APT Data Analysis towards Fission Products in TRISO Fuels
Tristructural isotropic (TRISO) particle is a promising candidate as fuel for high temperature gas reactors (HTGR) and other new generation fuel concepts like accident tolerant fuel for light water reactors. The TRISO coating is part of the HTGR functional containment and critical for the safety strategy for licensing purposes. The microstructure of TRISO particles typically consists of SiC and inner pyrolytic carbon (IPyC) layers, and has been an interesting topic, in particular, the behavior of fission products (FPs), such as Ag, Pd, etc. for many years. Historically, due to equipment and technique resolution limitations on radiological fuel materials, the distribution and behavior of FPs were not fully understood and resolved. Knowledge leapfrogged recently asAg-rich phase and Pd-rich precipitates were found along grain boundaries and inside SiC grains, respectively, by using scanning transmission electron microscopy (STEM) combined with energy dispersive x-ray spectrometry (EDS) and electron energy loss spectrometry (EELS) techniques [1]. However, as the Ag-rich phase and Pd-rich precipitate are much smaller than the STEM sample’s thickness, accurate quantitative analysis is difficult with TEM techniques. Furthermore, it is also extremely difficult to reveal the presence of other FPs in trace quantities. Atom probe tomography (APT) technique has been widely accepted and applied in the field of nuclear science, in particular for irradiated materials (e.g. ODS alloys), to reveal the distribution and composition of nano-sized features. However, there are very limited applications of APT towards studying FPs in fuels. Our preliminary results on neutron irradiated TRISO coated particles reveal a grain boundary containing multiple FPs [2]. This presentation will demonstrate though our study on the TRISO fuel sample how we identified the FPs in the SiC layer of the TRISO coated Particle, and challenged as FPs contains many unstable isotopes that are not shown in the CAMECA Periodic Table of the Isotopes for Atom Probe Tomography.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- DOE-NE
- DOE Contract Number:
- AC07-05ID14517
- OSTI ID:
- 1547324
- Report Number(s):
- INL/CON-19-54006-Rev000
- Resource Relation:
- Conference: APT 2019 User Conference, Fitchburg, Wisconsin, USA, 06/18/2019 - 06/21/2019
- Country of Publication:
- United States
- Language:
- English
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