The nuclear industry faces a persistent challenge: safely treating the complex waste streams generated during the decontamination of primary systems in power plants. These solutions often contain a hazardous mix of radionuclides and heavy metals, remnants of decades of operation. Now, research led by Jaewoong Hwang from Chungnam National University and the Korean Atomic Energy Research Institute (KAERI) offers a promising pathway forward—one that could reduce both environmental risk and operational costs.
Hwang’s team has developed a stepwise precipitation method that systematically removes contaminants from decontamination waste solutions, which are typically laden with oxalic acid residues. The approach combines inorganic precipitation, coprecipitation, and adsorption to achieve high removal efficiencies while minimizing the volume of secondary radioactive waste—a critical factor in nuclear facility cleanup.
One of the key innovations lies in the sequential treatment process. Organic compounds, which make up a significant portion of the waste, are first targeted through metal-oxalate precipitation under carefully controlled pH conditions. The results are striking: over 98% of organic contaminants are removed in this initial phase. “This step is crucial because it sets the stage for more selective removal of heavy metals and radionuclides,” Hwang explains. “By controlling the pH, we can maximize the precipitation of organic compounds while keeping the process stable.”
The next phase focuses on residual heavy metals and radionuclide simulants. Using hydrous ferric oxide and hydrous aluminum oxide as coprecipitating agents, the team achieved removal efficiencies exceeding 99% for cobalt (Co) and copper (Cu) at a pH of 10. However, the real breakthrough came with barium (Ba). Traditional methods struggled to remove Ba effectively, but the researchers discovered that aluminum-based coprecipitation in the prior step enabled BaSO4 precipitation during neutralization, pushing Ba removal efficiencies past 99%.
Cesium (Cs), however, proved more stubborn. Its low removal efficiency during coprecipitation necessitated an additional adsorption step using Prussian blue. By optimizing adsorbent dosage and contact time, the team successfully enhanced Cs removal, demonstrating the flexibility of the stepwise approach.
For the energy sector, the implications are significant. Nuclear power plants generate substantial volumes of decontamination waste, and current treatment methods often produce large quantities of secondary radioactive waste that require long-term storage. Hwang’s process not only improves contaminant removal but also reduces the volume of final solid waste—a critical factor in managing disposal costs and regulatory compliance.
The research, published in *Desalination and Water Treatment* (desalination and water treatment), underscores the potential for tailored precipitation strategies to address complex nuclear waste challenges. As nuclear facilities worldwide seek more efficient and sustainable cleanup methods, this study provides a blueprint for integrating selective precipitation, coprecipitation, and adsorption into a cohesive treatment workflow. The findings could influence future regulatory standards and operational practices, offering a model for balancing efficiency with environmental responsibility in nuclear waste management.