Chemical diffusion in uranium dioxide – influence of defect interactions

Simulations of heat and oxygen diffusion in UO2 nuclear fuel rods

“…It is also consistent with the recent model [40], especially in the low non-stoichiometry regime, x < 0.03.…”

“…Although new thermochemical models of defects and oxygen mobility have been recently developed for PuO 2Àx [39], a comprehensive model of defect formation and oxygen diffusion in UO 2+x is still lacking. The evaluation of oxygen diffusivity in UO 2+x [40] shows that several mechanisms contribute to oxygen diffusion and the chemical diffusion coefficient decreases with non-stoichiometry, x.…”

“…Using a set of experimental values from [40], we have optimized the parameters of the following function describing the chemical diffusivity D(T, x) of oxygen in hyper-stoichiometric urania: log DðT ; xÞ ½ ¼À 9:386 À 4:26  10 3 T þ 1:2  10 À3…”

Three dimensional coupled simulation of thermomechanics, heat, and oxygen diffusion in nuclear fuel rods

“…(17)- (19) are integrated in time using the implicit Euler method [21]. Let T k , x k and u k denote T, x and u at time step k. Then (17) and (18) are discretized in time as…”

Thermodynamic and kinetic aspects of UO2 fuel oxidation in air at 400–2000K

“…Ruello et al [40] have recently shown that the chemical diffusion coefficient for oxygen in UO 2+x is strongly dependent on x. Extrapolation of their results, obtained at 973-1673 K, indicates diffusion coefficients near 10 À5 cm 2 s À1 for x < 0.03, and 10 À6 cm 2 s À1 for 0.07 < x < 0.17, at 2000 K. They reported ÔsluggishÕ response in attempted measurements at still higher values of x.…”