Reactivity effects of oil contamination in the primary cooling loop of a sodium-cooled fast reactor

Reactivity effects of hydrocarbons entering the core of a sodium cooled fast reactor are evaluated. Calculations are performed using the SCALE-3 code system. For all cases analysed, reactivity increased. Reactivity effects are less pronounced if vaporization of the hydrocarbons is assumed. Reactivity changes are shown to be proportional to the amount of hydrogeneous material entering the core, all other parameters held constant. Results also show a marked influence of the isotopic composition of the plutonium used as fuel and a decrease of reactivity effects with increasing burnup. (Author)