A 15% enriched 235U-Graphite moderated reactor has been operating at equilibrium for some time. The average neutron flux is 2x10^14 neutrons/cm^2sec and the moderator fuel ratio is 250 moles per graphite per mole U. Determine the reactivity change due to xenon and samarium. The mean core temp is 500C.
The biggest problem I'm having is figuring out sigma-au and sigma-fu for the thermal utilization factor. Also the correction factor (k_eff).