• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2329-2333
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• 2022

Base metal corrosion forms a significant issue during the chemical decontamination of the primary coolant loop in nuclear power plants as it is directly related to the economic and safety viability of decommissioning. In this technical note, potentiodynamic evaluations of several base metals (304 stainless steel, SA106 Grade B carbon steel, and alloy 600) were performed to determine their corrosion behavior during the hydrazine (N₂H₄)-based reductive ion decontamination (HyBRID) process. The results suggested that N₂H₄ protected the surface of the base metals in the HyBRID solution, which is primarily composed of H₂SO₄. The corrosion resistance of the carbon steel was further improved through the addition of CuSO₄ to the solution. The corrosion rate of carbon steel in the H₂SO₄-N₂H₄-CuSO₄ solution was lower than that exhibited in an oxalic acid solution, a commonly used reaction medium during commercial decontamination processes. These results indicate the superiority of the HyBRID process with respect to the base metal stability.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.419-425
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• 2024

The purpose of this study is to improve the concentration of U(VI) in carbonate solution reasonably, which to improve the application potential of the alkaline reprocessing processes. The dissolution behavior of U₃O₈ in carbonate peroxide solutions was investigated under different conditions, including pH, carbonate concentration, and solid-liquid ratio. The results showed that the dissolution rate of U₃O₈ increased with the increase of pH from 8 to 11 in the mixed carbonate solution containing 0.5 mol/L H₂O₂. The role of carbonate ions in the dissolution of U₃O₈ was further elucidated by observing the dissolution of UO₄⋅4H₂O in carbonate solutions. Furthermore, the concentration of U(VI) in 3 mol/L Na₂CO₃ solution was successfully increased to 350 g/L under ultrasonic-assisted conditions at 60 ℃ and a solid-liquid ratio at 1/2 g/mL. Meanwhile, it is suggested that increasing the concentration of carbonate ions can improve the stability of the dissolved solution containing uranyl peroxycarbonate complex.

• 생물환경조절학회지
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• 제32권2호
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• pp.97-105
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• 2023

본 연구는 대표적인 엽채류인 로메인(Lactuca sativa L. var. longiflora) 'Caesar Green'의 수경재배에 적절한 양액 강도와 NH₄⁺ :NO₃^-의 비율을 찾기 위해 수행하였다. 첫 실험에서는 한 상업용 양액(Peters, 20-20-20)과 실험실에서 제조한 다목적 양액(GNU solution)을 2수준의 강도(GNU1, 100%; GNU2, 70%)로 조절하여 사용하였다. 발아속도는 GNU1보다 GNU2와 Peters에서 더 빨랐다. GNU1과 GNU2로 재배한 로메인이 Peters에서 재배된 것보다 초장, 엽장, 엽폭, 생체중이 더 컸다. 반면 Peters에서 재배한 로메인의 뿌리는 색이 어둡고 뿌리털이 짧았다. 조직 내 NH₄⁺ 함량은 Peters에서 GNU1 과 GNU2보다 유의하게 높았다. 두번째 실험에서는 GNU1과 GNU2 양액을 질소 형태 비율(NH₄⁺ :NO₃^-;100:0, 83.3:16.7, 66.7:33.3 및 50:50)에 따라 총 8가지로 조성하였다. NH₄⁺ :NO₃^- 비율을 50:50으로 처리했을 때 조직 내 NH₄⁺ 함량이 가장 높았고 독성 증상이 나타났다. 결론적으로 순환형 저면관수 수경재배 시스템에서 로메인에는 GNU2-2가 적합한 양액이었다. 두 실험 모두 비교적 이온 강도가 낮은 양액인 GNU2 그룹에서 더 많은 생장을 보였다. GNU2-2 양액에서 가장 높은 생체중을 보이면서도 NO₃^-의 조직 내 함량이 낮았다. 이는 GNU2 하위 그룹이 이온 강도가 낮기 때문에 조직 내 잉여 NO₃^-의 축적을 억제한다는 점에서 식품안전성 측면에서 더 유리했다. 또한 이것은 양액에의 무기양분 투입 절대량을 줄일 수 있다는 점에서 바람직하다.

• 대한기계학회논문집B
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• 제23권2호
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• pp.272-280
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• 1999

A cycle analysis was achieved to predict the characteristics by comprehensive modeling and simulation of an air-cooled, double-effect absorption system using a new $H_2O/LiBr+HO(CH_2)_3OH$ solution. The simulation results showed that the new working fluid may provide the crystallization limit 8% higher than the conventional $H_2O/LiBr$ solution. With a crystallization margin of 3wt%(weight%), the optimal solution distribution ratio was found in the range of 36 to 40%. Variation of cooling air Inlet temperature has a sensitive effect on the cooling COP and corrosion problem. The simulation of heat exchangers with UA value revealed that the absorber and the evaporator are relatively important for an air-cooled system compared with the condenser and the low temperature generator. The effect of cooling air flow rate, circulation weak solution flow rate and chilled water inlet temperature were also examined. The new working fluid may provide the COP approximately 5% higher than the conventional $H_2O/LiBr$ solution.

• 한국방사선학회논문지
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• 제14권2호
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• pp.85-95
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• 2020

본 논문에서는 고에너지 엑스선(6MV X선)을 조사한 세뇨관의 세포막 모델에서 오줌의 원료구성성분인 포도당 수용액(H₂O-C₆H₁₂O₆)의 압력차에 따른 여과작용특성에 대하여 연구하였다. 이 실험에 사용한 세포막 모델은 polysulfone 지지막에다가 m-phenylene-diamine(MPD)과 trimesoyl chloride(TMC)- hexane을 계면중합으로 만들어진 여과성 고분자 복합막을 사용하였다. 0.5 wt% TMC- hexane 용액으로 만들어진 여과성막(CM-2)은 0.5 wt% TMC- hexane 용액으로 만들어진 여과성막(CM-1)보다도 총 부피투과플럭스(Jv)와 배제계수(R)가 매우 높다. 압력차(1.5~4MPa)와 36.5℃에서 방사선을 조사한 세뇨관의 고분자 막(세포막모델)은 포도당수용액(H₂O-C₆H₁₂O₆)에서 총 부피투과플럭스(Jv)와 배제계수(R)가 비 조사된 세포막모델보다 각각 약 2 ~ 13배, 4 ~ 6배 정도 감소되었다. 세포막모델에서 포도당수용액(H₂O-C₆H₁₂O₆)의 농도가 증가하면 배제계수(R)가 증가하고 총 부피투과플럭스(Jv)는 감소하였다. 결국 방사선조사로 인해서 세뇨관의 세포막에서 포도당수용액(H₂O-C₆H₁₂O₆)의 여과기능이 비정상적으로 되어 세포장해가 발생하게 되었다고 사료됐다.

• 자원리싸이클링
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• 제32권3호
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• pp.38-44
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• 2023

국내산 흑연정광으로부터 불순물을 제거하기 위해 황산용액 및 수산화나트륨용액을 이용하여 침출실험을 진행하였다. 황산용액과 수산화나트륨용액을 각각 사용하여 침출실험을 진행한 결과, 수산화나트륨과 황산의 농도가 2 mol/L 이상에서 제거효과의 차이가 미미하고, 황산용액침출에서 온도가 증가함에 따라 고정탄소함량이 증가하는 것에 비해 수산화나트륨용액에서는 150℃ 이상에서 큰 차이가 나타나지 않았다. 수산화나트륨용액침출은 2 mol/L NaOH, 200℃, 1시간의 조건으로 선정하고, 황산용액침출은 2 mol/L H₂SO₄, 100℃, 1 시간의 조건으로 선정하여 5회까지 반복하여 침출을 진행하였다. 황산용액침출 후 수산화나트륨용액침출을 5회 반복했을 때 고정탄소는 99.95 %까지 증가하였고, 회분은 0.048 %까지 감소하였다. 수산화나트륨용액침출 후 황산용액침출을 5회 반복한 결과, 고정탄소는 99.98 %, 회분은 0.018까지 감소하여 수산화나트륨용액 침출 후 황산용액침출을 수행한 결과가 다소 높게 나타났다.

• Geomechanics and Engineering
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• 제25권4호
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• pp.303-315
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• 2021

A rigorous and generic similarity solution is developed for assessment of the undrained expansion responses of a cylindrical cavity expansion in K₀-consolidated anisotropic soils. A K₀-consolidated anisotropic modified Cam-clay (K₀-AMCC) model that can represent the initial stress anisotropy and the effects of stress-induced anisotropy is used to model the soil behaviors during cavity expansion. All the seven basic unknowns, the three stress components, the pore water pressure, the particle velocity, the specific volume and the hardening parameter, are reduced to the functions of a dimensionless radial coordinate and are taken as coupled variables to formulate the problem. The governing equations are formulated by making use of the equilibrium equation, the constitutive equation, the consistency condition, the continuity condition and the undrained condition, which are then solved as an initial value problem. The proposed rigorous similarity solution is compared with some well-documented rigorous solutions to validate the solution and to highlight the special expansion responses in anisotropic soils. The results reveal that the present solution can yield more predictions for cavity expansion problems in soils with initial anisotropic stresses.

• 전기화학회지
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• 제14권2호
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• pp.77-82
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• 2011

[Li,La]$TiO_3$ 코팅용액의 pH를 조절하여 이에 따른 코팅된 $Li[Ni_{0.35}Co_{0.3}Mn_{0.35}]O_2$ 양극활물질의 전기화학적 특성을 관찰하였다. 산화물인 양극분말은 접촉하고 있는 용액의 pH에 따라 표면 전하를 띄게 되는데 양이온인 코팅물질을 균일하게 반응시키기 위해서는 적절한 pH 조절을 통해 양극분말 표면을 음전하 상태로 조절해 주는 것이 필요하다. SEM, TEM 분석을 통해 코팅용액의 pH에 따른 코팅층의 형상변화를 관찰하였으며 다양한 전류밀도로 충전과 방전을 실시하여 코팅용액의 pH에 따른 방전용량, 사이클 특성, 고율특성을 분석하였다. 임피던스잴 cyclic voltammogram 측정을 통해 코팅용액의 pH에 따른 코팅층의 내부저항 변화를 관찰하였으며 이것을 전기화학적 특성과 연관됨을 확인하였다.

• 한국세라믹학회지
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• 제44권1호
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• pp.52-57
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• 2007

We synthesized $(La_{1-x}Sr_x)MnO_3$ as a cathode for SOFC by glycine nitrate process (GNP) and knew the different properties of $(La_{1-x}Sr_x)MnO_3$ by using nitrate solution and oxide solution as a starting material. In case of using nitrate solution as a starting material, main crystal phase peak of $LaMnO_3$ increased as Sr content added up and a peak of $Sr_2MnO_4\;and\;La_2O_3$ was showed as a secondary phase. We added Mn excess to control a crystal phase. In this case, the electrical conductivity had a high value 210.3 S/cm at $700^{\circ}C$. On the other side, when we used oxide solution as a starting material, we found main crystal phase of $LaMnO_3$ to increase as Sr content added up and a peak of $La_2O_3$ as a secondary phase. Similary, we added Mn excess to control a crystal phase in this case. We knew $(La,Sr)MnO_3$ powder to sinter well and the electrical conductivity of the sintered body at $1200^{\circ}C$ for 4 h was 152.7 S/cm at $700^{\circ}C$. The sintered $(La,Sr)MnO_3$ powder at $1000^{\circ}C$ for 4 h got the deoxidization peak, depending on the temperature and in case of using nitrate solution as a starting material, the deoxidization peak was showed at $450^{\circ}C$ which is lower than used a oxide solution as a starting material. As a result, when $(La,Sr)MnO_3$ powder was synthesized to add Mn excess and to use nitrate solution as a starting material, we found it to have the higher deoxidization property and considered it as a cathode for SOFC properly. And we found it to have different electrical conductivity the synthesized $(La,Sr)MnO_3$ powder by using different starting materials like nitrate solution and oxide solution which influence a sintering density and crystal phase.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.223-229
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• 2020

The present work proposes a solution to the static Boltzmann transport equation approximated by the simplified P₃ (SP₃) on angular, and the analytic coarse mesh finite difference (ACMFD) for spatial variables. Multi-group SP₃-ACMFD equations in 3D rectangular geometry are solved using the GMRES solution technique. As the core time dependent analysis necessitates the solution of an eigenvalue problem for an initial condition, this work is hence devoted to development and verification of the proposed static SP₃-ACMFD solver. A 3D multi-group static diffusion solver is also developed as a byproduct of this work to assess the improvement achieved using the SP₃ technique. Static results are then compared against transport benchmarks to assess the proximity of SP₃-ACMFD solutions to their full transport peers. Results prove that the approach can be considered as an acceptable interim approximation with outputs superior to the diffusion method, close to the transport results, and with the computational costs less than the full transport approach. The work would be further generalized to time dependent solutions in Part II.