Kinetics of the Oxidation of UO$sub 2$ in Air. Report No. 74; CINETICA DE OXIDACION DE UO$sub 2$ EN AIRE. Informe No. 74

Technical Report · Mon Jan 01 04:00:00 EST 1962

OSTI ID:4716460

Araoz, C

Thermal differential analyses were made of the oxidation in air of uranium dioxide powder between 25 and 600 un. Concent 85% C. The two characteristic exothermal peaks were obtained. The flrst corresponds to the diffusion-controlled reaction UO/sub 2/ and up to st r UO/sub 2.3/ at 210 un. Concent 85% C. The second corresponds to UO/sub 2.3/ and up to st rUU/sub 3/O/ sub 8/, a nucleation and rupture process of the powder grains. There is a small intermediate peak that is attributed to thermal inhomogeneities of the system. Contrary to reports cited in the literature, nonstoichiometric oxides are not shown by this method although they are more susceptible to oxidation than the stoichiometric oxides. A marked effect on the oxidation-reduction cycle is, however, noticed. Powders with different initial oxygen concentrations, O/U ratio from 2.02 to 2.37, show a variation of the height of the first peak with the oxygen concentration. The second peak remains constant. The O/U vs. height graph of the first peak indicates a shift toward compositions of the order of 2.25, which is interpreted as the appearance of the orthohombic phase. A new method for the calibration of the curves in calories is tested and heat quantities agreeing with those given in the literature for the reaction are obtained. (tr-auth)

• Research Organization: Argentina. Comision Nacional de Energia Atomica, Buenos Aires
• NSA Number: NSA-17-023303
• OSTI ID: 4716460
• Report Number(s): NP-12672
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AIR
CHEMISTRY
OXIDATION
OXYGEN
POWDERS
QUANTITY RATIO
REACTION KINETICS
SPECTRAL SHIFT
STANDARDS
TEMPERATURE
U3O8
URANIUM DIOXIDE