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Nagao, Seiya*; Sakamoto, Yoshiaki; Rao, R. R.*; Fujitake, Nobuhide*
Humic Substances Research, 5-6(1), p.9 - 17, 2009/00
Sorption behavior of Np(V) onto sandy materials (sand, tuffaceous sand and sandy rock) was studied in the absence and presence of humic substances (HS) using a batch method at pH 5-6 and ionic strength of 0.01M. The effects of shallow land groundwater HS on the Np(V) sorption depend on the mineralogical components of sandy materials. The distribution coefficient (Kd) of Np(V) increased in the presence of HS. The Kd values were in the order of sandtuffaceous sandsandy rock samples. The Np(V) sorption in the presence of HS with different origin for the sandy rock sample was divided into two groups. The Kd values were positively correlated with aliphatic carbon contents of the lake and the shallow groundwater HS, except for the deep saline groundwater HS. These results indicates that the characteristics of the sandy materials and groundwater HS are important factors determining the Np(V) sorption because of the presence of Np(V)-bound HS.
Yamaguchi, Tetsuji; Nakayama, Shinichi; Vandergraaf, T. T.*; Drew, D. J.*; Vilks, P.*
Journal of Power and Energy Systems (Internet), 2(1), p.186 - 197, 2008/00
In safety assessments of the geologic disposal of high-level radioactive wastes, the possibility that long-lived radionuclides may be leached from the wastes and may subsequently be transported through surrounding rock masses must be considered. It is therefore necessary to understand the transport of radionuclides through water-bearing fractures in rocks surrounding the repository. For this purpose, radionuclide migration experiments in quarried blocks of granite under in-situ conditions at the 240-m level in AECL's Underground Research Laboratory (URL) were performed under a five-year cooperative research program between Japan Atomic Energy Research Institute (JAERI, reorganized to Japan Atomic Energy Agency, JAEA) and Atomic Energy of Canada Ltd. (AECL). Migration experiments with Br, synthetic colloids, H, Sr, Tc, Np and Pu, and post-experimental alpha and scanning of the fracture surfaces were performed using 1 m granite blocks, each containing a single fracture, excavated from a water-bearing fracture zone. The transport of the radionuclides was affected by macroscopic mechanical dispersion, matrix diffusion and element specific sorption on fracture surfaces. Colloid transport exhibited a complicated process that may include sedimentation and diffusion into stagnant zones.
JAERI-Research 98-066, 62 Pages, 1998/11
no abstracts in English