Oxidation of uranium dioxide in air at 350–1000° C

Peakall, K.A.; Antill, J.E.

doi:10.1016/0022-3115(60)90051-9

Cited by 31 publications

(7 citation statements)

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“…In comparing gravimetric analysis with alpha assay and destructive coulometric analysis, White (1965) found that an accuracy of 30/~g could be achieved with fission foils very similar to those used in the present experiment. Several studies of UO2-U30 s stoichiometry indicate that no discrepancies in the UaOs mass of more than 0.1 ~o should be expected in the present case due to incomplete conversion of the oxide to the UsO s form (Rodriguez de Sastre et aL, 1967;Scott and Harrison, 1963;Peakall and Antill, 1960). Finally, an allowance of 0.1 ~ uncertainty is made for chemical impurities in the material supplied for these deposits.…”

Section: The Number Of Target Nucleimentioning

confidence: 68%

An absolute determination of the 235U fission cross section at 964 keV

Gilliam

Knoll

1975

Annals of Nuclear Energy

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An absolute measurement of the 235U fission cross section has been carried out using a S4Na-Be photoneutron source with median neutron energy of 964 keV. A symmetric two-foil experiment was set up to measure the fission rate in a low-albedo laboratory, and variations in the sourceto-foil spacing used to determine the room background. Fission fragments passing through a limited solid angle aperture were recorded from each foil by solid state tracketch techniques. The photoneutron source was calibrated after each run using the manganese bath method and the secondary national standard source NBS-II. A computed neutron source spectrum with 32 keV FWHM was derived by the Monte Carlo method and used in reducing the data to a cross section at 964 keV. The final value of 1.21 ~ 0.025 barns is absolute in that, except for small corrections, its determination was independent of any other cross section data.

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Section: The Number Of Target Nucleimentioning

confidence: 68%

An absolute determination of the 235U fission cross section at 964 keV

Gilliam

Knoll

1975

Annals of Nuclear Energy

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“…As can be seen, the particle size increases with the increase in temperature. This is most likely due to the agglomeration effects at high temperatures as reported in the literature [27,29,31], and a possible increasing of U 3 O 8 plasticity [27]. However, the small particle observed at 350 • C may be attributed to the presence of internal stresses, which promotes the pul- verization of the UO 2 pellet into fine U 3 O 8 powder [12].…”

Section: Oxidation Kineticsmentioning

confidence: 79%

Recycling process of defective aged uranium dioxide pellets

Mernache¹,

Boutarek

Bouchemaa

et al. 2015

Journal of Nuclear Science and Technology

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The work was devoted to study the recycling process of the unirradiated defective uranium dioxide pellets stored during 10 years. The effect of the temperature on the kinetics of the oxidation and reduction of dioxide uranium was investigated, respectively, in the range 250 • C-600 • C and 300 • C-800 • C. For the oxidation process, the kinetics is low below 350 • C, and is fast at higher temperatures. The same phenomenon is observed for the reduction process, where the rate accelerates at above 500 • C and the reduction completed in shorter time. Using a laser particle size analyzer and a Brunauer, Emmett, Teller (BET) analyzer, it was determined that the oxidation at 400 • C gives a triuranium octoxide powder with an adequate particle size (33 μm) and a specific surface area of 0.9 m 2 /g in reasonable time (210 min). Reducing the triuranium octoxide to uranium dioxide powder at 600 • C in pure hydrogen was completely achieved after only 16 minutes, without affecting its characteristics. To ameliorate the specific surface area, several oxidationreduction cycles were performed on the obtained uranium dioxide powder. It is found that after five cycles, the specific surface area of uranium dioxide was improved to more than 2.5 m 2 /g, minimum value required to the powder sinterability.

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“…Peakall and Antill [31] and McCracken [32] reported a gradual decrease in the overall oxidation rate of UO 2 pellets with increasing temperature between about 700 and 1200 K. This can be explained by a gradual change-over from rate control at the level of individual grains (with powder formation) below 700 K to that of individual fragments (which remain intact) above 1200 K. Rates are erratic, due to occasional breakaway of oxidation products from the fragment surface, but approximately linear kinetics were observed. The reported rates at 723-1173 K, measured after 30% oxidation to U 3 O 8 [31], yield Eq.…”

Section: Formation Of U 4 O 9 and U 3 O 8 At 700-1200 Kmentioning

confidence: 99%

Thermodynamic and kinetic aspects of UO2 fuel oxidation in air at 400–2000K

Taylor

2005

Journal of Nuclear Materials

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Oxidation of uranium dioxide in air at 350–1000° C

Cited by 31 publications

References 1 publication

An absolute determination of the 235U fission cross section at 964 keV

An absolute determination of the 235U fission cross section at 964 keV

Recycling process of defective aged uranium dioxide pellets

Thermodynamic and kinetic aspects of UO2 fuel oxidation in air at 400–2000K

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