Study on a suppression of sodium-water reaction in SFR by applying sodium with suspended nanoparticles - 15248

An important safety concern for SFR (sodium cooled fast reactor) is the possibility of steam leaking from a tube at high-pressure into surrounding liquid sodium within the steam generator. The steam/liquid pair is very reactive and the steam leak will form a sodium-water reaction jet which may attack and break adjacent tubes. We have studied the concept of suspended nanoparticles in liquid sodium (sodium nano-fluid) to decrease sodium reactivity. From the experimental results for sodium nano-fluid, it was clear that the reaction rate and the reaction heat were decreased by the atomic interaction of sodium with suspended nanoparticles. Experiments have shown that the surface tension of sodium nano-fluid is larger than that of sodium whatever the temperature and that the evaporation rate of sodium nano-fluid is smaller than that of sodium. These results suggest that the interaction between sodium and nanoparticles change fundamental physical properties of the sodium nano-fluid. Taking into account these changes, an analytical model giving the peak temperature within a sodium nano-fluid water reaction jet has been devised. Comparing calculation results using the analytical model with the experimental results of a steam injection experiment, we have shown that the analytical model for the temperature within the reaction jet is appropriate. We have used the analytical model to predict the consequences of tube failure in the steam generator of a SFR, it appears that the consequences are largely mitigated with the use of sodium nano-fluid