Illustration of the Horonobe Underground Research Laboratory and locations of the in situ experiments planned in each of the three HIP Joint Project task
The Horonobe International Project (HIP) is an international Joint Project with the main theme of Challenges for Developing Advanced Technologies and Human Resources Towards Long-Term Implementation of Geological Disposal. The first HIP Management Board meeting was held in April 2023 with the participation of 11 organisations from Australia, Bulgaria, Chinese Tapei, Germany, Japan, Korea, Romania and United Kingdom. The Project is structured around two phases: 2023-2025 and 2025-2029.
The main objectives of the HIP are to:
Task A - Solute transport experiment with model testing
Attempts have been made to enhance the technical reliability of solute transport models for repository safety assessments by tracer tests at in situ conditions. In general, the results of tracer tests are often modelled to produce a set of ‘best fit’ values for the transport parameters by comparing calibrated model curves with the experimental breakthrough curves but the modelled values are not always a unique solution. This could be due to the fact that the actual structures and processes of relevance to solute transport are unknown and hence these are represented in the solute transport models with effective parameters in a relatively simple manner. It is thus suggested that detailed, realistic information on the relevant structures and processes should be obtained through a series of tracer tests and the subsequent rock characterisation at the in situ conditions. This would allow the models and model assumptions to be rigorously tested and then the technical reliability of the models could be enhanced.
The main aim of this task is to develop more realistic 3D solute transport models that can be applied to repository safety assessments for fractured porous sedimentary rocks.
Task B - Systematic integration of repository technology options
In order to arrange and construct disposal tunnels and pits or holes in suitable rock volumes, it is of great importance to design the detailed layout of them taking into consideration the distribution, spatial scale and hydraulic properties of faults and fractures and their potential impacts on likely radionuclide migration and the long-term stability of an engineered barrier system (EBS). Criteria are thus required for locating the disposal tunnels and pits or holes and their adequacy should be ensured through the in situ demonstration of process from the initial geological characterisation to the design and final construction of a tunnel and pits or holes. As a range of technology options for each process have been developed to date, it is suggested that such options should be advanced using the state-of-the-art technology as possible and the systematic integration of available options should then be demonstrated.
The main aims of this task are to:
Task C - Full-scale EBS dismantling experiment
It is of importance to evaluate the evolution of near-field thermal-hydrological-mechanical-chemical (T-H-M-C) conditions over time during the transition period following the emplacement of waste forms. This is because such information would allow the near-field initial conditions to be defined for safety assessments and the overpack lifetime to be predicted. To this end, the full-scale EBS performance experiment for vertical EBS emplacement has been carried out at the 350 meters Gallery since 2014, with the aims of understanding the T-H-M-C coupled processes and testing the T-H-M-C coupled simulation code during backfilling the EBS and tunnel and its subsequent dismantling. The relevant data have been obtained by the previously installed sensors. However, as those only from the sensors would not allow the conditions and processes occurring at the interfaces of the different EBS materials to be understood in detail, the experimental setup is dismantled to acquire more detailed information.
The main aim of this task is to test the T-H-M-C coupled simulation code in a rigorous manner by understanding the near-field T-H-M-C coupled processes in more detail.