幌延深地層研究計画 令和8年度調査研究計画
Le résumé fourni par la source
The Horonobe Underground Research Laboratory Project is being pursued by the Japan Atomic Energy Agency to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2026, we continue R\&D on "Study on near-field system performance in geological environment" and "Demonstration of repository design options". These are identified as key R\&D challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. In the "Study on near-field system performance in geological environment", dismantling experiment will be conducted on the full-scale engineered barrier system performance experiment in the 350 m depth gallery. Regarding the "Demonstration of repository design options", tracer tests will be conducted in fractures surrounding the 250 m depth gallery and within the excavation damaged zone (EDZ) of the 500 m depth gallery in order to evaluate containment performance at both tunnel and pit scales. Vertical boreholes will be drilled from the floor of the 500 m depth gallery to assess the extent of the EDZ and the volume of water flow, which will inform the selection of the test pit location. A monitoring and assessment plan will then be established to evaluate the EDZ during pit excavation, including analytical approaches for EDZ characterization and their application to tunnel support design. Based on the outcomes of hydraulic disturbance tests performed in the 350 m depth gallery, an assessment will be conducted to evaluate the resistance of pre-existing fractures and faults to displacement. In addition, while continuing to collect the data required to address the issues outlined above, operational monitoring and maintenance inspections of the underground facility equipment will be conducted. Furthermore, we continue R\&D on the following three tasks in the Horonobe International Project; Task A: Solute transport experiment with model testing, Task B: Systematic integration of repository technology options, and Task C: Full-scale engineered barrier system dismantling experiment.
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