3D simulation of a power ramp including fuel thermochemistry and oxygen thermodiffusion

P. Konarski , J. Sercombe (1) , C. Riglet-Martial (2) , L. Noirot (2) , I. Zacharie-Aubrun (2) , K. Hanifi (2) , M. Fregonese (3) , P. Chantrenne (3)

1 DEC - Département d'Etudes des Combustibles
2 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
3 MATEIS - Matériaux, ingénierie et science [Villeurbanne]

This paper presents 3D simulations of power ramps in pressurized water reactors with the fuel performance code ALCYONE, which is part of the computing environment PLEIADES. The code has been upgraded to couple the description of irradiated fuel thermochemistry already available with oxygen transport taking into account thermodiffusion. The impact of oxygen redistribution during a power transient on irradiated fuel thermochemistry in the fuel and on chemically reactive gas release from the fuel (I ( g ) , I 2 ( g ) , CsI ( g ) , TeI 2 ( g ) , Cs ( g ) , Cs 2 ( g ) ) is studied. The simulations show that oxygen redistribution, even if moderate in magnitude, leads to the reduction of metallic oxides (molybdenum dioxide, cesium molybdates, chromium oxide) at the fuel pellet center and consequently to the release of a much greater quantity of gaseous cesium. Pellet-Cladding Interaction failure propensity is shown to decrease in consequence of the thermodynamically favourable reaction of iodine with released cesium in the free volume of the rod. © 2019 Elsevier B.V.

Mots clés: Cesium iodide; Chromium compounds; Computer simulation; Metals; Molybdenum oxide; Nuclear fuels; Oxygen; Pelletizing; Pressurized water reactors; Thermal diffusion in liquids; Thermochemistry; Computing environments; Fuel performance; Irradiated fuels; Molybdenum dioxide; Oxygen potential; Oxygen transport; Thermochemical modelling; Thermodiffusion; Fuels

Domaines: Matériaux

P. Konarski, J. Sercombe, C. Riglet-Martial, L. Noirot, I. Zacharie-Aubrun, et al.. 3D simulation of a power ramp including fuel thermochemistry and oxygen thermodiffusion. Journal of Nuclear Materials, 2019, 519, pp.104-120. ⟨10.1016/j.jnucmat.2019.03.021⟩. ⟨hal-02405439⟩