ICEM11 Final Program 9.7.11pm_ICEM07 Final Program ... - Events

Abstracts Session 52
The geological environment in the region of the LLWR consists of Quaternary age deposits overlying older bedrock. The site
has been subjected to a series of site investigation programmes from 1939 to the present day. The development of 3-D geological
models was necessary to integrate data from boreholes, trial pits, geophysical investigations and beach exposures and data gained
from site operations.
The understanding of the geology has developed with each new set of data. Early simple interpretations from a few boreholes
have been superseded by a series of more complex interpretations each incorporating the increasingly detailed observations. Initial
attempts to develop a lithostratigraphic representation of the geology proved difficult. It was also difficult provide a clear link
between the geology and the hydrogeology using a lithostratigraphic approach as required for the development of hydrogeological
models.
2) IN-SITU INTERFEROMETRIC MEASUREMENTS OF COMPACTED SMECTITE
UNDER HYPERALKALINE CONDITION (w/oP-59124)
Hisao Satoh, Susumu Kurosawa, Mitsubishi Materials Corporation; Tomoko Ishii,
Hitoshi Owada, Radioactive Waste Management Funding and Research Center (Japan)
Alteration of bentonite buffer at the repository for radioactive waste is an unavoidable phenomenon. However, precise kinetic
data is useful for evaluation of the endurance for long-term safety. Alkaline attack to bentonite by cement-leachates may enhance
alteration of smectite into the other phase such as zeolite. Until recently, there are a number of detailed dissolution studies (e.g.,
Cama et al., 2000; Yokoyama et al., 2005; Rozalen et al., 2008) for suspended smectite, using high precision measurements by ICP-
MS and AFM analyses. In contrast, dissolution study of compacted smectite is very limited (e.g., Nakayama et al., 2003). In order
to verify the previous data, the dissolution rate of compacted smectite with realistic density needs to be confirmed experimentally.
We have, for the first time, applied in-situ vertical scanning interferometry (VSI) along with the auto-compaction cell for measuring
dissolution rates of smectite compacted at 0.04-20.0 MPa and 70 ̊C in 0.3 M NaOH (pH12.1).
At less-compaction (0.04 MPa), Kunipia-P smectite initially showed a relatively fast dissolution of ~2E-11 mol/m2/s which is
comparable to the rate for suspended smectite under same pH-T condition. At high-compaction (