ANSTO’s Synroc Technology Options for the Treatment of Actinide Wastes from Next Generation Nuclear Reactors

Future nuclear fuel cycles including the next generation reactors currently being commercially developed will produce actinide wastes that require disposal solutions. As part of the approvals process for these new nuclear facilities, the demonstration of whole of life strategies which provide an ultimate waste disposition pathway is now required by the Nuclear regulator. In any such plan, a key element is treatment of the material into a stable ‘wasteform’, which can be safely disposed. Therefore, high feasibility solutions for the safe and responsible management of actinide wastes generated from the deployment of new nuclear technologies are essential. However, actinide management is one of the major environmental science challenges of modern society, for example plutonium isotopes have extremely long half-lives (e.g., Pu-239 has a half-life of 24,065 years), are radiologically and chemically-toxic, fissile and require criticality control and safeguards measures. As a result, actinides have a major impact on the risk assessment of any geological repository or disposal scenario.<br/><br/>Synroc technology is uniquely suited to the treatment of actinide wastes as it employs hot-isostatic processing (HIPing) as a consolidation approach where the waste is contained within a canister during consolidation into the final form. Importantly, the technology allows for the production of a range of wasteforms (ceramic, glass, and advanced composite wasteforms such as cermets and glass-ceramics) with the design tailored to maximise actinide immobilization within targeted mineral phases. Such mineral phases are based on natural analogues that have demonstrated their survival in the natural environment over geological timescales where they are impacted by natural processes of alteration and radiation damage. Their study provides a snapshot in time (after millions to billions of years) and therefore demonstratable and predictable long-term chemical and mechanical durability. This presentation will discuss concepts for advanced candidate wasteforms and processing options that use the HIP technology for the immobilization of actinides from advanced reactors and future fuel cycles.