| Summary: | Two basically different multibarrier concepts for high-level radioactive waste (HLW) are the often cited KBS-3 V/H concepts, for isolating nuclear waste at 400-600 m depth and Very Deep Boreholes concepts (VDH) for placement at 2000-4000 m depth. Both make use of expandable clay as isolating medium of canisters with HLW and as backfill material in shafts and tunnels in repositories for safe disposal of such waste. This licentiate thesis is based on three papers related to the properties of clays for use as engineered barriers, and to their performance at geological disposal. The first paper deals with the buffer criteria for the two disposal concepts. In this paper the possibilities and limitations of using clays of montmorillonite-, saponite- and mixed layer clay type are considered. The second paper discusses the swelling property and permeability of Na-montmorillonite clays (MX-80, GMZ) and illite-smectite mixed layer clay (Holmehus) saturated and percolated by distilled water and a salt solution. The third paper describes a lab-scale performance of VDH holes sealing using Holmehus clay. In this paper, methods for solving the problem of too quick hydration of the dense clay are investigated and evaluated. Godkänd; 2015; 20151026 (tinyan); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Ting Yang Ämne: Geoteknik/Soil Mechanics Uppsats: Borehole Sealing with Expandable Buffer Clays in HLW Disposal Lab-Scale Performance Third-cycle subject area: Soil Mechanics Examinator: Professor Sven Knutsson Institutionen för samhällsbyggnad och naturresurser Avdelning Geoteknologi Luleå tekniska universitet Diskutant: Professor Jörn Kasbohm GeoEnCon, Tyskland Tid: Tisdag 15 december 2015 kl 10.00 Plats: E1026, Luleå tekniska universitet
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