Kory Linton

Tristructural-isotropic (TRISO)–coated particle fuel is a promising advanced fuel concept being considered for several advanced reactor applications and for accident-tolerant fuel for light water reactors. One of the aspects studied in the development of this advanced fuel concept is the release of specific fission products (Ag, Eu, and Sr). The silicon carbide (SiC) layer of TRISO fuel serves as the primary barrier to metallic fission products and actinides not retained in the fuel kernel. The goal of this project is to evaluate the effect of irradiation on the diffusion of these fission products in the SiC layer of the fuel. For this purpose, rabbit capsules containing small slab diffusion couple specimens have been assembled to be irradiated in the High Flux Isotope Reactor (HFIR). The diffusion couple specimens have been fabricated using similar processes and equipment as those used to make TRISO particles; the desired fission products have been implanted in the specimens using an ion accelerator. Moreover, the effect of temperature on the fission products diffusion will be studied separately by performing thermal experiments in the absence of irradiation. This report describes the irradiation experiment design concept, summarizes the irradiation test matrix, and reports on the successful assembly of two rabbit capsules that will be irradiated in the HFIR.

This document outlines the irradiation of silicon carbide cladding tube specimens in the High Flux Isotope Reactor at Oak Ridge National Laboratory. The cladding tube specimens consisted of monolithic, composite, and coated SiC specimens in order to test the effect of these various materials on the overall cladding performance during irradiation. A total of 18 specimens were irradiated for one cycle, with 9 specimens irradiated at low heat flux conditions and 9 specimens at high heat flux conditions. The specimens were inserted in cycle 475 in September 2017 and reached an average irradiation dose of approximately 2.6 dpa.

This report provides a summary of the irradiation vehicle design and thermal analysis of absorber material specimens planned for irradiation in the flux trap of the High Flux Isotope Reactor (HFIR). Four different absorber materials will be inserted in the same capsule: hafnium carbide without additive (HfC), hafnium carbide with molybdenum silicide additive (HfC + MoSi2), samarium hafnate (Sm2HfO5), and europium hafnate (Eu2HfO5). The capsule design, with target temperatures of 300°C, will accommodate twelve specimens. Two capsules are planned to be built and irradiated to two different neutron fluence levels

This report provides a summary of the irradiation vehicle design and thermal analysis of SiC joint specimens planned for irradiation in the flux trap of the High Flux Isotope Reactor (HFIR). Two different capsule designs will be used to accommodate the two different specimen geometries: a small torsion joint specimen geometry to measure mechanical and thermal properties, and joint end plug representative cladding geometry to demonstrate strength and integrity. The capsule designs, with target temperatures of 350°C ± 50°C and 750°C ± 50°C, will accommodate either sixteen torsion joint specimens or one joint end plug specimen. Three joint variations will be studied in each capsule design: a hybrid SiC (preceramic polymer with chemical vapor deposition (CVD) SiC), a transient eutectic phase (TEP) process, and an oxide process.