[en] Time resolved spectrofluorometry is the most common method used for the determination of uranyl traces in solution. This element, when complexed in phosphoric medium has a fluorescence lifetime (100 us) very large compare to those of organic matters (<=5 ns) which create interferences in fluorometry without temporal resolution. Pulsed laser excitation and delayed fluorescence detection allow uranyl specific measurements. The apparatus made in our laboratory allows detection limit as low as 20 ng.^-1 (10^-10M).

[en] Laser Induced Breakdown Spectroscopy (LIBS) is a powerful technique for determining the elemental composition of materials based on measuring line emission from excited ions and neutral atoms in a transient laser-produced plasma. Nearly all the elements, even the light ones, can be simultaneously analysed at atmospheric pressure and without any preparation, or with limited sample preparation. Able to perform fast and remote analyses, it looks quite well suited to analyzing nuclear materials. Usually, quantitative analysis becomes possible as soon as the calibration curve is performed using reference samples. The presentation will first deal with the general aspects and characteristics of the technique. Examples of representative applications developed by Cea for the nuclear industry will be presented. The interest of the technique has been demonstrated for the analysis of simulated Ce-U Mox pellets or for the study of radionuclide migration through porous soil. As remote analysis is concerned, analytical results on samples isolated into glove boxes or hot cells will be discussed. The demonstrated versatility of this technique will allow online monitoring of reductive liquid-liquid extraction process as well as analysis of solid salt or metal samples. Other results obtained with a specific LIBS system designed for onsite measurements during decommissioning of nuclear installations will also be presented. As microanalysis is concerned, the microprobe LIBS instrument developed by Cea will be described and results of high resolution chemical mappings of simulated Mox nuclear fuel will be presented

[en] Time-resolved fluorescence spectroscopy (TRFS) was applied to an aluminate glass sample doped with Eu³⁺ cation as a fluorescent probe of the chemical environment and local symmetry. Conventional far-field experiments revealed the presence of two different phases: an amorphous phase featured by a highly disordered environment surrounding the Eu³⁺ cation and a more ordered polycrystalline phase that exhibits a significant increase in the Eu³⁺ fluorescence decay time compared to that of the amorphous phase. Near-field fluorescence spectra and decay kinetics were recorded in the frontier region between the two phases using a home-built scanning near-field optical microscope. SNOM-TRFS experiments confirmed the presence of local heterogeneities in this part of the glass at a sub-micrometric spatial scale. Polycrystalline sites featured an important shear-force interaction with the probing fiber optic tip, a longer fluorescence decay time, and a higher Stark splitting of the ⁵D₀ → ⁷F_J (J = 1-4) electronic transitions of the Eu³⁺ cations. (authors)

[en] Laser-Induced Breakdown Spectroscopy (LIBS) experiments are performed on standard metallic samples, in air at atmospheric pressure, using a Nd:YAG laser at 1064 nm and a fiber located close to the plasma to collect its emission. This configuration is chosen because it is representative of many LIBS setups. The influence of several experimental parameters is studied in order to optimize the analytical performances: signal-to-background ratio (SBR), line intensity and repeatability. Temporal parameters of the detector are adjusted for each measurement to maximize the SBR. The signal is found to linearly depend on the pulse energy over our range of investigation. This behavior is related to the increase of the number of vaporized atoms when the pulse energy increases. Complementary measurements of plasma dimensions support our conclusions. We show the existence of an optimum fluence on the sample that gives the highest signal and the lowest relative standard deviation (RSD), and which does not depend on the pulse energy. Finally we demonstrate that ablation is much more efficient using a laser beam with a high numerical aperture, other experimental parameters being unchanged, because of a less pronounced laser shielding by the plasma. Analytical consequences of this result are discussed

[en] After indications of the different fields of application of chemistry in the nuclear industry (in the cycle front-end, in reactor exploitation and safety, in the cycle back-end, in waste management, in the study of the impact on the environment and on health), and of the different associated chemical scientific themes, this report proposes an overview of the context and stakes related to these themes. It discusses the various scientific locks which remain to be solved for the different themes (chemistry of coordination of f elements, radiolysis, dissolution and precipitation, analytical chemistry and speciation, liquid-liquid interfaces, high temperature chemistry, thermodynamics and thermo-kinetics, fuel elaboration and behaviour, chemistry-transport coupled systems, conversion chemistry, migration of radionuclides in the environment, corrosion and long-term behaviour of materials, modelling and simulation). Then, it proposes an overview of theoretical and experimental research tools in these different specific fields. Objectives and propositions of actions are then formulated for these fields. Education programs (in university and engineering schools) and actors are finally indicated

[en] The ChemCam instrument suite on the Mars Science Laboratory (MSL) rover Curiosity provides remote compositional information using the first laser-induced breakdown spectrometer (LIBS) on a planetary mission, and provides sample texture and morphology data using a remote micro-imager (RMI). Overall, ChemCam supports MSL with five capabilities: remote classification of rock and soil characteristics; quantitative elemental compositions including light elements like hydrogen and some elements to which LIBS is uniquely sensitive (e.g., Li, Be, Rb, Sr, Ba); remote removal of surface dust and depth profiling through surface coatings; context imaging; and passive spectroscopy over the 240-905 nm range. ChemCam is built in two sections: The mast unit, consisting of a laser, telescope, RMI, and associated electronics, resides on the rover's mast, and is described in a companion paper. ChemCam's body unit, which is mounted in the body of the rover, comprises an optical de-multiplexer, three spectrometers, detectors, their coolers, and associated electronics and data handling logic. Additional instrument components include a 6 m optical fiber which transfers the LIBS light from the telescope to the body unit, and a set of onboard calibration targets. ChemCam was integrated and tested at Los Alamos National Laboratory where it also underwent LIBS calibration with 69 geological standards prior to integration with the rover. Post-integration testing used coordinated mast and instrument commands, including LIBS line scans on rock targets during system-level thermal-vacuum tests. In this paper we describe the body unit, optical fiber, and calibration targets, and the assembly, testing, and verification of the instrument prior to launch. (authors)