10th Asian Regional Conference of IAEG (2015)

Invited speaker Topic 4
Professor Hidekazu Yoshida
ProfileNagoya University Museum / Graduate School of EnvironmentalStudies, Furocho, Chikusa, Nagoya 464-8601, Japan
Email: dora@num.nagoya-u.ac.jp
Date of Birth: 1962, Feb. 10
Nationality: Japanese
Titles2000 ~ :Chairman of the committee of ‘Research of Geologicalstability of Japan’ in Geological Society of Japan.
Position Held
2010: Director of Nagoya University Museum (Professor of Graduate
School of Environmental Studies)
2009: Nagoya University (Professor; University Museum/Graduate School of Environmental Studies)
2000: Nagoya University (Associate Professor; University museum/Graduate School of Science)
1990-1995: JAEA, Tono GeoScience Center (Senior Researcher; Head of Tono Uranium NaturalAnalogue Project)
1986: Japan Nuclear Fuel Development Cooperation (Present as JAEA/ Japan Atomic Energy Agency/Researcher)
Research Interests
Since graduated Nagoya University, more than 25 years, main research relevant to HLW andutilization of underground environment as shown below has been conducted.
・ Uranium series migration study using by uranium mine (natural analogue)
・ Redox front development and related elemental migration study
・ Fracture and filling generation with fluid interaction study
・ Biogenic Fe concretion formation study
・ Fault damage zone, fracture development and elemental migration study
・ Carbonate and Fe concretion formation study
Education
1994: Doctor of Science (Nagoya University)
1986: Graduate School of Science, Nagoya University (Earth Science; MSc. (Structural Geology))
1984: Faculty of Science, Kumamoto University (Geology; Bc)
Abstract

Ferric oxyhydroxide in underground geological environments and high-level
radioactive waste disposal: influence on siting and site characterization
Ferric oxyhydroxide in the underground geological environments is an important factor that may
influence the long-term natural barrier function with respect to nuclide migration, in scenarios for thegeological disposal of high-level radioactive wastes (HLW). Here, examples of Ferric oxyhydroxide seen in
the underground environment of Japan were reviewed in order to: 1) evaluate suitable repository depths thatwill need to be characterized; and 2) assess how Ferric oxyhydroxide will need to be treated in nuclide
migration scenarios at a future repository site. The Ferric oxyhydroxide examined provide the following
insights into the features relevant to site characterization and the rock’s barrier function: 1) Ferric
oxyhydroxide has been formed along the connective fracture network that extends from the surface, but there
is a certain depth limit of oxidation due to geochemical buffering by redox reactions; 2) Past Ferric
oxyhydroxide will remain even after the environment returns to a reducing condition; 3) Ferric oxyhydroxide
produced in the rock matrices, however, can contribute to retarding nuclide migration by sorbing
radionuclides and clogging micro-pores. The evidence shows that Ferric oxyhydroxide formed in thegeological environment may influence on the siting as well as the geosphere barrier function in and aroundrepository caverns for the disposal of HLW constructed in the deep geological environment of Japan.
Keywords: Ferric oxyhydroxide, barrier function, radioactive waste, geological disposal