Vattenfall, based in Sweden, contacted the fuel management team at NRG. Vattenfall has 4 operational reactors at Ringhals. Because of the complex core design of these installations, reducing operating costs was challenging. We applied our ROSA software to the problem. Together with help from the Vattenfall engineers, the software tool was adapted to the Ringhals 4 installation. ROSA outperformed Vattenfall’s reference case with a higher than required increase of the assembly discharge burnup of 0.6 MWd/kgU per reactor core assembly. This relates to fuel cost savings of about 500,000 Euro per cycle.