Gas-Phase Reactivity of Cesium-Containing Species by Quantum Chemistry

Abstract

Thermodynamics and kinetics of cesium species reactions have been studied by using high-level quantum chemical tools. A systematic theoretical study has been done to find suitable methodology for calculation of reliable thermodynamic properties, allowing us to determine bimolecular rate constants with appropriate kinetic theories of gas-phase reactions. Four different reactions have been studied in this work: CsO + H2 = CsOH + H (R1), Cs + HI = CsI + H (R2), CsI + H2O = CsOH + HI (R3), and CsI + OH = CsOH + I (R4). All reactions involve steam, hydrogen, and iodine in addition of cesium. Most of the reactions are fast and (R3) and (R4) proceed even without energetic barrier. In terms of chemical reactivity in the reactor coolant system (RCS) in the case of severe accident, it can be expected that there will be no kinetic limitations for main cesium species (CsOH and CsI) transported along the RCS. Cs chemical speciation inside the RCS should be governed by the thermodynamics.

Chemical stability of caesium iodide deposits in air/steam atmosphere

“…The reaction between CsO and H 2 have been investigated by Louis at al. [28]. Based on all these studies, it is possible to estimate the concentrations of some iodine and caesium species in the gas phase depending on the experimental conditions [29].…”

Spectroscopic properties of diatomic molecules CdI and CsCd: ab initio calculations

“…Caesium can exist in reactor coolant system in various simple compounds (Cs 2 , CsH, CsO, Cs 2 O, CsX, and Cs 2 X 2 (X = OH, Cl, Br, I)) [9]. The paper by Šulková et al [10] brings better understanding of the chemical speciation along the transport of fission products in the reactor coolant system to estimate the source term in the case of a nuclear power plant accident. Iodine and caesium are of high importance for health consequences in the case of outside releases.…”