Assessment of SFR core disassembly behavior

An effort has been made to analyze the hypothetical super-prompt-critical power excursions triggered by the reactivity insertion at an extremely large ramp rate into the sodium-voided core of a SFR. The system investigated in this study is the KALIMER-150 core, which is a pool-type sodium cooled prototype fast reactor that uses U-TRU-Zr metallic fuel to generate 392 MWt of power. The core utilizes a heterogeneous core configuration with the driver fuel and internal blanket zones alternately loaded in the radial direction. The density-dependent equations of state of pressure-energy density relationship developed for the metallic fuel U-Pu-Zr were implemented into the VENUS-II code, which was subsequently used in this study for analyzing the core disruptive accident. The equations of state for the single-phase liquid of the metallic uranium fuel were derived based on the van der Waals model, while a correlation recently developed for the saturated vapor pressure is used when the fuel is in the two-phase region. The results show that the extreme power excursion driven by inserting the reactivity at a rate of 100$/s is terminated without progressing into the single-phase region. (author)