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New project iCross - taking a holistic view on safe repository systems

Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis

The reliable and consistent safety assessment for a repository for high-level, heat generating radioactive wastes over time scales of hundred thousands of years requires the development of a new quality of process understanding and simulation for the realistic description of repository evolution scenarios. This is notably required due to the challenging task to compare and assess the safety of different repository concepts in different host rocks in depth within the German site selection process. The basis of simulations needs to take into account the knowledge on molecular level reactions and must consider properly the coupled thermo-hydrological-mechanical-chemical-biological (THM/CB) processes influencing the integrity of repository barriers and controlling radionuclide behaviour in repository systems on different scales.


The recently started project iCross (July 2018 to June 2021, total budget 9 million €), jointly funded by the "Initiative and Networking Fund" of the Helmholtz-Association (HGF) and the Federal Ministry of Education and Research (BMBF), aims at a holistic scientific view onto safe repository systems and towards a realistic description of repository system evolution across different spatial and temporal scales. Within iCross, in-depth process understanding will be achieved by intensive interaction between

  1. novel, cross-scale experimental approaches using high-end research infrastructures,
  2. system analysis and process modelling,
  3. advanced numerical simulations applying cutting edge software engineering and high-performance computing, and
  4. process analysis utilizing scientific visualization tools.

This systematic and interdisciplinary approach across the different scales is unique in nuclear waste repository research. The cross-scale research concept will provide a considerably enhanced scientific basis for an in-depth comparison of different repository concepts as specifically required for the site selection procedure in Germany. The project will pave the way to establish a multidisciplinary scientific entity with high international visibility providing a unique research platform to solve urgent questions related to the future safe disposal of radioactive waste. iCross integrates the internationally renowned multidisciplinary research activities of Forschungszentrum Jülich, Karlsruhe Institute of Technology (KIT), and Helmholtz-Zentrum Dresden-Rossendorf (HZDR) within the Helmholtz program NUSAFE (research field Energy) on radio-/geo-/biochemistry, with the expertise of the GFZ German Research Centre for Geosciences und the Helmholtz Centre for Environmental Research – UFZ (research field Earth & Environment) on earth system analysis, understanding and simulation. The future-oriented research concept of iCross aims at developing the research area, tackling urgent and challenging questions related to the safe disposal of radioactive wastes, and training the next generation of experts required in view of the extended time scales of radioactive waste disposal projects of many decades.

Within iCross, contributions of Jülich (IEK-6) concern in particular

  1. dedicated and innovative laboratory experiments on radionuclide transport in natural host rock samples characterized by structural and mineralogical heterogeneity, and on the impact of strong chemical gradients at near field barrier component interfaces on pore structures and their back coupling to aqueous chemistry and transport of radionuclides, and
  2. the development of mathematically and physically consistent descriptions of processes and their couplings to be expected in nuclear waste repository systems, as well as coupled process analytics in order to describe coupled processes across scales, employing advanced scientific computing methods.

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