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Fundamental Study on Transport Model for Radionuclides under Unsaturated Condition around Near-Surface Underground

Published online by Cambridge University Press:  27 January 2020

Takenori Ozutsumi ,
Masayuki Kogure ,
Yuichi Niibori  and
Taiji Chida
Takenori Ozutsumi*
Affiliation:
Tohoku University, Aobayama 6-6-01-2, Sendai 980-8579, JAPAN
Masayuki Kogure
Affiliation:
Tohoku University, Aobayama 6-6-01-2, Sendai 980-8579, JAPAN
Yuichi Niibori
Affiliation:
Tohoku University, Aobayama 6-6-01-2, Sendai 980-8579, JAPAN
Taiji Chida
Affiliation:
Tohoku University, Aobayama 6-6-01-2, Sendai 980-8579, JAPAN
*
*(Email: ozutsumi@michiru.qse.tohoku.ac.jp)
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Abstract

The low-level nuclear wastes such as decontamination waste from Fukushima are disposed in near-surface underground, where the intermittent recharge of rain and groundwater causes spatial distribution of water content. Therefore, pores of soils are not filled with water, that is, an unsaturated zone will be formed. In such a condition, since the water flow path are detoured by clogged gas in pores of soil in the unsaturated zone, the migration path of radionuclide would be different from the saturated zone. So far, the one-dimensional advection-dispersion equation (ADE) model has been widely used in order to explain experimental results under an unsaturated condition. However, the detouring of local flow-paths remarkably affects the mass transfer. The one-dimensional ADE evaluates such a detouring effect by using Peclet number and retardation coefficient as fitting parameters. In other words, the one-dimensional ADE model is difficult to explain mass transfer under an unsaturated condition. Therefore, the purpose of this study is explaining such complicated transport of radionuclides using a multi-path model based on phenomena in underground. The proposed multi-path model considering both water saturation and permeability distributions showed good agreement with the experimental data under an unsaturated condition.

Keywords

transportationmodelingwaste managementwater
Type
Articles
Information
MRS Advances , Volume 5 , Issue 5-6: Scientific Basis for Nuclear Waste Management XLIII , 2020 , pp. 223 - 232
Copyright
Copyright © Materials Research Society 2020

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References

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