[en] The important heterogeneity of neritic carbonates reflects: 1 - the facies characteristics of the initial sediments, linked with the diversity of sedimentation environments, and 2 - the post-sedimentation diagenesis characteristics. The aim of this work is to explore this heterogeneity using the δ¹⁸O isotopic signal. A three step pluri-disciplinary approach with different observation scales is established: 1 - a sedimentology study (facies inventory, paleo-environment variations, stratigraphic cycles), 2 - an inventory and chronology of the diagenesis phases and products which have modified he initial sediments, and 3 - a geochemical approach based on the δ¹⁸O signal. This last step combines ionic microprobe measurements performed on separated phases and measurements performed on the whole rock carbonated phase. The carbonate formations under study correspond to the HTM102 borehole made by the ANDRA in the Malm of the eastern edge of the Paris basin. For the stratigraphic approach, some field analogues have been studied (Pagny-sur-Meuse and Gudmont-Villiers sections). (J.S.)

[en] Paul Langevin personifies the figure of popular scientist, buried in the Pantheon, because he was in all great fights: to diffuse knowledge, for improvement and democratization of teaching, for justice and peace. Great theoretician of physics, comparable to Einstein whom he rejoined the approach, he was a fertile discoverer, author, in particular, of a proceeding to detect submarines. He fought politically, regardless of his career, in the ranges of pacifists and opponents of fascism. This book reveals, in his warm diversity, a badly known personality, in spite of the legend in his lifetime. (N.C.)

[en] Work carried out at Berkeley Nuclear Laboratories to develop a fast-response thermocouple for use in liquid metals is described. This thermocouple because of its unique construction, has a junction mass approaching zero and hence its frequency response should be very high. Some of the problems of manufacture are discussed, in particular the high quality of seal required to avoid ingress of liquid metal. A comparison of results obtained with the fast-response thermocouple and with conventional stainless-steel-sheathed thermocouples is made. The improved response of the new thermocouple is clearly visible, hence confirming that measurements made with sheathed thermocouples suffer attenuation. It is concluded that results obtained with the fast-response thermocouple are close to the real magnitude of temperature fluctuations present in turbulent flow. It is also demonstrated that, with suitable corrections, results obtained with sheathed thermocouples can be used to estimate the real signals present in the flow. (author)

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[en] Single crystals of zinc selenide are grown containing indium in concentrations ranging from 5 to 1000 ppm, using a vapour phase technique. Solubility of the indium in the zinc selenide is complete under the growth conditions employed. Examination of chemically thinned samples of such crystals in the transmission electron microscope shows that the only observable crystallographic defects are long thin twins. Similar observations are made with undoped crystals. When samples containing concentrations of indium in excess of 50 ppm are heated in molten zinc at 850 ⁰C, they become darker and more opaque as precipitation effects occur. In addition to long thin twins which are still present, the samples now contain stacking faults and dislocations. All of these defects are usually decorated with precipitates. At low concentrations the precipitates are spherical, but at higher concentrations they begin to assume definite crystallographic shapes with three- and fourfold symmetry depending on the crystallography of the boundary that they decorate and on the orientation of the foil. Random precipitation also occurs. With crystals with the highest indium concentrations, the precipitates may be observed in the optical microscope. They occur as features with much larger dimensions, approximately 50 μm, and consist of short segments which often intersect to produce an overall impression of badly formed rosettes. The nature of the precipitates and the mechanism of their formation are discussed. (author)

[en] Over recent years, the condensers in Electricite de France (EDF) nuclear power plants have been subjected to increased surveillance. This is performed both during operation to detect water intake, and during unit outages to acquire precise knowledge on the general state of the heat exchangers, and especially the tube bundle. The main reason for this increased surveillance is the qualitative importance of the condenser in PWR technology. In effect, the condenser can largely contribute to the long lifetime of steam generators by preserving the quality of extraction water chemistry. The surveillance is based on operating feedback and is part of the overall preventive maintenance program applicable to all our nuclear plants. It implies technico-economic choices regarding condenser renovation and design. In this paper, we will first briefly describe the technology of the nuclear power plant condensers operated by EDF. Then, we will examine the main operating feedback data, and finally outline the surveillance performed on condensers. (author)

[en] This paper successively deals with the four main questions pertaining to operation and maintenance of the cooling source in nuclear power stations: treatment of water for cooling, watching for silt in various parts of the cooling circuit and the cleanliness of the condenser, operating and maintenance problems pertaining to the condenser (erosion, corrosion and vibratory fatigue of tubes and solutions developed) and the cooling towers (freezing and freeze protection)

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[en] As a young physicist at the turn of this century, P. Langevin was one of the most promising figures in French science. His doctoral dissertation on gas ionization and his research on magnetic theory earned him international reputation. All along his career he championed the new physical theories and made efforts to spread them in France. Through his research and his teaching, he thus fostered the development of atomistics, of theory of relativity and of quantum physics. After a brief survey of his physicist's work the paper seeks to discuss his influence on French physics