[en] Niger through Areva ranks number four amongst uranium producing countries and holds the fourth world resources. Niger Uranium story started fifty years ago and AREVA is its first partner since. AREVA/COGEMA inherited the exploration programs conducted by former 'Bureau Minier de la France d'Outre-mer' and 'Commissariat a l'Energie Atomique' in the early sixties. Arlit's deposits came out of that. In association with other partners (Niger government through ONAREM, Japan and Spain), uranium production started in 1967 with joint venture company SOMAIR followed by COMINAK. That partnership stands sound through the 1980-2003 market depression and production rate never slows since. Near by prospects allow extension and keeping activities ahead as it is the case now where the two companies have more than ten years production assured reserves. New major project is also on hand with more than 150,000 tonnes of uranium. AREVA/COGEMA foresaw the current market upraise when it launched a large exploration program three years ago in its previous allotted area. Regulatory agreement is underway for more prospecting areas allocation. More decades of uranium production resources are expected. This long partnership is supported by a sustainable development commitment in a hard to live desert area: health care, school, training, water supply, energy and employment. (author)

[en] Full text: Niger ranks number three amongst uranium producing countries and holds the fourth world resources. Niger Uranium story started fifty years ago and AREVA is its first partner since. AREVA/COGEMA inherited the exploration programs conducted by former 'Bureau Minier de la France d'Outre-mer' and 'Commissariat a l'Energie Atomique' in the early sixties. Arlit's deposits came out of that. In association with other partners (Niger government through ONAREM, Japan and Spain), uranium production started in 1967 with joint venture company SOMAIR followed by COMINAK. That partnership stands sound through the 1980-2003 market depression and production rate never slows since. Near by prospects allow extension and keeping activities ahead as it is the case now where the two companies have more than ten years production assured reserves. New major project is also on hand with more than 100 000 tons of uranium. AREVA/COGEMA foresaw the current market upraise when it launched a large exploration program three years ago in its previous allotted area. Regulatory agreement is underway for more prospecting areas allocation. More decades of uranium production resources are expected. This long partnership is supported by a sustainable development commitment in a hard to live desert area: health care, school, training, water supply, energy and employment. (author)

No abstract available

[en] An evaluation of the importance of the thermo-hydro-mechanical couplings (THM) on the performance assessment of a deep underground radioactive waste repository has been made as part of the international DECOVALEX III project. It is a numerical study that simulates a generic repository configuration in the near field in a continuous and homogeneous hard rock. A periodic repository configuration comprises a single vertical borehole, containing a canister surrounded by an over-pack and a bentonite layer, and the backfilled upper portion of the gallery. The thermo-hydro-mechanical evolution of the whole configuration is simulated over a period of 100 years. The importance of the rock mass's intrinsic permeability has been investigated through scooping calculations with three values: 10-17, 10-18 and 10-19 m2. Comparison of the results predicted by fully coupled THM analysis as well as partially coupled TH, TM and HM analysis, in terms of several predefined indicators of importance to performance assessment, enables us to identify the effects of the different combinations of couplings, which play a crucial role with respect to safety issues. The results demonstrate that temperature is hardly affected by the couplings. In contrast the influence of the couplings on the mechanical stresses is considerable

No abstract available

[en] Geological disposal of the spent nuclear fuel uses often the concept of multiple barrier systems. In order to predict the performance of these barriers, mathematical models have been developed, verified and validated against analytical solutions, laboratory tests and field experiments within the international DECOVALEX III project. These models in general consider the full coupling of thermal (T), hydraulic (H) and mechanical (M) processes that would prevail in the geological media around the repository. For Bench Mark Test no. 1 (BMT1) of the DECOVALEX III project, seven multinational research teams studied the implications of coupled THM processes on the safety of a hypothetical nuclear waste repository at the near-field and are presented in three accompany papers in this issue. This paper is the first of the three companion papers, which provides the conceptualization and characterization of the BMT1 as well as some general conclusions based on the findings of the numerical studies. It also shows the process of building confidence in the mathematical models by calibration with a reference T-H-M experiment with realistic rock mass conditions and bentonite properties and measured outputs of thermal, hydraulic and mechanical variables

[en] In order to demonstrate the feasibility of a radioactive waste repository in the Callovo-Oxfordian clay-stone formation, the French national radioactive waste management agency (ANDRA) started in 2000 to build an underground research laboratory at Bure (East of France). One of the key issues is to understand long term behavior of the drifts. More than 400 m horizontal galleries at the main level of -490 m have been instrumented since April 2005. The continuous measurements of convergence of the galleries are available, allowing a better understanding of the time-dependent response of the clay-stone at natural scale. Results indicate that the viscoplastic strain rates observed in the undamaged area far from the gallery walls are of the same order of magnitude as those obtained on rock samples, whereas those recorded in the damaged or fractured zone near the gallery walls are one to two orders of magnitude higher, indicating the significant influence of damage or/and macro-fractures on the viscoplastic strains. Based on these observations, a macroscopic viscoplastic model which aims to improve the viscoplastic strain prediction in the EDZ is proposed and implemented in FLAC^3Dc. Both the instantaneous and the time-dependent behavior are considered in the model. The short term response is assumed to be elastoplastic with strain hardening/softening whereas the time-dependent behavior is based on the concepts of visco-plasticity (Lemaitre's model). Finally, the damage-induced viscoplastic strains changes is examined through the plastic deformation (assumed to approach the damage rate).In order to verify both constitutive equations and their implementations, several simulations are performed: (a) triaxial tests at different confining pressures; (b) single- and multi-stage creep tests; (c) relaxation tests with different total axial strain levels, etc. Finally, an example of a blind prediction of the excavation of a drift parallel to the horizontal minor stress, σh (gallery GED) is presented and compared to in situ measurements. The results show the influence of damage on viscoplastic strain rates and the advantages and disadvantages of this new approach are discussed. (authors)

[en] This session gathers 13 articles dealing with: three-dimensional and time stepping modelling of the whole Meuse/Haute-Marne ANDRA URL (F. Laouafa, J.B. Kazmierczak, G. Armand, J. Vaunat, M. Jobmann, M. Polster); a constitutive model for a deep argillaceous rock using Hoek-Brown criteria (K. Su, C. Chavant, M. Souley); the long term behaviour of the Boom clay: influence of viscosity on the pore pressure distribution (C. Coll, R. Charlier, X.L. Li, F. Collin); the microstructural changes induced by viscoplastic deformations in argillaceous rocks (F.L. Pellet, G. Fabre, K. Su, P. Lebon); the engineered barrier experiment at Mont Terri rock laboratory (J.L. Garcia-Sineriz, M. Rey, J.C. Mayor); the chemical influence on the Hydro-Mechanical behaviour of high-density FEBEX bentonite (E. Castellanos, M.V. Villar, E. Romero, A. Lloret, A. Gens); the influence of water exchanges on the gallery convergence (P. Gerard, R. Charlier, R. Chambon, F. Collin); a new method for ageing resistant storage of argillaceous rock samples to achieve reproducible experimental results even after long intermediate storage times (O. Czaikowski, K.H. Lux); the installation and evaluation of a large-scale in-situ shaft seal experiment in Boom clay the RESEAL project M. Van Geet, W. Bastiaens, G. Volckaert, E. Weetjens, X. Sillen, A. Gens, M.V. Villar, Ch. Imbert, M. Filippi, F. Plas); the hydro-Mechanical response of the Callovo-Oxfordian mud-stone around a deep vertical drift (J. Vaunat, B. Garitte, A. Gens, K. Su, G. Armand); the sensitivity of total stress to changes in externally applied water pressure in KBS-3 buffer bentonite (J.F. Harrington, D.J. Birchall, P. Sellin); the comparison of the poro-elastic behavior of Meuse/Haute Marne and Tournemire argillites: effect of loading and saturation states (E. Bemer, A. Noiret, F. Homand, A. Rejeb); and the multi-scale modelling of the argillites mechanical behaviour (A. Abou-Chakra Guery, F. Cormery, K. Su, J.F. Shao, D. Kondo)