PNNL

Abstract

The objective of this project is to support collaboration between PNNL and Curio to address technical gaps in the immobilization of waste streams generated by the NuCycle® process, thereby improving the overall viability of the technology. This work will be carried out in two phases, described below. Phase 1 – Waste Management Study The first phase consists of a comprehensive waste management study focused on the waste streams produced during the NuCycle® process, including those containing long lived fission products (LLFPs, e.g., I 129) and transuranic elements (TRUs). This phase involves compiling waste compositions and characteristics based on recently completed NuCycle® testing and modeling efforts. Established waste forms and processing methods will be identified for streams where they are applicable. For more challenging waste streams—such as LLFPs and trace actinides present in metallic or fluoride chemical forms—this study will provide recommendations for appropriate waste management strategies. For example, the preferred waste form should accommodate radionuclide decay heat and the formation of daughter products without compromising performance. The resulting assessment will outline a clear waste management pathway that minimizes processing requirements (i.e., uses as few waste form types as practical), supports low impact storage and transportation, and remains broadly compatible with multiple disposal scenarios. Additionally, the study will identify key testing needs required to validate the waste management strategy as the NuCycle® technology progresses toward maturity. The PNNL–Curio team will document all findings and recommendations in a project report. Phase 2 – Lab Scale Demonstration of Selected Waste Form The second phase will focus on laboratory scale demonstration of the most promising waste form identified in Phase 1 for immobilizing LLFPs and trace actinides in their expected chemical forms within the NuCycle® flowsheet. An engineering scale waste form (4–6 inches in diameter) will be fabricated using representative non radioactive surrogate materials. Fabrication parameters and waste form properties will be measured and evaluated. This demonstration is a critical step toward validating the feasibility of the proposed waste management strategy and enabling successful commercialization of the NuCycle® process.