Estimation of Cs Migration under an Unsaturated Condition by Parallel-plate Experiments and 2D Advection-dispersion Model - 17188

Conference · Sat Jul 01 04:00:00 EDT 2017

OSTI ID:22794582

Nemoto, Takumi; Ozutsumi, Takenori; Chida, Taiji; Niibori, Yuichi ^[1]

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1. Tohoku University Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-2, Aoba-ku, Sendai 980-8579 (Japan)

For the assessment of the radioactive waste facility in the near-surface underground, it is important to consider the influence of the unsaturated condition flow field (hereinafter referred to as unsaturated condition) on the migration of radionuclides through the porous medium. The unsaturated condition, which is not completely saturated with liquid phase, will change the retardation effect for the migration of nuclides by interrupting the interaction of nuclides and solid phase, and by clogging flow paths with gas phase. In this study, considering the spatial distribution of the water saturation, the migration of radionuclides in the two-dimensional (2D) porous medium under the saturated flow field (hereinafter referred to as saturated condition) and unsaturated condition was examined by using the parallel-plate type's packed bed and the 2D advection-dispersion model. Besides, for comparison, the one-dimensional (1D) flow experiment using the column type's packed bed was also examined. In the experiments, a 1 mM Cs solution was injected into the beds packed with silica sand under a given constant pressure condition controlled by an overflow system. The overall effective values of retardation coefficient were estimated by applying the theoretical models to the experimental results. As a result, the overall retardation coefficient under the unsaturated condition became smaller than that under the saturated condition. This means the decrease in the effective surface area for the sorption of tracer ions in the presence of gas phase. Furthermore, under the unsaturated condition, the retardation coefficient of the 2D flow condition was estimated smaller than that of the 1D condition. That is, in the 2D flow system, the tracer ions migrate through more selective flow-paths caused by the heterogeneous spatial-distribution of water saturation which is the ratio of the volume of water to the volume of pores. (authors)

• Research Organization: WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
• OSTI ID: 22794582
• Report Number(s): INIS-US--19-WM-17188
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CESIUM
PACKED BEDS
RADIOACTIVE WASTE FACILITIES
RADIOISOTOPES
RADIONUCLIDE MIGRATION
SPATIAL DISTRIBUTION
TWO-DIMENSIONAL CALCULATIONS
WATER SATURATION