Accelerated Dissolution Process of the Spent Fuel (UO2) under Repository Conditions

2008 ◽  
Vol 1104 ◽  
Author(s):  
Eduardo Iglesias ◽  
Javier Quiñones ◽  
Nieves Rodriguez
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nuclear Energy ◽  
Fuel Pellet ◽  
Deep Geological Repository ◽  
Spent Fuel ◽  
General Law ◽  
Geological Repository ◽  
The Matrix

AbstractNowadays, nuclear energy is one of the options for developed countries in order to maintain the demand of electric energy. One of the problems of this kind of energy generation is the residual waste form after a fuel cycle (spent fuel). These kind of material is so difficult to characterize -due to their composition and the thermal treatment in the reactor- that exhaustive studies are necessaries for a complete knowledge, helping to build, with complete reliability, a very safety underground facility. In this way, the option known as Deep Geological Repository (DGR) is been developed by each country taking part in the nuclear energy industry. The unique via for the migration to the biosphere of the radionuclides -actinides and lanthanides content in the spent fuel pellet (UO2) after the closing of the deep geological repository is by the water transport phenomena. It is a fundamental question to know how much time they will spend in their trip; and the first step is the rate of liberation of these radionuclides from the spent fuel pellet. In this way, the matrix dissolution rate of the spent fuel pellet no dependent on the specific surface area after a normalization by the initial value- is a key parameter to begin the performance assessment for any deep geological repository and the specific surface value is, following the Matrix Alteration Model (MAM) sensitivity analysis, one of the most important parameters controlling the radionuclides liberation. In this way, several measurements were carried out to obtain values in different conditions for different sieves of UO2 powder, treated as fresh fuel. First of all, the specific surface area was measured with a multi-point isothermal procedure with N2 and Kr, the both. The values obtained were presented in order to obtain a general law for the evolution with the particle size. These data are part of a bigger project about the complete description of the spent fuel analogous; very useful to obtain new dissolution rates for the spent fuel under repository simulated conditions.

scholarly journals Modificação das propriedades da poliamida 12 pela incorporação de carbonato de cálcio nanoparticulado

2020 ◽  
Author(s):  
◽  
R. M. S. Teotonio
Keyword(s):  
Impact Strength ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Flexural Modulus ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Crystallinity Degree ◽  
Bet Analysis ◽  
The Matrix

Polyamide 12 (PA12) was modified by incorporating calcium carbonate nanoparticles (NPCC) to analyze the effect of the filler content on the mechanical and thermal properties of the final nanocomposites. Compositions containing 0.1, 0.2, 0.5, 1, 5 and 10 wt% of Socal 312 and 10 wt% of Socal U1S2 were analyzed. Furthermore, extruded and non-extruded PA12 were compared. NPCC was characterized through BET analysis (Brunauer, Emmett and Teller), which confirmed that Socal 312 had a specific surface area superior to Socal U1S2. Scanning electron microscopy revealed a tendency of the particles to agglomerate at 1 wt% NPCC and higher. However, all samples showed good distribution of the filler throughout the matrix. Differential Scanning Calorimetry (DSC) analyses did not show differences in the melting temperature of the compositions. Crystallization temperature tends to increase as the amount of filler in the matrix increases. Crystallinity degree showed differences only when comparing extruded and non-extruded PA12, the same occurs with Socal 312 in relation to Socal U1S2 containing 10 wt% of filler. Thermogravimetric analysis (TGA) showed that for contents from 0.5 wt% NPCC, increasing NPCC content reduces the thermal stability of the material. Muffle calcination tests confirmed the residues content obtained with TGA at 5 wt% NPCC higher, and evidenced good distribution of the filler along the specimen. Tensile and flexural strength and tensile and flexural modulus started increasing at 1 wt% NPCC and HDT started increasing at 0.2 wt% NPCC, showing the reinforcing effect of nanofiller and the increase in stiffness of the materials. Impact strength at 23 °C decreased at 0.5 wt% NPCC. Impact strength at -40 °C reduced only with addition of 10 wt% NPCC. Strain at break, toughness and impact strength at 23 °C showed reduction in extruded PA12 when compared to non-extruded PA12, possibly because extrusion favors the increase in crystallinity, as verified in the DSC analysis. Socal U1S2 also showed differences in relation to Socal 312 in strain at break, flexural modulus and HDT, probably due to its lower specific surface area in relation to Socal 312. Therefore, the incorporation of 1 wt% NPCC in PA12, already allows to obtain a nanocomposite with greater mechanical strength compared to neat PA12, which can be a feasible alternative for applications where an increase in mechanical properties is desired

Fuels Desulphurisation by Adsorbtion on Fe / Bentonite

2017 ◽  
Vol 68 (3) ◽  
pp. 483-486
Author(s):  
Constantin Sorin Ion ◽  
Mihaela Bombos ◽  
Gabriel Vasilievici ◽  
Dorin Bombos
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Pore Diameter ◽  
Adsorption Process ◽  
Continuous System ◽  
Gas Oil ◽  
Average Pore ◽  
Atmospheric Distillation

Desulfurisation of atmospheric distillation gasoline and gas oil was performed by adsorption process on Fe/ bentonite. The adsorbent was characterized by determining the adsorption isotherms, specific surface area, pore volume and average pore diameter. Adsorption experiments of atmospheric distillation gasoline and gas oil were performed in continuous system at 280�320oC, 5 atm and volume hourly space velocities of 1�2 h-1. The efficiency of adsorption on Fe / bentonite was better at desulphurisation of gasoline versus gas oil.

scholarly journals Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 345 ◽  
Author(s):  
Lianzan Yang ◽  
Yongyan Li ◽  
Zhifeng Wang ◽  
Weimin Zhao ◽  
Chunling Qin
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hierarchical Porous

High-entropy alloys (HEAs) present excellent mechanical properties. However, the exploitation of chemical properties of HEAs is far less than that of mechanical properties, which is mainly limited by the low specific surface area of HEAs synthesized by traditional methods. Thus, it is vital to develop new routes to fabricate HEAs with novel three-dimensional structures and a high specific surface area. Herein, we develop a facile approach to fabricate nanoporous noble metal quasi-HEA microspheres by melt-spinning and dealloying. The as-obtained nanoporous Cu30Au23Pt22Pd25 quasi-HEA microspheres present a hierarchical porous structure with a high specific surface area of 69.5 m2/g and a multiphase approximatively componential solid solution characteristic with a broad single-group face-centered cubic XRD pattern, which is different from the traditional single-phase or two-phase solid solution HEAs. To differentiate, these are named quasi-HEAs. The synthetic strategy proposed in this paper opens the door for the synthesis of porous quasi-HEAs related materials, and is expected to promote further applications of quasi-HEAs in various chemical fields.

scholarly journals Experimental Study on Activated Carbon-MIL-101(Cr) Composites for Ethanol Vapor Adsorption

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3811
Author(s):  
Zhongbao Liu ◽  
Jiayang Gao ◽  
Xin Qi ◽  
Zhi Zhao ◽  
Han Sun
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ethanol Vapor ◽  
Future Application ◽  
Working Fluid ◽  
Relative Pressure ◽  
Adsorption Refrigeration ◽  
Vapor Adsorption

In this study, the hydrothermal method was used to synthesize MIL-101(Cr), and activated carbon (AC) with different content was incorporated in to MIL-101(Cr), thereby obtaining AC-MIL-101(Cr) composite material with a huge specific surface area. The physical properties of MIL-101(Cr) and AC-MIL-101(Cr) were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), nitrogen adsorption and desorption and specific surface area testing, and ethanol vapor adsorption performance testing. The results show that with the increase of activated carbon content, the thermal stability of AC-MIL-101(Cr) is improved. Compared with the pure sample, the BET specific surface area and pore volume of AC-MIL-101(Cr) have increased; In the relative pressure range of 0–0.4, the saturated adsorption capacity of AC-MIL-101(Cr) to ethanol vapor decreases slightly. It is lower than MIL-101(Cr), but its adsorption rate is improved. Therefore, AC-MIL-101(Cr)/ethanol vapor has a good application prospect in adsorption refrigeration systems. The exploration of AC-MIL-101(Cr) composite materials in this paper provides a reference for the future application of carbon-based/MOFS composite adsorbent/ethanol vapor working fluid in adsorption refrigeration.

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