NSUF 18-1151: Electron Tomography for Three-Dimensional Characterization of Intragranular Fission Product Transport in Neutron-Irradiated Silicon Carbide in TRISO Fuel
The overall goal of this project is to demonstrate the use of electron tomography in characterization of advanced nuclear fuel. This project will unveil the three-dimensional (3D) complexity of fission products transport phenomena in neutron-irradiated tristructural isotropic (TRISO) fuel. The traditional characterization of silicon carbide (SiC), a coating layer in TRISO fuel, is done via transmission electron microscopy; in this method, the structural-defect-assisted intragranular fission product transport is poorly understood due to the two-dimensionality of the imaging technique. In spite of advanced microscopy methods and modeling efforts, the microstructural stability of SiC under high temperature and neutron fluence remains controversial. Recent research effort has demonstrated that the intragranular fission product precipitation is accomplished via an interesting two-step nucleation route. In the first step, nanoscale alpha-SiC precipitates in a beta-SiC matrix unexpectedly nucleate heterogeneously at structural defects. This occurs at significantly lower temperatures compared with the usual beta-alpha transition temperature. Subsequently, alpha-SiC precipitate acts as a surrogate template for its structural and compositional transition into a fission product precipitate. The success of TRISO fuel further requires innovative characterization approaches, such as electron tomography, to fully comprehend this unexplored nucleation mechanism in the SiC layer in Advanced Gas Reactor (AGR) experiments. The ability to resolve both structural and compositional 3D information at sub-nanometer scale by electron tomography is a complementary, yet vital, addition to the present methods for AGR post-irradiation microstructural characterization.
Additional Info
| Field | Value |
|---|---|
| Abstract | The overall goal of this project is to demonstrate the use of electron tomography in characterization of advanced nuclear fuel. This project will unveil the three-dimensional (3D) complexity of fission products transport phenomena in neutron-irradiated tristructural isotropic (TRISO) fuel. The traditional characterization of silicon carbide (SiC), a coating layer in TRISO fuel, is done via transmission electron microscopy; in this method, the structural-defect-assisted intragranular fission product transport is poorly understood due to the two-dimensionality of the imaging technique. In spite of advanced microscopy methods and modeling efforts, the microstructural stability of SiC under high temperature and neutron fluence remains controversial. Recent research effort has demonstrated that the intragranular fission product precipitation is accomplished via an interesting two-step nucleation route. In the first step, nanoscale alpha-SiC precipitates in a beta-SiC matrix unexpectedly nucleate heterogeneously at structural defects. This occurs at significantly lower temperatures compared with the usual beta-alpha transition temperature. Subsequently, alpha-SiC precipitate acts as a surrogate template for its structural and compositional transition into a fission product precipitate. The success of TRISO fuel further requires innovative characterization approaches, such as electron tomography, to fully comprehend this unexplored nucleation mechanism in the SiC layer in Advanced Gas Reactor (AGR) experiments. The ability to resolve both structural and compositional 3D information at sub-nanometer scale by electron tomography is a complementary, yet vital, addition to the present methods for AGR post-irradiation microstructural characterization. |
| Award Announced Date | 2018-02-01T14:11:02.507 |
| Awarded Institution | Center for Advanced Energy Studies |
| Facility | Microscopy and Characterization Suite |
| Facility Tech Lead | Alina Zackrone, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Subhashish Meher |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1151 |