Advanced treatment strategies for challenging radioactive Wastes: Recent Developments and future directions

• Detailed comparative analysis of treatment methods for diverse challenging wastes. • Case study insights illustrate upscaling obstacles and costly delays. • Challenges remain for scaling up, regulatory approval and stakeholder acceptance. • Harmonized and flexible regulations are needed to deploy new treatment solutions. • Hybrid and modular systems offer tailored solutions for diverse radioactive waste streams. The management of low- and intermediate-level radioactive waste (LILW) presents increasing challenges, particularly for waste streams with complex chemistries, variable radioactivity, or combined toxic and radiological risks. Conventional treatment methods, while effective for conventional waste types, are often inadequate for these problematic streams, which require advanced and tailored approaches. This review evaluates recent progress in thermal (pyrolysis, plasma processes, fluidized bed steam reforming, molten salt oxidation) and chemical technologies (wet and electrochemical oxidation) for treating such wastes. The novelty of this work lies in its integrated analysis, which combines comparative technology mapping with assessments of scalability, regulatory and societal acceptance, and the integration of lifecycle environmental and economic metrics. Cross-technology performance matrices are presented to support process selection, together with a strategic research roadmap that prioritizes secondary waste minimization, flexible acceptance criteria, and the inclusion of Life Cycle Assessment (LCA). The study also highlights future trends such as mobile modular treatment systems, hybrid technologies that integrate multiple treatment approaches, and the increasing use of artificial intelligence (AI) and Internet of Things (IoT) technologies for real-time monitoring and process optimization. Overall, this review aims to provide a practical framework to guide researchers, industry, and regulators toward safe, sustainable, and industrially viable solutions for complex radioactive waste management.