Euradwaste '08 - EU Bookshop - Europa

maintaining and develop competence networks (which he considered of interest for all and being a
consequence of advanced programs).
As an example of on-going FP7, implementation oriented research he mentioned the Collaborative
Project "Redox Phenomena Controlling Systems" (ReCosy). He specified the various issues dealt
within this project, and especially mentioned methods of redox determination, redox responses of
repository systems upon environmental changes, and redox reactions of selected elements such as
actinides, technetium iodine and selenium. Other issues mentioned were a better understanding of
sorption on crystalline rock, sorption on the overburden of salt host rocks, and especially the interpretation
of data resulting from existing projects.
Pierre Toulhoat put his emphasis on geochemistry of elements and species relevant for disposal in
the geosphere. He advocated more use of specific underground laboratories to investigate geochemical
processes, especially for the in situ validation of speciation predictions. He saw the need
to improve our understanding on conditions when thermodynamic equilibrium dominates, the possibility
of the continuation on the long term of non-equilibrium situations and more knowledge on
competition between various reactions. On the side of direct and obvious impact in the safety case
he mentioned investigations on isotopic dilution and isotopic exchange.
Scott Altmann directly and in detail addressed the questions listed above. He saw the major scientific
progress in our present understanding of pore water solutions in clays. He also mentioned the
progress in sorption modelling and especially the use of thermodynamic models putting on a firmer
basis the retardation considerations within the safety case. However, for some safety relevant elements
such as iodide and selenite the understanding of retardation processes need improvement. In
line with such requirements he advocated a better understanding of mineral reactions and the radionuclide
interaction in this context. When scientific fields develop they start to differentiate. In
the context of this general fact, he did essentially not see much commonality between host rocks
and very fruitful interactions – limited to the far-field, of course - between repository projects in
different host rocks.
After these statements by the panellists the floor was open for questions and comments by the participants.
Jordi Bruno emphasised the increased credibility of safety cases resulting from such large projects
as NF-PRO and FUNMIG. In the future he saw more utilisation of micro-approaches in experimental
investigations.
Gérald Ouzounian did not fully agree and reminded the audience that developing new analysis
methods is not the main issue in the safety case.
From the floor came the question where one could find guidance on what to study. Scott Altmann
recommended looking into the literature and especially existing performance assessments.
Jon Harrington asked for clarification on the importance of coupling processes. Scott Altmann
responded that the strength is dependent on the radionuclide in question. In performance assessment
this coupling is less of importance. However, the sensitivity analysis is all-important. This is
also a result from the variability of the far-field properties. It is hard to correlate variability of the
various properties; and after all, the question is which variability the nuclides are seeing.
Wernt Brewitz reminded the audience that each safety case is unique and, as a matter of fact, cannot
be verified by experimentation.
362