A Numerical Simulation Study on the Migration of the 90 Sr Nuclide of Buffer Material Under the Coupling Effect of Multiple Factors

Yu-Ping Wang (), Zhe Wang, Zhi-Qiang Zeng, Fa-Cheng Yi and Ying Luo
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Yu-Ping Wang: Department of Quality Management and Inspection Testing, Yibin University, Yibin 644000, China
Zhe Wang: School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China
Zhi-Qiang Zeng: School of Mathematics and Physics, Yibin University, Yibin 644000, China
Fa-Cheng Yi: School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China
Ying Luo: School of Environment and Resource, Southwest University of Science and Technology, Mianyang 621010, China

Sustainability, 2024, vol. 16, issue 23, 1-14

Abstract: With the development of nuclear energy in China, the geological disposal of high-level radioactive waste (HLW) is increasingly receiving national attention. Among them, the study of nuclide migration is an important and complex technical system, which requires continuous in-depth research. Under the decay heat, radiation, and groundwater effects of HLW, buffer materials generate complex coupled thermo-hydro-mechanical-chemical (THMC) processes. The migration and diffusion of nuclides in buffer materials are controlled by the coupling effect of THMC. It is of great significance for the long-term safety of a HLW repository to study the long-term retarding effect of buffer material on nuclide strontium under the coupling effect of multiple factors. This study leverages the solving advantages of COMSOL Multiphysics 5.6, using a combination of the self-developed Mock-up experimental device as a geometric model and numerical simulations to study the multi-field coupling performance and radionuclide migration evolution characteristics of THMC buffer materials, which overcomes the difficulties due to the limitations of the experimental time and spatial scale. The simulation results can predict the migration range and distance variation of strontium in buffer materials at different time scales. In the initial stage, the migration and diffusion of nuclide in buffer materials are relatively slow, and the migration distance increases by about 0.03 m with time. In the mid-to-late stage, the migration distance increases by about 0.05 m over time; to ensure that, in 1000 years, core strontium does not penetrate the buffer material and migrate into the surrounding rock groundwater of the disposal facility, a buffer material thickness of 0.3 m needs to be set. The construction of THMC control equations for the migration and diffusion of nuclides in buffer materials under multi-field coupling conditions has been revealed, providing an important reference for a deeper understanding of the risk analysis of radionuclide contamination in disposal environments.

Keywords: high-level radioactive waste; nuclide migration; thermal-hydro-mechanical-chemical coupling; COMSOL Multiphysics; numerical simulation (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2024
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