Calculation of the effect of fuel particle size on reactor dynamics

Abstract

The effect of fuel particle size on the dynamic behaviour of a 500 MW beryllia moderated reactor fuelled with oxide particles of diameter 2 to 500 microns dispersed in beryllia is discussed. Negative feedback of reactivity proportional to the reactor power occurs because of the very small thermal time constant of the fuel particles. For large fuel particles the feedback considerably reduces the peak power and the energy release following a reactivity accident.