ThORN – in-situ experiment design for the investigation of the relevance of thermo-osmotic flow in clay for radioactive waste disposal

As part of the ThORN project, an in-situ experiment to quantify thermo-osmotic (TO) flow in Callovo-Oxfordian clays will be carried out at the Bure Underground Research Laboratory (URL) in Meuse/Haute-Marne, France.This project aims to fill an existing gap in the literature regarding the impact, importance and parameterization of TO in the context of nuclear waste storage in clay rocks. An in-situ experiment is being developed in order to address this gap. The design and evaluation of all stages of the experiment will be supported by numerical simulations in the open source-simulator OpenGeoSys [1]. Parallel to OpenGeoSys, COMSOL Multiphysics was used for verification. The results obtained from both were compared and iterated on. This allowed to catch and correct errors and ensure the assumptions and parameterization are consistent between the institutions participating in the ThORN project. The resulting models will be used to analyze near and far field effects in a repository environment.This contribution delivers an overview of the highlights and conclusions from the experiment design phase. The parameters and assumptions on which the design is based are presented and discussed. Predictive simulations of the design are presented with focus on the pressure development and water flows. We show how the numerical simulations can aid in exploring the potential experiments of thephysical experiments before they are build.AcknowledgmentsThis work has been funded by the German Federal Office for the Safety of Nuclear Waste Management(BASE), ThORN project: “Experimental investigations on thermo-osmotic flow in argillaceousmaterials relevant to deep geological repositories for radioactive waste” (Grant number: 4723F00104).Reference[1] Lars Bilke, Dmitri Naumov, Wenqing Wang, Thomas Fischer, Feliks K. Kiszkurno, ChristophLehmann, Jäschke Max, Florian Zill, Jörg Buchwald, Norbert Grunwald, Kristof Kessler, LudovicAubry, Maximilian Dörnbrack, Thomas Nagel, Lion Ahrendt, Sonja Kaiser, and TobiasMeisel. OpenGeoSys. Zenodo, January 2025.