Since 1992 the international DECOVALEX (DEvelopment of COupled models and their VALidation against Experiments) research project has been at the forefront of advancing the understanding of coupled thermal-hydrological-mechanical-chemical (THMC) processes in support of the safe geological disposal of radioactive wastes.

Quintessa is participating in the current phase (DECOVALEX-2015) on behalf of the Nuclear Decommissioning Authority (NDA) Radioactive Waste Management Directorate (RWMD) as part of a project on coupled processes awarded to a consortium led by AMEC. A team from Quintessa, the University of Edinburgh and AMEC is developing and applying mathematical models for the following tasks:

  • Task A is based on the SEALEX in-situ experiments in a tunnel in argillite at Tournemire in France. The objective is to predict the hydro-mechanical performance of bentonite-based seals in horizontal boreholes.
  • Task C1 is analysing coupled THMC processes in experiments on rock fractures, in particular changes to fracture permeability through fluid-rock reactions under hydrothermal conditions.

At the third DECOVALEX-2015 workshop held recently in South Korea, presentations were made on modelling the hydro-mechanical properties of bentonite, which forms the first two stages of Task A, and modelling flow through and chemical process in a fracture for the initial stages of Task C1.

Quintessa is also providing direct support to DECOVALEX-2015 by leading Task C1, which involves determining the work programme and collating results from the participating teams.