Cesium chemisorbed species onto stainless steel surfaces: An atomistic scale study

Abstract

Under the scope of Fukushima Daiichi Nuclear Power Station (1-F) severe accident (SA), Cs retention is of high interest, as it impacts Cs distribution, decommissioning and dismantling work of the reactor. To derive consistent and appropriate models for such process, accurate thermodynamic properties of Cs chemisorbed species are required by the SA analysis codes. In particular, for CsFeSiO4, a newly identified Cs chemisorbed species under conditions similar to 1-F SA, the thermodynamic data are unknown in literature. We propose in this work the obtention of the fundamental properties of this substance by theoretical approaches. The consistency and appropriateness of derived computational methodology have been investigated by calculating the thermodynamic properties of relatively known Cs–Si–O substances. It was found that our computational methodology provides excellent agreement with literature data lying between 1 and 4% for the formation energy, 1–5% for standard entropy and heat capacity. The thermodynamic properties of CsFeSiO4 as function of temperature have been estimated for the first time using harmonic and quasi-harmonic approximations, values being consistent with both methodologies.