ALLIANCES : Simulation Platform for Radioactive Waste Disposal

The safety assessment of nuclear waste disposals needs to predict coupled thermo-hydro-mechanical and chemical (T-H-M-C) processes, involving phenomena such as heat generation and transport (due to radioactive decay of nuclear waste), infiltration of groundwater (hydrological processes), swelling pressure of buffer material due to saturation (mechanical processes) and chemical evolution of buffer material and porewater (chemical processes). It appeared as necessary to develop and assess numerical tools that model these physical mechanisms. Therefore, the French Atomic Energy Commission (CEA), and the French Agency for Radioactive Waste Management (ANDRA) have been jointly developing since 2001 the software platform ALLIANCES. The French Electric company (EDF) joined the project in 2003. The aim of the project is to obtain a numerical platform enabling the simulation of all phenomena governing storage and disposal safety. Alliances goal is not to develop a new scientific tool but to accumulate within the same simulation environment the already acquired knowledge and to gradually integrate new ones. Therefore, it is based on the following characteristics: (i) Seamless integration of legacy codes as software components; (ii) Allow efficient coupling of different numerical codes; (iii) Improve results quality evaluation by using various codes for the same application (iv) Integration of specific tools for uncertainties analysis (iv) Sharing open source components for pre and post processing. The current version of Alliances contains the following modules: Hydraulics in unsaturated and saturated media; Extended transport in saturated media (involving convection/diffusion/dispersion transport, sorption via retardation coefficient and radioactive decay); Chemistry/Transport coupling in saturated media with feedback of porosity changes; Thermo-Hydraulics; Thermo-Aerolics; Container degradation models; Sensitivity analysis tools. The next releases will include more physical phenomena like reactive transport in unsaturated flow, thermo-aeraulics, thermal and mechanical models and their coupling with hydraulics, alteration of waste package coupled with the environment. Since the distribution of the first release of Alliances (December 2003), the Platform was used by ANDRA for his 2004 safety simulation program and by CEA for reactive transport simulations (migration of uranium in a soil, diffusion of different reactive species on laboratory samples).Presenters: name: montarnal, philippe affiliation: CEA Sacla