Impact of methods and data on calculational results for LWR lattices employing uranium free plutonium fuels

A systematic study has been carried out of cell calculations for three different types of uranium-free LWR fuels, considered earlier within the framework of an international benchmark exercise. The approach adopted is the application of a single computational route in conjunction with data libraries based on several different evaluations, attention being given mainly to k, void coefficients and fuel temperature coefficients under beginning-of-life conditions. The impact of methods and data has been assessed via comparisons of the new results among themselves, as well as with those reported earlier employing the same data base but different calculational methods. In particular, it has been found that the large spread in predicted values of void coefficients for such innovative, plutonium-incinerating fuels (especially at high voidage) results mainly from uncertainties in the epithermal absorption cross sections for zirconium (the inert matrix) and erbium (the burnable poison)