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A model of fission gas behavior during steady-state operation

Thesis/Dissertation ·
OSTI ID:5492955

A model of fission gas behavior during the steady-state operation of a nuclear reactor that uses uranium dioxide as fuel is developed. The basic physical phenomena encountered in analyzing the disposition of fission gas have been retained, but in a simplified form for ease of calculation. The analysis code, includes treatment of intragranular, grain face, and grain edge gas and release to the open spaces. The code is utilized to obtain comparisons with experimental data and to perform fuel behavior sensitivity studies. The results obtained in the sensitivity studies indicate the importance of including grain face and grain edge bubbles treatments in modeling fission gas. It is found that representation of release in different sections of the fuel pin is possible in a simple way by assuming evenly spaced bubbles on the edge, and that grain edge bubble interlinkage is a necessary condition for release to the open spaces. It is also indicated by the sensitivity studies that fission gas swelling is mainly due to grain edge bubbles. Grain face bubbles, although large in size, are few in number and contribute little to swelling. Intragranular swelling is intermediate between these two values. The resulting code can be used in predicting fuel element performance, that is necessary in nuclear fuel design, safety analysis, and interpretation of experimental data on fuel element behavior.

Research Organization:
California Univ., Los Angeles (USA)
OSTI ID:
5492955
Country of Publication:
United States
Language:
English