Analysis of Power Excursion in KALIMER-600

Sodium fast reactors(SFRs) can be very sensitive to dimensional changes or relocation of materials since the intact SFR core is not in its most reactive configuration. Therefore it is theoretically possible that a rearrangement of the geometry can lead to prompt-critical reactivity excursions and to a hydrodynamic disassembly of the reactor resulting in a sizable energy release to the reactor system. In this study, a core disassembly analysis in the sodium-voided core of the KALIMER-600 was performed using the VENUS-II code for the extremely large reactivity insertion rate of 100 $/s. The core kinetics and hydraulic behavior of the KALIMER is followed over the period of the super-prompt critical power excursion induced by the ramp reactivity insertion, starting at the time that the sodium-voided core reaches the melting temperature of the metallic fuels. For this purpose, the equations of state of pressure-energy density relationship were derived for the saturated- vapor as well as the solid liquid of metallic fuel, and implemented into the formulations of the disassembly reactivity in the VENUS code