Fluorination method for classification of the waste generated by fuel debris removal, 4; Preparation and analysis of the simulated waste by arc melting method

Sudo, Ayako ; Takano, Masahide ; Watanabe, Daisuke*

The simulated wastes, which simulates the completely melted state near the melting front between molten corium and concrete, were prepared and provided for the fluorination tests. As simulated wastes, (U,Zr)O, Zr, SUS316L, GdO, and concrete powders were pressed into tablets. The tablets with two compositions with varying Zr metal content were prepared (Zr-rich reducing condition: sample A and Zr-lower oxidizing condition: sample B). The tablets were melted and solidified by arc melting method. Cross-sections of solidified samples were observed and elemental analyzed. The cross-sectional image of sample A showed white metal and gray oxide. The main component of oxide was (U,Zr)O, where a small amount of Ca, Al, and Gd dissolved. As for metal, a part of Si, U, and Al were reduced from oxide materials and consequently rodlike (Fe,Cr,Ni)-Si-Zr and (Fe,Cr,Ni)-Si-Al-Mo-(Zr,U) alloy phase were observed. On the other hand, oxide of sample B showed that (U,Zr)O was precipitated in the silicate glass phase. As for metal, an alloy phase that has Cr,Fe-lower SUS component was observed because all of Zr and a part of Cr and Fe were oxidized. The phase relationships during MCCI is considered to be significantly affected by Zr metal content in metallic melt.