[2C10-15] Debris

[2C13] Clarification of Debris Formation Conditions on the Basis of the Sampling Data and Experimental Study Using Simulated Fuel Debris

(4)Metallic debris formation mechanism by interaction between molten Fe-Zr alloy and stainless steel

*Ayumi Itoh¹ (1. Tokyo Tech)

Keywords:Metal-rich debris, severe accident, non-isothermal reaction, Fukushima Daiichi Nuclear Power Station

In Fukushima Daiichi Nuclear Power Station accident, the formation of “metal-rich pool” in the lower plenum during the late phase of core degradation has been considered to have taken place, which could have triggered the failure of reactor pressure vessel. In this study, the formation mechanism of “metal-rich debris”, which could be source of the metal-rich pool, was investigated by an experiment in which the high-temperature Fe-Zr melt at 1450-1600 ^oC was dropped onto stainless steel at 1180^oC. The stainless steel had been oxidized in advance by high-temperature steam. The results showed that at melt temperatures above 1500°C, the FeCr₂O₄ oxide layer was replaced by ZrO₂, and that the eutectic melt passed through the oxide film and significantly damaged the stainless steel. The knowledge was obtained to model the process of metal melt corrosion of a structure with an oxide film.