and Technology
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• 제52권4호
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• pp.674-680
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• 2020

We used MCNP6 computer code to model HTR-10 core reactor. We used two types of fuel; UO₂ and (Th+Pu)O₂ mixture. We determined the critical height at which the reactor approached criticality in both two cases. The neutronic and burnup parameters were investigated. The results indicated that the core fueled with mixed (Th+Pu)O₂, achieved about 24% higher fuel cycle length than the UO₂ case. It also enhanced safeguard security by burning Pu isotopes. The results were compared with previously published papers and good agreements were found.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.224-225
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• 2018

Modern people are more interested in the indoor environment as they spend more time indoors than in the past. Among the air pollutants in the indoor air, ladon gas is a colorless, tasteless, odorless, inert gas produced by nuclear decomposition of naturally occurring uranium in rocks and soils. It has been proven that ladon gas is introduced into the room through cracks on the floor of the building or basement wall, and it causes various diseases such as lung cancer when exposed to radon during human breathing. The US Environmental Protection Agency (EPA) specifies 4pCi / L as a necessary measure for radon, and the Korea Environmental Protection Agency has implemented comprehensive indoor radon management measures since 2007. Therefore, in this study, we intend to adsorb and reduce radon in indoor air pollutants.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.863-868
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• 2014

The evaluation of thermal properties of actinide oxide fuels is a problem of high importance for the development of new generation reactors. In the present study, an expression obtained for n-dimensional Debye functions is used to derive a simple analytical expression for the specific heat capacity of nuclear fuels. To test the validity and reliability of this expression, the analytical expression is applied to $UO_2$, $NpO_2$, $ThO_2$, and $PuO_2$. It is seen that the formula was in agreement with the experimental and theoretical results reported in the literature.

• Bulletin of the Korean Chemical Society
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• 제21권12호
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• pp.1187-1192
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• 2000

Ternary (Mo-Ru-Pd) and binary (Mo-Ru, Mo-Pd) alloys have been prepared using an Ar arc melting furnace. Mo and the noble metals, Ru and Pd, are the constituents of metallic insoluble residues, which were found in the early days of post-irradiation studies on uranium oxide fuels. In the present study, the structure of the alloys was evaluated using a powder X-ray diffractometer. Unit cell parameters were determined by least squares refinements of powder X-ray diffraction data. Scanning electron microscopic analyses of the surface of the alloys indicated that surface morphology was dependent on the crystallographic structure as well as its composition. Measurements of the magnetic susceptibility of the alloys showed evidence of superconducting transition from 3 to 9.2 K. Among the ternary and binary alloys, the ${\sigma}-phase$ showed the highest superconducting transition temperature,~9.2 K.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1541-1548
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• 2022

The thermal conductivity of uranium oxide (UO₂) containing pores and grain boundaries is investigated using continuum-level simulations based on the finite-difference method in two and three dimensions. Steady-state heat conduction is solved on microstructures generated from the phase-field model of the porous polycrystal to calculate the effective thermal conductivity of the domain. The effects of porosity, pore size, and grain size on the effective thermal conductivity of UO₂ are quantified. Using simulation results, a new empirical model is developed to predict the effective thermal conductivity of porous polycrystalline UO₂ fuel as a function of porosity and grain size.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.631-640
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• 2019

Thorium ($^{232}Th$) is four times more abundant than uranium in nature and has become a new important source of energy in the future. This is due to the ability of thorium to undergo the bombardment of neutron to produce uranium-233 ($^{233}U$). The aim of this study is to investigate the production cost of thorium oxide ($ThO_2$) resulted from the thorium extraction process. Four main parameters were studied which include raw material and chemical cost, total capital investment, direct cost and indirect cost. These parameters were justified to obtain the final production cost for the thorium extraction process. The result showed that the raw material costs were $63,126.00 - $104,120.77 (0.5 ton), $126,252.00 - $178,241.53 (1.0 ton), and $1,262,520.00 - $1,782,415.33 (10.0 tons). The total installed equipment and total cost investment were estimated to be approximately $11,542,984.10 and $13,274,431.715 respectively. Hence, the total costs for producing 1 kg $ThO_2$ were $6829.79 - $6911.78, $3540.95 - $3592.94, and $501.18 - $553.17 for 0.5, 1.0, and 10.0 tons respectively. The result concluded that with higher mass production, the cost of 1 kg $ThO_2$ would be reduced which in this scenario, the lowest production cost was $$501.18kg^{-1}$-$$553.17kg^{-1}$ for 10.0 tons of $ThO_2$ production.

• 방사성폐기물학회지
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• 제8권1호
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• pp.19-32
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• 2010

고온 용융염 전해환원 공정은 후행핵연료 주기의 대안 공정인 파이로공정의 산화물 사용후핵연료의 확대를 위해 필수적인 공정이다. 사용후핵연료는 다성분 산화물로 이루어져 있으며 각 산화물은 전해환원 공정에서 화학적 특성에 따라 산소를 잃게 된다. 본 연구에서는 건식분말화 공정 이후 전해환원 반응기에 도입되는 사용후핵연료 조성을 기준으로 각 금속-산소 시스템을 독립적인 이상고용체로 가정하여 전해환원 반응거동을 계산하였다. 전해환원을 Li의 환원과 이어지는 Li과의 화학반응의 결합으로 산정하여 U을 비롯한 금속 환원 거동을 계산하였다. 계산결과 대부분의 산화물들은 전해환원 공정에 의해 금속으로 전환되는 것으로 예상되었다. 란타나이드 원소들의 경우 $Li_2O$의 농도가 낮아지면 금속 전환율이 높아지나 대부분 산화물로 존재하는 것으로 나타났다. 추가적으로 $U_3O_8$의 전해환원 거동에 대해 Li의 확산과 Li과의 화학반응을 고려하여 반실험적 모델이 제시되었다. 실험데이터를 활용하여 매개변수를 결정하였으며 시간에 대한 환원율 및 전류에 대한 99.9% 환원 시간을 계산하였다.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1330-1337
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• 2016

A visualization test of the fuel-coolant interaction in the Test for Real cOrium Interaction with water (TROI) test facility was carried out. To experimentally simulate the In-Vessel corium Retention (IVR)- External Reactor Vessel Cooling (ERVC) conditions, prototypic corium was released directly into the coolant water without a free fall in a gas phase before making contact with the coolant. Corium (34.39 kg) consisting of uranium oxide and zirconium oxide with a weight ratio of 8:2 was superheated, and 22.54 kg of the 34.39 kg corium was passed through water contained in a transparent interaction vessel. An image of the corium jet behavior in the coolant was taken by a high-speed camera every millisecond. Thermocouple junctions installed in the vertical direction of the coolant were cut sequentially by the falling corium jet. It was clearly observed that the visualization image of the corium jet taken during the fuel-coolant interaction corresponded with the temperature variations in the direction of the falling melt. The corium penetrated through the coolant, and the jet leading edge velocity was 2.0 m/s. Debris smaller than 1 mm was 15% of the total weight of the debris collected after a fuel-coolant interaction test, and the mass median diameter was 2.9 mm.