Leaching of radionuclides from solidified waste and its migration characteristics are tested using a model sand layer, whose depth 50cm, width 40cm, length 105cm and consist of 306kg sand taken from Japan Atomic Energy Research Institute, Tokai Site. Model solidified waste (19.6cm dia. and 50cm height), solidified with portland cement containing seven nuclide (
90Sr,
137Cs,
60Co,
65Zn,
54Mn,
59Fe and
110mAg), is set in the saturated sand layer and the concentration of nuclides in a pore water of the layer is checked after specific intervals of time. After about 1, 280 days, the saturated sand layer is taken to pieces and a distribution of a nuclide in a bedded sand is also checked.
The results obtained through this experiment are as follows: (1) Among seven radionuclides, only
90Sr are detected in both pore water and bedded sand. (2) The distribution of
90Sr in a pore water of the layer becomes steady after about 500 days. This steady distribution is closely related to the steady leaching of
90Sr out of solidified waste. (3) First stage leaching of
90Sr out of solidified waste close after the contact with water is large, but it results in flat distribution rapid as the nuclide migrates through a sand layer, which means a large
90Sr exchange capacity of bedded sand. (4) Theory of
Kf-factor depicts well a migration rate of
90Sr in a model saturated sand layer.
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