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To determine the lattice constant variation with burn-up and the oxidation behaviour at high temperatures, simulated UO(2)-spent fuels with burn-ups up to 200 GWd/tM were prepared by cold pressing and sintering and characterized by X-ray diffraction analysis and thermogravimetry. The fcc-lattice parameter of the sintered samples determined at room temperature, showed a continuous decrease with the simulated burn-up. During oxidation the conversion of the simulated fuels to the (U,FP)(4)O(9) and (U,FP)(3)O(8)-type phases was strongly delayed when the simulated burn-up exceeded 80 GWd/tM. Also, at high burn-ups (> 100 GWd/tM), large fractions of the (U,FP)(4)O(9)-type phase remained untransformed to (U,FP)(3)O(8) after prolonged exposure to air at between 950 C and 1000 C. This suggests a marked widening of the (U,FP)(4)O(9)-phase field when the amount of substituted uranium atoms exceeds values of about 8%.

Additional information

Authors: COBOS J, JRC Karlsruhe (DE);PAPAIOANNOU D, JRC Karlsruhe (DE);SPINO J, JRC Karlsruhe (DE);COQUERELLE M, JRC Karlsruhe (DE)
Bibliographic Reference: Paper presented: Actinides '97, Baden-Baden (DE), 21-26 September 1997
Availability: Available from (1) as Paper EN 41109 ORA
Record Number: 199810231 / Last updated on: 1998-03-09
Original language: en
Available languages: en