Associations of Pd, U and Ag in the SiC layer of neutron-irradiated TRISO fuel
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
Knowledge of the associations and composition of fission products in the neutron irradiated SiC layer of high-temperature gas reactor TRISO fuel is important to the understanding of various aspects of fuel performance that presently are not well understood. Recently, advanced characterization techniques have been used to examine fuel particles from the Idaho National Laboratory’s AGR-1 experiment. Nano-sized Ag and Pd precipitates were previously identified in grain boundaries and triple points in the SiC layer of irradiated TRISO nuclear fuel. Continuation of this initial research is reported in this paper and consists of the characterization of a relatively large number of nano-sized precipitates in three areas of the SiC layer of a single irradiated TRISO nuclear fuel particle using standardless EDS analysis on focused ion beam-prepared transmission electron microscopy samples. Composition and distribution analyses of these precipitates, which were located on grain boundaries, triple junctions and intragranular precipitates, revealed low levels, generally <10 atomic %, of palladium, silver and/or uranium with palladium being the most common element found. Palladium by itself, or associated with either silver or uranium, was found throughout the SiC layer. A small number of precipitates on grain boundaries and triple junctions were found to contain only silver or silver in association with palladium while uranium was always associated with palladium but never found by itself or in association with silver. Intergranular precipitates containing uranium were found to have migrated ~23 μm along a radial direction through the 35 μm thick SiC coating during the AGR-1 experiment while silver-containing intergranular precipitates were found at depths up to ~24 μm in the SiC layer. Also, Pd-rich, nano-precipitates (~10 nm in diameter), without evidence for the presence of either Ag or U, were revealed in intragranular regions throughout the SiC layer. Because not all grain boundaries and triple junctions contained precipitates with fission products and/or uranium, along with the differences in migration behavior between Pd, Ag and U, it was concluded that crystallographic grain boundary and triple junction parameters likely influence migration behavior.
- Research Organization:
- Tampere Univ. of Technology (Finland)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- DOE Contract Number:
- AC07-05ID14517
- OSTI ID:
- 1177608
- Report Number(s):
- INL/JOU-14-33248; TRN: US1500049
- Journal Information:
- Journal of Nuclear Materials, Vol. 460; ISSN 0022-3115
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
Similar Records
Investigation of the Distribution of Fission Products Silver, Palladium and Cadmium in Neutron Irradiated SIC using a Cs Corrected HRTEM
Progress in Solving the Elusive Ag Transport Mechanism in TRISO Coated Particles: What is new?
Related Subjects
SILICON CARBIDES
GRAIN BOUNDARIES
NUCLEAR FUELS
PALLADIUM
SILVER
URANIUM
NEUTRONS
PRECIPITATION
FISSION PRODUCTS
LAYERS
IDAHO NATIONAL LABORATORY
IRRADIATION
TRANSMISSION ELECTRON MICROSCOPY
TEMPERATURE RANGE 1000-4000 K
NANOPARTICLES
COATED FUEL PARTICLES
PERFORMANCE
Materials Characterization
AGR
EDS
FUEL
STEM
TRISO