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Diffusion of HTO and cement pore fluids through host rock

Stellan Holgersson (Institutionen för kärnkemi) ; Yngve Albinsson (Institutionen för kärnkemi)
Radiochimica Acta (0033-8230). Vol. 90 (2002), p. 99-108.
[Artikel, refereegranskad vetenskaplig]

In the post-closure period of a deep disposal facility for low- to intermediate-level radioactive waste, highly alkaline pore-fluids chemically equilibrated with cementious components of the engineered barriers will migrate into the surroundings. Primary minerals in the host rock could dissolve and secondary calcium silicate hydrate (CSH) phases might be formed in the micro pore system of the rock and change the available porosity for radionuclides and hence the permeability. Since the retardation of radionuclides in the host rock depend on sorption and matrix diffusion, the study of the mineral reactions are of importance. Experiments with diffusion of HTO and synthetic cementitious pore-waters through 1 cm thick discs of Äspö diorite have been made in a nitrogen-flushed glovebox facility. Synthetic cementitious pore-waters representative of fresh and leached concrete were used. For the fresh pore-water the results show that hydroxide ion diffusion is retarded relative to HTO tracer, indicating that reactions between hydroxide and host rock take place. The result can be interpreted as hydroxide sorption in the rock. Al and Si did also accumulate on the sampling side which was attributed to mineral dissolution. For the evolved pore-water no through-diffusion of hydroxide ions or accumulation of other elements in the sampling cell were observed during the sampling period, indicating that the through-diffusion of hydroxide is hindered by this type of pore-water.

Nyckelord: radioactive waste, alkaline degradation of grano-diorite, diffusion in grano-diorite

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Denna post skapades 2008-06-12. Senast ändrad 2012-11-29.
CPL Pubid: 71682


Institutioner (Chalmers)

Institutionen för kärnkemi (1960-2002)


Geovetenskap och miljövetenskap

Chalmers infrastruktur