Analysis of Beyond Design Basis Events for the Fast Flux Test Facility UO sub 2 core

An analysis of two Beyond Design Basis Events (transient overpower without scram and loss of flow without scram) was performed for the proposed UO{sub 2} core design in the Fast Flux Test Facility using the SASSYS/SAS4A accident analysis computer code. Numerical results are presented for two different cases: with and without the reactivity feedbacks for core and structure movement (core radial expansion, assembly duct bowing, control rod driveline expansion, and fuel axial expansion). When all of the reactivity feedbacks are included, no sodium boiling or fuel failure is predicted. When the reactivity feedbacks for core and structure movement are neglected, sodium boiling and fuel failure are predicted, but the amount of core damage is substantially lower compared to previous analyses for the initial mixed oxide core. 6 refs., 10 figs., 1 tab.