3.2.1 Suitable Host Geologies

Globally, at least 39 countries have produced significant amounts of HAW and of these, 25 have chosen geological disposal as their long term HAW management pathway, and a further six have expressed a preference for geological disposal. However, whilst the current implementation pathway for geological disposal is relatively recent in the UK, several countries are more advanced in the implementation of their geological disposal strategies (see Table 1). Typically, these strategies have developed over several decades and all have included detailed geological characterisation programmes, often including construction of in situ rock testing laboratories to assess the

Stage: advanced — incep­tion in mid 1970s; two suitable host geologies have been identified; generic geodisposal concepts developed;

Site: final site has not been decided but two suitable geolo­gies have been identified.

Geologies: boom clay

HLW (vitrified waste from fuel reproces­sing).

Long-lived ILW.

Vitrified HLW/spent fuel (contained in steel with silica glass frit used to fill voids) placed in carbon steel super-

HLW/spent fuel: void space between super-container and tunnel wall will be filled with cementi — tous material.

rock characterisation has been was conducted an in situ testing facil­ities have been con­structed in both rock types; the sedimentary assessment (Opalinus clay/NAGRA) is pre­sented here; material and host rock feasibility tests have been con­ducted.

Repository, access tunnels leading to disposal tun­nels; waste is emplaced axially; all waste will be disposed of in one facility; waste emplace­ment will be phased with retrievability considered.

Germany/DBE Stage: advanced — his-

Technology6,11,25 torically, salt rock was considered optimal for German HAW storage; final site (Government approved) selected in the late 1970s after

Table 1 Continued.

Country/Responsible Current stage and Waste types managed

body Repository type Site/Geology by geodisposal Waste package Buffer/Backfill

suitability of regional geologies. As a consequence, several generic host lithologies have been deemed suitable for HAW disposal (see Table 1). For example, the Belgian and French programmes have identified suitable clay formations; the Finnish and Swedish programmes have identified crystalline host rocks; the Germans have suggested potential evaporite deposits; and the Swiss have identified both crystalline and sedimentary formations (see review by Baldwin et al. 2008; ref. 6). Furthermore, Sweden has successfully advanced to the stage of choosing their likely geodisposal site, and Finland has begun pre-construction of their facility pending final government approval (see Table 1). Interestingly, the most successful national pro­grammes have had public participation during site selection at the core of their implementation programmes. They also have less complicated nuclear legacies compared with that of the UK.