Forschungszentrum Karlsruhe - Wissenschaftliche Berichte - FZKA 6721

TRePro 2002 - Modelling of Coupled Transport Reaction Processes. Workshop of the Forschungszentrum Karlsruhe held at 20th and 21st of March 2002

V. Metz, W. Pfingsten, J. Lützenkirchen, W. Schüßler

Preface
A wide variety of geochemical processes including the migration of radiotoxic and chemotoxic materials are intimately related to reactive transport processes. The relevant rock-water systems can be regarded as open geochemical reactors where chemical changes occur via the transient interactions between the aqueous, solid and gas phases. The evolution of these open systems is affected by diverse processes including fluid flow, transport of solutes and colloids, and chemical

reactions.

Reactive transport codes may be used to simulate the chemical interactions and the transient migration of relevant species in one-, two- or even three-dimensional spatial configurations. The ability to model reactive transport in natural systems and the near- and far-fields of waste repositories has advanced considerably over the past decade. Numerous comprehensive reactive transport codes have been developed and applied. However, all modelling approaches implicitely apply certain simplifications. At the present stage of process understanding and the state of computational capabilities, it is still impossible to predict the evolution of a natural system or a repository. Nevertheless, reactive transport modelling may provide insight into some of the relevant phenomena.

TRePro 2002 deals with “Modelling of Coupled Transport Reaction Processes”. The field of reactive transport involves a number of diverse scientific disciplines, such as those related to advective, convective, dispersive and diffusive transport of solutes and colloids, and interactions among aqueous species, redox reactions, dissolution/precipitation, surface complexation and ion exchange, as well as radioactive decay and biochemical reactions, and those scientific disciplines related to the required numerical aspects of the modelling.

The workshop focuses on the following major topics:

   . Coupling of sorption processes and transport

   . Coupling of redox processes and transport

   . Coupling of dissolution / precipitation processes and transport

   . Influence of colloids on transport phenomena

Coupled transport reaction modelling may become one of the cornerstones to evaluate the performance of a geological repository for radiotoxic and chemotoxic wastes. Therefore, the challenge of involving coupled transport reaction processes in the frame of performance assessment is included in TRePro 2002. Indeed, it is one of the objectives of the workshop to learn to what extent this may be done at present. The workshop is an attempt to bring together researchers from the disciplines

mentioned above, experimentalists and modellers, for stimulating discussion on the latest developments in modeling of coupled transport reaction processes and their relevance to performance assessment.

TRePro 2002 is the third meeting in the series of the Karlsruhe Geochemical Workshops. The first workshop was held in 1997 at the Forschungszentrum Karlsruhe. Its main topic was “Geochemical Modelling - Radio Toxic and Chemical Toxic Substances in Natural Aquatic Systems”. The second workshop was held in 1999 in Speyer focusing on “Mineral / Water Interactions Close to Equilibrium”. The present workshop was jointly organized by Institut für Nukleare Entsorgung, Forschungszentrum Karlsruhe (FZK-INE) and Labor für Endlagersicherheit, Paul Scherrer Institut (PSI-LES). This book of abstracts contains the contributions presented at TRePro 2002 held at the Forschungszentrum Karlsruhe, March 20-21, 2002.

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