Chemical stability of caesium iodide deposits in air/steam atmosphere

ToF-SIMS and XPS characterizations of model fission products (I, Cs) deposits after thermal treatment simulating late phase conditions of a nuclear power plant severe accident

“…ToF-SIMS analysis of the sample confirmed this assumption with the detection of CsCrO + (Figure 2) and Cs2CrO2 + fragments. Based on these data, we can deduce that Cs in the residue is mainly CsOH (90% of total residual Cs)) and also Cs-Cr mixed oxide form (10%) identified as Cs2CrO4 This oxide is indeed the main mixed Cs-Cr oxide form reported in the literature in the same conditions [4], [8], [9]).…”

“…Hence, coupons (1.2 cm 2 ) of SS representative of RCS (304L) are oxidized to simulate the RCS oxidation. These pieces of oxidized SS will be used as a substrate for aerosol deposits; 2) CsI deposition: a previous study [4] showed that deposits obtained by aerosol impaction at room temperature behave as deposits obtained at higher temperatures. Thus, we retained the technique of aerosol deposition at room temperature.…”

“…CsI powder revaporization is thus reported to start below 500°C and to be completed around 750°C in a steam atmospherethe main revaporized species is CsI as vapor which can be transported by the steam flow in colder zones where it condenses as submicrometric aerosols. More recent work focused on the revaporization of CsI aerosol deposits in a temperature ramp (250-750°C) [4]. Under pure air, iodine (I) was released mainly (up to 90% of the initial amount of I) as molecular iodine (I2) whereas, under pure steam, only CsI was vaporized.…”