1,721,556 research outputs found
Experimental investigation of high He/dpa microstructural effects in neutron irradiated B-alloyed Eurofer97 steel by means of small angle neutron scattering (SANS) and electron microscopy
No full textHigh He/dpa microstructural effects have been investigated, by means of small-angle neutron scattering (SANS) and transmission electron microscopy (TEM), in B-alloyed ferritic/martensitic steel Eurofer97-1 (0.12 C, 9 Cr, 0.2 V, 1.08 W wt%, B contents variable between 10 and 1000 ppm), neutron irradiated at the High Flux Reactor of the JRC-Petten at temperatures between 250 °C and 450 °C, up do a dose level of 16 dpa. Under these irradiation parameters, B activation is expected to produce corresponding helium contents variable between 80 and 5600 appm, with helium bubble distributions relevant for the technological applications. The SANS measurements were carried out under magnetic field to separate nuclear and magnetic SANS components; a reference, un-irradiated sample was also measured to evaluate as accurately as possible the genuine effect of the irradiation on the microstructure. Increasing the estimated helium content from 400 to 5600 appm, the analysis of the SANS cross-sections yields an increase in the volume fraction, attributed to helium bubbles, of almost one order of magnitude (from 0.007 to 0.038); furthermore, the difference between nuclear and magnetic SANS components is strongly reduced. These results are discussed in correlation with TEM observations of the same samples and are tentatively attributed to the effect of drastic microstructural changes in Eurofer97-1 for high He/dpa ratio values, possibly relating to the dissolution of large B-carbides due to transmutation reactions. © 2016 The Author
Frasquita : tango [pour] piano solo / de R. Coppola ; [ill. par] Margerie
No full textTitre uniforme : Coppola, R. (18..-19.. ; compositeur). Compositeur. [Frasquita. Piano]Piano, Musique de -- +* 1900......- 1999......+:20e siècle:Tangos (piano) -- +* 1900......- 1999......+:20e siècle
Neutron diffraction stress determination in W-laminates for structural divertor applications
No full textNeutron diffraction measurements have been carried out to develop a non-destructive experimental tool for characterizing the crystallographic structure and the internal stress field in W foil laminates for structural divertor applications in future fusion reactors. The model sample selected for this study had been prepared by brazing, at 1085 °C, 13 W foils with 12 Cu foils. A complete strain distribution measurement through the brazed multilayered specimen and determination of the corresponding stresses has been obtained, assuming zero stress in the through-thickness direction. The average stress determined from the technique across the specimen (over both 'phases' of W and Cu) is close to zero at -17 ± 32 MPa, in accordance with the expectations. © 2015 The Authors
High resolution neutron diffraction crystallographic investigation of Oxide Dispersion Strengthened steels of interest for fusion technology
No full textHigh resolution neutron diffraction measurements have been carried out to characterize the crystallographic phases present in different Oxide Dispersion Strengthened (ODS) steels of interest for fusion technology. The different lattice structures, Im3m for the ferritic ODS and Fm3m for the austenitic ODS, are resolved showing line anisotropy effects possibly correlated with differences in dislocation densities and texture. Many contributions from minority phases are detected well above the background noise; none of the expected crystallographic phases, such as M23C6and including Y2O3, fits them, but the TiN phase is identified in accordance with results of other microstructural techniques
Caratterizzazione di materiali e componenti per il nucleare da fissione mediante tecniche neutroniche
Full text linkL'attività ha consistito nella caratterizzazione di materiali e componenti per il nucleare da fissione mediante tecniche neutroniche utilizzate presso il Reattore ad Alto Flusso dell'ILL-Grenoble. Sono stati studiati acciai strutturali e materiali metallici a rinforzo ceramico (ODS) sottoposti a invecchiamento termico e prove meccaniche, al fine di valutarne la resistenza negli impianti e migliorarne le prestazioni. In base alla caratterizzazione microstrutturale ottenuta da tali misure neutroniche il risultato di queste prove ha fornito una prima valutazione dell'affidabilità dei materiali studiati in condizioni di servizio, costituendo la necessaria base tecnico-scientifica di un sistematico programma di prove, da svilupparsi negli anni successivi per contribuire alla qualifica di materiali e componenti nucleari sotto alte dosi di irraggiamento. L'analisi dei dati neutronici è stata condotta in collaborazione con l'Università Politecnica delle Marche, che ha consentito di mettere a punto un metodo innovativo di calcolo per ottenere dai risultati delle prove neutroniche informazioni microstrutturali di rilevanza per l'impiego di tali materiali in condizioni di esercizi
An invited commentary on: Optimizing response in surgical systems during and after COVID-19 pandemic: Lessons from China and the UK - Perspective. Zheng Liu (IJS-D-20-00464)
No full textInvited Commentary to: Enhanced Recovery After Surgery protocols in patients undergoing liver transplantation: A retrospective comparative cohort study
No full textMicro-structural effects of irradiation temperature and helium content in neutron irradiated B-alloyed Eurofer97-1 steel
No full textThe micro-structural effects of different neutron irradiation temperatures and helium contents, for 16 dpa dose, have been investigated by means of small-angle neutron scattering (SANS) in B-alloyed ferritic/martensitic steel Eurofer97-1 (0.12 C, 9 Cr, 0.2 V, 1.08 W wt%, B concentrations up to 1000 ppm); due to B transmutations, fusion relevant He/dpa values are expected to be produced under neutron irradiation. SANS measurements have been carried out on a sample irradiated at 350 °C, with estimated helium content of 5600 appm, and compared to previous SANS results, obtained on two other irradiated samples of this same B-alloyed steel. These new measurements confirm that for such high helium contents the SANS cross-section increases in order of magnitude and the magnetic SANS component is strongly reduced, compared to lower helium content (400 appm). Such effects are attributed to increase in helium bubbles density and to the presence of micro-cavities, produced after dissolution of large B-carbides. The SANS data analysis procedure has been improved, also thanks to the additional information provided by the new measurements, and more accurate helium bubble size distributions have been obtained for all the investigated samples. For 5600 appm helium content, bubble volume fractions are found of 0.025 for the sample irradiated at 350 °C and of 0.041 for the previously investigated sample irradiated at 400 °C, significantly increasing with the irradiation temperature. These values are approximately one order of magnitude larger than the value of 0.003 previously found for the sample with 400 appm helium. The size distributions are compared with electron microscopy observations of these same samples. It appears that the occurrence of complex micro-structural changes in irradiated Eurofer97-1 steel should be taken in due account when considering its application under high He/dpa ratio values. © 201
An invited commentary on "Critical appraisal of gastric conduit ischaemic conditioning (GIC) prior to oesophagectomy: A systematic review and meta-analysis" (Int J Surg 2020; epub ahead of print).
No full textDose dependence of micro-voids distributions in low-temperature neutron irradiated Eurofer97 steel
No full textThe microstructural effects of mixed spectrum neutron irradiation at 250◦ C and 300◦ C, for 2.7 dpa, 8.4 dpa, and 16.3 dpa doses, have been investigated in standard Eurofer97 (0.12 C, 9 Cr, 0.48 Mn, 0.2 V, 1.08 W, 0.14 Ta wt%) by means of small-angle neutron scattering (SANS) compared with un-irradiated Eurofer97. The observed SANS effects are attributed to the development of micro-voids, also detected by electron microscopy. The micro-voids distributions have been obtained by an improved transformation method of the SANS cross-sections providing consistent results both before and after subtraction of the un-irradiated reference. Mono-disperse micro-voids distributions are found, with average radii increasing with the dose, namely 4.4 Å for irradiation to 2.7 dpa at 300◦ C, 6.6 Å for 8.4 dpa at 300◦ C, and 12.9 Å for 16.4 dpa at 250◦ C; the corresponding volume fractions are 0.001, 0.006, and 0.004, respectively. The differences in such distributions might reflect different damage evolution mechanisms for the different irradiation conditions, as also suggested by the comparison with a Eurofer97 sample irradiated under fast spectrum. A good resistance of Eurofer97 to micro-structural radiation damage, at least under these irradiation conditions, is suggested by the analysis of these experimental results
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