NSUF 24-5050: Mechanical Assessment of Pd Corroded Surrogate and Irradiated TRISO Particles

Pd, a high yield fission product, has been shown to migrate and cluster throughout the kernel, OPyC, SiC, and IPyC layers in TRISO particles especially at rapid diffusion sites such as grain boundaries and layer interfaces. Collection of Pd in and around the SiC layer leads to degradation through the formation of Pd silicides and free carbon. As such, Pd corrosion of the SiC layer is expected to have deleterious effects on the mechanical performance of this layer. However, little work has been done to evaluate the effects of Pd corrosion on the mechanical performance of the SiC or the PyC-SiC interlayers. The existing investigations are typically conducted on post irradiated specimens, but neutron irradiation is challenging because of irradiation time requirements, hazards associated with handling radioactive materials, and limited access to neutron irradiation sources. The mechanical investigation of surrogates is an attractive alternative because challenges associated with neutron irradiated samples do not exist. A necessary first step to evaluating the mechanical behavior of neutron irradiated specimens through the investigation of surrogate materials, is determining whether surrogate mechanical data is representative of neutron irradiated sample behavior. This study aims to determine the relevance of surrogate mechanical data to actual neutron irradiated specimen behavior through SEM in situ tensile experiments and the comparison of as received, surrogate, and neutron irradiated SiC-PyC interlayer mechanical results. The as received and surrogate samples to be used in this study are composed of ZrO2, graphite, and SiC while the MNT64X sample irradiated in AGR 2 is composed of UO2, graphite, and SiC. Surrogate sample Pd attack was driven by Pd sputtering and heat treatment while Pd attack in the irradiated samples were driven by neutron irradiation. The study will require 52 hours which includes approximately 45 hours to prepare samples and approximately 7 hours to carry out tensile tests. This work will begin when the grant is awarded, and completion will depend on the availability of equipment. However, sample preparation and experimentation should require no more than two normal working weeks. These experiments will provide valuable information regarding the use of surrogate specimens in place of neutron irradiated specimens and may lead to more efficient, less costly experiments in the future.

Additional Info

Field	Value
Award Announced Date	2024-08-15T09:37:30.137
Awarded Institution	University of Texas-San Antonio
Facility Tech Lead	Alina Montrose
Irradiation Facility
PI	Patrick Warren
PI Email	[email protected]
Project Type	RTE
RTE Number	None