Current status of Horonobe URL project in construction phase

The Horonobe URL project has been pursued by JAEA (Japan Atomic Energy Agency) to establish and demonstrate site characterization methodologies, engineering technologies, and safety assessment methodologies for HLW geological disposal in relevant geological environment with sedimentary rock and saline groundwater distributing in the Horonobe area, Hokkaido, Japan. In the Horonobe URL project, surface-based investigation phase (Phase I) has already completed in the year 2005, and then construction phase (Phase II) has initiated in the same year. Currently, construction of the underground facilities such as shafts/galleries which were designed in Phase I, investigations of the geological environment in the excavated shafts/galleries and confirmation of applicability of engineering technologies has been alternately carried out as Phase II activities of the project. During the construction so far, monitoring for the construction safety such as convergence measurements, tunnel wall observation, sampling of groundwater and rock, investigations for evaluating excavation damaged/disturbed zone (EDZ/EdZ) along shafts/galleries were carried out. In addition, a shotcrete construction test and a grout injection test by using low alkaline cement material were carried in the horizontal galleries. In this paper, status of the URL construction and research activities mentioned above are outlined as the current achievement of the Horonobe URL project. (author)