Kinetics of hydrogen reduction of uranium trioxide
The reaction between uranium trioxide (UO3) and pure hydrogen was investigated in the temperature range 575 to 750°. It was determined that, after an induction period in which the reduction rate reached its maximum value, the reaction proceeded at a constant rate which was independent of the thickness of the reduced uranium dioxide (UO2) layer. The rate-limiting step in the reduction was the reaction at the UO3-UO2 interface. Microscopic examination and X-ray powder patterns of samples partly reduced below 750° failed to reveal the presence of oxides intermediate between UO3 and UO2 at this interface. The activation energy for the reduction was determined experimentally to be 33.3 ± 0.3 kcal./mole. Absolute reaction rate theory was used to develop an analytical expression for the rate of reduction assuming an immobile adsorbed H2O layer as part of a (H2O-UO2) complex. The rate constants calculated with this model agreed favorably with experimental values when compared on an equivalent basis.
Journal of Physical Chemistry
Kinetics of hydrogen reduction of uranium trioxide.
Journal of Physical Chemistry,
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