Une enquête épidémiologique, initiée en 1989, a été réalisée dans les centrales nucléaires de la vallée de la Loire et du Blayais.Elle porte sur les conditions de travail, l'organisation du travail et leurs liens avec la santé lors des arrêts de maintenance annuels dits arrêts de tranche programmés (ATP).Dans cette étude, transversale, la santé a été essentiellement examinée sous ses aspects psychologiques : anxiété et symptômes dépressifs (échelles de Spielberger et CES-D).Des comparaisons ont été effectuées en et hors arrêt, sur quatre groupes professionnels différemment sollicités, chaque sujet étant pris pour son propre témoin.Le test du khi-deux a été utilisé pour les variables qualitatives et le test sur la différence pour les variables quantitatives.On observe en ATP des heures supplémentaires et des horaires atypiques déclarés plus fréquents (p < 0,01), un rythme de travail et des règles de sécurité jugés plus contraignants, une exposition à l'irradiation jugée plus importante (p < 0,01).Des modifications de l'état psychologique en ATP ont été objectivées pour les agents de conduite alors qu'elles étaient attendues pour les agents de maintenance.Des résultats analogues ont été obtenus en tenant compte de la fréquence des arrêts.Des interprétations sont données en faisant référence à des études qualitatives sur le sujet.Ceci invite à prolonger la réflexion selon les deux axes d'approches, quantitatif et qualitatif.

The decay of radiochemically separated $^{144}\mathrm{Ce}$ source in equilibrium with $^{144}\mathrm{Pr}$ isomers has been reinvestigated with HPGe detectors. The energies and intensities of 19 \ensuremath{\gamma} rays were measured, of which three are new. A $^{144}\mathrm{Nd}$ level scheme allows the incorporation of most of the transitions between 13 excited states. Levels at 2072.8 (${2}^{+}$), 2368.3 (${2}^{+}$), 2581.8 (${3}^{+}$), and 2742.8 (${0}^{+}$) keV, observed earlier in nuclear reactions, are found to be fed in these decays. A 2675.3 keV (${J}^{\ensuremath{\pi}}$${=0}^{+}$) level seems to be a component of the 2.663 MeV multiplet observed in the (p,t) reaction.

AbstractEs soll festgestellt werden, wie das dreiwertige Eu die zwei nicht äquivalenten Y‐Plätze (C2 und S6) in Y2O3 (C‐Form) besetzt.

A versatile sum-coincidence γ-spectrometer is studied. The use of Ge(Li)NaI(Tl) detectors for measurements allows good resolution with acceptable efficiency. No confusion is possible between real and false cascades. An arrangement with a well scintillator NaI(Tl) shows up cascades involving more than two γ rays without any loss of efficiency, as shown on the 75Se decay scheme as an example.

The concentration dependence curves of several , , and activated phosphors for different excitations have been studied. The optimum activator concentration was found to be a function of the number of excited activator ions as well as the exciting wavelength. For exciting radiation having a high absorption coefficient, the optimum activator concentration of a given phosphor shifted to low concentration. The concentration dependence curves of and phosphors under cathode‐ray excitation are almost identical to the curves obtained with host photoexcitation.

This paper is an investigation of whether trivalent europium occupies the two inequivalent yttrium sites (C2 and S6) in (C‐form) randomly or preferentially. The distribution is found to be approximately random for concentrations greater than 1 atom per cent by comparing the reflection spectra of and C‐form powders. From the uncertainty of the measurements, an estimate is made for the ordering energy (∼250 cm−1) which is the maximum difference in the energy of Eu3+ located at the two sites.

In the Schoen-Klasens mechanism of luminescence in II-VI compounds, after excitation a hole is trapped at the acceptor; this charged activator can then act as a recombination site for an electron and the recombination is at the activator and is radiative. In the cathodoluminescence of certain ozygen-dominated phosphors containing rare-earth activators a different mechanism is believed to be applicable. Although hot carriers are generated by electron irradiation, the activator does not act as a major recombination site although it is shown that some carriers are trapped at Eu3+ sites. Recombination is shown to occur at a host site and is usually not radiative; the excited host center acts as an energy donor (as in photoluminescence), subsequently transferring energy to the activator by the usual resonant mechanism. This conclusion is suggested by low temperature experiments showing wide differences in the efficiency of energy storage in YVO4 : Eu3+ and ZnS : Ag and supported by comparisons of the CL and PL emission spectra of YVO4 : Eu3+ (0.05%). The latter experiments show that the excited state of the host just prior to Eu3+ luminescence is the same in CL as in host-excited PL. In general this mechanism is expected to apply whenever the lowest excited state of the host is a bound state such as (WO2−4)*, (MoO2−4)*, (NbO3−4)*.