Bentonite barriers in integrated performance assessment - BENIPA Project

The overall objective of BENIPA project is to assess the state of the art in the treatment of bentonite barriers in Integrated Performance Assessment, evaluating the capacity and consistency of methods and data available to convincingly justify the capacity of bentonite barriers to perform their assigned safety functions. The relevant design concepts for bentonite barriers have been reviewed and the understanding of the safety roles of the bentonite barriers has been re-assessed. FEP's databases for bentonite barriers have been generated using innovative approaches. A Project handbook compiling relevant information for the safety assessment of bentonite barriers has been produced as a reference book. An in depth analysis and cross comparison of the different models available in the participating organisations for the numerical simulation of the behaviour of bentonite barriers at different levels of detail has been made. The consistency and fulfillment of data needed by the models has been evaluated. Finally, numerical simulations have been carried out at both process and integrated levels in order to test the capacity of bentonite barriers to fulfill their safety functions with respect to hydraulic, mechanical, chemical and transport processes. Modelling efforts at process level included reactive transport, especially to assess the effects of cementitious degradation products on bentonite minerals, coupled thermo-hydro-mechanical modelling, including the growth of canister corrosion products, and radionuclide transport associated with colloids potentially generated by bentonite barriers. Sensitivity and optimisation analysis have also been performed, considering a wide range of alternative cases regarding the assumptions and data used in the assessments. (authors)