A5026449567- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Radioactive element chemistry and processing
- Nuclear materials and radiation effects
- Thermodynamic and Structural Properties of Metals and Alloys
- Nuclear and radioactivity studies
- Nuclear Physics and Applications
- Laser-induced spectroscopy and plasma
- Fusion materials and technologies
- Metallurgical Processes and Thermodynamics
- Vehicle emissions and performance
- Radioactive contamination and transfer
- Glass properties and applications
- High-pressure geophysics and materials
- nanoparticles nucleation surface interactions
- Rare-earth and actinide compounds
- Risk and Safety Analysis
- Crystallization and Solubility Studies
- Nuclear Engineering Thermal-Hydraulics
- Chemical Thermodynamics and Molecular Structure
- Calibration and Measurement Techniques
- High-Temperature Coating Behaviors
- Ion-surface interactions and analysis
- Air Quality Monitoring and Forecasting
- Air Quality and Health Impacts
Joint Research Centre
2020-2024
Joint Research Centre
2014-2023
European Commission
2008-2023
European Union
2022
John Wiley & Sons (United States)
2010
Institut de Recherche sur la Fusion par Confinement Magnétique
2007-2009
Direction des énergies
2009
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2006-2009
CEA Marcoule
2006
Los Alamos National Laboratory
2004
A comprehensive review of the thermodynamic properties oxide compounds lanthanide and actinide elements is presented. The available literature data for solid, liquid, gaseous state have been analysed recommended values are In case experimental missing, estimates made based on trends in two series, which extensively discussed.
Abstract TaC, HfC and their solid solutions are promising candidate materials for thermal protection structures in hypersonic vehicles because of very high melting temperatures (>4000 K) among other properties. The slightly hypostoichiometric three solution compositions (Ta 1−x Hf x C, with = 0.8, 0.5 0.2) have long been identified as the highest known. In current research, they were reassessed, first time last fifty years, using a laser heating technique. They found to melt range...
This study is focused on the behavior of ternary SiO2-Na2O-B2O3 borosilicate glasses at temperatures between 298 and 1800 K. Unpolarized Raman spectra were measured up to high temperature. glass samples prepared with different values ratio R = [Na2O]/[B2O3], while K [SiO2]/[B2O3] was kept constant equal 2.12. Spectra room temperature in 0.43 ≤ 1.68, effect modifier content clearly observed these glasses, only partial agreement previous literature results. In particular, formation...
This paper reviews the recent advances in management of nitrogen oxide (NOx) emissions from internal combustion engine light-duty and heavy-duty vehicles, addressing both technical legal aspects. Particular focus is devoted to often-virtuous interaction between new legislation imposing more restrictions on permitted pollutant emission levels technologies developed order meet these restrictions. The review begins first with American then European directives promulgated 1970s, aimed at...
Recently, novel container-less laser heating experimental data have been published on the melting behaviour of pure PuO2 and PuO2-rich compositions in uranium dioxide–plutonium dioxide system. Such showed that previous obtained by more traditional furnace techniques were affected extensive interaction between sample its containment. It is therefore paramount to check whether so far used nuclear engineers for uranium-rich side pseudo-binary system can be confirmed or not. In present work, new...
Oxalate precipitation is a powerful technique for actinide oxide preparation at either laboratory or industrial scales. In this study we focus on the low temperature decomposition of Th(C2O4)2⋅2H2O and (N2H5)2U2(C2O4)5⋅nH2O into nanograined ThO2 UO2 powders, which will be used later as precursors generation materials emulating nuclear fuel high burn up structure (HBS). The evolution with nanoparticles properties has been investigated using several solid state analytical techniques...
UO 2 samples doped with 6, 11, 22 mol% lanthanum were examined before and after air oxidation. To verify the formation of uranium–lanthanum‐mixed oxide solid solutions, powder X‐ray diffraction ( XRD ) analyses crystalline phases in materials carried out. The presence oxygen vacancies La‐doped was identified by Raman spectrometry. It evidenced changes induced spectra This latter out either increasing laser power or thermally treating at 500 K for 370 h. In addition, oxidation behavior...
Analysis of X-ray absorption fine structure spectra UO(2+x) for x = 0-0.20 (UO(2)--U(4)O(9)) reveals that the adventitious O atoms are incorporated as oxo groups with U--O distances 1.74 A, most likely associated U(VI), occur in clusters so UO(2) fraction material largely remains intact. In addition to formation some additional longer bonds, U sublattice consists an ordered portion displays original U--U distance and a spectroscopically silent, glassy part. This is very different from...
The electrical conductivity and viscosity of borosilicate glass-forming melts were studied over a wide composition temperature range above the transition ${T}_{g}$. High-temperature Raman spectroscopy was used to characterize structure both molten glassy states system. dependence are well described by Vogel-Fulcher-Tammann (VFT) law. Contrary solid state, it appears that in state boron coordination number is no longer relevant parameter account for compositional viscosity. Our results reveal...
An original technique for the measurement of high-temperature phase transitions was implemented based on a laser-heating method, enabling chemically unstable, refractory materials to be melted under controlled conditions. This includes two independent but correlated methods: In first, fast multichannel pyrometry is employed measure thermograms and spectral emissivity; in second, low-power probe laser beam used detection reflectivity changes induced by sample surface. The experiments are...
Pulsed laser heating and optical pyrometry were used to generate time–temperature thermogram data suitable for the determination of extremely high‐temperature (>3000 K) solidus, liquidus, eutectic transitions ceramics in Zr–C system. Transition temperatures correlated well with phase boundaries individual measurements published previously. Microstructural diffraction analysis melted specimens confirmed that ZrC existed liquid resolidified or a ZrC+graphite eutectic. insensitive pulse...
Abstract Apart from its technological importance, plutonium (Pu) is also one of the most intriguing elements because non‐conventional physical properties and fascinating chemistry. Those fundamental aspects are particularly interesting when dealing with challenging study plutonium‐based nanomaterials. Here we show that ultra‐small (3.2±0.9 nm) highly crystalline oxide (PuO 2 ) nanocrystals (NCs) can be synthesized by thermal decomposition plutonyl nitrate ([PuO (NO 3 ] ⋅ H O) in a...
The performances of three different Raman spectrometers were compared and evaluated as a suitable tool for the analysis range uranium compounds with view to application in nuclear forensics. These included ore concentrates chemical composition dioxide form powder sintered fuel pellet. are termed 'portable' or 'hand-held' from Ahura Scientific (785 nm), 'Senterra' Bruker (532 785 'T64000′ HORIBA Jobin Yvon (488.0, 514.5, 647.1 752.5 nm). Figures merit such sensitivity, signal-to-noise ratio...
Actinide oxalate decomposition under hot compressed water is proposed as a milder production route for nanometric sized (mixed) actinide oxides.
The high-temperature phase diagram of the UO2–ThO2 system has been experimentally revisited in present study for first time since 1970, using a laser heating approach combined with fast pyrometry thermal arrest method. melting/solidification temperature, which is fundamental information reactor design was studied here. It found that low addition ThO2 to UO2 would result slight decrease solidification temperature. A minimum at 3098 K around composition 5 mol% ThO2. solid/liquid transition...
Abstract To assure the safety of oxide-fuel based nuclear reactors, knowledge atomic-scale properties U 1−y M y O 2±x materials is essential. These compounds show complex chemical properties, originating from fact that actinides and rare earths may occur with different oxidation states. In these mostly ionic materials, aliovalent cationic configurations can induce changes in oxygen stoichiometry, dramatic effects on fuel. First studies Am indicated exhibit particularly electronic...
The melting behavior is a fundamental property of material, closely related to its structure and thermodynamic stability, has therefore been crucial subject research for ages. point also an important engineering parameter, as it defines the operational limits material in application environment. This becomes critical nuclear where thermo-mechanical stability fuel element key factor determining performance safety. However, experimental difficulties stemming from extreme temperatures, complex...