Equilibrium partition coefficients of cesium and iodine between sodium pool and the inert cover gas

Miyahara, Shinya  ; Nishimura, Masahiro ; Nakagiri, Toshio  

Equilibrium partition coefficients were experimentally measured using "Transpiration method" for volatile fission products of cesium and iodine between liquid sodium pool and the inert cover gas. The objectives of the experiments are to : (1) Obtain the equilibrium partition coefficients of cesium and iodine at high temperature between 600 and 850 C and (2) Study the dependence of the partition coefficients upon the concentration in the sodium pool. The obtained empirical equations are consistent with Castleman's theoretical equations. The partition coefficients of cesium measured at five different points of mole concentration in the pool were almost consistent with the theoretical values. On the other hand, the measured partition coefficients of iodine increased with the increase in the concentration in the pool and this tendency was incompatible with the theoretical consideration. The reason of this discrepancy might be attributed to the formation of NaI in the cover gas.