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).