Thermal Properties of Irradiated UO2 and MOX

Analysis of fabrication and crack-induced porosity migration in mixed oxide fuels for sodium fast reactors by the finite element method

“…The results at the end of the simulations are compared in Figure 11. As it is noticeable, the configuration considering the migration of the porosity induced by cracks 5 yields results that are closer to the experimental data then the one 4 It is worth to notice that one can in principle choose a different number of fragments and a different angle to model the cracking pattern. In this case, the thickness of the crack would need to be adjusted to preserve the total free volume.…”

“…with straight, radial cracks. As for the crack thickness, we consider that the 8 fragments are fully displaced and in contact with the cladding, thus the initial internal void surface/volume due to the gap is conserved and transfered into the cracks 4 For both configurations, conforming and a priori refined first order triangular elements are used (see details in AppendixB). The results at the end of the simulations are compared in Figure 11.…”

“…In this work, our attention is drawn on modeling the pore migration mechanism from an engineering-scale perspective, i.e., in the framework of continuum mechanics. The local porosity influences a number of key properties, including fuel thermal conductivity, local power generation, and elastic properties [1,3,4], thus it is a dominant factor in determining the thermal condition in the fuel region.…”

“…Other approaches for the porosity correction of the thermal conductivity are available in the open literature (e.g., see[4]). Indeed, the correction employed here allows to directly pass from the conductivity of pure oxide to the conductivity of pure gas (helium) when the central hole forms, without the need of introducing step-wise thresholds.…”

Thermal Energy Transport in Oxide Nuclear Fuel

“…In particular, A can be represented as A = A 0 + ∑ i x i A i ′ , where the summation is over defects i , x i is the concentration of defect i , A i ′ is the scattering parameter for defect i , and A 0 is the residual value for a pristine material. , Recommended values of A 0 and B for pristine samples of UO 2 , ThO 2 , and CeO 2 are summarized in Table , and representative conductivity profiles as functions of temperature are shown in Figure . The simplified formulation and minor variations thereof have been used to describe the thermal conductivity of fresh and irradiated UO 2 fuel, , mixed uranium–plutonium dioxide (MOX) fuel, − and rare-earth-doped UO 2 …”