Transport Phenomena of Iodine and Noble Gas Mixed Bubbles Through Liquid Sodium

Abstract

In the fuel pin failure accident in a liquid metal fast breeder reactor, volatile fission products play an important role in the assessment of radiological consequences. Especially the radioisotopes of elemental iodine are important because of their high volatility and of the low permissible dose to human thyroid. Although the coolant, liquid sodium, has a high retention capability of elemental iodine due to the chemical affinity between alkali metals and halogens, it may be directly released from the fuel to the cover gas, if the iodine might be carried by means of bubbles of xenon or krypton through the sodium pool. So far, the only few experimental results [1] were available concerning the decontamination factor (DF: the ratio of the initial mass in a bubble to the released mass into the cover gas) of iodine in this phenomenon. Thus, an experimental study was performed to investigate the transport phenomena of iodine by means of iodine and noble gas mixed bubbles rising through the liquid sodium pool.