TOYODA Kazuhiro Univ. of Tokyo, Fac. of Science Research Assoc., 理学部, 助手 (10207649)
HAGA Nobuhiko Univ. of Tokyo, Fac. of Science Research Assoc., 理学部, 助手 (60011748)
OZAWA Tohru Univ. of Tokyo, Fac. of Science Lecturer, 理学部, 講師 (00011651)
HORIUCHI Hiroyuki Univ. of Tokyo, Fac. of Science Associate Prof., 理学部, 助教授 (80029892)
High-level radioactive wastes unavoidably remain whenever the used nuclear fuels are reprocessed for the next effective use. These wastes must be kept away from human being and animals in safety for a very long period. Thus, the search of the best way of their disposal is an emergency subject for the use of atomic energy. Most of researches on this problem are performed from technological point of view, however, basic researches of wasted substances are not strongly promoted.
In this project, microtextures of minerals which are related to radioactive wastes are mainly investigated because such textures might be observed for the radioactive wastes after a geologically long period. In order to study microtextures, we investigated radioactive minerals or rare-earth minerals which are thought as analogues to show a future's feature for the radioactive wastes. As a result, behaviors of the process of transfer, concentration, substitution of various atoms will be clarified.
Main contents which
we contributed to these subjects are; (1) Developments of Microarea X-ray Diffractometer : Conventional microarea X-ray diffractometer is only available to take powder diffraction pattern of such a small area as 50mum, and it is difficult to get a crystallographic information from smaller area than that. We could get a crystallographic information from 10mum area by single crystal diffraction technique by making a control of a specially designed X-ray gonioneter combined with a developed soft-ware system. By this technique, it will become possible to identify small minerals and to analyze orientation relationship among minerals. (2) Many of rare-earth minerals which are obtained from alkali-carbonatite complexes of Brazil are studied on mineral assemblage, textures, weathering, element concentration etc. by means of X-ray diffraction, scanning microscopy, photon activation analysis and so on. These results will be available to expect the change of rocks around radioactive wastes. (3) International collaboration with overseas scientists in order to discuss geological environments for disposal of radioactive wastes. Tokonami contributed to potentially useful materials for sealing cracks of rocks. Less