Gas Chromatographic and Gravimetric Studies of Uranium Oxidation Mechanism

Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour

“…The underlying corrosion mechanism of uranium in the presence of water vapour and/or oxygen, has been a longstanding topic of debate 1 2 3 4 5 6 7 8 . Although anionic diffusion is agreed upon, several reaction mechanisms have been proposed with different dominant diffusing species, either OH − 1 2 3 , O 2− 4 5 or a combination 6 .…”

“…Although anionic diffusion is agreed upon, several reaction mechanisms have been proposed with different dominant diffusing species, either OH − 1 2 3 , O 2− 4 5 or a combination 6 . In some cases it is suggested that uranium hydride is formed during the reaction 1 2 7 8 as part of several proposed mechanisms: (1) as a product of reaction between uranium metal and free hydrogen (a known gas phase by-product of the oxidation of uranium by water); (2) as a possible intermediate ( e.g. transition state) in the oxidation of uranium by hydroxyl species; or (3) that both hydride and oxide form as competing products of the hydroxyl oxidation mechanism.…”

A review of the corrosion and pyrophoricity behavior of uranium and plutonium

“…The addition of oxygen to the uranium-water vapor system considerably slows the rate of reaction (Kondo et al, 1964;Ritchie, 1981;Baker et al, 1966b;Colmenares et al, 1981;Colmenares, 1984), although these rates are still greater than those observed for the reaction with dry air. The effect of water vapor pressure (relative humidity) in the uranium-oxygen-water vapor system has been investigated by a number of researchers (Bennett et al, 1975;Ritchie et al, 1986;McGillivray et al, 1994).…”

“…However, less than the stoichiometric amount of hydrogen expected to be generated according to equation (6) has been observed, and several authors report the presence, detected by various means, of small amounts of uranium hydride UH3 (Kondo et al, 1964(Kondo et al, , 1974Baker et al, 1966a;Winer et al, 1987), uranium hydroxide U(OH)3 (Waber, 1958), or a hydrated uranium oxide U02+yy H2O (Waber, 1958;Wilkinson, 1962) to account for the deficient hydrogen. Of these compounds, uranium hydride is the most consistently and conclusively observed.…”

“…This is one possible explanation for the increased oxidation rates observed for water vapor compared to dry air oxidation. Another possibility is the loss of coherence (perhaps due to the incorporation of hydrogen containing compounds), and hence protective nature, for oxides formed by reaction with water (Kondo et al, 1964(Kondo et al, ,1974.…”