Status of the Horonobe Underground Research Laboratory Project, Hokkaido, Japan, and future plan

Sato, Haruo; Sugita, Yutaka ; Nakayama, Masashi 

The Horonobe Underground Research Laboratory (URL) project has been being pursued for a sedimentary rock and saline groundwater in the Horonobe town, Hokkaido, Japan, as an off-site URL, since 2001. This project, extended over a period of about 20 years as a whole, has been being advanced divided into 3 phases (surface-based investigation phase (Phase I), construction phase (Phase II) and operation phase (Phase III)). Phase I was completed in March, 2006 and Phase II started in November, 2005. The URL consists of the Ventilation shaft, the East and the West access shaft and horizontal drifts of 140m, 250m, 350m and 500m in depth. Up to date, the Ventilation shaft and the East access shaft were excavated up to 250m in depth and the 140m depth gallery was completed. So far, experiments and investigations for the geological environment and engineering technology such as measurements for EDZ/EdZ, cross-hole hydraulic tests, initial rock stress measurements, construction test of shotcrete by low alkaline cement, etc. were carried out in the 140m depth gallery. Monitoring of groundwater chemistry, in-situ experiments for redox buffer capacity, etc. are presently on-going. Phase III started from the latter half of FY2010. Various in-situ investigations and experiments such as performance test of EBS, corrosion test of overpack material, backfilling test of a tunnel, etc. are planned in the underground facilities.