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Prepared for the 18th Official Meeting of the VHTR Fuel and Fuel Cycle Project Management Board
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Prepared for the 18th Official Meeting of the VHTR Fuel and Fuel Cycle Project Management Board
In past work, an effective diffusivity coefficient was determined for Ag transport through the silicon carbide layer of a tristructural isotropic fuel particle. The effective diffusivity coefficient accounts for the microstructure of the silicon carbide and includes both bulk diffusion and grain boundary diffusion of Ag. In this report, the model has been improved by accounting for the enhanced concentration of vacancies in the bulk due to irradiation, which substantially influence bulk diffusivity at low temperatures. To improve the BISON model and make it fission rate dependent, effective diffusivity calculations have been performed that incorporate the radiation modified bulk diffusivity. The microstructure and irradiation-dependent effective diffusivity has also been implemented into BISON, and its predictions for Ag release from tristructural isotropic fuel have been successfully compared to AGR-1 post irradiation measurements. Moreover, a new feature has been developed in the Multiphysics Object-Oriented Simulation Environment (MOOSE) to account for different grain boundary types. The Ag diffusivity in 5 (210)/[001] grain boundaries has been computed and was found to be greater than in random high-angle grain boundaries. The presence of the fission product Pd can also have an important effect on the properties of the silicon carbide layer in tristructural isotropic particles. The penetration of Pd into the silicon carbide layer causes a corrosion reaction that can lead to the failure of the silicon carbide layer; however, this corrosion reaction is not well understood. To enable an improved understanding of the mechanism, ab-initio molecular dynamics simulations of Pd interaction with bulk silicon carbide have been performed. The improved understanding of the reaction will form a basis for future improvements to the BISON’s Pd penetration failure model
A review of analysis work done on the AGR 3/4 experiment transport profiles July 2022-July 2023. Graphite ring modeling and transport barriers discussed. Powerpoint presentation
This plan describes the post irradiation examination (PIE) activities to be performed by Oak Ridge National Laboratory (ORNL) on irradiated Compact 5-6-2 taken from the Advanced Gas Reactor (AGR) experiment, AGR 5/6/7. This work will be performed in accordance with the general objectives outlined in the AGR 5/6/7 PIE Plan and guidance in the ORNL PIE Statement of Work.
This report documents the current status of the fuel performance modeling initiative to support the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program in the development of tristructural-isotropic-coated fuel particles. It includes a brief summary of the codes that have been developed to support tristructural isotropic modeling along with a summary of the behavior of fuel particles during irradiation and the modeling used to capture these effects. In addition, this report identifies further modeling and material property needs for further development based on experience from previously performed AGR experiments. In general, the remaining activities to support fuel performance modeling for the AGR program include continued AGR experiment support for AGR-3/4 and AGR-5/6/7 as well as modeling improvements identified throughout the course of the program. These modeling improvements can be summarized as thermomechanical particle behavior and fission product transport. Additional modeling needs may be identified while processing the data collected during the AGR post-irradiation examination campaign and may lead to further improvements that are not included in this report.
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The document is a slide deck meant to be presented to the Nuclear Science User Facilities (NSUF) 2022 Science review board in August 2022.
AGR Program activities for FY24 and future, including DOE Organizational changes impacting AGR Program and future coated particle fuel development.
AGR-5/6/7 goals and test train configuration, status of AGR-5/6/7 mass balance work, preliminary results of Ag-110m, Cs-134, and Eu-154.
Presentation of efforts in the AGR 3/4 PIE/data analysis
Analysis results for AGR 3/4 fission product transport
An overview of work done on the AGR 3/4 PIE experiment is presented, with some modeling results and description of the R-DLBL of as-irradiated and heating test samples
NEAMS fuels modeling for HTGRs: FY24 accomplishments and outlook for FY25
No abstract, presentation is a review on AGR micro tensile specimen analysis for FY 2024.
A presentation on the current status of the AGR 3/4 experiment and its modeling
NEAMS fuels modeling for HTGRs: FY25 accomplishments and outlook for FY26