Simulation with DIONISIO 2.0 of a whole nuclear fuel rod under extended irradiation

A. SOBA; M. LEMES; A. DENIS

CABA

Congreso; Technical Meeting on High Burn-up Economics and Operational Experience; 2013

The version 2.0 of the DIONISIO code has been recently developed with the purpose of improving the accuracy of the simulation of the whole fuel rod. To this end, the rod is divided into a number of axial segments. The local values of linear power and coolant temperature are given as input data to DIONISIO 1.0 which is executed in each segment obtaining as outputs the local values of temperature, stress, strain, among other physical variables. Then, the general rod parameters (internal rod pressure, amount of fission gas released, pellet stack elongation, etc.) are evaluated at the end of every time step, conveniently combining the results of all the axial segments. The new code architecture allows taking into account the axial variation of the linear power and, consequently, evaluating the dependence of all the significant rod parameters with the longitudinal coordinate. Moreover, new calculation tools designed to extend the application range of the code to high burn up have also been incorporated to DIONISIO 2.0 in recent times and are the subject of other presentation. With these improvements, the code results are compared with some experiments published in the IAEA data base, covering more than 380 fuel rods irradiated up to average burnup levels of 40-60 MWd/kgU. The results of these comparisons, which are presented here, reveal the good quality of the simulations.