Water-ingress accident, caused by steam generator heating tube rupture of a high temperature gas-cooled reactor (HTGR) is an important accident to consider because it will introduce positive reactivity leading the nuclear power increase rapidly, as well as the chemical reaction of graphite fuel elements and reflector structure material with steam. Researches and simulations (Zuoyi Zhang et al. 1995; Zheng Yanhua et al. 2009) have been carried out for calculating the total amount of water ingress and to validate the safety and security of HTR. The water ingress amount, which is our mainly concerned, ranges from a few hundred kilograms to thousands of kilograms, because of the different reactors and different computing methods. The place, where the water deposits, is most likely to be the bottom of the steam generator.. Such liquid water removal, with the approach of providing a forced circulation in primary loop and accelerating the evaporation, is analyzed in this paper.
Many experimental data have been got on water evaporation rate (Dalton et al.; Willis Carrie et al. 1914; Yoshida, Hyodo et al. 1970; Sweer et al. 1976; Pauken et al. 1995). All these formulas have a common form, ṁ = hc(Pw − Pa)/hw, which shows the relationship between evaporation rate and velocity over water face, water temperature and the relative partial pressure of the water vapor. This formula has been used widely in chemical industry and other fields and shows good agreement.
FLUENT CFD code (ANSYS Fluent 14) is used for the calculation of the distribution of the flow and temperature fields. The evaporation rate is estimate combined thermal fluid data with empirical formula. As the working condition of empirical formula and that of actual reactor don’t match very well, sensitivity analysis is necessary in this report.
Gas Turbine Heat Recovery Steam Generators for Combined Cycles Natural or Forced Circulation Considerations
