Oxidation behaviour of plutonium and uranium mixed oxide powder; Oxidation process and oxidation rate

Kato, Masato ; Uno, Hiroki*; Tamura, Tetsuya*; Endo, Hideo

JNC have been manufacturing MOX fuels from Plutonium and Uranium mixed oxide powder (1:1 MOX) that were prepared by microwave direct denitration method. It is well known that MOX raw material oxidize in storage and manufacturing process due to heat generation by self-radiation. The oxidation process and rate of MOX powder were examined for three kinds of powders having different surface area. The examination of isothermal and non-isothermal oxidation was carried out by TG-DTA. The oxidized samples were analyzed by X-ray diffraction measurement. The oxidation of MOX powders proceeded in two steps and the oxidation process changed depending on the surface area of the powder as follows. Process 1 (Surface Area : 2.24m $^{2}$ /g) First Step : MO $_{2}$ MO $_{2-x}$ MO $_{2.25}$ Second Step : MO $_{2.25}$ MO $_{2.25}$ +M $_{3}$ O $_{8-y}$ Process 2 (Surface Area : 5.59, 3.86m $^{2}$ /g) First Step : MO $_{2}$ MO $_{2+x}$ +MO $_{3-z}$ MO $_{2.25}$ +MO $_{3-z}$ Second Step : MO $_{2.25}$ +MO $_{3-z}$ MO $_{2.25}$ +M $_{3}$ O $_{8-y}$ +MO $_{3-z}$ The kinetic analysis of the oxidation was evaluated by Avrami-Erofeev equation. The equation of O/M change on the MOX powder was obtained as function of temperature, keeping time and the surface area of the powder.

Language	:	Japanese
Report No.	:	JNC TN8400 2003-013
Pages	:	48 Pages
Publication Year/Month	:	2003/05
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PDF	:	JNC-TN8400-2003-013.pdf:29.92MB
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Registration No. : GJ0820030022
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