40th Anniversary of the first international topical meeting on nuclear reactor thermal-hydraulics: Highlights of thermal-hydraulics research in the past four decades.

• We review the history of the International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH) conference series. • We provide a summary of progress in the thermal-hydraulic field in the last 4 decades. The year 2020 marks the 40th anniversary of the first International Topical Meeting on Nuclear Reactor Thermal-hydraulics (NURETH-1). Hosted by the thermal-hydraulics division (THD) of the American Nuclear Society, the NURETH series is the premier topical meeting exclusively dedicated to advances in nuclear reactor thermal-hydraulics. In this article, which opens a special issue dedicated to the 40th anniversary of NURETH-1, we provide a brief history of the NURETH series. We dedicate the bulk of the manuscript to a summary of the progress in thermal-hydraulics in the past 40 years, highlighting, key contributions presented in the NURETH series of conferences. We emphasize that, given the size and complexity of the field examined, this cannot be considered a comprehensive review. However, We hope the reader will find this article useful to reflect on the advances in the past 40 years and the current state of the art. [ABSTRACT FROM AUTHOR]