Trial study for recovery of radioactively contaminated soil: Establishing framework of separation and mixing techniques

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K21994
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 22:Civil engineering and related fields
• Research Institution: Kyoto University
• Principal Investigator: Katsumi Takeshi 京都大学, 地球環境学堂, 教授 (60233764)
• Co-Investigator(Kenkyū-buntansha): 高井 敦史 京都大学, 地球環境学堂, 准教授 (30598347)
• Project Period (FY): 2019-06-28 – 2021-03-31
• Keywords: 災害廃棄物 / 津波堆積物・堆積土 / 分別土 / 分級 / 付着性 / コンシステンシー

Outline of Final Research Achievements

This research focuses on "sieving process", which is a main component of waste treatment system, mainly for recovering soils contained in disaster wastes. Laboratory sieving test using a vibration screen was conducted for soil-waste mixtures with different fine contents and water contents. The results indicate that: 1) The fractions remained on screen increases with an increase in water content, while decreasing after a threshold water content, and 2) While varying with the type of mixtures, the threshold water content may be possibly expressed with consistency limits of soil contained in the waste mixtures. These observations can imply that sun-drying before separation should be done for more effective segregation of soil.

Free Research Field

環境地盤工学

Academic Significance and Societal Importance of the Research Achievements

本研究は，2011年の福島第一原子力発電所事故で発生した約1400万m3にものぼる除去土壌を土木資材として活用するため，土砂混合廃棄物の分別しやすさに及ぼす土砂の性状の影響を評価したもので，極力含水比を低下させてから分別することで，土の剥離を促進できることを明らかにしている。含水比の制御は現場で容易に実施できる事項であり，追加費用を抑制しつつ混合状態の災害廃棄物・除去土壌から各材料を精度良く分別し取り出すための重要な知見と言える。また，混合廃棄物の分離しやすさを土砂分の基礎物性で統一的に表現できたことは，土砂分の物性を評価することで分別効率や処理速度を予測できる可能性を示唆している。