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Metallic alloy fuels from fast reactors will be reprocessed by a non‐aqueous electrochemical technique known as electrorefining. Electrorefining of spent metal fuel results in the accumulation of heat‐generating fission products, especially 137Cs in the eutectic salt. These fission products need to be removed from the salt so as to reduce the decay heat load and contamination. The melt crystallization technique is a simple separation process being pursued for the separation of fission products. This is a single‐step process that utilizes the difference in solubility of fission products in the solid and liquid phase. This process is also less energy intensive. Crystallization involves the purification of a substance from a liquid mixture by solidification of the desired component. Since separation is based on selective solidification, which involves phase change, it is essential to evaluate the transient solidification pattern, liquid fraction distribution, solute distribution, and separation time and efficiency. Numerical modeling of the separation of CsCl from a LiCl‐KCl eutectic mixture has been carried out using Ansys Fluent (19.2). The effect of crystallizer geometry and cooling rates on the separation of CsCl has been numerically simulated. [ABSTRACT FROM AUTHOR]

Ternary alloy fuel will be used as driver fuel for future fast reactors. Reprocessing of this spent alloy fuels will be carried out by pyrochemical reprocessing which is based on molten salt electrorefining at high temperature. During electrorefining, fission products get accumulated in the electrolyte along with some actinides in the form of their chlorides. The presence of fission products in the salt will add to the radioactivity levels and hence have to be stripped off. Melt crystallization is pursued to remove fission products from contaminated salt and to reuse the purified salt for electrorefining. Numerical modeling and experimental studies on tracking the phases during solidification of molten sodium nitrate salt were carried out. The numerical predictions closely matched with the experimental results. A resistance measurement technique was developed to accurately track the solidification interface so as to validate the numerical predictions. [ABSTRACT FROM AUTHOR]

To improve the ignition and combustion performance of aluminum, complementary metal is introduced into it to form binary alloy like Al−Mg, Al−Ti, Al−Zr and Al−Li. This paper mainly investigated the preparation, characterization, ignition, and combustion characteristics of Al−Mg alloy powder. Melt atomization technique was used to produce the spherical Al−Mg alloy powder containing 20 % mass content of Mg composition. The crystalline structure, morphology, element distribution, and thermal performance were characterized by XRD, TEM, SEM, EDS, and TG‐DSC. Results show that the Al−Mg alloy had intermetallic phases of Al12Mg17 and Al3Mg2, uniform element distribution, and no dense oxide shell at the surface. The laser‐induced ignition and combustion characteristics of Al−Mg alloy powder were investigated by microscopic high‐speed cinematography, photoelectric detection, and infrared thermal imaging methods. It is testified that Al−Mg alloy powder took intermetallic phase decomposition, then followed the two‐stage combustion mode, and demonstrated gaseous emission and multiple microexplosion behavior during combustion. The ignition delay and ignition temperature were measured at elevated laser ignition power density. It is found that the temperature rise rate had a significant effect on the ignition delay. [ABSTRACT FROM AUTHOR]

In this paper, the Aluminum−boron−europium ternary alloy fuels with boron content of 1.5∼4.85 wt. % and europium content of 3 wt. % were prepared by the close‐coupled gas atomization. XRD, SEM, TG‐DTA and oxygen bomb test were used to analyze the phase constituents, morphology, thermal oxidation behavior and combustion exothermic property of powders, respectively. The functions of boron and europium on the combustion of metal fuels were studied, and a reasonable oxidation model of the alloy particles was proposed. The results show that there are Al, AlB2, Al4Eu and B6Eu in the alloy. When the europium content is constant, the combustion enthalpy of the Al−B−Eu alloy powder firstly increases and then decreases as the boron content increases. Additionally, at oxygen pressure of 3.0 MPa, the Al−3.5B−3Eu ternary alloy powder burned completely with the maximum combustion enthalpy of 33324.5 J g−1. This increases by 11 % compared with theoretical combustion enthalpy of aluminum powder (31.1 kJ g−1). Al−3.5B−3Eu undergoes a dramatic oxidation exothermal phenomenon at 1110 °C with the weight increase efficiency of 53.66 %, which is 1.7 times that of aluminum. Due to the synergistic effects between the phase of B6Eu and AlB2 inside the alloy particles, the Al−3.5B−3Eu alloy powder shows excellent exothermic performance. [ABSTRACT FROM AUTHOR]

Ceramic plasma-spray coatings with single and multiple layers have been applied to melting crucible material substrates for the development of a reusable crucible for the fabrication of metal fuel slugs for a sodium-cooled fast reactor (SFR). Various combinations of vacuum plasma-spray (VPS) coated specimens have been applied to investigate the bonding effect on the crucible substrate and the interaction between the metal fuel and the VPS-coated crucible substrate. All VPS-coated methods maintained a sound coating state after a dipping test with U-10 wt%Zr melt. A single coating of a Y2O3(150) layer and a double coating layer of TaC(50)- Y2O3(100) showed some degradation or penetration, respectively, after 2 cycles of dipping test with an aggressive U-10 wt%Zr-5 wt%RE melt. Injection castings of U-10 wt%Zr and U-10 wt%Zr-5 wt%RE fuel slugs were also conducted to investigate the feasibility of a reusable melting crucible of metal fuel slugs. The U-10 wt% Zr fuel slugs were soundly fabricated without significant interactions of the graphite crucibles; however, the U-10 wt%Zr-5 wt%RE fuel slugs had some degradation or penetration, respectively, after injection casting. [ABSTRACT FROM AUTHOR]

This paper presents the experiments and numerical calculations on the laser-induced ignition of single micron-sized aluminum particle in an atmospheric pressure air flow at low Reynolds number. Experimental results demonstrate that the radiation intensity of single micron-sized aluminum particle, during ignition, experiences first sharp rising, stable equilibrium and second steep rising stages. A simplified analytical model was built and numerically solved. Numerical results show that the three distinctive stages represent the heating, melting and evaporation, respectively. Laser radiation mainly contributes to heat aluminum particle, leading to phase transition (melting). The heat released from heterogeneous surface reaction (HSR) dominates the temperature rise of the liquid aluminum and accelerate its evaporation. During ignition, the heat loss of natural convection significantly affects the ignition performance of aluminum particle, while the heat loss of radiation toward the surrounding air only affects the evaporation rate. Threshold ignition energy of aluminum particle based on numerical calculations is in good agreement with the experiments, which strongly depends on the particle diameter. Ignition delay time depends on the particle diameter and ignition energy. This study will be beneficial to deeply recognize the ignition mechanism of single micron-sized aluminum particle, especially in the transition region between nanoscale and microscale. [ABSTRACT FROM AUTHOR]