Informe Tecnico

SOBA; DENIS

2005-01-01/2007-05-01

1-22

Informática (software)

Prom.Gral.del Conoc.-Cs.Exactas y Naturales

We summarize the present status of the code DIONISIO 1.0 that describes most of the main phenomena occurring in a PWR/PHWR fuel rod throughout its life under normal operation conditions. Two calculation scenarios are permitted: system constituted by pellet and cladding, assuming a closed gap from the beginning of life, or constituted by pellet, gap and cladding, where the possibility of gap closure and reopening during burnup is allowed. 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 free 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. The effects of an internal or external corrosive atmosphere (SCC) 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. In the present occasion, results corresponding to PHWR reactors are presented. Good results are obtained for the simulation of irradiation tests contained in IAEA databases: IFPE/AECL-BUNDLE, performed in the NRU experimental reactor at the Chalk River Laboratories; the CONTACT series of experiments performed in the Siloe Reactor, Grenoble, designated IFPE/CONTACT REV.1; the irradiation tests EFE N51 and EFE N89 performed in the Nuclear Research Institute Pitesti, Romania, and several experiments selected from the FUMEX II cases.