High temperature thermal physical performance of BeO/UO2 composites prepared by spark plasma sintering (SPS)

BeO Utilization in Reactors for the Improvement of Extreme Reactor Environments - A Review

“…Reliable, high-density samples were prepared using compaction pressure between 200 and 225 MPa and sintering times between 4 and 6 h. It was found that the thermal conductivity of UO 2 improved approximately 10 pct for each 1 vol pct BeO added over the measured temperature range 298.15-523.15 K (25-250°C) with the maximum observed improvement being ∼100 pct, or doubled, at 10 vol pct BeO. Li et al (2018) reported coefficient of thermal expansion and thermal conductivity evolutions of SPS fabricated UO 2 -10 vol% BeO fuel against temperature from room temperature to 1,600°C and found that the coefficient of thermal expansion increases flatly while the thermal conductivity is significantly improved, which demonstrated UO 2 -BeO composite fuel is one of the most effective thermal enhanced candidates for high-temperature operation. Camarano et al (2019) investigated the influence of the beryllium oxide addition to increase the thermal conductivity in uranium dioxide fuel pellets containing gadolinium oxide as the burnable poison was investigated.…”

Thermal Energy Transport in Oxide Nuclear Fuel

“…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. − …”

UO2/BeO interfacial thermal resistance and its effect on fuel thermal conductivity

“…However, its low thermal conductivity has led to a variety of problems related to the performance and safety of the reactor, such as large centerline temperatures, pellet cracking and fuel relocation. An approach that has been demonstrated to be effective in improving the thermal conductivity of UO2 is to incorporate a high conductivity phase in UO2 fuel [1][2][3][4][5][6][7][8].…”

“…Beryllium oxide (BeO) is a promising additives due to its high thermal conductivity, low thermal neutron absorption cross-section, good chemical compatibility with UO2, and high resistance to water steam. Significant efforts have been made to investigate the effects of BeO content and distribution on UO2 thermal conductivity [1][2][3][4][5][6]. It was demonstrated that the increase in BeO content can lead to an effective improvement of UO2 thermal conductivity, and a continuous BeO phase leads to a higher thermal conductivity than dispersed BeO.…”