Determination of Diffusion Parameters by a Computer Code (FDP) Based on Mathematica 6.0
Journal article

Determination of Diffusion Parameters by a Computer Code (FDP) Based on Mathematica 6.0

  • Wu, Tao Huzhou Teachers College, Huzhou, China
  • Samer, Amayri Johannes Gutenberg-Universita¨t Mainz, Mainz, Germany
  • Drebert, Jakob Johannes Gutenberg-Universita¨t Mainz, Mainz, Germany
  • Van Loon, Luc R. Paul Scherrer Institut, Villigen PSI, Switzerland
  • Reich, Tobias Johannes Gutenberg-Universita¨t Mainz, Mainz, Germany
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  • 2011-4-8
Published in:
  • 18th International Conference on Nuclear Engineering: Volume 3. - ASMEDC. - 2010
English A computer code named Fitting for Diffusion Parameters (FDP) based on Mathematica 6.0 has been developed for modeling through- and out-diffusion experiments. FDP was used to determine the diffusion coefficients (De) and the rock capacity factors (α) for tritiated water (HTO) and 22Na+ and the distribution coefficient (Kd) of 22Na+ in Opalinus Clay (OPA). The values for De and α were obtained by fitting the results of experimental data of both transient and steady-state phases to the analytical solution of accumulated activity. The quality of the parameters De and α was tested by using them as input parameters in the equation of flux. Moreover, the diffusion parameters of HTO and 22Na+ were determined also by out-diffusion experiments. Under ambient condition at pH 7.6, the De value of (1.5 ± 0.1) × 10−11 m2/s for HTO is lower than that of (1.9 ± 1.1) × 10−11 m2/s for 22Na+, which could be explained by the electrostatic attraction between the negative surface charge of OPA and the sodium cations. For the non-sorbing species HTO, α was 0.15 ± 0.01. For the weakly sorbing species 22Na+, α was 0.50 ± 0.02 and Kd equaled (1.5 ± 0.3) × 10−4 m3/kg. The obtained diffusion parameters for HTO and 22Na+ in OPA are in good agreement with previous results by Van Loon et al. [1, 2]. FDP developed in this study has been used successfully to determine the parameters De and α for the diffusion of 237Np(V) in OPA [3].
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https://sonar.ch/global/documents/235331
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