Technical know-how of selection process for the Horonobe Underground Research Laboratory area and site

Kunimaru, Takanori; Takeuchi, Ryuji  ; Matsuzaki, Tatsuji

This study will be demonstrated the selection process for the URL area and URL site in sequence. Horonobe URL has been declared to be constructed within whole Horonobe Town to be selected early in the fiscal year 2002. The Horonobe URL area/site is required existence of host argillaceous sedimentary formations and saline groundwater. Further fundamental requirements are rock mechanical property and underground flammable (e.g. methane) gas content which meet with safe construction and operation of underground facility. Next, based on surveys of existing information and aerial and ground reconnaissance surveys on a regional scale, and taking into consideration preliminary requirements on the geological environment and safety, as well as social and environmental constraints, an area of 3 km 3 km in the north-central part of Horonobe Town was selected as the main area for the surface-based investigations (URL area). A site for constructing the underground and surface facilities (URL site) was subsequently selected in the URL area, 3 km from the center of Horonobe Town. The selection was based on social conditions and the availability of infrastructure, including roads and land use restrictions, in addition to available geological and hydrogeological information. This study is only fruit of selecting the URL site based on the social and technical requirements in Japan. These stepwise approaches and experiences for selecting the site are applicable when the implementer (e.g. Nuclear Waste Management Organization of Japan) will select the site such as the phase of literature survey, preliminary investigation and detailed investigation in the future.