地層処分の性能評価におけるシナリオ解析の高度化(III); 成果報告書

The Advanced Scenario Analysis for Performance Assessment of Geological Disposal (III); Main Document

大久保 博生*

Okubo, Hiroo*

第2次取りまとめにおけるシナリオ解析では、国際的なコンセンサスの得られたアプローチを踏襲しつつシナリオの作成を行い、一定の評価を得ているものの、シナリオから解析ケース設定までの手順の透明性の向上が課題として指摘された。そこで、本年度は、この成果を踏まえ、まず、シナリオ解析の透明性や追跡性をさらに向上させるとともに、結果をわかりやすく示していくための方法論のより実務的なワークフレームの構築、さらにシナリオの試作などを通じた方法論の見直しや今後の課題の整理を行った。次に、変動シナリオに関する解析技術の検討を行った。まず、諸外国で検討されている変動シナリオを調査し、その評価状況を整理した。特に、日本における地震、断層活動、火成活動の3つのシナリオを評価するための技術的知見を整理した。さらに、これらの変動シナリオ毎に、想定される発生様式と影響パターンに基づき、解析対象とすべき変動タイプを設定し、その取り扱い概念、モデリング要件、必要なデータ情報を明らかにした。以上の検討結果により、今後の性能評価におけるシナリオ解析の高度化の方向性と取り組むべき課題が明確化された。

In H12 Project to Establish Technical Basis for HLW Disposal in Japan an approach that is based on an international consensus was adopted to develop scenarios to be considered in performance assessment. Adequacy of the approach was, in general term, appreciated through the peer review. However it was also suggested that there are issues related to improving transparency and traceability of the procedure.Therefore, in the current financial year, in the first place a scenario development methodology was constructed taking into account the requirements identified last year. Furthermore a practical work-frame was developed to support the activities related to the scenario development. This work-frame was applied to an example scenario to check its applicability and identify issues for further research. Secondly, scenario analysis method with regard to perturbation scenario has been studied. First of all, a survey of perturbation scenario discussed in different countries has been carried out and its assessment has been examined. Especially, in Japan, technical information has been classified in order to assess three scenarios, which are seismic activity, faulting and igneous activity. Then, on the basis of assumed occurrence pattern and influence pattern for each perturbation scenario, variant type that should be considered in this analysis has been identified, and the concept of treatment, modeling data and requirements have been clarified. As a result of these researches, a future direction for advanced scenario analysis on performance assessment has been indicated, as well as associated issues to be discussed have been clarified.