Fracture of Zircaloy-4 fuel cladding tubes with hydride blisters

International audienceThe influence of hydride blister on cold worked stress relieved Zircaloy-4 cladding tubes fracture toughness at room temperature was studied using hoop tensile tests and plane strain tensile tests. The experimental macroscopic fracture stress and strain values and an elastic-plastic finite element analysis of the mechanical tests with the CAST3 M code were used to calculate the J-integral and estimate the fracture toughness for several blister depths from 120 to 240 μm

Stress corrosion crack initiation of Zircaloy-4 cladding tubes in an iodine vapor environment during creep, relaxation, and constant strain rate tests

During accidental power transient conditions with Pellet Cladding Interaction (PCI), the synergistic effect of the stress and strain imposed on the cladding by thermal expansion of the fuel, and corrosion by iodine released as a fission product, may lead to cladding failure by Stress Corrosion Cracking (SCC). In this study, internal pressure tests were conducted on unirradiated cold-worked stress-relieved Zircaloy-4 cladding tubes in an iodine vapor environment. The goal was to investigate the influence of loading type (constant pressure tests, constant circumferential strain rate tests, or constant circumferential strain tests) and test temperature (320, 350, or 380 °C) on iodine-induced stress corrosion cracking (I-SCC). The experimental results obtained with different loading types were consistent with each other. The apparent threshold hoop stress for I-SCC was found to be independent of the test temperature. SEM micrographs of the tested samples showed many pits distributed over the inner surface, which tended to coalesce into large pits in which a microcrack could initiate. A model for the time-to-failure of a cladding tube was developed using finite element simulations of the viscoplastic mechanical behavior of the material and a modified Kachanov's damage growth model. The times-to-failure predicted by this model are consistent with the experimental data

SnapNet-R: Consistent 3D Multi-View Semantic Labeling for Robotics

International audienceIn this paper we present a new approach for semantic recognition in the context of robotics. When a robot evolves in its environment, it gets 3D information given either by its sensors or by its own motion through 3D reconstruction. Our approach uses (i) 3D-coherent synthesis of scene observations and (ii) mix them in a multi-view framework for 3D labeling. (iii) This is efficient locally (for 2D semantic segmentation) and globally (for 3D structure labeling). This allows to add semantics to the observed scene that goes beyond simple image classification, as shown on challenging datasets such as SUNRGBD or the 3DRMS Reconstruction Challenge

Gestion dynamique de la variabilité : réponses de populations de blé tendre à différentes forces sélectives dont l’oïdium.

International audienceA programme of dynamic conservation of genetic resources has been conducted on winter wheat in France since 1984. One allogamous and 2 preferential selfing populations, with a large genetic base, made up the initial gene pools. Seed samples of these pools were distributed throughout a multi-site experimental network. The populations obtained were multiplied each year in each site. Populations developed significantly after 8 years of multiplication: plant height had increased, the proportion of viable pollen grains had increased in male-fertile plants of allogamous populations and a north-south gradient for precocity was observed for autogamous populations. Resistance to powdery mildew had developed in local populations, both for adult-plant resistance and the frequency of specific resistance genes to Erysiphe graminis f sp tritici. The differentiation depended on the gene pool of the host populations. Virulence frequencies of the parasite populations varied according to the site and the year. There was no clear relationship between virulence frequencies and resistance gene frequencies. The proportion of plants without specific resistance genes seems to correlate with adult-plant susceptibility in local autogamous populations. Most of the variability was maintained through propagation under various natural selection forces.Un programme de gestion dynamique des ressources génétiques est développé en France depuis 1984 sur le blé tendre. Deux populations préférentiellement autogames et une population conduite en allogamie, toutes 3 à large base génétique, constituaient les pools génétiques de départ. Des échantillons de grains de ces pools ont été distribués dans un réseau multilocal. Les populations ainsi obtenues sont multipliées année après année dans chaque lieu du réseau. Après 8 ans de multiplication, les populations ont nettement évolué. On constate une augmentation de la taille des plantes adultes, une meilleure production de grains de pollen viable chez les plantes mâles fertiles des populations allogames et la mise en place d’un gradient de précocité Nord-Sud pour les populations autogames. La résistance à l’oïdium a évolué dans les populations, à la fois pour la résistance au stade adulte et pour les fréquences de gènes de résistance spécifique vis-à-vis d’Erysiphe graminis f sp tritici. La différenciation dépend du pool génétique auquel appartiennent les populations hôtes. Les fréquences de virulence des populations du parasite varient selon les sites et les années. Aucune relation claire n’a été mise en évidence entre les fréquences de virulences du parasite et celles des gènes de résistance spécifique de l’hôte. La proportion de plantes sans résistance spécifique semble corrélée à la sensibilité au stade adulte dans les populations autogames. La diversité des milieux formant le réseau a globalement permis le maintien de la variabilité

Gestion dynamique de la variabilité : réponses de populations de blé tendre à différentes forces sélectives dont l’oïdium.

National audienceA programme of dynamic conservation of genetic resources has been conducted on winter wheat in France since 1984. One allogamous and 2 preferential selfing populations, with a large genetic base, made up the initial gene pools. Seed samples of these pools were distributed throughout a multi-site experimental network. The populations obtained were multiplied each year in each site. Populations developed significantly after 8 years of multiplication: plant height had increased, the proportion of viable pollen grains had increased in male-fertile plants of allogamous populations and a north-south gradient for precocity was observed for autogamous populations. Resistance to powdery mildew had developed in local populations, both for adult-plant resistance and the frequency of specific resistance genes to Erysiphe graminis f sp tritici. The differentiation depended on the gene pool of the host populations. Virulence frequencies of the parasite populations varied according to the site and the year. There was no clear relationship between virulence frequencies and resistance gene frequencies. The proportion of plants without specific resistance genes seems to correlate with adult-plant susceptibility in local autogamous populations. Most of the variability was maintained through propagation under various natural selection forces.Un programme de gestion dynamique des ressources génétiques est développé en France depuis 1984 sur le blé tendre. Deux populations préférentiellement autogames et une population conduite en allogamie, toutes 3 à large base génétique, constituaient les pools génétiques de départ. Des échantillons de grains de ces pools ont été distribués dans un réseau multilocal. Les populations ainsi obtenues sont multipliées année après année dans chaque lieu du réseau. Après 8 ans de multiplication, les populations ont nettement évolué. On constate une augmentation de la taille des plantes adultes, une meilleure production de grains de pollen viable chez les plantes mâles fertiles des populations allogames et la mise en place d’un gradient de précocité Nord-Sud pour les populations autogames. La résistance à l’oïdium a évolué dans les populations, à la fois pour la résistance au stade adulte et pour les fréquences de gènes de résistance spécifique vis-à-vis d’Erysiphe graminis f sp tritici. La différenciation dépend du pool génétique auquel appartiennent les populations hôtes. Les fréquences de virulence des populations du parasite varient selon les sites et les années. Aucune relation claire n’a été mise en évidence entre les fréquences de virulences du parasite et celles des gènes de résistance spécifique de l’hôte. La proportion de plantes sans résistance spécifique semble corrélée à la sensibilité au stade adulte dans les populations autogames. La diversité des milieux formant le réseau a globalement permis le maintien de la variabilité

Development and validation of a new experimental device for studies of iodine stress corrosion cracking of zirconium alloys

International audienceZirconium alloys are widely used in the nuclear industry as cladding material due to their good thermo-mechanical, chemical and neutronic properties as well as an excellent general corrosion resistance in many environments. Nonetheless, Iodine-induced Stress Corrosion Cracking (ISCC) is an identified failure mechanism that can occur in nuclear fuel cladding as a result of Pellet Cladding Interaction (PCI) during incidental power transients in the reactor. In this study a new experimental device allowing studies of ISCC in a controlled chemical environment is presented. The experiments are performed in an environment that is free of contaminants. First results show that the time to rupture of the specimen is inversely related to the iodine partial pressure. The lowest tested iodine partial pressure, 150 Pa, resulted in an ISCC crack. Post-Mortem microstructural observations provide evidence of iodine corrosion of Zircaloy-4

Imagem corporal: a descoberta de si mesmo Body image: discovering one's self

Este trabalho estuda a contribuição da imagem corporal a partir de seus múltiplos componentes e suas implicações tanto fisiológicas como sociais. O trabalho fornece um breve histórico do surgimento dos estudos de imagem corporal; algumas considerações sobre a fisiologia e os aspectos sociais, e quais as suas influências na imagem de corpo. Optou-se por fazer uma pesquisa bibliográfica para construir um conceito de imagem corporal que fosse consistente, baseado em grandes estudiosos como Paul Schilder, Thomas F. Cash e Thomas Pruzinsky. Mostramos que a todo instante construímos nossas próprias imagens corpóreas, uma vez que cada imagem construída influencia quem está ao nosso redor e vice-versa.<br>The article examines body image from the perspective of its various components and its physiological and social implications. It provides a brief historical background on the beginnings of body image studies, as well as some considerations about physiology and social aspects and how they influence body image. Lastly, bibliographic research based on such great scholars as Paul Schilder, Thomas F. Cash, and Thomas Pruzinsky is used to underpin the construction of a consistent concept of body image, showing how at each and every moment we create our own body image, since each image that we create influences whoever is around us, and vice versa