DIAMOND: Decommissioning, Immobilisation And Management Of Nuclear wastes for Disposal

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Legacy waste treatment and disposal, as well as decommissioning and site remediation, from the last 60 years of the UK's civil nuclear program are conservatively estimated at a cost of 70B for the UK taxpayer. The diversity of issues that must be addressed in tackling this problem is immense and requires a wide range of innovative solutions drawn from an equally wide range of technology discipline areas. The proposed research program is divided into three work packages (WPs): (1) Environment, Migration and Risk; (2) Decommissioning, the Historic Legacy and Site Termination; and (3) Materials - Design, Development and Performance.WP 1: Environment, Migration and RiskCleaning up contaminated land is a substantial component of nuclear site restoration. The range of radioactive contaminants present, and the potential for mixed contamination, represents a major challenge. In particular, the potential for migration of soluble and colloidal species in the subsurface is a key uncertainty in defining site end points. Currently, most cleanup is expected to be through invasive technologies; hence, we will explore more cost-effective in situ technologies such as barrier treatment systems. Many of the uncertainties and technical challenges associated with geological disposal of immobilised radioactive wastes are critically dependent on the rate of release from the engineered facility, and on the subsequent behaviour of the radionuclides in the disturbed zone and the far field. Work Package 2: Decommissioning, the Historic Legacy and Site TerminationHeterogeneous wastes present in fuel storage and handling facilities are a key target of the consortium. These wastes comprise irradiated fuel, contaminated materials and corrosion products. Total volumes and compositions (both chemical and radioactive) are poorly known, although there are believed to be several hundred m3 in each of the main storage ponds. Improved and accurate characterisation is therefore a priority, and novel technologies for retrieval and treatment are proposed here. In addition, historical activities have created small volumes of orphan wastes for which no clear management route exists; their diversity requires new and versatile treatment methods which will be developed in this programme. We also focus on the quantification of radionuclide inventories, contaminant transport through engineered pathways and waste retrieval as areas where we can make a further contribution.Work Package 3: Materials- Design, Development and PerformanceGeological disposal has been accepted by Government as the best available approach for the long term management of UK radioactive wastes, supported by a robust programme of interim storage . The focus of research in this WP is therefore to address key knowledge gaps in the conditioning, storage and disposal of wastes in order to underpin future decision making in waste management. Research is based on three key themes, aimed at: 1) understanding the effects of radiation and radiolysis on the stability of nuclear ceramics during interim storage; 2) understanding the corrosion mechanisms of spent nuclear fuels, steel packaging and HLW glasses under conditions of storage and disposal; 3) development of new materials and processing routes with the flexibility to immobilise a spectrum of wastes, including fuel debris and graphite, in a form suitable for storage and disposal. A further aspect of this WP will be development of new synthetic routes to advanced inert matrix fuels.