Gel structure of the corrosion layer on cladding pipes of nuclear fuel

Medek, J.; Weishauptová, Zuzana

doi:10.1016/j.jnucmat.2009.06.019

Cited by 4 publications

(2 citation statements)

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“…The surfaces in contact with water are usually oxides or metals covered with an oxide layer. Hence, radiation-induced processes at the interface between water and a solid oxide would appear to be crucial. − Nevertheless, very little is known about these processes.…”

Section: Introductionmentioning

confidence: 99%

Surface Reactions of H₂O₂, H₂, and O₂ in Aqueous Systems Containing ZrO₂

2016

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In radiolysis of water, three molecular products are formed (H2O2, O2, and H2). It has previously been shown that aqueous hydrogen peroxide is catalytically decomposed on many oxide surfaces and that the decomposition proceeds via the formation of surface-bound hydroxyl radicals. In this work, we have investigated the behavior of aqueous H2 and O2 in contact with ZrO2. Experiments were carried out in an autoclave with high H2 pressure and low O2 pressure (40 and 0.2 bar, respectively). In the experiments the concentration of H-abstracting radicals was monitored as a function of time using tris(hydroxymethyl)aminomethane (Tris) as scavenger and the subsequent formation of formaldehyde to probe radical formation. The plausible formation of H2O2 was also monitored in the experiments. In addition, density functional theory (employing the hybrid PBE0 functional) was used to search for reaction pathways. The results from the experiments show that hydrogen-abstracting radicals are formed in the aqueous H2-/O2-system in contact with solid ZrO2. Formation of H2O2 is also detected, and the time-dependent production of hydrogen-abstracting radicals follows the time-dependent H2O2 concentration, strongly indicating that the radicals are produced upon catalytic decomposition of H2O2. The DFT study implies that H2O2 formation proceeds via a pathway where HO2 • is a key intermediate. It is interesting to note that all the stable molecular products from aqueous radiolysis are precursors of quite intriguing radical reactions at water/oxide interfaces.

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Section: Introductionmentioning

confidence: 99%

Surface Reactions of H₂O₂, H₂, and O₂ in Aqueous Systems Containing ZrO₂

2016

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“…The fuel material in a nuclear reactor is protected by cladding pipes made of alloyed zirconium. In contact with water near and above its critical temperature, a corrosion layer of hydrated zirconium dioxide ZrO 2 · n H 2 O is formed and has implications on the chemistry of the reactor. − One of the most important water radiolysis products to concern about in reactor chemistry is hydrogen peroxide . Hydrogen peroxide is an important compound that has found innumerous uses such as a bleaching agent, disinfectant, oxidizer, or as a nontoxic monopropellant in rocket fuel .…”

Section: Introductionmentioning

confidence: 99%

Kinetics, Mechanism, and Activation Energy of H₂O₂ Decomposition on the Surface of ZrO₂

2010

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The kinetics, mechanism, and activation energy of H2O2 decomposition in ZrO2 particle suspensions were studied. The obtained first-order and second-order rate constants for the decomposition of H2O2 in the presence of ZrO2 at T = 298.15 K produced the values k 1 = (6.15 ± 0.04) × 10−5 s−1 and k 2 = (2.39 ± 0.09) × 10−10 m·s−1, respectively. The dependency of the reaction first-order rate constant with temperature was studied; consequently, the activation energy for the reaction was obtained in the temperature interval 294.15−353.15 K having yielded the value E a = 33 ± 1.0 kJ·mol−1. The dependency of the zeroth-order reaction rate constant with pH was investigated and discussed. A mechanistic study encompassing the investigation of the dynamics of formation of hydroxyl radicals during the course of the reaction was performed. A version of the modified Hantzsch method was applied for this purpose, and it was verified that the dynamics of formation of hydroxyl radicals during the reaction are in good agreement with the proposed reaction mechanism.

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