Thermal conductivity evaluation of high burnup mixed-oxide (MOX) fuel pellet

BISON Theory Manual The Equations behind Nuclear Fuel Analysis

“…The second model available in BISON has been proposed by Amaya et al [35]. Unlike the previous model, Amaya provides a plutonium concentration dependence.…”

“…whereė is the creep rate (1/s), s is the effective (Mises) stress (Pa), T is the temperature (K), D is the fuel density (percent of theoretical), G is the grain size (µm),Ḟ is the volumetric fission rate (fissions/m 3 -s), Q i are the activation energies (J/mol), R is the universal gas constant (8.3143 J/mol-K) and A 1 7 are material constants given as A 1 = 0.3919, A 2 = 1.3100x10 19 , A 3 = 87.7, A 4 = 2.0391x10 25 , A 6 = 90.5, and A 7 = 3.7226x10 35 . The first term represents diffusional thermal creep and is applicable to low stress and low temperature conditions.…”

BISON Theory Manual The Equations behind Nuclear F

“…• Unirradiated thermal conductivity of UO 2 fuel: [9] • Irradiated thermal conductivity of UO 2 fuel: [10] • Review of available models for thermal conductivity of UO 2 and MOX: [15] • Ronchi model for thermal conductivity of MOX: [16] • Duriez model for thermal conductivity of MOX: [17] • Amaya model for thermal conductivity of MOX: [18] Three models are available to compute MOX thermal properties in BISON. For these models, thermal conductivity of unirradiated material is first defined.…”

“…The second model available in BISON has been proposed by Amaya et al [18]. Unlike the previous model, Amaya provides a plutonium concentration dependence.…”

“…Amaya model's coefficients have been fitted in the temperature range from 400 K to 1500 K and the plutonium concentration up to 30 wt.% ( [18]). Figure 8.5 shows a comparison of the computed thermal conductivities for the Fink-Lucuta (for reference), Fink-Amaya, and Duriez-Ronchi models for unirradiated MOX at 95% theoretical density.…”