Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2017, Vol. 28 ›› Issue (5): 67 doi: 10.1007/s41365-017-0221-z

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Diffusion characteristics of HTO and 99TcO4- in compacted Gaomiaozi (GMZ) bentonite

Tsuey-Lin Tsai1 • Shih-Chin Tsai2 • Yu-Hung Shih1 • Liang-Cheng Chen1 • Chuan-Pin Lee3 • Te-Yen Su1   

  1. 1 Chemistry Division, Institute of Nuclear Energy Research, No. 1000, Wenhua Rd., Jiaan Village, Longtan District, Taoyuan, China
    2 Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, China
    3 Department of Earth Sciences, National Cheng Kung University, No. 1, University Road, Tainan, China
  • Contact: Shih-Chin Tsai
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Tsuey-Lin Tsai, Shih-Chin Tsai, Yu-Hung Shih, Liang-Cheng Chen, Chuan-Pin Lee, Te-Yen Su. Diffusion characteristics of HTO and 99TcO4- in compacted Gaomiaozi (GMZ) bentonite.Nuclear Science and Techniques, 2017, 28(5): 67     doi: 10.1007/s41365-017-0221-z


The characteristics of diffusion are essential to the transport of radionuclides through buffer/backfill materials, such as bentonite, which are commonly found in
waste repositories. This study used through-diffusion techniques to investigate the diffusion behavior of HTO and 99TcO4- on GMZ bentonite of various densities. Diffusion rates were calculated by measuring the diffusion coefficients (De, Da), plotting breakthrough curves and interpreting experiment data. The apparent and effective diffusion coefficients of HTO ranged from (1.68 ± 0.40) x 10-11 to (2.80 ± 0.62) x 10-11 m2/s and from (4.61 ± 1.28) x 10-12 to (16.2 ± 2.50) x 10-12 m2/s, respectively. The apparent and effective diffusion coefficients of 99TcO4- ranged from (5.26 ± 0.16) x 10-12 to (7.78 ± 0.43) x 10-12 m2/s and from (1.49 ± 0.002) x 10-12 to (4.16 ± 0.07) x 10-12 m2/s, respectively. The distribution coefficients of HTO and 99TcO4- ranged from (0.70 ± 0.12) x10-2 to (1.36 ± 0.53) x 10-2 mL/g and from (1.12 ± 0.06) x 10-2 to (5.79 ± 2.22) x 10-2 mL/g, respectively. The De and Kd values were shown to decrease with an increase in the bulk dry density of compacted bentonite. Our results show that HTO and 99Tc could be considered nonsorbent radionuclides. The data obtained in this study provide a valuable reference for the safety assessment of waste repositories.

Key words: Distribution coefficient, Apparent diffusion coefficient, Effective diffusion coefficient, Compacted bentonite, Through-diffusion