Noncoherence and Two-Phase Heat Transfer in LMFBR Fuel-Coolant Interaction

Abstract

Models were developed for the analysis of non-coherent mixing of fuel and sodium, reduction in two-phase heat transfer between fuel and sodium, and heat loss from sodium to cladding during a fuel-coolant interaction in a liquid-metal fast breeder reactor (LMFBR). The analysis is based on the supposition that fragmentation of molten fuel followed by its relatively rapid intimate mixing with sodium can occur in an LMFBR accident, a supposition still under widespread investigation. Calculations were made for whole-core accidents to evaluate the extent to which reductions in mechanical work might be expected from these phenomena. Although reductions in work were indicated for each phenomenon and reductions were more significant when the several phenomena were considered simultaneously, large order-of-magnitude reductions were not indicated.