Analysis of air ingress process during the primary-pipe rupture accident of the HTGR

In order to predict or analyze the process of air ingress during the primary-pipe rupture accident of HTGRs, it is very important to develop computer programs and to validate them by experiments. This paper describes a computer program, which is named FLOWGR, developed to analyze the process of air ingress during the first stage of the primary-pipe rupture accident. FLOWGR provides a numerical method for analyzing the transient thermal hydraulic behavior by solving the one-dimensional basic equations for continuity, momentum conservation, energy conservation of the gas mixture, and mass conservation of each gas species. The numerical results are in good agreement with the experimental ones regarding the density of the gas mixture, the concentration of each gas species produced by the graphite oxidation reaction and the onset time of the natural circulation of air. (author)