NSUF 23-1868: Elucidating the Effect of Radiation-Induced Defect Accumulation on Swelling in UN using in-situ TEM Irradiation
Uranium mononitride (UN) is under consideration as an advanced nuclear fuel alternative to UO2. Its advantageous properties (e.g. high U density and high thermal conductivity) lead to improvements in fuel performance and safety. During irradiation, the fuel swells due to the formation and growth of fission gas bubbles. A key limiting factor for its in-reactor application is runaway swelling; a phenomenon where at high temperatures (and burnups) changes to the mobility of defects combined with microstructural changes cause the swelling of the fuel to rapidly accelerate. The phenomena governing runaway swelling are poorly understood meaning that accurate fuel performance predictions are challenging. It is thought that the accumulation of irradiation-induced defects and fission gas play a key role. The rate of dislocation loop and bubble evolution is expected to change with temperature. We aim to investigate the in-situ growth and evolution of defects in UN (e.g. dislocation loops, cavities), when exposed to ion irradiation at reactor relevant temperatures (in-situ TEM ion irradiation at elevated temperatures). This real-time observation will provide essential information regarding the growth, accumulation and migration of defects that are responsible for swelling in UN. In-situ ion irradiations will be conducted in as-fabricated UN and UN pre-implanted with Xe to determine the effect of fission gas on the damage microstructure and dislocation dynamics. 10 days are requested to complete the experiments, which will be performed within 4-6 months. The results will be used to validate a UN swelling model under development at LANL (using cluster dynamics code Centipede) that will predict the radiation-induced defect growth and mobility under those same conditions. Since the swelling model is mechanistic, validation under ion-irradiation conditions would validate the underlying parameters that also govern its predictions for reactor-irradiation conditions (~1 dpa/day for LWR). This combined modeling-experimental approach will enable the proposed ion-beam experiments to have a direct impact on the development and qualification of UN. C. Matthews, R. Perriot, M. W. D. Cooper, C. R. Stanek, D. A. Andersson, “Cluster dynamics simulation of xenon diffusion during irradiation in UO2”, J. Nucl. Mater., 540, 152326 (2020)
Additional Info
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| Abstract | Uranium mononitride (UN) is under consideration as an advanced nuclear fuel alternative to UO2. Its advantageous properties (e.g. high U density and high thermal conductivity) lead to improvements in fuel performance and safety. During irradiation, the fuel swells due to the formation and growth of fission gas bubbles. A key limiting factor for its in-reactor application is runaway swelling; a phenomenon where at high temperatures (and burnups) changes to the mobility of defects combined with microstructural changes cause the swelling of the fuel to rapidly accelerate. The phenomena governing runaway swelling are poorly understood meaning that accurate fuel performance predictions are challenging. It is thought that the accumulation of irradiation-induced defects and fission gas play a key role. The rate of dislocation loop and bubble evolution is expected to change with temperature. We aim to investigate the in-situ growth and evolution of defects in UN (e.g. dislocation loops, cavities), when exposed to ion irradiation at reactor relevant temperatures (in-situ TEM ion irradiation at elevated temperatures). This real-time observation will provide essential information regarding the growth, accumulation and migration of defects that are responsible for swelling in UN. In-situ ion irradiations will be conducted in as-fabricated UN and UN pre-implanted with Xe to determine the effect of fission gas on the damage microstructure and dislocation dynamics. 10 days are requested to complete the experiments, which will be performed within 4-6 months. The results will be used to validate a UN swelling model under development at LANL (using cluster dynamics code Centipede*) that will predict the radiation-induced defect growth and mobility under those same conditions. Since the swelling model is mechanistic, validation under ion-irradiation conditions would validate the underlying parameters that also govern its predictions for reactor-irradiation conditions (~1 dpa/day for LWR). This combined modeling-experimental approach will enable the proposed ion-beam experiments to have a direct impact on the development and qualification of UN. *C. Matthews, R. Perriot, M. W. D. Cooper, C. R. Stanek, D. A. Andersson, “Cluster dynamics simulation of xenon diffusion during irradiation in UO2”, J. Nucl. Mater., 540, 152326 (2020) |
| Award Announced Date | 2023-02-08T10:46:30.24 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Wei-Ying Chen |
| Irradiation Facility | None |
| PI | Caitlin Taylor |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 4552 |