Corium stratification test using core materials

Tokushima, Kazuyuki; Shirasu, Noriko  ; Hoshino, Kuniyoshi*; Ohara, Hiroshi*; Kurata, Masaki 

At the fuel assembly degradation stage in severe accidents, chemical features of the intermediate products are expected to be changed depending upon the accident progressions. These differences are originated from the differences in oxygen potential and temperature, and are highly important for evaluating the relocation and stratification progress of the fuel debris. Two types of sim-test with the different oxygen potentials were performed to investigate these tendencies. The chemical features of the intermediate materials used in the tests were determined from the observations for the control blade and channel box degradation in our previous study. The present results indicate that the U concentration in the metallic layer is largely varied depending upon the oxygen potential of the atmosphere. Also, when the BC-Fe alloy, as of a typical intermediate product, coexists with UO and Zr, the apparent red-ox reaction rate between UO and Zr are mitigated.