SHIGEMATSU Hirotake Nagoya University, Grad.School of Engn., Research Assoc., 工学研究科, 助手 (40281068)
ARITA Yuji Nagoya University, Grad.School of Engn., Research Assoc., 工学研究科, 助手 (50262879)
NAGASAKI Takanori Nagoya University, Grad.School of Engn., Assoc.Prof., 工学研究科, 助教授 (40273289)
|Budget Amount *help
¥6,300,000 (Direct Cost : ¥6,300,000)
Fiscal Year 1997 : ¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1996 : ¥3,100,000 (Direct Cost : ¥3,100,000)
The actinide elements, due to their long half-life, in high-level nuclear waste should be conditioned so as to minimize a release from the final repository to the biosphere. There are two suitable matrix forms for fixation of the fission-products : one is borosilicate glass matrix and the other is a ceramic matrix. For fixation of actinide elements, the latter seems to be better than the former because of its thermodynamic stability for long time. From the view point of bonding energy, perovskite, pyrochlore and fluorite oxides containg Zr and Ti as the main constitment elements seemed to be prost suitable as the fircation ceramics. On CaTiO_3, La_2Zr_2O_7, CeO_2, ZrO_2 doped with Pu, U,Nd, Ce and Y,the determination of solubility limits, leaching test, heat capacity measurements, the determination of the mechanism of the phase transitions were carried out by X-ray diffraction DSC,ASC,EXAFS and electron microscope. It was found that the leaching rates of doped elements in CaTiO_3, La_2Zr_2O_7 are similar to those of Pu-rock-like fuel and synrock, and are lower by 1-2 orders of magnitude than that of borosilicate glass matrix.