PHWRs slightly enriched fuel. Some calculations for Atucha I and Embalse

We have analized the neutronic behaviour of the Atucha I NPP when the natural uranium fuel is replaced by uranium slightly enriched in U235. We have evaluated the exit burnup, channel power, linear power density and power form factor as a function of enrichment. We included a simple thermalhydraulics feedback effect in the fuel temperature and coolant density. The exit burnups reached were 11415, 16050 and 21010 Mwd/ton corresponding to 0.85%, 1.0% and 1.2% enrichments. For this last case incompatible channel powers were detected. We have also included a simple cost analysis for both Atucha I, and Embalse NPPs showing that within the limitations of this study, the enrichment is also an economic alternative. (author)