Experiment and analysis on natural convection characteristics in the experimental fast reactor joyo

Abstract A series of decay heat removal tests by natural convection were carried out at various decay heat levels in the experimental fast reactor JOYO to study thermohydraulic behavior in fast breeder reactors (FBR). The principal results obtained are as follows: 1. (1) It was proved that the decay heat could be safely removed by natural convection even at 100 % full power (100 MWt). 2. (2) A plant-wide dynamics code, MIMIR-N2, was developed and verified through experimental data in order to establish an analysis technique for evaluating natural convection behavior. 3. (3) Verification data for assessing the natural convection ability in future plants were obtained through this test.