The 13th International Conference on Environmental ... - Events

Abstracts
kinetic solubility limited dissolution (KSLD) boundary condition in fractured media. <strong>The</strong> release rate of nuclide would
proportional to the difference between the saturation concentration and the inlet aqueous concentration of nuclide. <strong>The</strong>
presence of colloids could decrease the aqueous concentration of nuclide and thus could increase the release flux of
nuclide from the waste form.
2) 40013 – Modeling hydraulic conductivity and swelling pressure of several kinds of bentonites affected by
salinity of water
Yukihisa Tanaka, Takuma Hasegawa, Kunihiko Nakamura, CRIEPI (Japan)
In case of construction of repository for radioactive waste near the coastal area, the effect of salinity of water on
hydraulic conductivity as well as swelling pressure of bentonite as an engineered barrier should be considered because it
is known that the hydraulic conductivity of bentonite increases and swelling pressure decreases with increasing in salinity
of water. Though the effect of salinity of water on hydraulic conductivity and swelling pressure of bentonite has been
investigated experimentally, it is necessary to elucidate and to model the mechanism of the phenomenon because various
kinds of bentonites may possibly be placed in various salinity of ground water. Thus, in this study, a model for evaluating
hydraulic conductivity as well as swelling pressure of compacted bentonite is proposed considering the effect of salinity
of water as follows :
a) Change in number of flakes of a stack of montmorillonite because of cohesion
b) Change in viscosity of water in interlayer between flakes of montmorillonite.
Quantitative evaluation method for hydraulic conductivity and swelling characteristics of several kinds of bentonite
under saline water is proposed based on the model mentioned above.
3) 40018 – Current R & D activities of the study on long-term stability of geological environments
Takahiro Hanamuro, Kenichi Yasue, Yoko Saito-Kokubu,Koichi Asamori,
Tsuneari Ishimaru, Koji Umeda, JAEA (Japan)
Japanese islands are located in a tectonically active zone, where earthquakes and volcanic eruptions frequently
occur. <strong>The</strong>refore the understanding of the long-term stability of geological environment is required for assessing the
long-term behaviour of the geological disposal system of high level radioactive waste (HLW) in Japan. <strong>The</strong> Japan
Atomic Energy Agency (JAEA) is promoting the establishment of investigation and assessment methods of the long-term
stability of geological environment necessary for site selection and safety assessment of HLW geological disposal.
<strong>The</strong> Nuclear Waste Management Organization of Japan (NUMO) is the implementation body of HLW disposal in
Japan. <strong>The</strong> preliminary investigation areas for HLW disposal site, selected by NUMO in the future, are supposed to be
selected excluding the zones affected by already-known active faults identified by nationwide and site-specific literature
surveys. <strong>The</strong>y are also supposed to be selected with excluding the area within 15 km radius of the center of a Quaternary
volcano and the zones affected by thermal and hydrothermal activities identified by site-specific literature surveys. For
uplift, denudation and climatic/sea-level changes, it is necessary that the change of geological environment caused by
uplift/denudation and climatic/sea-level changes is assessed for HLW geological disposal system.
For seismicity and faulting, some detection techniques for active faults with no surface expression, by using helium
isotope ratio of hot spring gas or detection of hydrogen gas, and studying on the assessment of fault activities are
developed. For volcanism and geothermal activity, heat source of geothermal anomaly area in the non-volcanic region are
considered and some detection techniques for high-temperature fluid and magma at deep underground, by using seismic
tomography, magnetotelluric method and helium isotope ratio of hot spring gas, are constructed. For uplift, denudation
and climatic/sea-level changes, a methodology to understand future topographic change with time is developed. Also, for
dating techniques as an essential part to proceed on these studies, C-14 dating by using AMS and (U-Th)/He dating by
using QMS and ICP-MS have developed, and Be-10 dating by using AMS has been being developed.
We are planning the establishment of assessment methods for long-term stability of geological environment;
assessment of activities of faults encountered by underground excavation, development of long-term estimation methods
of volcanisms and hydrothermal activities, and hydrogeological analyses considering topographic change in the future.
4) 40019 – In Situ Stress Measurements in Siliceous Mudstones at Horonobe Underground Research Laboratory,
Japan
Hiroyuki Sanada, Takahiro Nakamura, Yutaka Sugita, JAEA (Japan)
As part of the research and development program on the HLW geological disposal, JAEA has been implementing
the Horonobe Underground Research Laboratory (URL) Project investigating sedimentary rock formations distributed in
Horonobe area, Hokkaido, Japan. To optimize the design and construction of underground excavations for any HLW
repository, a thorough evaluation of initial stress condition will be required. Studies of initial stress conditions in
sedimentary rock aren't enough, since important underground structures such as those for underground power plants and
caverns for storage of liquefied petroleum or natural gas in Japan have mainly been constructed in hard rock.
Additionally, initial stress measurements in sedimentary rocks are inherently more difficult compared to hard rock. <strong>The</strong>
authors have been implementing the research and development program at Horonobe to clarify the in situ stress
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