[en] The pipe rupture protection device is housed in a hollow cylinder connecting a sheathed bleed line for radioactively contaminated (He) gas and an unsheathed pressurization line. Inside the hollow cylinder there is a pendulum flap tilted in the direction of the flow by the impact pressure generated when a set flow velocity is exceeded, thus closing the pressurization line. It will not be plugged up by graphite dust. (DG)

No abstract available

[en] Carbonate rock aquifers are one of the main water supply sources for the French Western Pyrenees. The discontinuous structure of these reservoirs is a main obstacle to the development of such resources. By the way, since no other aquifer can be tapped, many communities have decided to improve their knowledge of the main springs over the whole region. Four sites have been considered from 2003 to 2006 and have been the object of multidisciplinary investigations including: geological mapping, geophysical investigations, dye tracing experiments and in situ hydrochemical survey. Stable isotopes have been analysed on both rainfall (¹⁸O, ²H) and spring waters (¹⁸O, ²H, ¹³C, ³⁴S) in order to evaluate the origin of groundwaters, their residence time within the systems and to appreciate the occurrence of exchanges with other aquifers. Finally, this study provides a good example of how to include hydrogeochemistry and isotopic tools in a water supply management policy. (author)

[en] Carbonate rock aquifers are one of the main water supply sources for the French Western Pyrenees. The discontinuous structure of these reservoirs is a main obstacle to the development of such resources. By the way, since no other aquifer can be tapped, many communities have decided to improve their knowledge of the main springs over the whole region. Four sites have been considered from 2003 to 2006 and have been the object of multidisciplinary investigations including: geological mapping, geophysical investigations, dye tracing experiments and in situ hydrochemical survey. Stable isotopes have been analysed on both rainfall (¹⁸O, ²H) and spring's waters (¹⁸O, ²H, ¹³C, ³⁴S) in order to evaluate the origin of groundwaters, their residence time within the systems and to appreciate the occurrence of exchanges with other aquifers. Finally this study provides a good example of how to include hydrogeochemistry and isotopic tools in a water supply management policy. (author)

[en] The sitting of a nuclear waste repository in a geological medium involves, among other aspects, predicting water inflows in the shafts and drifts, and evaluating possible geometries for the waste handling and storage galleries. In sedimentary host rocks, porous medium hydrogeology can be used easily to provide water inflow estimates, while geology will describe the geometry of the various layers, as well as the limited number of faults that may cut them. However, crystalline rocks such as the Vienne site, may be cut by numerous faults and fractures. To deal with such host rocks, we need new concepts - which have been under development during the last 15 years - in order to describe properly the spatial arrangement of discontinuities, its consequences in terms of the site hydrogeology, and in terms of the geometry of volumes available between faults for designing the underground storage cavities. A starting point is building a model of the fractures, using the statistical description of the investigated fracture field, including dips, dip directions, sizes, and intensities noted in boreholes or on outcrops. Such a model can then be used to compute flows. It is based on idealizing fractures as planar objects, often disks, with statistical geometrical properties inferred from available data. The model realism can be improved by conditioning the geometry on data, either directly observed - by fixing in space observed fractures - or indirectly inferred - by integrating the results of hydraulic, or even tracer tests. Discrete fracture models can then be used for many treatments, well beyond simple flow and transport computations. We illustrate this through two studies applied to the crystalline Vienne massif. First, image analysis techniques that were first developed for two dimensions, and have been recently extended to three dimensions, help with describing the space available between discontinuities, in order to define the sound rock blocks available for the waste emplacement. The statistical distribution of the block properties, i.e. volume, sizes, shape, is computed first by a procedure using standard image analysis algorithms called 'erosion-dilatation', and then by a morphological study. This phase accounts for special constraints on block shapes, such as the need for a minimum distance between fractures and the boundaries of the blocks. (authors)

[en] This session gathers 4 articles dealing with: the seismic imaging of the variability in the Callovo-Oxfordian argillite (D. Guillemot, B. Yven); the identification of homogeneous zones from well logging measurements by statistical tools (A. Marache, J. Riss, A. Denis, B. Yven, A. Trouiller); the geostatistical characterization of Callovo-Oxfordian clay variability from high resolution log data (M. Lefranc, B. Beaudoin, J.P. Chiles, D. Guillemot, C. Ravenne, A. Trouiller); and the Magnetic properties, magnetic mineralogy and fabric of the argillites of the Meuse/Haute-Marne URL (J.L. Bouchez, L. Esteban, Y. Geraud, A. Trouiller, R. Siqueira)