Advection-Dispersion Behavior for Simulation of H-3 and Pu-238 Transport in Undisturbed Argillaceous Shale of a Near-Surface Repository

Yunfeng Shi; Song Yang; Enhui Wu; Longjiang Wang; Wenjie Chen; Weijia Xiong; Yanna Zhang; Aiming Zhang; Bing Lian

doi:10.3390/toxics11020124

Advection-Dispersion Behavior for Simulation of H-3 and Pu-238 Transport in Undisturbed Argillaceous Shale of a Near-Surface Repository

Toxics. 2023 Jan 27;11(2):124. doi: 10.3390/toxics11020124.

Authors

Yunfeng Shi¹, Song Yang¹, Enhui Wu², Longjiang Wang¹, Wenjie Chen¹, Weijia Xiong³, Yanna Zhang¹, Aiming Zhang¹, Bing Lian¹

Affiliations

¹ Department of Nuclear Environmental Science, China Institute for Radiation Protection (CIRP), Taiyuan 030006, China.
² School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, China.
³ CNNC Environmental Protection Corporation (ECPC), Beijing 100045, China.

Abstract

In this study, a column experiment was employed to evaluate the nuclide migration behavior in the surrounding rock medium of a near-surface disposal site in China and to investigate the advection-dispersion behavior of tritium (H-3) and plutonium-238 (Pu-238) in highly weathered argillaceous shale. A reasonable numerical model was selected to fit the experimental breakthrough curves (BTCs) and to obtain the relevant migration parameters. The results show the following: (1) the internal structure of the highly weathered argillaceous shale exhibited heterogeneity, and the nuclide migration BTC showed characteristics of a "curve peak moving forward" and a "tail curve trailing"; (2) compared with other models, the stream tube mode could better fit the BTCs and obtain the average dispersion coefficient <D>, average distribution coefficient <K_d>, and other parameters; (3) compared to the results of the batch experiment, the distribution coefficient K_d obtained from the column experiment was smaller than that obtained from the batch experiment, which is speculated to be due to the influence of contact time and the contact area between the nuclide and the medium.

Keywords: H-3; Pu-238; batch experiment; stream tube model; undisturbed column experiment.

Grants and funding

This project was mainly supported by the “Fundamental Science on Radioactive Geology and Exploration Technology Laboratory” (No.2022RGET02); East China University of Technology, Shanxi Province Basic research Project (No.20210302124176); and The National Natural Science Foundation of China (No. U2267218).