The future of nuclear thermal-hydraulics

An attempt is made to identify perspectives in nuclear thermal-hydraulics based on devoted papers published during the last seven years. An understandable target is fixed which also appears consistent with the framework of this Special Issue (SI). Nevertheless, the target revealed ambitious and having multiple solutions: one might expect this situation considering the universe of topics which characterize nuclear thermal-hydraulics (e.g. according to a recently published book, see paper PI-2 of this SI). The key (obvious) finding is that developments follow different directions independent among each other. In order to arrive at a reasonable achievement, the Computational Fluid Dynamics (CFD) and the system thermal-hydraulics are distinguished first; then it is recognized that (a) developments in procedures, modeling and experiments are typically pursued by groups of scientists having little or no connections, and (b), different science and technology areas are connected with nuclear thermal-hydraulics, e.g. including, uncertainty, licensing, structural mechanics, numerics. Finally, technology sectors of Boiling Water Reactors (BWR), Pressurized Water Reactors (PWR) and non-water cooled reactors, advanced and Gen IV reactors typically pursue different directions in developments within nuclear thermal-hydraulics. Having this in mind, a few dozen topics or elements for reflections are selected and classified which hopefully are informative for understanding the current status and trends in nuclear thermal-hydraulics.