UO2–UN composites with enhanced uranium density and thermal conductivity

Thermal Energy Transport in Oxide Nuclear Fuel

“…347 Laboratory-based slow positrons or variable-energy positron beams begin with a positron source having a continuous energy distribution. The most commonly used source is the radioactive isotope 22 Na. Some of the fast positrons emanated from the source are moderated down to ∼75 meV as they pass through a thin foil (e.g., W and Ni).…”

“…The myriad of defect types and interactions in nuclear fuel under irradiation has motivated researchers to consider improving function by controlling defect evolution and structure. Examples include using dopants to control defect concentrations by modifying grain size [10,11,12,13], simulating HBS using nanocrystalline UO2 to improve fission gas retention and improve mechanical properties [14,15], and directly adding other materials to UO2 to raise the thermal conductivity [16,17,18,19,20,21,22,23,24]. Expediting progress towards tailoring defects and microstructure to bring about desired thermal properties will require further development of fundamental, predictive models of phonon transport in actinide oxide fuels containing irradiation-induced defects [25,26,27,28,29].…”

“…For example, in the high-burnup structure (HBS) of nuclear fuels, where considerable irradiation-driven restructuring greatly increases the grain boundary surface area and decreases the lattice defect concentration because of segregation to grain boundaries, the thermal conductivity is higher than that in similar fuel that has not formed HBS. , The myriad defect types and interactions in nuclear fuel under irradiation have motivated researchers to consider improving function by controlling defect evolution and structure. Examples include the use of dopants to control defect concentrations by modification of the grain size, − simulation of HBS using nanocrystalline UO 2 to improve fission gas retention and mechanical properties, , and direct addition of other materials to UO 2 to raise the thermal conductivity. − Expediting progress toward tailoring defects and microstructure to bring about desired thermal properties will require further development of fundamental predictive models of phonon transport in actinide oxide fuels containing irradiation-induced defects. − …”

Fabrikasi Kernel TRISO-UN dan Karakternya, Sebuah Kajian

“…Yang disampaikan dalam makalah ini adalah hasil analisis Bessman dari Oak Ridge National Laboratory, USA, dengan computer code PERFUME (PARticle FUel ModeEL) untuk menghitung gas produk fisi dan digabung dengan perangkat lunak COMSOL Multiphysics untuk kalkulasi elemen hingganya (finite element) (Yang, 2015). Urutan kalkulasi yang dilakukan adalah mencari probabilitas mampu bertahan (survival) dan tekanan maksimum ke arah tangensial, untuk kernel ukuran kernel 0,65 mm dan 0,80 mm sebagai fungsi dari tebal buffer, tebal PyC dan tekanan maksimum.…”

Multiphysics modeling of UO2-SiC composite fuel performance with enhanced thermal and mechanical properties

“…(8) (9) where is the temperature in , is the porosity, and is the burnup in at %. The Fink-Lucuta model is valid from 298 to 3,120 K [19][20] for pure UO 2 fuels.…”