Surface analyses of cesium hydroxide chemisorbed onto type 304 stainless steel

Lemma, Fidelma Giulia Di; Nakajima, Kunihisa; Yamashita, Shinichiro; Osaka, Masahiko

doi:10.1016/j.nucengdes.2016.06.023

Cited by 29 publications

(15 citation statements)

References 16 publications

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“…On the other hand, Fe-pollucite, CsFeSi 2 O 6 · nH 2 O, is identified for the first time in CsMPs. None of the previous studies reported pollucite during meltdown; however, a recent experimental study reported formation of pollucite and CsFeSiO 4 during the CsOH chemisorption onto stainless steel containing 5% Si 38 . Both materials have a zeolite structure that can be synthesized by annealing a mixture of gels 39 and appropriate elements, such as Cs 40 .…”

Section: Discussionmentioning

confidence: 91%

Isotopic signature and nano-texture of cesium-rich micro-particles: Release of uranium and fission products from the Fukushima Daiichi Nuclear Power Plant

Imoto

Ochiai

Furuki

et al. 2017

Sci Rep

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Highly radioactive cesium-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) provide nano-scale chemical fingerprints of the 2011 tragedy. U, Cs, Ba, Rb, K, and Ca isotopic ratios were determined on three CsMPs (3.79–780 Bq) collected within ~10 km from the FDNPP to determine the CsMPs’ origin and mechanism of formation. Apart from crystalline Fe-pollucite, CsFeSi2O6 · nH2O, CsMPs are comprised mainly of Zn–Fe-oxide nanoparticles in a SiO2 glass matrix (up to ~30 wt% of Cs and ~1 wt% of U mainly associated with Zn–Fe-oxide). The 235U/238U values in two CsMPs: 0.030 (±0.005) and 0.029 (±0.003), are consistent with that of enriched nuclear fuel. The values are higher than the average burnup estimated by the ORIGEN code and lower than non-irradiated fuel, suggesting non-uniform volatilization of U from melted fuels with different levels of burnup, followed by sorption onto Zn–Fe-oxides. The nano-scale texture and isotopic analyses provide a partial record of the chemical reactions that occurred in the fuel during meltdown. Also, the CsMPs were an important medium of transport for the released radionuclides in a respirable form.

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Section: Discussionmentioning

confidence: 91%

Isotopic signature and nano-texture of cesium-rich micro-particles: Release of uranium and fission products from the Fukushima Daiichi Nuclear Power Plant

Imoto

Ochiai

Furuki

et al. 2017

Sci Rep

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“…As the result, it was found that the vd for the water-insoluble Cs deposit at temperatures above 1073 K depended not only on temperature but also on both of the Si content and the gaseous CsOH concentration. Furthermore, it was found that the main Cschemisorbed compound at temperatures around 873 K changed from Cs silicates, which have already been known to be present (Elrick et al, 1984;Di Lemma et al, 2016;Di Lemma et al, 2017;Kobata et al, 2018), to a Cs ferrate. Therefore, we tried to construct the modified Cs chemisorption model valid above 1073 K where the main Cs-chemisorbed compound was a Cs silicate.…”

Section: Construction Of Modified Chemisorption Modelmentioning

confidence: 95%

“…In 1980's, thermodynamic equilibrium calculation (Cubicciotti and Sehgal, 1984) predicted that main chemical forms of Cs vapor species were CsOH and cesium iodide (CsI) and then the Cs chemisorption behavior was investigated between gaseous CsOH or CsI and stainless steel type 304 (SS304) used as a structural material of the RPV internals in 1F. However, experiments performed by Elrick and Powers (Elrick and Powers, 1987) indicated that the chemisorption rate between gaseous CsI and SS304 was less than 3×10 -5 (cm/s) at 1273 K. Thus, our studies have focused on investigation of Cs chemisorption behaviors between gaseous CsOH and stainless steels and development of a more mechanistic model for improvement of the existing chemisorption model (Di Lemma et al, 2016;Di Lemma et al, 2017;Kobata et al, 2018;Nakajima et al, 2018;Nishioka et al, 2019). As other important points we should consider as simulation of the chemisorption behavior during SA, there can be effects of the pre-oxidized layer forming on stainless steels and the irradiation damages.…”

Section: Existing Cs Chemisorption Model Onto Stainless Steel Type 304mentioning

confidence: 99%

Study on chemisorption model of cesium hydroxide onto stainless steel type 304

Nakajima

Nishioka

Suzuki

et al. 2020

Mechanical Engineering Journal

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A large amount of cesium (Cs) chemisorbed onto stainless steel is predicted to be present especially in the upper region of reactor pressure vessel (RPV) during light water reactor severe accident. A chemisorption model was developed for estimation of such amounts of Cs for stainless steel type 304 (SS304) exposed to cesium hydroxide (CsOH) vapor. However, this existing chemisorption model cannot accurately reproduce experimental results and is considered not to be suitable for the estimation of the Cs-chemisorbed amounts under various conditions experienced in Fukushima Dai-ichi nuclear power station. Our recent laboratory study indicated that the surface reaction rate constant used in the exiting chemisorption model depended on both of silicon content in SS304 and concentration of gaseous CsOH as well as on temperature. Therefore, in this study, a modified Cs chemisorption model which accounts for these effects was constructed by combining penetration theory for gas-liquid mass transfer with chemical reaction and mass action law for CsOH decomposition at interface between gaseous and solid phases. As a result, it was found that the modified model was able to adequately describe effects on concentration of CsOH in gaseous phase and Si content in SS304 and more accurately reproduce the experimental data than the existing model.

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“…Nevertheless, it is still inapplicable to extend the study to Fukushima Daiichi case since the insulator material likely consists of different mineral phases of calcium silicate, xonotlite and tobermorite. Moreover, with regard to a severe accident, most researches were intensively centered on cesium adsorption on structural material such as stainless steel (Chang et al, 1992;Haste et al, 2013;Kalilainen et al, 2014;Di lemma et al, 2016). Therefore, as an initial effort to study cesium adsorption on calcium silicate insulation, the room-temperature adsorption study is conducted to construct fundamental information of the interaction of a calcium silicate insulator material and cesium.…”

Section: Introductionmentioning

confidence: 99%

Room-temperature adsorption behavior of cesium onto calcium silicate insulation

Rizaal

Saito

Okamoto

et al. 2020

Mechanical Engineering Journal

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Room-temperature adsorption behavior of cesium onto calcium silicate insulation Abstract A calcium silicate insulator material was investigated for its interaction with non-radioactive cesium at room temperature by batch-type adsorption experiments. An industrial-grade calcium silicate was weighted and ground into powder with an average size of 15.4 ± 0.1 µm, which was then placed into polypropylene (PP) tube containing cesium chloride aqueous solution. Cesium concentrations were range between 1.3×10 -6 -3.5×10 -3 M. Adsorption kinetics of cesium was evaluated based on pseudo-first order and pseudo-second order models, while the adsorption isotherm was modeled using the Langmuir model and modified BET model. Physicochemical properties of calcium silicate before and after the adsorption was investigated using XRD, SEM/EDS and FT-IR. Chemisorption was found as the underlying sorption process between calcium silicate insulator material and cesium.

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Surface analyses of cesium hydroxide chemisorbed onto type 304 stainless steel

Cited by 29 publications

References 16 publications

Isotopic signature and nano-texture of cesium-rich micro-particles: Release of uranium and fission products from the Fukushima Daiichi Nuclear Power Plant

Isotopic signature and nano-texture of cesium-rich micro-particles: Release of uranium and fission products from the Fukushima Daiichi Nuclear Power Plant

Study on chemisorption model of cesium hydroxide onto stainless steel type 304

Room-temperature adsorption behavior of cesium onto calcium silicate insulation

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