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

Takenori Ozutsumi, Masayuki Kogure, Yuichi Niibori, Taiji Chida

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Pages (from-to)223-232
Number of pages10
JournalMRS Advances
Volume5
Issue number5-6
DOIs
Publication statusPublished - 2020

Keywords

  • modeling
  • transportation
  • waste management
  • water

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Materials Science(all)
  • Condensed Matter Physics

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