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A phase field study of the thermal migration of gas bubbles in UO2 nuclear fuel under temperature gradient
- Source :
- Computational Materials Science. 183:109817
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- Phase field models are developed to study the gas bubble migration in uranium dioxide nuclear fuel in which a large temperature gradient exists during the operation. In this work, thermal diffusion mechanism for nanosized gas bubbles and vapor transport process for micron-sized gas bubbles are considered, respectively. In both cases, gas bubbles migrate to the high-temperature area. Due to the velocity difference between leading and trailing edges of the gas bubbles, nanosized gas bubbles are elongated along the temperature gradient direction when thermal diffusion is dominated. Micron-sized gas bubbles are either compressed along temperature gradient direction to form lenticular shape bubbles or elongated along temperature gradient direction, depending on the location of the gas bubbles within the fuel pellet. Initial gas bubble radius has no significant effect on the gas bubble migration velocity for both thermal diffusion and vapor transport mechanisms. We notice that the shape change of the gas bubble due to vapor transport mechanism has no significant effect on the migration velocity. Furthermore, the center cavity formation is also captured by our model which is due to the migration and accumulation of lenticular gas bubbles at the center of the fuel pellet. The modeling results compare well with experimental observations and theoretical analysis in the literature.
- Subjects :
- Materials science
General Computer Science
Uranium dioxide
General Physics and Astronomy
Phase field models
02 engineering and technology
010402 general chemistry
Thermal diffusivity
01 natural sciences
Physics::Fluid Dynamics
chemistry.chemical_compound
Phase (matter)
Thermal
General Materials Science
Astrophysics::Galaxy Astrophysics
Nuclear fuel
General Chemistry
Mechanics
Radius
021001 nanoscience & nanotechnology
0104 chemical sciences
Computational Mathematics
Temperature gradient
chemistry
Mechanics of Materials
0210 nano-technology
Subjects
Details
- ISSN :
- 09270256
- Volume :
- 183
- Database :
- OpenAIRE
- Journal :
- Computational Materials Science
- Accession number :
- edsair.doi...........f1320350d46468d52cad8df03586a539