Preface and framework for nuclear thermal-hydraulics

Nuclear Thermal-Hydraulics (NTH) constitutes a fundamental discipline at the basis of the design, the operation and the safety evaluation of Water Cooled Nuclear Reactors (WCNR). Huge research investments that began to be available in 1970 in conjunction with the publication of 10 CFR 50.46 stepwise declined roughly around the year 2000; a further decline is expected nowadays (year 2020) in most of the Countries where nuclear technology was developed. Nevertheless, those investments brought to the current understanding, as characterized in recently issued textbooks; otherwise, ‘new Countries’, where nuclear technology is florescent nowadays, are supposed to provide new impulse to the research. The present Special Issue (SI) aims at collecting ideas for streamlining researches in nuclear thermal-hydraulics. Topics of expertise of renowned authors are collected and form the basis for a reflection. The scope for the papers is limited to NTH with emphasis to the design conditions of WCNR and to accidents within the Design Basis Accident envelope, including countermeasures to be taken in the conditions of core still intact. Papers connecting the fundamentals to the applications of nuclear thermal-hydraulics have been solicited and constitute the main content of the SI. Topics related to Design Extension Conditions (DEC) and/or connected with the application of NTH to nuclear technology are the focus for a few papers: this is also consistent with the dedication of the SI to the memory of deceased scientists as from below.