The accident at Fukushima Dai-ichi Nuclear Power Station of Tokyo Electric Power Company entirely lost people\u27s trust in nuclear power. We learned from the accident the importance of continuous effort to pay attention to improving the safety of nuclear power plant by reflecting new knowledge and experience. Concerning thermal-hydraulics research, severe accident research in particular, the question arises whether or not research results were reflected to safety measures or those obtained deserved it. In view of these, thermal-hydraulics research concerning nuclear safety up to the present will be reviewed and some suggestions will be presented in this paper
