Nuclear energy has been considered an important part of the long-term energy mixture in China. Accompanying the development of the nuclear power program, extensive research and development (R&D) activities were initiated. Nuclear thermal hydraulics has been recognized as a key subject in the development of nuclear technology because the target of nuclear thermal hydraulics is to remove heat safely from the fuel. The thermal hydraulics activities in China cover three main areas, namely, reactor core thermal hydraulics, safety-related thermal hydraulics, and fundamental thermal hydraulics.

This paper gives a brief summary of the ongoing R&D activities in these three areas with a focus on a few selected topics: (1) transversal mixing and nonuniform heat transfer distribution in fuel assemblies, (2) two-phase distribution at external reactor vessel cooling conditions, and (3) heat transfer of supercritical fluids. The state-of-the-art ongoing works and challenging aspects are presented and discussed.