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Li, J., Liu, X. & Jonsson, M. (2024). UO2 dissolution in aqueous halide solutions exposed to ionizing radiation. Applied Surface Science, 646, Article ID 158955.
Open this publication in new window or tab >>UO2 dissolution in aqueous halide solutions exposed to ionizing radiation
2024 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 646, article id 158955Article in journal (Refereed) Published
Abstract [en]

In this work, we have experimentally studied UO2 dissolution in pure water and in 1 M aqueous solutions of either Cl- or Br- exposed to γ-radiation. It has previously been found that high ionic strength can facilitate adsorption of dissolved UO22+ on UO2 surfaces. The adsorption is also affected by the solution pH relative to the point of zero charge of UO2. In our experiments, Br3- was observed in 1 M Br- solution exposed to γ-radiation. Experiments confirmed that Br3- can quantitively oxidize UO2. XPS and UPS were used to characterize potential surface modifications after exposure. The XPS results show that the UO2 surfaces after exposure to γ-radiation in pure water and in 1 M aqueous solutions of either Cl- or Br- were significantly oxidized with U(V) as the dominating state. U 4f7/2 and O 1 s spectra of the UO2 surface after exposure to γ-radiation in pure water demonstrates the formation of uranyl peroxide secondary phases. UPS results indicate that there is a large percentage of U(VI) on the ultra-thin outer layer of UO2 after exposure to γ-radiation in 1 M aqueous solutions of Br- and Cl-, and 100 % of U(VI) in the pure water case.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Radiolysis, Studtite, Tribromide ion, UO 2, XPS
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-340964 (URN)10.1016/j.apsusc.2023.158955 (DOI)001125775700001 ()2-s2.0-85178239016 (Scopus ID)
Note

QC 20231218

Available from: 2023-12-18 Created: 2023-12-18 Last updated: 2024-01-10Bibliographically approved
Bulone, D., Dispenza, C., Ditta, L. A., Giacomazza, D., Jonsson, M., Antonietta Sabatino, M., . . . Biagio, P. L. a. (2023). Effect of gamma irradiation on HPC phase separation. Biophysical Journal, 122(3S1)
Open this publication in new window or tab >>Effect of gamma irradiation on HPC phase separation
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2023 (English)In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 122, no 3S1Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier BV, 2023
National Category
Biophysics
Identifiers
urn:nbn:se:kth:diva-330010 (URN)10.1016/j.bpj.2022.11.1659 (DOI)000989629701547 ()36783460 (PubMedID)2-s2.0-85148108363 (Scopus ID)
Note

QC 20230629

Available from: 2023-06-29 Created: 2023-06-29 Last updated: 2023-08-14Bibliographically approved
Hansson, N. L. & Jonsson, M. (2023). Exploring H2-effects on radiation-induced oxidative dissolution of UO2-based spent nuclear fuel using numerical simulations. Radiation Physics and Chemistry, 210, 111055, Article ID 111055.
Open this publication in new window or tab >>Exploring H2-effects on radiation-induced oxidative dissolution of UO2-based spent nuclear fuel using numerical simulations
2023 (English)In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 210, p. 111055-, article id 111055Article in journal (Refereed) Published
Abstract [en]

Using a recently developed approach for numerical simulation of radiation-induced oxidative dissolution of spent nuclear fuel, we have explored the impact of three possible contributions to the inhibiting effect of molecular hydrogen. The three contributions are (1) effect on oxidant production in irradiated water, (2) reduction of oxidized uranium catalyzed by noble metal inclusions (fission products) and (3) reaction with surface-bound hydroxyl radicals preventing the oxidation of uranium. The simulations show that the first contribution is of fairly small importance while the second contribution can result in complete inhibition of the oxidative dissolution. This is well in line with previous work. Interestingly, the simulations imply that the third contribution, the reaction between H2 and the surface-bound hydroxyl radical formed upon reaction between the radiolysis product H2O2 and UO2, can account for the inhibition observed in systems where noble metal inclusions are not present. This is discussed in view of previously published experimental data.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Oxidative dissolution, UO2, Hydrogen effect, Surface bound hydroxyl radical
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-330529 (URN)10.1016/j.radphyschem.2023.111055 (DOI)001007255600001 ()2-s2.0-85160330020 (Scopus ID)
Note

QC 20230630

Available from: 2023-06-30 Created: 2023-06-30 Last updated: 2023-06-30Bibliographically approved
Li, J., Liu, X. & Jonsson, M. (2023). Exploring the Change in Redox Reactivity of UO2 Induced by Exposure to Oxidants in HCO3– Solution. Inorganic Chemistry, 62(19), 7413-7423
Open this publication in new window or tab >>Exploring the Change in Redox Reactivity of UO2 Induced by Exposure to Oxidants in HCO3 Solution
2023 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 62, no 19, p. 7413-7423Article in journal (Refereed) Published
Abstract [en]

Understanding the possible change in UO2 surface reactivity after exposure to oxidants is of key importance when assessing the impact of spent nuclear fuel dissolution on the safety of a repository for spent nuclear fuel. In this work, we have experimentally studied the change in UO2 reactivity after consecutive exposures to O2 or γ-radiation in aqueous solutions containing 10 mM HCO3-. The experiments show that the reactivity of UO2 toward O2 decreases significantly with time in a single exposure. In consecutive exposures, the reactivity also decreases from exposure to exposure. In γ-radiation exposures, the system reaches a steady state and the rate of uranium dissolution becomes governed by the radiolytic production of oxidants. Changes in surface reactivity can therefore not be observed in the irradiated system. The potential surface modification responsible for the change in UO2 reactivity was studied by XPS and UPS after consecutive exposures to either O2, H2O2, or γ-radiation in 10 mM HCO3- solution. The results show that the surfaces were significantly oxidized to a stoichiometric ratio of O/U of UO2.3 under all the three exposure conditions. XPS results also show that the surfaces were dominated by U(V) with no observed U(VI). The experiments also show that U(V) is slowly removed from the surface when exposed to anoxic aqueous solutions containing 10 mM HCO3-. The UPS results show that the outer ultrathin layer of the surfaces most probably contains a significant amount of U(VI). U(VI) may form upon exposure to air during the rinsing process with water prior to XPS and UPS measurements.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
National Category
Inorganic Chemistry Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-331565 (URN)10.1021/acs.inorgchem.3c00682 (DOI)000984325300001 ()37128775 (PubMedID)2-s2.0-85159619188 (Scopus ID)
Note

QC 20230711

Available from: 2023-07-11 Created: 2023-07-11 Last updated: 2023-09-04Bibliographically approved
Jonsson, M. (2023). Exploring the impact of groundwater constituents and irradiation conditions on radiation-induced corrosion of copper. Radiation Physics and Chemistry, 211, Article ID 111048.
Open this publication in new window or tab >>Exploring the impact of groundwater constituents and irradiation conditions on radiation-induced corrosion of copper
2023 (English)In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 211, article id 111048Article in journal (Refereed) Published
Abstract [en]

In this work, the impact of groundwater constituents and irradiation conditions on radiation induced corrosion of copper have been studied using numerical simulations based on the recently published mechanism. The simulations show that the amount of corrosion at a given total absorbed radiation dose will increase with decreasing dose rate. Furthermore, hydroxyl radical scavengers in general have a very marginal effect on the rate of corrosion while scavengers of the hydrated electron almost double the rate of corrosion. Sulfide present under relevant conditions has a significant effect on the corrosion rate and reduces the rate by 80% already at the lowest expected concentration and flux. Fe2+ present under relevant conditions does not influence the rate of corrosion significantly. Also initially dissolved oxygen has a very marginal effect on the process. Dissolved organic material scavenge hydroxyl radicals upon formation of C-centered radicals which in turn react with molecular oxygen. In systems where peroxyl radical recombination is not dominating, i.e., where there are solutes reactive towards peroxyl radicals, the presence of dissolved organic material can reduce the rate of corrosion by almost 99%. The pH and the presence of Cl-, HCO3- and SO42-have relatively small effects. In general, radiation induced corrosion is 20-40% slower at pH = 9 as compared to pH = 7.4 and the presence of HCO3- increases the rate of corrosion somewhat at pH = 9 as compared to pure water at the same pH.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Radiolysis, Copper, Corrosion, Spent nuclear fuel, Groundwater
National Category
Oceanography, Hydrology and Water Resources Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-331200 (URN)10.1016/j.radphyschem.2023.111048 (DOI)001010498500001 ()2-s2.0-85162833030 (Scopus ID)
Note

QC 20230706

Available from: 2023-07-06 Created: 2023-07-06 Last updated: 2023-07-06Bibliographically approved
Li, J., Li, L. & Jonsson, M. (2023). Formation and stability of studtite in bicarbonate-containing waters. Ecotoxicology and Environmental Safety, 263, Article ID 115297.
Open this publication in new window or tab >>Formation and stability of studtite in bicarbonate-containing waters
2023 (English)In: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 263, article id 115297Article in journal (Refereed) Published
Abstract [en]

Studtite and meta-studtite are the only two uranyl peroxides found in nature. Sparsely soluble studtite has been found in natural uranium deposits, on the surface of spent nuclear fuel in contact with water and on core material from major nuclear accidents such as Chernobyl. The formation of studtite on the surface of nuclear fuel can have an impact on the release of radionuclides to the biosphere. In this work, we have experimentally studied the formation of studtite as function of HCO3- concentration and pH. The results show that studtite can form at pH = 10 in solutions without added HCO3-. At pH <= 7, the precipitate was found to be mainly studtite, while at 8 = pH = 9.8, a mixture of studtite and meta-schoepite was found. Studtite formation from UO22+ and H2O2 was observed at [HCO3-] <= 2 mM and studtite was only found to dissolve at [HCO3-] > 2 mM.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Studtite, XRD, PH, gamma-radiation, Geological repository
National Category
Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-335138 (URN)10.1016/j.ecoenv.2023.115297 (DOI)001049649300001 ()37494736 (PubMedID)2-s2.0-85166629672 (Scopus ID)
Note

QC 20230901

Available from: 2023-09-01 Created: 2023-09-01 Last updated: 2023-09-04Bibliographically approved
Hansson, N. L., Jonsson, M., Ekberg, C. & Spahiu, K. (2023). Modelling radiation-induced oxidative dissolution of UO2-based spent nuclear fuel on the basis of the hydroxyl radical me diate d surface mechanism Exploring the impact of surface reaction mechanism and spatial and temporal resolution. Journal of Nuclear Materials, 578, 154369, Article ID 154369.
Open this publication in new window or tab >>Modelling radiation-induced oxidative dissolution of UO2-based spent nuclear fuel on the basis of the hydroxyl radical me diate d surface mechanism Exploring the impact of surface reaction mechanism and spatial and temporal resolution
2023 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 578, p. 154369-, article id 154369Article in journal (Refereed) Published
Abstract [en]

A combined kinetic and diffusion model with an accurate alpha-dose rate profile was used to model radiation induced dissolution of UO 2 . Previous experimental data were used to fit the surface site reaction system involving the surface bound hydroxyl radical as an intermediate species for both UO 2 oxidation and surface catalysed decomposition of H 2 O 2 . The performance of the model was explored in terms of sensitivity to spatial and temporal resolution as well as simplifications in the models describing the surface reactions and the reactions in solution. As a result, optimal conditions for running the numerical simulations were identified.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Oxidative dissolution, UO 2, H 2 O 2, Kinetic modelling, Surface bound, hydroxyl radical
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-325751 (URN)10.1016/j.jnucmat.2023.154369 (DOI)000955847500001 ()2-s2.0-85149733643 (Scopus ID)
Note

QC 20230414

Available from: 2023-04-14 Created: 2023-04-14 Last updated: 2023-04-14Bibliographically approved
Zschiesche, H., Soroka, I., Jonsson, M. & Tarakina, N. V. (2023). Non-classical crystallization of CeO2 by means of in situ electron microscopy. Nanoscale, Article ID d3nr02400.
Open this publication in new window or tab >>Non-classical crystallization of CeO2 by means of in situ electron microscopy
2023 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, article id d3nr02400Article in journal (Refereed) Published
Abstract [en]

During in situ liquid-phase electron microscopy (LP-EM) observations, the application of different irradiation dose rates may considerably alter the chemistry of the studied solution and influence pro-cesses, in particular growth pathways. While many processes have been studied using LP-EM in the last decade, the extent of the influence of the electron beam is not always understood and comparisons with corresponding bulk experiments are lacking. Here, we employ the radiolytic oxidation of Ce3+ in aqueous solution as a model reaction for the in situ LP-EM study of the formation of CeO2 particles. We compare our findings to the results from our previous study where a larger volume of Ce3+ precursor solution was subjected to ?-irradiation. We systematically analyze the effects of the applied irradiation dose rates and the induced diffusion of Ce ions on the growth mechanisms and the morphology of ceria particles. Our results show that an eight orders of magnitude higher dose rate applied during homogeneous electron-radiation in LP-EM compared to the dose rate using gamma-radiation does not affect the CeO2 particle growth pathway despite the significant higher Ce3+ to Ce4+ oxidation rate. Moreover, in both cases highly ordered structures (mesocrystals) are formed. This finding is explained by the stepwise formation of ceria particles via an intermediate phase, a signature of non-classical crystallization. Furthermore, when irradiation is applied locally using LP scanning transmission electron microscopy (LP-STEM), the higher conversion rate induces Ce-ion concentration gradients affecting the CeO2 growth. The appearance of branched morphologies is associated with the change to diffusion limited growth.

Place, publisher, year, edition, pages
Royal Society of Chemistry (RSC), 2023
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-336020 (URN)10.1039/d3nr02400h (DOI)001053920000001 ()37610726 (PubMedID)
Note

QC 20230911

Available from: 2023-09-11 Created: 2023-09-11 Last updated: 2023-09-11Bibliographically approved
El Jamal, G., Gouder, T., Eloirdi, R., Idriss, H. & Jonsson, M. (2023). Study of Water Interaction with UO2, U2O5, and UO3: Tracking the Unexpected Reduction of Uranium Cations and Characterization of Surface-Bound Hydroxyls. The Journal of Physical Chemistry C, 127(29), 14222-14231
Open this publication in new window or tab >>Study of Water Interaction with UO2, U2O5, and UO3: Tracking the Unexpected Reduction of Uranium Cations and Characterization of Surface-Bound Hydroxyls
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2023 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 127, no 29, p. 14222-14231Article in journal (Refereed) Published
Abstract [en]

The interaction of water with the surfaces of metal oxides is important to many fields of research, extending from nuclear science to catalysis to energy and biomedical materials. One intriguing phenomenon is the observation that, for a few oxides, water seems to reduce (not oxidize) the oxide substrate. In this work, ultraviolet photoelectron spectroscopy (UPS) has been used to study the reactions of H2O with prototype oxide nuclear fuels: UO2, U2O5, and UO3. On UO2, water adsorbs largely in a molecular state. On U2O5, water partially dissociates at −60 °C, thus forming surface −OH groups, and a fraction of the uranium cations are reduced from U5+ to U4+. On UO3, a similar reduction process is seen (reduction of a fraction of uranium cations from U6+ to U5+), albeit less pronounced. The chemisorbed H2O and −OH states via their molecular orbitals (MOs), 1b2, 3a1, and 1b1 for H2O and 1σ and 1π for −OH, were further analyzed. The 3a1-1b1 binding energy difference (ΔE) was taken as a measure of the bond strength. It was found to be larger on UO2 and U2O5 (2.9-3.0 eV) than on UO3 (2.2 eV). The charge state of the surface hydroxyl was found to be related to the 1π /1σ intensity ratio, from which, and in conjunction with the created U 5f states, electron transfer to the conduction band under UPS collection was facilitated by the hole trapping capacity of surface −OH groups, at least in the case of UO3. An energy band diagram is constructed that may explain the redox process observed on UO3 under UV photon excitation.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2023
Keywords
Band diagram, Binding energy Electrochemical impedance spectroscopy, Molecular orbitals, Nuclear fuels, Photoelectrons, Photons, Positive ions, Uranium
National Category
Condensed Matter Physics Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-335365 (URN)10.1021/acs.jpcc.3c02795 (DOI)001024816500001 ()2-s2.0-85165917100 (Scopus ID)
Note

QC 20230907

Available from: 2023-09-07 Created: 2023-09-07 Last updated: 2023-09-07Bibliographically approved
El Jamal, S., Mishchenko, Y. & Jonsson, M. (2023). Uranium nitride stability in aqueous solutions under anoxic and oxidizing conditions – Expected behaviour under repository conditions in comparison to alternative nuclear fuel materials. Journal of Nuclear Materials, 578, Article ID 154334.
Open this publication in new window or tab >>Uranium nitride stability in aqueous solutions under anoxic and oxidizing conditions – Expected behaviour under repository conditions in comparison to alternative nuclear fuel materials
2023 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 578, article id 154334Article in journal (Refereed) Published
Abstract [en]

Uranium nitride (UN) has good thermo-physical properties which makes it a promising fuel candidate for generation IV nuclear reactors. In addition to its performance as a nuclear fuel, it is important to elucidate every novel fuel material in terms of its stability in aqueous environments. This can be highly relevant under certain accident scenarios and also for the safety assessment of geological repositories for used nuclear fuel. The fuel matrix contains the fission products and heavier actinides formed under normal reactor operation. Upon dissolution of the fuel matrix, these highly radiotoxic constitiuents can be released. In this work UN has been studied under aqueous conditions similar to a geological repository for spent nuclear fuel. For UN, direct hydrolysis as well as oxidative dissolution induced by water radiolysis can lead to degradation of the fuel matrix. The latter process leads to formation of oxidative radiolysis products of which H2O2 has been shown to be the most important oxidant for other fuel materials. The experiments show that hydrolysis of UN in aqueous solutions and exposure to solutions containing H2O2 resulted in matrix dissolution. However, this oxidative dissolution induced by H2O2 is more prominent than hydrolysis in water with or without added HCO3−. The dissolution of UN was compared with other nuclear fuel materials (UC, UO2 and U3Si2) under the same conditions. The results show that UN is the second most reactive fuel material towards H2O2. However, the so-called dissolution yield is the lowest for UN. The rationale for the observed differences in reactivity are discussed.

Place, publisher, year, edition, pages
Elsevier B.V., 2023
Keywords
Different uranium based materials, H O 2 2, Oxidative dissolution, Stability
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-330961 (URN)10.1016/j.jnucmat.2023.154334 (DOI)000949014600001 ()2-s2.0-85148685265 (Scopus ID)
Note

QC 20230704

Available from: 2023-07-04 Created: 2023-07-04 Last updated: 2023-07-04Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0663-0751

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