[Reading Science] High-Level Radioactive Waste Disposal Containers Proven Safe for at Least 1.7 Million Years with Korean Evaluation Model

First-Ever Development of a Multiphysics Corrosion Model Reflecting Korea’s Geological Environment

A team of Korean researchers has developed a Korean-style evaluation model that precisely predicts the long-term corrosion characteristics of high-level radioactive waste disposal containers tailored to Korea's geological environment. Using this model, they have scientifically demonstrated that disposal containers can withstand at least 1.7 million years. This achievement is significant as it marks a departure from reliance on foreign models and data, such as those from Sweden and Canada, and establishes Korea’s independent verification capabilities.

The Korea Atomic Energy Research Institute announced on December 9 that it has developed a “Korean-style multiphysics integrated corrosion model” capable of predicting the corrosion behavior of high-level radioactive waste disposal containers over extended periods. According to the model analysis, even under conservative estimates, the expected lifespan of domestic disposal containers is about 1.7 million years. This duration far exceeds the time required for the natural reduction of radioactive toxicity.

Korea Atomic Energy Research Institute has demonstrated the long-term safety of disposal containers using a Korean-style multiphysics integrated corrosion model. Photo by Korea Atomic Energy Research Institute

High-level radioactive waste is managed by isolating it hundreds of meters underground in bedrock, completely separating it from human living environments. Therefore, the key issue is whether the disposal containers can securely block radioactive materials in long-term corrosive environments lasting hundreds of thousands to millions of years. Most existing foreign models use a one-dimensional single-physics approach, which has limitations in reflecting Korea’s groundwater chemistry, bedrock characteristics, and temperature conditions.

To address these limitations, the research team developed a two-dimensional multiphysics model that simulates the actual disposal environment, where groundwater flow, chemical reactions, thermal conditions, and electrochemical reactions occur simultaneously. The model’s predictive reliability was enhanced by incorporating domestic geological conditions, laboratory experiments under extremely low oxygen concentrations, and over ten years of long-term experimental data accumulated at the institute’s Korea Underground Research Tunnel (KURT).

The comparison with foreign models is also notable. While models from Sweden, Finland, and Canada overestimated corrosion by predicting that oxygen would remain inside disposal sites for over 100 years, the Korean model forecasted that oxygen effects would disappear after about 2.3 years. This result closely matches the values measured at the Mont Terri underground research facility in Switzerland (0.5-1.5 years), suggesting that the Korean model more accurately reflects real-world conditions.

Based on the model, the maximum corrosion depth of domestic disposal containers during the initial years was found to be only 9.3 micrometers (μm). This performance is equal to or exceeds that of advanced countries such as Sweden and Canada.

This research achievement has been recognized for its scientific excellence, with 13 papers published in international journals, including “npj Materials Degradation,” a prestigious journal in the field of materials degradation. The research was supported by the Ministry of Science and ICT’s “Core Technology Development Project for Securing the Safety of Spent Nuclear Fuel Storage and Disposal.”

The research team plans to further enhance prediction accuracy by expanding the model to three dimensions and incorporating additional variables such as microbial reactions. They also intend to accelerate demonstration research by applying the model to the verification of engineered barrier systems and the design of disposal containers at the underground research facility (URL) to be constructed in Taebaek City.

Kwon Jangsoon, Director of the Disposal Performance Demonstration Research Division at the Korea Atomic Energy Research Institute, stated, “With the development of this multiphysics integrated model, we can now directly verify the safety of high-level radioactive waste disposal containers using our own technology. We will also promote the competitiveness of Korean disposal technology through international joint research.”