MELODIE: radioactive solute transport in a repository
The MELODIE code, which provides 3D simulations of radionuclide plume evolution in a geological environment, is being used for the first time by an IRSN partner as part of a European project. The AVN (Association Viçotte Nucléaire), IRSN’s counterpart institute in Belgium, has selected the tool - developed by IRSN – to participate in coordinated action MICADO as part of FP6. MICADO kicked off in October 2006 and aims to produce a review of the uncertainties (linked to lack of knowledge, model simplification, etc.) associated with the decay of spent fuel. Furthermore, IRSN is managing one of the MICADO tasks, assessing the influence of these uncertainties on the migration of radionuclides in terms of repository components.
MELODIE’s originality lies, above all, in the schemes chosen to solve equations representing water flow and solute transport. Indeed, they are adapted to the strong contrasts found in the properties of the diverse materials making up the structured or natural components in a repository. Moreover, MELODIE offers a means of meshing the space that takes account of the diverse heterogeneities of these components, whilst respecting certain geometric constraints imposed by its high-performance digital schemes.
The MELODIE code was one of the elements used by IRSN to prepare the assessment documentations on the feasibility of a geological repository in a clay formation, presented by ANDRA. Moreover, the IRSN Scientific Committee assessed the code in 2006 and supported its development. MELODIE will be enhanced by use at different scientific bodies, thanks to their feedback and participation in open dialogue with the Institute's partners.