| 1. |
- Börjesson Sandén, Fredrik, 1995, et al.
(author)
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Effects of boric acid on volatile tellurium in severe accident conditions
- 2024
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In: Annals of Nuclear Energy. - 0306-4549 .- 1873-2100. ; 200
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Journal article (peer-reviewed)abstract
- Boric acid is used in light-water nuclear reactors to control the reactor and is expected to be present as part of the chemistry of a severe accident. Therefore, its influence on other prominent species expected in an accident must be investigated. One such species is tellurium. In the present study, tellurium is volatized, and boric acid is dissolved and injected into the system as a means of studying the interaction between it and tellurium. The experiments were evaluated with ICP-MS and XPS. Results suggest that while there is no direct interaction, boric acid still affects the tendency for tellurium to oxidize. In general, less oxidation was detected in the presence of boric acid than in its absence, especially at high temperatures. The species formed upon oxidation was determined to be TeO2. Since tellurium metal is more volatile than TeO2, this may have implication in a wider severe accident context.
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| 2. |
- Börjesson Sandén, Fredrik, 1995
(author)
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Volatized Tellurium Interactions with Organics and with Boric Acid
- 2024
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Licentiate thesis (other academic/artistic)abstract
- Tellurium is a volatile fission product with a complex chemistry that must be accounted for in case of a nuclear accident. Specifically, its interactions with organic species and with boric acid, both which are expected in the accident chemistry, are largely unknown. This study aims to explore the interactions between tellurium aerosols and three organic species (acetone, propanol, and methane), and with boric acid at temperatures representing the primary circuit of a pressurized water reactor. Oxidizing (Air), inert (N2) and reducing (Ar/H2) atmospheres are all investigated. Analysis involves ICP-MS of liquid samples, XPS of solid filter samples, as well as online measurements, mainly to categorize the aerosols produced during the experiments, as well as FTIR. Furthermore, neutron activation and gamma spectroscopy are used. The results indicate that tellurium may form small amounts of organic tellurides in these conditions, specifically under inert and reducing conditions. These results are not conclusive, as no analysis detected these species. However, data from both XPS and ICP-MS may imply their formation. In general though, the ICP-MS data imply low volatility of tellurium in these conditions, as the concentration in the liquid trap remains in the μM to nM range. As for boric acid, no indication was found of direct interaction between boric acid and tellurium. However, XPS analysis does imply that the oxidation of the tellurium is reduced by the presence of boric acid. This was inferred mainly from XPS analysis and may potentially be an important consideration for future studies of tellurium in the context of severe nuclear accidents. Volatility remains at the low μM level, though formation of H2Te does serve to increase it. This only occurs at high temperature in reducing atmosphere, however.
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| 3. |
- Pasi, Anna-Elina, 1993, et al.
(author)
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Gas phase interactions between tellurium and organic material in severe nuclear accident scenarios
- 2024
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In: Annals of Nuclear Energy. - 0306-4549 .- 1873-2100. ; 197
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Journal article (peer-reviewed)abstract
- One of the volatile fission products potentially released during a severe nuclear accident is tellurium. Recently, tellurium has been shown to form volatile organic tellurides from paint solvents in aqueous solutions which could further increase the release. However, not much is known about the possible interactions between tellurium and organic material in gas phase. In this study, tellurium was exposed to conditions simulating the containment atmosphere during an accident. Moreover, volatile organic compounds were introduced to the gas phase representing the presence of organic material in the containment during the accident. The results suggest that tellurium aerosols and organic material interact in the gas phase which was observed as an increase in the gaseous fraction and a change in the XPS spectra. Although no exact species were identified, the results raise questions about the behavior of tellurium in severe accident conditions, especially, regarding the reactions involving organic material.
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