Adventures in study of the pressure losses in wire-wrapped rod bundle arrays

For the occasion of celebrating the 40th anniversary of the NURETH conference series, we present a brief overview of our work on the thermal-hydraulics of wire-wrapped rod bundles over these past four decades. In this context, this short technical note presents a personal perspective about this topic in a colloquial narrative. Particular focus is placed on a model for calculating hydraulic performance of rod bundles with wire spacers as used in sodium- and lead-cooled fast reactors. Since its first publication in 1986, this model has been often discussed by the international community at events like NURETH, sparking some suggestions for improvement. These issues have been addressed in a recent series of articles leading to an upgraded version published in 2018. This upgraded model yields a better overall prediction of all available experimental data and accurately represents some relevant geometrical aspects, such as the friction factor for two otherwise identical bundles but with different number of pins (bundle size effect). An outlook on the next steps for this effort is given, particularly from the point of view of using this model for licensing purposes.