On the catalytic effects of UO2(s) and Pd(s) on the reaction between H2O2 and H2 in aqueous solution

Nilsson, Sara; Jönsson, Mats

doi:10.1016/j.jnucmat.2007.03.040

Cited by 43 publications

(57 citation statements)

References 14 publications

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“…On the basis of this observation, one can expect that H 2 will inhibit oxidation of the spent nuclear fuel matrix. In order to elucidate this effect, further experiments using UO 2 pellets containing Pd particles have been performed [75]. When exposing these pellets to H 2 O 2 solutions in the presence of H 2 , the oxidative dissolution of UO 2 was effectively inhibited.…”

Section: (17)mentioning

confidence: 99%

Oxidation of UO2(s) in aqueous solution

Roth

Jönsson

2008

Open Chemistry

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Abstract:In this review the kinetics and mechanism of oxidative dissolution of UO 2 (s), mainly under conditions of relevance for the safety assessment of a deep geological repository for spent nuclear fuel, are discussed. Rate constants for the elementary processes involved (oxidation of UO 2 and dissolution of oxidized UO 2 ) are used to calculate the rates of oxidative UO 2 (s) dissolution under various conditions (type of oxidant, oxidant concentration and HCO 3 -/CO 3 2-concentration) for which experimental data are also available. The calculated rates are compared to the corresponding experimental values under the assumption that the experimental numbers reflect the steady-state conditions of the system. The agreement between the calculated rates and the corresponding experimental ones is very good, in particular for the higher rates. In general, the calculated rates are somewhat higher than the experimental numbers. This can be due partly to the use of initial concentrations rather than steady-state concentrations in the calculations. The kinetic data are also used to quantitatively discuss the dynamics of spent nuclear fuel dissolution under deep geological repository conditions. © Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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Section: (17)mentioning

confidence: 99%

Oxidation of UO2(s) in aqueous solution

Roth

Jönsson

2008

Open Chemistry

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“…In addition to radionuclides in the SNF itself, activation products are present in the cladding. The very intense radiation field of fresh SNF is dominated by short-lived β-and γ -emitters, such as 85 Kr, 89 Sr, 90 Sr/ 90 Y, 91 Y, 95 Zr/ 95 Nb, 106 Ru/ 106 Rh, 125 Sb, 134 Cs, 137 Cs/ 137m Ba, 144 Ce/ 144 Pr, 147 Pm, and 154,155 Eu. After few hundreds of years most of the β-and γ -emitters will have decayed, and α-emitters ( 238,239,240 Pu, 241,243 Am, 242,244 Cm) will dominate the radiation field.…”

Section: Alteration Of Spent Nuclear Fuel and Radionuclide Release Unmentioning

confidence: 99%

“…Depending on these SNF properties, the IRF comprises few percent of the inventories of fission gases (Kr and Xe), other volatiles fission products ( 129 I, 137 Cs, 135 Cs, 79 Se) and segregated metals ( 99 Tc, 107 Pd, 126 Sn) [102]. Additionally, some of the activation products from the cladding and fuel assembly structural materials notably 14 C and 36 Cl, are considered to be subject to a fast release upon contact with aqueous solution.…”

Section: Fast/instant Release Of Radionuclides From Spent Nuclear Fuelmentioning

confidence: 99%

“…Leaching experiments with SNF and UO 2 (s) samples as well as electrochemical studies in diluted Na + -Cl − -HCO 3 − / CO 3 2− solutions demonstrate clearly a hydrogen inhibition effect mediated by Ru-Pd-Rh-doping and ε-particles [133][134][135][136][137][138][139]]. An ε-particle surface mediated hydrogen effect depends on the availability of these particles and might be affected by "poisoning" of these noble metal alloys with dissolved sulfides present in the near-field, whereas a radiolytic driven hydrogen effect will be weakened by counteracting groundwater constituents, such as bromide.…”

Section: Radionuclide Release Due To Corrosion Of the Uo 2 Matrixmentioning

confidence: 99%

“…Potential radionuclide retention by coprecipitation with and sorption to solids being present in the near-field of a repository for spent fuel as primary and secondary phases (references are exemplary). 90 Sr, 137 Cs, and 99 Tc in significantly enriched amounts and thus can also be considered to contribute to fission product retention [152].…”

Section: Radionuclide Retention By Coprecipitation and Sorptionmentioning

confidence: 99%

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Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

et al. 2012

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UO 2 fuel corrosion / Radionuclide release / Instant release fraction / Hydrogen effect / Coprecipitation / SorptionSummary. Even though chemical processes related to the corrosion of spent nuclear fuel in a deep geological repository are of complex nature, knowledge on underlying mechanisms has very much improved over the last years. As a major result of numerous studies it turns out that alteration of irradiated fuel is significantly inhibited under the strongly reducing conditions induced by container corrosion and consecutive H 2 production. In contrast to earlier results, radiolysis driven fuel corrosion and oxidative dissolution appears to be less relevant for most repository concepts. The protective hydrogen effect on corrosion of irradiated fuel has been evidenced in many experiments. Still, open questions remain related to the exact mechanism and the impact of potentially interfering naturally occurring groundwater trace components. Container corrosion products are known to offer considerable reactive surface area in addition to engineered buffer and backfill material. In combination, waste form, container corrosion products and backfill material represent strong barriers for radionuclide retention and retardation and thus attenuate radionuclide release from the repository near-field.

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Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H₂

Maier

Jönsson

2019

ChemCatChem

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To assess the influence of metallic inclusions (ϵ‐particles) on the dissolution of spent nuclear fuel under deep repository conditions, Pd‐catalyzed reactions of H2O2, O2 and UO22+ with H2 were studied using Pd‐powder suspensions. U(VI) can efficiently be reduced to less soluble U(IV) on Pd‐particles in the presence of H2. The kinetics of the reaction was found to depend on the H2 partial pressure at pH2≤5.1×10−2 bar. In comparison, the H2 pressure dependence for the reduction of H2O2 on Pd also becomes evident below 5.1×10−2 bar. Surface bound hydroxyl radicals are formed as intermediate species produced during the catalytic decomposition of H2O2 on oxide surfaces. While a significant amount of surface bound hydroxyl radicals were scavenged during the catalytic decomposition of H2O2 on ZrO2, no scavenging was observed in the same reaction on Pd. This indicates a different reaction mechanism for H2O2 decomposition on Pd compared to metal oxides and is in contrast to current literature. While Pd is an excellent catalyst for the synthesis of H2O2 from H2 and O2, a similar catalytic activity that was previously proposed for ZrO2 could not be confirmed.

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On the catalytic effects of UO2(s) and Pd(s) on the reaction between H2O2 and H2 in aqueous solution

Cited by 43 publications

References 14 publications

Oxidation of UO2(s) in aqueous solution

Oxidation of UO2(s) in aqueous solution

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H₂

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On the catalytic effects of UO2(s) and Pd(s) on the reaction between H2O2 and H2 in aqueous solution

Cited by 43 publications

References 14 publications

Oxidation of UO2(s) in aqueous solution

Oxidation of UO2(s) in aqueous solution

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H2

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Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H₂