Interaction between caesium iodide particles and gaseous boric acid in a flowing system through a thermal gradient tube (1030 K–450 K) and analysis with ASTEC/SOPHAEROS

The present work aimed at studying the interaction between caesium iodide particles and gaseous boric acid through a Thermal Gradient Tube (TGT) from 1023 K to 453 K under Ar/H2O. Particles size range of transported particles was measured by ELPI and the fraction of gaseous compounds by ICP-MS and UV–visible spectroscopy. Reaction between the two compounds was deduced by measuring a significant fraction of gaseous iodine at the outlet of the facility, representing more than 80% of the total iodine sampled at the outlet. The reaction rate was shown to be lower when the flow rate inside the facility was increased. Analysis with SOPHAEROS module of ASTEC code was performed. The ASTEC fission products models allowed performing the evaluation of the experimentally observed results for the analysis of the transport of pure compounds. However, the heterogeneous interaction between the caesium iodide particles and the gaseous boric acid was not reproduced, as the models are not taken into account in the version v2.1_1_6 of the ASTEC/SOPHAEROS module. The next step would be to identify the mechanism of the reaction by comparing the results with other studies and to determine the reaction rates. Then, a first development in SOPHAEROS would be to implement such phenomena.