Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2010, Vol. 21 ›› Issue (6): 339-346 doi: 10.13538/j.1001-8042/nst.21.339-346

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Colloid-facilitated effects on migration of radionuclides in fractured rock with a kinetic solubility-limited dissolution model

Chun-ping JEN~(1,*) Neng-chuan TIEN~2   

  1. 1 Department of Mechanical Engineering,Chung Cheng University,Taiwan 62102 2 Energy and Environment Research Laboratories,Industrial Technology Research Institute,Taiwan 31040
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Chun-ping JEN, Neng-chuan TIEN. Colloid-facilitated effects on migration of radionuclides in fractured rock with a kinetic solubility-limited dissolution model.Nuclear Science and Techniques, 2010, 21(6): 339-346     doi: 10.13538/j.1001-8042/nst.21.339-346

Abstract:

Nuclides can move with groundwater either as solutes or colloids,where the latter mechanism generally results in much shorter traveling time as the nuclides interact strongly with solid phases,such as actinides.In the performance assessment,it is therefore essential to assess the relative importance of these two transport mechanisms for different nuclides.The relative importance of colloids depends on the nature and concentration of the colloids in groundwater.Plutonium(Pu),neptunium(Np),uranium(U) and americium(Am) are four nuclides of concern for the long-term emplacement of nuclear wastes at potential repository sites.These four actinides have a high potential for migrating if attached to iron oxide,clay or silica colloids in the groundwater.Strong sorption of the actinides by colloids in the groundwater may facilitate the transport of these nuclides along potential flow paths.The solubility-limited dissolution model can be used to assess the safety of the release of nuclear waste in geological disposal sites.Usually,it has been assumed that the solubility of the waste form is constant.If a nuclide reaches its solubility limit at an inner location near the waste form,it is unlikely that the same nuclide will reach its solubility limit at an outer location unless this nuclide has a parent nuclide.It is unlikely that the daughter nuclides will exceed their solubility limit due to decay of their parent nuclide.The present study investigates the effect of colloids on the transport of solubility-limited nuclides under the kinetic solubility-limited dissolution(KSLD) boundary condition in fractured media.The release rate of the nuclides is proportional to the difference between the saturation concentration and the inlet aqueous concentration of the nuclides.The presence of colloids decreases the aqueous concentration of nuclides and,thus,increases the release flux of nuclides from the waste form.

Key words: Radionuclides, Colloid, Kinetic solubility-limited dissolution