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Abstract

Atomic diffusion processes in UO-2 and in the fast breeder reactor fuel, (U,Pu)O-2 are reviewed. Emphasis is given to the slower moving species, i.e. U and Pu. Self-diffusion, chemical diffusion, diffusion in a thermal gradient, enhancement of diffusion by radiation and fission and the operative diffusion mechanisms are discussed. The main parameter, besides the temperature, is the oxygen to metal (O/M) ratio of the oxide. The experimental results are compared with recent calculations reported elsewhere in this volume. Further treated are effects of the possible lambda transition at about 2600 K in Uo-2 on high temperature kinetic processes. The present knowledge on the diffusion and mobility of fission products with emphasis on volatile and gaseous elements, and of other actinides with emphasis on their valence state are treated. Gaps in our knowledge are pointed out, and the relevance of the available results for oxide fuel during reactor operation is discussed. Whereas much is known for the as-produced "virgin" fuel, more results are urgently needed for oxides with higher burn-ups containing a few percent fission products. Finally technological applications of the diffusion results are treated. As an example, important savings in cost, energy and time in fuel sintering were recently achieved based on basic studies of diffusion properties of UO-2.

Additional information

Authors: MATZKE HJ JRC KARLSRUHE ESTAB. (GERMANY), JRC KARLSRUHE ESTAB. (GERMANY)
Bibliographic Reference: INTERNATIONAL MEETING "FUNDAMENTAL PROPERTIES OF UO-2 AND ACTINIDE OXIDES", OXFORD (UK), MARCH 24-26, 1986 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 33025 ORA
Availability: Can be ordered online
Record Number: 1989125059600 / Last updated on: 1987-11-01
Category: PUBLICATION
Available languages: en
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