NSUF 15-541: APT Study of Fission Product Transport in Unirradiated/Neutron Irradiated TRISO Fuel Particles
Tristructural isotropic (TRISO) particle is a promising candidate as fuel for the Generation IV VHTR. The TRISO coating is part of the high temperature gas-cooled reactor functional containment and critical for the safety strategy for licensing purposes. The release of radioactive Ag from TRISO particles raises a significant safety concern due to plate-out on cooler turbine metallic parts which can pose a risk for maintenance personnel. In addition, Pd was identified as a main constituent of fission product precipitates, and Pd corrosion to SiC layer is a potential problem. It is critical to identify fission products and understand their transport mechanisms in SiC in order to provide feedback to improve design of TRISO coating to reduce release of fission products from the TRISO coated particles. Therefore, the proposed study aims at obtaining accurate compositional information and three-dimensional spatial distribution of fission products in the SiC layer of neutron irradiated TRISO fuel by using the atom probe tomography (APT) technique. This information will assist in gaining insight into the transport mechanisms of fission products, particularly Ag, Pd, released from neutron irradiated TRISO fuel. Research that has been performed provided information on elements potentially present in the fission product precipitates, but no in-depth characterization of composition and distribution of the precipitates was concluded yet. Knowledge of the accurate composition and spatial distribution of the fission products is critical to understand their formation and transport. This proposed study continues the APT study part of completed RTE proposal with University of Wisconsin in 2014 (Title: STEM/LEAP Study of Fission Product Transportation in Neutron Irradiated TRISO Fuel Particles) and research conducted under the INL Very High Temperature Reactor (VHTR) development program. Three sample series, i.e., unirradiated TRISO fuel, unirradiated surrogate TRISO fuel and irradiated TRISO fuel will be studied in this project. LEAP sample tips will be prepared using FIB technique and then characterized in TEM using STEM/EDS to ensure the desired microstructure is obtained before LEAP experiment. Due to license limitations on radioactive materials at MaCS, CAES, the irradiated and fueled unirriadiated samples will be prepared at the MFC-EML, and then the prepared samples will be shipped to CAES for TEM and LEAP experiments. The unirradiated surrogate samples will be prepared at MaCS, CAES. The proposed research will be performed in two weeks at MFC-EML (FIB), and in two weeks at MaCS, CAES (1 work day for FIB on unirradiated surrogate sample, 2 work days for TEM, and 7 work days for LEAP) from November 2014 to February 2015.
Additional Info
| Field | Value |
|---|---|
| Abstract | Tristructural isotropic (TRISO) particle is a promising candidate as fuel for the Generation IV VHTR. The TRISO coating is part of the high temperature gas-cooled reactor functional containment and critical for the safety strategy for licensing purposes. The release of radioactive Ag from TRISO particles raises a significant safety concern due to plate-out on cooler turbine metallic parts which can pose a risk for maintenance personnel. In addition, Pd was identified as a main constituent of fission product precipitates, and Pd corrosion to SiC layer is a potential problem. It is critical to identify fission products and understand their transport mechanisms in SiC in order to provide feedback to improve design of TRISO coating to reduce release of fission products from the TRISO coated particles. Therefore, the proposed study aims at obtaining accurate compositional information and three-dimensional spatial distribution of fission products in the SiC layer of neutron irradiated TRISO fuel by using the atom probe tomography (APT) technique. This information will assist in gaining insight into the transport mechanisms of fission products, particularly Ag, Pd, released from neutron irradiated TRISO fuel. Research that has been performed provided information on elements potentially present in the fission product precipitates, but no in-depth characterization of composition and distribution of the precipitates was concluded yet. Knowledge of the accurate composition and spatial distribution of the fission products is critical to understand their formation and transport. This proposed study continues the APT study part of completed RTE proposal with University of Wisconsin in 2014 (Title: STEM/LEAP Study of Fission Product Transportation in Neutron Irradiated TRISO Fuel Particles) and research conducted under the INL Very High Temperature Reactor (VHTR) development program. Three sample series, i.e., unirradiated TRISO fuel, unirradiated surrogate TRISO fuel and irradiated TRISO fuel will be studied in this project. LEAP sample tips will be prepared using FIB technique and then characterized in TEM using STEM/EDS to ensure the desired microstructure is obtained before LEAP experiment. Due to license limitations on radioactive materials at MaCS, CAES, the irradiated and fueled unirriadiated samples will be prepared at the MFC-EML, and then the prepared samples will be shipped to CAES for TEM and LEAP experiments. The unirradiated surrogate samples will be prepared at MaCS, CAES. The proposed research will be performed in two weeks at MFC-EML (FIB), and in two weeks at MaCS, CAES (1 work day for FIB on unirradiated surrogate sample, 2 work days for TEM, and 7 work days for LEAP) from November 2014 to February 2015. |
| Award Announced Date | 2014-12-04T00:00:00 |
| Awarded Institution | Illinois Institute of Technology |
| Facility | Materials Research Collaborative Access Team (MRCAT) |
| Facility Tech Lead | Jeff Terry, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Yaqiao Wu |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 541 |