[en] Xenon instabilities lead to increase initial errors. So it is extremely difficult to get an accurate calculation schema able to deal with these problems which are very important for electrical grid whose electronuclear output is large. The main task was to build a tridimensional calculation schema including nuclear, thermal hydraulic feedback. It was qualified by comparing its results with an actual experiment. Many technical problems were investigated through analytical studies or calculation results: time step, spatial mesh, finite element, convergence criterion, modelization for grids and fast control rod moves. Moreover, a 1D model, for less expensive, was studied. Its comparison with the 3D results allowed to check its accuracy and to validate the modelization of the radial laplacien and the modelization of the control rods

[en] Proposals are made for improving current second-generation superhomogeneisation (SPH) methods in three different ways and to use them in heterogeneous and homogeneous diffusion procedures for reactor design and operating calculations. The first improvement consists of using a surface radial leakage model in the flux calculation to represent the macroscopic flux curvature in the assembly. The second improvement is accomplished by the introduction of the Selengut normalization in the SPH equivalence procedure replacing the flux-volume normalization currently used with second-generation methods. Finally, the buckling calculation is improved to better represent the target color-set. Second- and third-generation SPH techniques for heterogeneous or homogeneous diffusion procedures are now implemented as a unified algorithm in a lattice code. Two-group benchmarks are proposed to measure precisely the equivalence effectiveness and the improvement gained with third-generation methods

[en] I-tese, the Institute of technico-economy of energy systems of the French atomic energy and alternate energies commission (CEA), carries out technical-economical studies and multi-criteria and prospective analyses of energy technologies or systems from the primary sources to the end-use. The quarterly I-tese newsletters present some news elements allowing to better understand the stakes of the new energy supply challenges under its different aspects: economy, energy independence, environment and Earth preservation. This issue treats of the following topics: Special issue: optimization of energy investment choices and time cost: what choice of discounting rate? Presentation: the Copenhagen meeting at short steps, the saga of photovoltaic power repurchase prices, biomass energy: towards worldwide trades?, what advantages for thorium reactors? (J.S.)

[en] APPOLO-II is a new-generation multigroup transport code for assembly calculation. The code has been designed to be used as a tool for reactor design as well as for the analysis and interpretation of small nuclear facilities. As the first step in a criticality calculation, the collision probability module of the APPOLO-II code can be used to generate cell or assembly homogenized reaction-rate preserving cross sections that account for self-shielding effects as well as for the fine-energy within cell flux spectral variations. These cross section data can then be used either directly within the APPOLO-II code in a direct discrete ordinate multigroup transport calculation of a small nuclear facility or, more generally, be formatted by a post-processing module to be used by the multigroup diffusion code CRONOS-II or by the multigroup Monte Carlo code TRIMARAN

[en] Conclusion: • A large-scale deployment of nuclear reactors will require more Uranium; • U resources are limited and not well known: – U from Seawater : Major technical breakthrough needed; – U from phosphate rocks : 4 Mt, an upper bound limit => Mining exploration is necessary; => What about the annual production capacity? • If only PWRs are deployed in this century: – All the U identified resources are engaged before 2050 and consumed before the end of the century => The deployment of PWR only is not sustainable in the long term; => The FR deployment is inescapable for a long term development of nuclear power. But the installation rate of the FR fleet is limited by the Pu availability.

[en] According to almost all forward-looking studies, the world’s energy consumption will increase in the future decades, mostly because of the growing world population and the long-term development of emerging countries. The effort to contain global warming makes it hard to exclude nuclear energy from the global energy mix. Current light water reactors (LWR) burn fissile uranium (a natural, finite resource), whereas some future Generation IV reactors, as Sodium fast reactors (SFR), starting with an initial fissile load, will be capable of recycling their own plutonium and already-extracted depleted uranium. This makes them a feasible solution for the sustainable development of nuclear energy. Nonetheless, a sufficient quantity of plutonium is needed to start up an SFR, with the plutonium already being produced in LWR. The availability of natural uranium therefore has a direct impact on the capacity of the reactors (both LWR and SFR) that we can build. This paper discusses the correspondence between the resources and the nuclear power demand as estimated by various international organisations. Uranium is currently produced from conventional sources. The estimated quantities of uranium evolve over time in relation to their rate of extraction and the discovery of new deposits. Contrary to conventional resources, unconventional resources – because they are hardly used – also exist. These resources are more uncertain both in terms of their quantities and the feasibility of recovering them. Recovering uranium from seawater would guarantee a virtually infinite resource of nuclear fuel, but its technical and economic feasibility has yet to be demonstrated, and huge advances need to be achieved in this direction. According to different publications on phosphate reserves, the potential amount of uranium recoverable from phosphates can be estimated at around 4 MtU. Furthermore, the production of uranium as a by-product of phosphate is determined by the world production of phosphoric acid. Uranium recovery as a by-product of phosphate rocks could be competitive for the moment, but limited at the most to 10 kt U per year, i.e. less than 20% of current world demand. The only way to lift the constraint of capacity production is to produce uranium as a primary product of phosphates. Unfortunately, this solution is very unlikely due to its high unit cost. In line with these considerations, the correspondence between the estimated resources and the forecast energy scenarios is examined, first with the current type of light water reactors which burn uranium, and secondly with a mixed fleet with both light water reactors and fast reactors which use plutonium. (author)

No abstract available

[en] Specific technical features of fast reactors make them more expensive than water-cooled reactors in terms of initial investment, an over cost of 30% is acknowledged in this study. Their consumption of natural uranium is negligible being fed on depleted uranium (except for the very first cycle when an important quantity of plutonium is necessary). In the context of the scarcity of natural uranium, fast reactors could provide a competitive KWh compared with PWR. The study shows that sodium-cooled fast reactor could be economically competitive somewhere in the second part of the 21. century. The development of fast reactors could be accelerated by other arguments than economic competitiveness, for instance some governments might value more the energy independence given by a fleet of fast reactors or by considerations linked to non-proliferation or to the burning of actinides. In addition the article details the worldwide resource in natural uranium. (A.C.)

[en] I-tese, the Institute of technico-economy of energy systems of the French atomic energy and alternate energies commission (CEA), carries out technical-economical studies and multi-criteria and prospective analyses of energy technologies or systems from the primary sources to the end-use. The quarterly I-tese newsletters present some news elements allowing to better understand the stakes of the new energy supply challenges under its different aspects: economy, energy independence, environment and Earth preservation. This issue treats of the following topics: Financial needs for the abatement of greenhouse gas emissions: 100 billion euros per year; News: the Orme Club role in the framework of the Campus project of the Plateau de Saclay area, the bio-diesel market: from Europe today to the USA tomorrow, opening of the electricity market: will France succeed in meeting the European requirements?; Special issue: Energy-Climate contribution (ECC): what challenge for tomorrow and after? ECC's amount and modalities: a difficult adjusting, the incentive tax: what assets?; Presentations: low power nuclear reactors: history and technical-economical perspectives, fuel management and burnup, the lithium market. (J.S.)

[en] The 4. generation reactors meet the demand for sustainability of nuclear power through the saving of the natural resources, the minimization of the volume of wastes, a high safety standard and a high reliability. In the framework of the GIF (Generation 4. International Forum) France has decided to study the sodium-cooled fast reactor. Fast reactors have the capacity to recycle plutonium efficiently and to burn actinides. The long history of reprocessing-recycling of spent fuels in France is an asset. A prototype reactor named ASTRID could be entered into operation in 2020. This article presents the research program on the sodium-cooled fast reactor, gives the status of the ASTRID project and present the scenario of the progressive implementation of 4. generation reactors in the French reactor fleet. (A.C.)