A burnup survey of Pu-Th-BeO fuels and comments on selection of fuel for pebble bed reactors

Abstract

The results of a burnup survey for a BeO pebble bed reactor system studied by the Australian Atomic Energy Commission are reported. The survey was based on equilibrium model and carried out by means of the GYMEA complex of codes. A once-through fuel cycle was assumed with plutonium and thorium as the fissile and fertile materials. The selection of a fuel composition is discussed taking into consideration reactivity lifetime, initial power density, and temperature coefficients of reactivity. With a 200 MWe pebble bed reactor design, values of F.I.F.A. (fissions per initial fissile atom) of 1.2 to 1.4 appear to be achievable at an average bulk power density of 11W/cm3.