Annual Report 2003

    APPLIED RESEARCH

Formation of high burn-up structures in UO2 nuclear fuel materials, known as rim effect, attracts attention mainly due to its possible catastrophic influence on the operation conditions of modern nuclear power stations. This process is of particular scientific interest as well, because physical mechanisms and relevant parameters are still poorly understood. A new, based on the cellular automata (CA), approach for processing and modelling the structure dynamics of nuclear fuel at different burn-ups was proposed. Some evidences for existence of self-organization processes in the fuel at high burn-ups were established. It has been found that the fractal dimension of the surface structures strongly depends on the radiation damage of the material [20].

A micrograph of original pattern transformed into CA checkerboard is shown in Fig. 5. Black points are pores filled with fission gas products, white background is ceramic UO2.

Results of Ising CA simulation of pattern evolution under temperature changes are shown in Figs. 6 and 7. One can see processes of joining the pores during their subdivision depending on temperature.

Fig. 5.
Fig. 5.

Fig. 6.
Fig. 6.

Fig. 7.
Fig. 7.

© Laboratory of Information Technologies, JINR, Dubna, 2004
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