Present status of research on thermal hydraulic behavior in conventional light water reactors during severe accidents and in advanced light water reactors

After having experienced TMI and Chernobyl nuclear power accidents, the importance of reactor containment vessels has become to be recognized anew. It is very important to grasp the thermal hydraulic behavior in the severe accidents that cause core damage. Atomic Energy Society of Japan organized the special committee on the investigation and research of the thermal hydraulic behavior in containment vessels in July, 1991. It was decided to investigate this problem related to severe accidents for three years. In this book, the results of the investigation carried out for three years are summarized. The thermal hydraulic flow in containment vessels at the time of severe accidents, the problems in the thermal hydraulic flow at the time of severe accidents such as the interaction of melted core with coolant and structural materials and others, the analysis codes for the thermal hydraulic flow in containment vessels at the time of severe accidents, and the design of new type containment vessels and statically safe reactors and the main problems are reported. (K.I.)