Migration of Radioactive 85 Sr, 134 Cs and 60 Co Through a Loess Soil Layer
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85 Sr, 134Cs and THROUGH A LOESS SOIL LAYER
.MIGRATION OF RADIOACTIVE
6
0 Co
Zhentang LI*, Hui WANG*, Shinichi TAKEBE** and Tadao TANAKA** *China Institute for Radiation Protection, P. 0. Box 120 Taiyuan, Shanxi, 030006, P. R. China
"**JapanAtomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken,
Japan
ABSTRACT Column experiments have been completed on the migration of 85Sr, "34Cs and 6"Co through a loess layer in order to examine the migration behavior of radionuclides in an aerated soil layer. Radionuclide concentration distributions between the effluent and the soil layer were measured after the solution containing the radionuclides was introduced into the column from the top of the soil layer and Fifty liters of the underground water were introduced at a constant flow. Results indicate most of the 85Sr, 34Cs and 6"Co remained attached to the soil layer, and only a small amount of radionuclide was released from the soil layer. Within the soil layer, the migration depths of three radionuclides are 85Sr > "'34Cs = 6"Co.
INTRODUCTION The majority of low-level radioactive waste generated at a nuclear power plant are disposed in shallow land burial waste disposal sites. Therefore, the migration of radionuclides in soil layer has been extensively studied by many researchers 1-6 To assess the safety of shallow land disposal, investigated the migration of radionuclides in a typical site soil. The objective of this paper is to examine the migration behavior of "5Sr, "34Cs and 6"Co through a loess layer to evaluate retardation
'capacity
of the loess layer as natural barrier.
SAMPLING OF SOIL AND GROUNDWATER Undisturbed soil samples were used for the experiments of radionuclide migration in aerated soil layer. The soil samples were taken from the field test site of China Institute for Radiation Protection (CIRP). Undisturbed soil samples were obtained in a column made of stainless steel tube, being 5 cm in diameter and 20 cm in length for the measurement of dispersion coefficient. Also groundwater samples were taken from the CIRP's field test site. To obtain background data of the experiments, the section of soils and groundwater were sampled for the measurement of the physical and chemical properties. Table I to fl show the analytical results of soil and groundwater used in the experiments.
EXPERIMENT APPARATUS The experimental apparatus is schematically shown in Fig 1. It is composed of soil column, microtube pump and fraction collector. The soil samples were taken from the location field test site. The soil column was prepared by putting polyethene beads (4 mm in diameter) to
Mat. Res. Soc. Symp. Proc. Vol. 353 0 1995 Materials Research Society
1110
Table I
Chemical composition of loess medium
Chemical composition
Sample name*
% (wt) YS-1A
YS-1B
YS-1C
YS-ID
2.26 1.70 61.04 11.41 3.61 0.70 7.52 1.71
2.20 1.65 59.06 11.05 3.02 0.65 9.09 1.64
2.24 1.65 59.24 11.18 3.07 0.65 8.89 1.92
2.26 1.73 60.24 11.25 3.31 0.65 7.91 2.06
K2 0 Na 2 0 SiO 2 A12 0 3 Fe2 0 3 TiO2 CaO MgO MnO
0.07
0
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