Simulation of PHWR fuel rods behavior with the code DIONISIO 1.0

SOBA; DENIS

Mumbai

Congreso; IAEA Technical Meeting on “Pressurised Heavy Water Reactor (PHWR) Fuel Modelling”; 2006

IAEA

We summarize the present status of the code DIONISIO 1.0 that describes some of the main phenomena occurring in a PWR/PHWR fuel rod throughout its life. Two calculation scenarios are permitted: the simulation domain can be either pellet-gap-cladding or pellet-cladding (assuming a closed gap from the beginning of life).   Starting from an idealized power history, the code predicts the temperature distribution in the domain, elastic and plastic stress and strain, creep, swelling and densification, release of fission gases, cesium and iodine to the internal volume of the rod, gas mixing, pressure increase, irradiation growth of the Zircaloy cladding, development of an oxide layer on its surface and hydrogen uptake, restructuring and grain growth in the pellet. One of the modules, starting from an initiating crack in the cladding, simulates its propagation under the stress field of the rod. The effect of a corrosive atmosphere (SCC) either internal or external as well as the possibility of pellet-cladding interaction (PCI) are also considered.   The code is two-dimensional, assumes cylindrical symmetry for the rod and uses the finite element method to integrate the differential equations, some of which are non-linear. The diverse models are interconnected and mutually dependent.   Good results are obtained for the simulation of irradiation tests contained in the IAEA data base: experiments performed in the Bruce-A Ontario Hydro Reactor, Canada, within the program IFPE/AECL-BUNDLE; the CONTACT series of experiments performed in the Siloe Reactor, Grenoble, within the program IFPE/CONTACT REV.1; two irradiation tests of CANDU type fuels carried out in the C2 device from the TRIGA 14MW Reactor, Romania, within the program IFPE/EFE-RO and the cases 27-3.a and 3.b of the FUMEX II exercise corresponding to CANDU fuels.