[en] Microstructure of tungsten thin films deposited by RF-sputtering is studied as a function of their thicknesses. These films have been deposited on (100) oriented single crystal Si substrate and Si substrate covered by a 100-nm-thick Ti layer. The crystalline structure is studied by X-ray Diffraction (XRD) and Grazing Incidence XRD (GIXRD). The surface and the cross-section morphology are observed by high resolution Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). XRD patterns exhibit peaks corresponding to pure W phase. GIXRD analysis shows that the more the thickness increases, the more the film is oriented along the [110] direction. AFM observations show that films exhibit a particular morphology constituted of 'piles of platelets' oriented perpendicularly to the wafer surface. These 'piles of platelets' are in plane randomly oriented and are sometime observed upon all the thicknesses of the layer. This particular morphology is observed whatever the substrate is, and is explained by thin layer growth theories

[en] Gamma spectroscopy is carried out directly after compacting for improvement of accuracy and characterization of waste before storage. Detector amplifier and analysis system are described. Qualitative and quantitative analysis are realized for waste packaging with dose rate in the range 2 m Gy/Hr to few tens of Gy/Hr. An example of application for characterization of wastes from a cell for spent fuel element dismantling is given

[en] In this paper, the structure of nanometer tungsten thin films has been correlated to their surface morphology. Films have been deposited by RF-sputtering at a working pressure of 0.5 Pa and with a power density of 1.18 W/cm². Two phases with different morphology have been observed: W₃O with a nanograins structure is present in the first step of the tungsten growth; and, when the thickness is increased, a pure tungsten Wolfram phase (W) with a lamellar structure appears. We demonstrate that W₃O is related to a pollution of the target surface between two growth runs. We succeed to suppress this phase and to obtain pure tungsten Wolfram nanolayer, in order to realize (W/WO₃)_n multilayer

[en] TRIRAD is a facility specialized in sorting and decontaminating the technological actinides-contaminated waste. The purpose of this original facility is to reduce the waste activity level and keep it below the standard limits prevailing in the French surface waste-disposal site of ANDRA. TRIRAD comprises 16 glove-boxes in two sections. The first section (known as TRI), is dedicated to sorting, according to the waste nature and contamination level. In the other section (known as RAD), automatic decontamination is provided by steeping the waste in a solvent bath stirred by a powerful ultrasonic generator. Provision is also made for high-pressure solvent sprinkling (250 bar). Six γ-spectrometry units ensure appropriate monitoring of the decontamination factors, as well as management in real time of the quantities of actinides present in the whole facility. The processing capacity is currently 0.05 m³/h, and the average decontamination factor is 10. The results obtained in TRIRAD cover the first 2-year processing period, with respect to old technological waste coming from a glove-box dismantling unit. On the basis of the evaluation made with respect to 50 m³ of waste processed in TRIRAD, 90% of such technological waste result to be compatible with the specifications of the relevant surface waste repository. Such satisfactory results have grounded the decision made by the CEA to set up a new facility of this kind at Cadarache Nuclear Research Centre

[en] During the years 1999-2005 a series of incubation experiments were conducted under controlled conditions to investigate the effect of plant litter quality and residue location (surface vs. incorporated) on residue decomposition, C storage and N dynamics in soils. Comparisons between decomposition of roots and other plant parts (leaves and stems) were emphasized in order to better evaluate the contribution of root systems to nutrient release and soil C sequestration. The second aspect investigated was the decomposition of residues from forest, grassland and annual crops. The aim was to assess the relative effects of soil past history and residue quality on short term biodegradation. During the initial phase of decomposition, the principal factor determining decomposition kinetics was the nature of the added carbon, which strongly affected the nature and activity of the decomposing microbial biomass. Initial C mineralization (after 3 d of incubation) was significantly related to the percentage of soluble compounds in the residue, while after 142 d, a linear relationship was observed between cumulative C mineralization and the percentage of the lignin-like fraction. The amount of N mineralized was strongly related to the initial N content of the residues. No specific interaction with the origin of the residues (agro-, pasture or forest ecosystem) was observed, indicating that concepts for describing crop residue decomposition may be generalized for the decomposition of grass roots and tree leaves, and therefore for mixed residues in agroforestry systems. The C and N mineralization of leaf and stem residues from four tropical species were related to their biochemical composition and could be predicted from their N content, thus indicating a similar behaviour for a range of temperate crop residues. C mineralized from roots was 20 to 30% less than for leaves and stems, and this was assumed to be related to the presence of a high lignin-suberin content. The lower decomposition of root-C translated into higher stabilisation of root-derived C into the soil, suggesting a higher contribution of root systems than above ground parts to the soil organic C pool. This suggests that inputs of C from roots contribute proportionally more than other plant parts to the long-term build up of soil organic matter. When residues were placed on the soil surface or were incorporated into the soil when N availability was not a factor limiting decomposition, and where there was no gradient in soil and air humidity and temperature, there was no significant effect of placement on C dynamics and little difference in N dynamics, whatever the biochemical quality of the residues. When residues were placed either at the soil surface as a mulch or incorporated, in an experimental system that mimics actual conditions, i.e. allowing water and solute transport into the soil after rain and evaporation, the main effect of residue location was a change in evaporation rate, and therefore in soil moisture content and distribution, acting in turn on microbial activity and N mineralization. (author)

[en] The ARIANE5 On Board Computer (OBC) and Inertial Reference System (SRI) are based on Motorola MC68020 processor and MC68882 coprocessor. The SRI data acquisition board also uses the DSP TMS320C25 from Texas Instruments. These devices were characterized to proton induced SEUs. But representativeness of SEU test results on processors was questioned during ARIANE5 studies. Protons test of these devices were also performed in the actual equipments with flight (or representative of) softwares. The results show that the On Board Computer and the Inertial Reference System can satisfy the requirements of the ARIANE5 missions

[en] Hard errors from single heavy ions have been reported in advanced commercial CMOS memories. The authors examine the physical interactions of ions with MOS gate oxides-charge generation, recombination, transport and trapping. They also consider device and circuit characteristics. They conclude that hard errors from single ions are to be expected, and should not be considered surprising

[en] Proton motions in α- and β-PbO₂ varieties have been studied using quasielastic neutron scattering. In electrochemical samples two kinds of proton motions are evidenced: (i) a rotation-like local motion (R=1.1 A) and a translational motion. The presence of clusters is also observed. 11 refs.; 2 figs

[en] The variation of the cubic parameter thermal expansion coefficient of lead magnesium niobate (PMN) ceramics was studied by very precise X-ray diffraction at fourteen temperatures between 297 and 1023 Κ. The refinement of the Pb and Nb atom positions at room temperature gives the lowest value of the discrepancy factor R for Pb atoms shifts of 0.33 A along [110] direction and Nb atoms shifts of 0.18A along [110] and [111] directions. At temperatures higher than 600 Κ, the Nb atoms are no more located at any local disordered position and above 900 Κ, the Pb atoms are also on the special position of the ideal cubic perovskite structure

[en] Recent progress in the understanding of soil microbial processes at micrometric scales has created a need for models that accurately predict the microscale distribution of water, and the location of air-water interfaces in pores. Various models have been developed and used for these purposes, but how well they fare against real data has yet largely to be determined. In this context, for the first time, this article compares the prediction of two of these models to experimental data obtained on soil material. The distribution of water and air in soil samples constituted of repacked aggregates, equilibrated at three matric potentials (-0.5 kPa,-1 kPa and -2 kPa),was measured via synchrotron X-ray computed tomography at a resolution of 4.6 μm.Water distribution was simulated by a two-phase lattice Boltzmann model (LBM) and a morphological model (MOSAIC). Results indicate that, when one lifts the assumption, motivated by capillary theory, that a pore can drain only if a connecting pore is already full of air, MOSAIC gives an acceptable approximation of the observed air-water interfaces. However, discretization of pores as geometrical primitives causes interfaces predicted by MOSAIC to have non physical shapes. By contrast, LBM is able to predict remarkably well the location of air-water interfaces. Nevertheless, given the huge difference in computing time (minutes versus tens of hours) required to run these two models, it is recommended that further research be carried out on the development of both, in parallel. (authors)