The Oxide Dispersion Strengthened (ODS) materials are potential candidates as cladding tubes for Sodium-cooled Fast Reactors. The nano-oxides are finely dispersed within the grains and confer excellent mechanical properties to these alloys. Hence, assessing nano-particle stability under irradiation remains crucial to guarantee safe use of these materials. Although neutron irradiation remains a binding and challenging experimental study to conduct, difficulties can be overcome by ion beam processing. Ion beam processing of the ODS material allows to identify the radiation-induced Ostwald ripening as the mechanism governing the nano-particle response under irradiation. The result is the increase in size and a decrease in density of the finely dispersed Y2Ti2O7 nano-particles. Under neutron irradiation, radiation-induced Ostwald ripening appears to be less effective since a slight growth of nano-particles is observed. Further, our approach shows that nanoparticle growth kinetics should scale as φ1/3, φ being the radiation flux. This suggests that the low irradiation flux is at the origin of the slower growth kinetics of the neutron irradiated particles. Both neutron and ion irradiation induce a modification of the nanoparticles/matrix interfaces which are generally flat and sharp prior to irradiation and present steps after irradiation. This could alter the nano-particle coarsening during irradiation.

Five semi-structured interviews were conducted, using the psychological autopsy method, in order to document the causes of geriatric suicide and to describe the interaction among suicidal elderly persons, their personal and social environments, and health care professionals. The results of this study support our hypothesis that elderly persons view suicide as a means of alleviating the psychological suffering associated with the frustration they experience on account of their inability to satisfy their basic needs. Three types of basic needs that affect the suicidal tendency of elderly persons were identified: the need to self-actualize, the need to belong, and the need to feel safe. The results also show that the people who make up the social and personal environment of elderly persons have a limited role in the prevention of suicide. This is due to their unfamiliarity with the problems surrounding the fulfilment of the basic needs of the suicidal elderly. Furthermore, as revealed in the cases studied here, the intervention of the health care system has centred mainly on the use of medication as a treatment for symptoms of psychological distress. The health care system pays little attention to the dissonance associated with the frustration suicidal elderly persons experience on account of their inability to satisfy their basic needs. Finally, the outcome of this qualitative study suggests that understanding the basic needs of the elderly can be very useful in understanding geriatric suicide.

We calculated the atomic structure of the (310)[001] symmetric tilt grain boundary (GB) in B2 ordered Fe-Al, using empirical and ab initio potentials. Including a proper treatment of the influence of small departures from bulk B2 stoichiometry on chemical potentials through a thermodynamic point-defect model, we obtain low energy GB variants geometrically close to the usual ones deduced from the coincidence site lattice (CSL) theory. In Al-rich alloys, both methods predict GB Al segregation whereas in Fe-rich alloys, the empirical (resp. ab initio) approach leads to Fe (resp. Fe or no) segregation. With both methods, strong GB chemical effects triggered by the bulk composition appear, showing that in B2 Fe-Al, GB properties may be strongly influenced by small bulk composition changes.

The role of the interatomic potentials on the primary damage has been investigated by Molecular Dynamics (MD) simulations of displacement cascades with three different interatomic potentials dedicated to α-Fe. The primary damage, caused by the neutron interaction with the matter, has been found to be potential sensitive. We have investigated the equilibrium parts of the potential as well as the “short distance interactions” which appear to have a strong influence on the cascade morphology and defects distribution at the end of the cascade. The static properties as well as dynamical (thermal) characteristics of the potentials have been considered; the kinetic and potential energy transfers during the collisions have also been studied.

In nuclear power plants, Zr–based cladding is corroded by the primary coolant. Concomitantly, it undergoes hydrogen pick–up which induces modifications of its mechanical properties, especially creep and recrystallization rates. Below 600K, the deformation in hcp Zr is partially controlled by screw dislocations, which due to their intricate core structure have reduced intrinsic mobility. Here, we address the possible hydrogen induced modifications of the core structure of screw dislocations. We used first–principle calculations based on the density functional theory to evaluate the interaction between hydrogen and screw dislocation cores and also to evaluate the hydrogen induced modifications of the prismatic and basal gamma surfaces. We show that the presence of hydrogen results in significant reductions of the stacking fault energies.