[en] In order to contribute to the knowledge of protactinium species existing in aqueous solution, the author of this research thesis first addresses experimental techniques and methods, more particularly those based on the theory of solvent-based extraction of hydrolysed ions in presence of chelating agents. Then, after having reported researches on protactinium hydrolytic properties (experimental results of the hydrolysis of pentavalent or tetravalent protactinium, interpretation and discussion of these results), the author reports the study of protactinium complexes in aqueous solution: study of the complexing of pentavalent protactinium (sharing between complexing aqueous environments and benzene solutions, peculiar case of a hydrochloric environment, absorption spectra of aqueous solutions of pentavalent protactinium), and the study of the complexing of tetravalent protactinium (sharing between complexing aqueous environments and benzene solutions, absorption spectra of protactinium aqueous solutions). Hydrolytic properties of pentavalent and tetravalent protactinium, and ionic or molecular species of protactinium in a complexing environment are finally discussed

[en] After the presentation of an opinion on the role of low power modular nuclear reactors (SMRs) in the future of nuclear in the world, a report presents these reactors. It proposes a classification of SMRs, comments the maturity level of projects in the world (France excluded), discusses benefits associated with SMRs, presents scientific and technological problems which remain to be solved, and describes the French situation and current studies

[en] The aim of this paper is to discuss the behaviour of Pu in environmental-like situations. This is an illustration of the concepts of subtracer chemistry because most of the nuclear and chemical properties of Pu isotopes fit well the criterias required for observable reactions. The predicted behaviour of Pu quantities, down to few atoms, based on the situation known for usual concentrations is discussed. First, a short survey of Pu concentrations in environmental situations is given. Then the most probable equilibria of Pu species to be achieved, now or in a far future are selected. Finally how these equilibria are modified in the case of few Pu atoms is examined. (author). 50 refs., 4 tabs., 6 figs

[en] Uranium (Z = 92) is known since 1789 and it remained the heaviest element of the periodic table until 1940. In 1925 all the stable or radioactive natural elements were known and assigned in this table, the latest being discovered that year being rhenium. Three boxes in the table remained empty (Z = 43, 61 and 85) and despite the efforts of the chemists to fill them, the periodic table remained unchanged until 1937. After the discovery of artificial radioactivity in 1934 it was quickly understood that man-made elements could be produced and that the periodic table could be completed and extended beyond Z = 92. The first synthetic element with Z < 92 was the technetium (Z = 43), the first of those with Z > 92 was the neptunium. This article deals with the discovery and chemical identification of the first transuranic elements Z = 93 to 96 and the following ones, up to Z = 103, and how they have been incorporated into the series of actinides

[en] X-ray photoelectron spectroscopic (XPS) analysis has been carried out on samples of crystalline uranium dioxide following exposure to deionised or mineral water at 60 and 90degC for several weeks. A surface layer formed on UO₂ samples immersed in mineral water at 90degC has been identified as magnesium silicate precipitated from the mineral water. Depth-profiling experiments showed that this magnesium silicate deposit was ca. 100-200 nm in thickness and revealed the formation of a thin film of UO₃ between the bulk UO₂ and the outer magnesium silicate deposit. (author)

[en] The discharged nuclear fuel from current thermal neutron reactors contains fissile material: plutonium that is formed in the fuel and uranium that has not been consumed. If it is separated, it can be used. Thus France recycles, but only once, the plutonium in the spent fuel of its nuclear power plants. This reduces but does not eliminate the need for natural uranium. The multi-recycling of plutonium and uranium is only possible in fast neutron reactors (RNR). A fast reactor fleet can thus be self-sufficient in nuclear fuel without the need for natural uranium. The transition from one fleet to another is a major challenge, at the heart of which is chemistry. Indeed, the performance of spent fuel reprocessing will have to be increased well beyond what it is today. This article discusses why plutonium could be the fissile material source of the future of nuclear power and the major chemistry issues that need to be overcome to achieve this

[en] The nuclear industry generates radioactive waste. Some of it is especially dangerous for the public because of its high activity and long life. According to the provisions of the 2006 law, the long-term management of this waste has three components: its industrial storage, its disposal in geological repositories and the separation-transmutation of long-lived radioactive elements. In addition, the nuclear industry and the dismantling of decommissioned facilities also produce waste of lower activity which requires specific management, in particular because of the large quantities produced. This report assesses the state of progress of studies and research on these topics and reviews the approach to these issues in different countries with a nuclear industry

[en] Shale gases have been the centre of heated debates for a few years. The opinions range from an outright ban on their exploitation to the notion that they might in an unexpected and almost miraculous way restore growth in our country and create jobs. In view of the importance of the questions raised by this topic, the Comite de Prospective en Energie de l'Academie des Sciences (CPE) provides elements to help clarify the debate and to formulate recommendations with the aim in particular of reducing current uncertainties. This report first describes the various contextual elements and then some recommendations that have been formulated. The first four recommendations concern research and exploration; the following five concern the exploitation of shale gases which could be potentially undertaken provided that necessary conditions, in particular for reducing environmental risks, are fulfilled. 1. Launch a research effort involving academic laboratories and major organizations to study all the scientific issues arising from the exploration and exploitation of shale gases. 2. Prepare exploration by making use of existing or archived geological, geophysical and geochemical data and involve geologists in the evaluation of reserves. 3. Develop studies and experiments aimed at evaluating and reducing the environmental impact of any potential exploitation. 4. Create an independent and multidisciplinary scientific authority to monitor actions taken to evaluate resources and their methods of exploitation. 5. Address issues of water management, a major problem in the exploitation of shale gases. 6. Implement environmental monitoring before, during and after exploitation. 7. Launch developments to improve the processes of hydraulic fracturing and develop alternative methods. 8. Initiate a research program to develop appropriate regulations to address the long-term tightness issues in exploitation drilling. 9. Full-scale tests should be carried out under conditions that conform to current French regulations, which ban hydraulic fracturing, in former coal-mining areas that have already undergone fracturing in order to better assess resources and maximize production performance

[en] As it is commonly stated that it would be possible to massively developed renewable energies in order to de-carbonate our energy system by getting rid of fossil and nuclear energies, the authors recall and discuss some facts. They outline that the solution depend on geographical and climatic constraints which are proper to each country, that renewable energies only represents about a quarter of our consumption and raise the problem of intermittency. Moreover, the present status of energy storage technology does not provide a viable and possible solution, and is still to be further developed. They also outline problems faced in Germany where coal fired plants had to be created to solve issues of electricity availability. They outline that France is one of the less carbon-emitting country, due to the importance of nuclear energy. Thus, they outline that realistic scenarios must be proposed in which nuclear will still have its role in a de-carbonated system, and with investments in basic, technological and industrial research on various fields (nuclear wastes and safety, energy storage, CO_2 capture and sequestration)

[en] The nuclear industry generates radioactive waste. Some of it is especially dangerous for the public because of its high activity and long life. According to the provisions of the 2006 law, the long-term management of this waste has three components: its industrial storage, its disposal in geological repositories and the separation-transmutation of long-lived radioactive elements. In addition, the nuclear industry and the dismantling of decommissioned facilities also produce waste of lower activity which requires specific management, in particular because of the large quantities produced. This report assesses the state of progress of studies and research on these topics and reviews the approach to these issues in different countries with a nuclear industry