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

幌延深地層研究所設置場所選定に関する考え方の整備

國丸 貴紀; 竹内 竜史  ; 松崎 達二

Kunimaru, Takanori; Takeuchi, Ryuji; Matsuzaki, Tatsuji

幌延深地層研究計画では、既存情報に基づき研究所設置場所選定の要件として、地質環境特性(技術要件)と地下施設を安全に建設できること(安全要件)を設定し、既存情報や地上からの地質環境特性調査により取得した情報に基づき、これらの要件について適合性を確認した。さらに、これらの技術要件と安全要件に加え、土地利用やインフラストラクチャーなどの社会的条件を考慮して、段階的に絞り込みながら幌延町全域から研究所設置場所を設定した。このように、段階的に技術要件,安全要件及び社会的条件を考慮して、研究所設置地区及び研究所設置場所を設定するプロセスは、実際の地層処分事業においても有効であると考えられる。本件では、このような考え方を整理するとともに、意思決定過程を分析・整理し、エキスパートシステム(ES)を構築した結果について報告する。

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.