3D thermo-chemical-mechanical simulation of power ramps with ALCYONE fuel code

This paper presents the coupling of the fuel performance code ALCYONE with the thermochemical code ANGE and its application to Iodine-Stress Corrosion Cracking (I-SCC). The coupling is illustrated by a 3D simulation of a power ramp. The release of chemically active gases (CsI(g), Te-x(1<x<7)(g), TeI2(g), I-(g), I-2(g)...) is studied. The calculated radial distributions of iodine, cesium, tellurium and inert fission gas in the pellet fragment before and after the power ramp are successfully compared to Secondary Ion Mass Spectrometry (SIMS) measurements. Based on the 3D simulation, the definition of a stress corrosion initiation criterion is discussed. The combination of the hoop stress and of the quantity of reactive iodine (I-(g), I-2(g) and TeI2(g) only) released by the pellet is used to show that the necessary conditions for Pellet Cladding Interaction-Stress Corrosion Cracking (PCI-SCC) initiation, based on out-of-pile I-SCC laboratory tests criteria, are met during the simulated power transient. (C) 2014 Elsevier B.V. All rights reserved.