Adsorption of volatile polonium species on metals in various gas atmospheres: Part II – Adsorption of volatile polonium on platinum, silver and palladium

Maugeri, E. A.; Neuhausen, Jörg; Misiak, R.; Eichler, Robert; Dressler, R.; Piguet, D.; Vögele, Alexander; Schumann, D.

doi:10.1515/ract-2016-2575

Cited by 10 publications

(6 citation statements)

References 16 publications

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“…A silver tube, 2 cm length and 0.020 ± 0.003 mm thickness, was lining the inner surface at end of each column downstream from the gradient to catch 206 Po not retained in the column. The adsorption enthalpy of polonium on silver was determined as −216 kJ mol −1 and −230 kJ mol −1 in inert and reducing atmosphere, respectively, and as −234 kJ mol −1 in oxidizing conditions [10]. These values, if compared with the value of adsorption enthalpy reported in this work, indicate a stronger affinity of polonium for silver than for SS316L.…”

Section: Polonium Not Deposited On the Columnsupporting

confidence: 57%

“…[5,7,8], or to permanently absorb it from the gas plenum above the LBE using dedicated filter materials. For the latter purpose, the first two papers of this series studied the interaction of polonium with different noble metals as candidates for filtering materials [9,10].…”

Section: Introductionmentioning

confidence: 99%

“…The present investigation was carried out using the thermochromatography method (TC) [14,15]. A detailed description of the method used is given in the first papers of this series [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Adsorption of volatile polonium species on metals in various gas atmospheres: Part III – Adsorption of volatile polonium on stainless steel 316L

et al. 2017

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AbstractThis article summarizes the results obtained studying the interaction between polonium and stainless steel 316L in different atmospheres by the thermochromatography method. This issue is particularly important in terms of licensing of the MYRRHA prototype ADS reactor, where highly radiotoxic α-emitting polonium isotopes are produced in lead-bismuth eutectic used as both spallation target material and coolant, while stainless steel 316L is going to be the main structural material. The polonium adsorption enthalpy on stainless steel 316L in inert atmosphere was measured as −147±6 kJ mol−1. The findings obtained using reducing atmospheres show that the affinity of polonium for stainless steel 316L increases with the metallic character of the stainless steel surface. The presence of moisture in inert and reducing atmosphere does not significantly influence the polonium adsorption. Oxidizing atmospheres induce the formation of polonium dioxide which has a stronger interaction with the stainless steel 316L, with an adsorption enthalpy of −225±6 kJ mol−1. A prolonged exposure of the stainless steel to strong oxidants, such as pure oxygen, reduces the metallic character of the stainless steel surface and, consequently, its affinity to the polonium oxide. Furthermore, it was found that in all experiments at least 5 ppm of the total polonium present in the starting material were not retained on the stainless steel 316L surface at all.

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Section: Polonium Not Deposited On the Columnsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

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Adsorption of volatile polonium species on metals in various gas atmospheres: Part III – Adsorption of volatile polonium on stainless steel 316L

et al. 2017

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“…Based on the strong adsorption of iodine to the silver surface observed in hydrogen gas we may generally consider hydrogen as a cleaning agent, which when combined with heat results in the surface with the highest number of available metallic adsorption sites [25]. Generally, adsorption in hydrogen atmosphere in many cases is stronger than what is found between the same species and metallic surface in dry helium even if the surface has been pre-treated in hydrogen [26,27]. This is likely caused by diffusion of oxygen or similar impurities from the bulk to the surface of the material in the helium experiments, making the repopulation of minor impurities present on the surface very fast.…”

Section: Hydrogen Carrier Gasmentioning

confidence: 99%

Silver as a capturing material for iodine released from lead–bismuth eutectic in various conditions

Karlsson

Neuhausen

Eichler

et al. 2021

J Radioanal Nucl Chem

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The usage of silver as a filtering material for removal of iodine from the gas phase of a lead–bismuth eutectic based nuclear reactor was investigated in various atmospheres representing normal operation as well as accident conditions. Thermochromatography experiments were performed to quantify the retention experienced on a silver surface by iodine species evaporated from a lead–bismuth eutectic sample. Measured adsorption enthalpies ranged from −171 to − 208 kJ mol−1 with observed differences attributed to various surface effects rather than a change in iodine speciation. The postulated adsorption mechanism is chemisorption of iodine atoms on the silver surface. Metallic silver fulfills the desired criteria for a capturing material in water-free filtering systems to be used as an alternative to traditional alkaline scrubbers commonly used in LWR systems.

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“…These properties cannot be measured using traditional methods because of the low concentration of gaseous polonium molecules in experiments. We rely instead on thermochromatography experiments [27][28][29][30] which provide qualitative information on the nature of the gas species under various conditions, and on modeling. Two approaches towards modeling are adopted in parallel, viz.…”

Section: Polonium Chemistry In Lbementioning

confidence: 99%

The LBE Coolant Chemistry R&D Programme for the MYRRHA ADS: Chemistry and Control of Oxygen, Corrosion and Spallation Products

Aerts

Gladinez

Prieto

et al. 2020

Proceedings of the 14th International Workshop on Spallation Materials Technology

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Compatibility with structural materials and activation are major challenges of the use of heavy liquid metal (HLM) spallation targets and coolants such as lead-bismuth eutectic (LBE). Steel exposed to HLM is prone to corrosion which results in the release of steel elements in the HLM coolant. A commonly accepted strategy to reduce corrosion rates is to maintain a sufficiently elevated dissolved oxygen concentration in order to stabilize a protective oxide layer on the steel surface in contact with HLM. We present a brief overview of the oxygen sensing and control technology for LBE, developed in the frame of the MYRRHA accelerator driven system (ADS) demonstrate its performance on a large scale in the MEXICO chemistry loop (Mass Exchanger In Continuous Operation). MYRRHA stands for Multipurpose hYbrid Research Reactor for High-tech Applications accelerator driven system and is currently under development at the Belgian Nuclear Research Centre, and will operate between 200 °C and 400 °C with a target oxygen concentration level of 10-7 wt-%. Numerical simulations allowed mapping of the local oxygen concentration in MYRRHA, enabling identification of the regions in the core which could be prone to corrosion. On the other hand, oxygen concentrations must be sufficiently low to avoid formation of solid lead oxide (PbO) in the primary circuit. When designing a nuclear system such as an ADS, one must take into account accidents that may lead to increase of the oxygen concentration in the LBE and assess the probability for PbO formation and its consequences. In this context, we have studied the formation of lead oxide from oxygen-oversaturated LBE and determined the metastable limit for PbO nucleation. Corrosion products that are released in the LBE will interact with dissolved oxygen in LBE to form corrosion product oxides. These interactions influence the concentration of both dissolved oxygen and dissolved corrosion products. This in turn can cause changes in the corrosion process itself by altering the driving force for steel element dissolution or protective oxide layer decomposition. Experimental results will be presented which provide evidence for the precipitation and dissolution of oxides of iron impurities in LBE. Numerical simulations based on computational fluid dynamics (CFD) and chemical equilibrium complement experiments in understanding the interactions between coolant chemistry and reactor thermal-hydraulics. A similar approach was adopted for simulating the chemistry of spallation and other radioactive impurities in the primary LBE of MYRRHA. Simulations allow the prediction of released fraction, vapor composition and precipitation/dissolution phenomena in the LBE, as function of the oxygen concentration in the LBE and of the oxygen and humidity content of the cover gas in contact with the LBE. Simulations of the chemical behavior of several critical

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Adsorption of volatile polonium species on metals in various gas atmospheres: Part II – Adsorption of volatile polonium on platinum, silver and palladium

Cited by 10 publications

References 16 publications

Adsorption of volatile polonium species on metals in various gas atmospheres: Part III – Adsorption of volatile polonium on stainless steel 316L

Adsorption of volatile polonium species on metals in various gas atmospheres: Part III – Adsorption of volatile polonium on stainless steel 316L

Silver as a capturing material for iodine released from lead–bismuth eutectic in various conditions

The LBE Coolant Chemistry R&D Programme for the MYRRHA ADS: Chemistry and Control of Oxygen, Corrosion and Spallation Products

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