Integrated Subsurface Modeling and Co-location Concept for Offshore Radioactive Waste Management: A Case Study of Mesozoic Basement in the Taiwan Strait

Establishing a robust geoscientific foundation is essential for the long-term safety of radioactive waste repositories. However, public acceptance remains a significant challenge for the siting of radioactive waste storage and disposal facilities. A strategic approach to mitigate this challenge involves the co-location of diverse management operations within a single site. This study explores this potential by developing a conceptual framework for an offshore island in the Taiwan Strait, targeting the Mesozoic basement as the host rock.

This study develops a 3D geological model using JewelSuite, integrating disparate datasets including geological surveys, seismic reflection profiles, and deep borehole logs to define key stratigraphic interfaces. Based on this structural framework and hydraulic parameters derived from literatures, 3D groundwater flow simulations were implemented using DarcyTools to assess the hydraulic performance of the site. The simulation outputs provide critical insights into the spatial distribution of hydraulic pressure and flow velocity within potential host formations.

These hydrogeological results serve as a primary reference for the conceptual design and spatial configuration of subsurface engineering. By bridging geoscientific characterization with engineering layout, this research proposes a comprehensive conceptual framework for an integrated subsurface complex. This includes a generic Underground Research Laboratory (URL), underground interim storage, and a combined repository for high-level and low-level waste. Distinct from the crystalline rock geological disposal concepts currently prioritized in Taiwan, this study focuses on Mesozoic basement rocks as the geological foundation. The proposed framework demonstrates the technical viability of an offshore co-located solution, providing a critical alternative option for Taiwan's national radioactive waste disposal strategy.