NSUF 22-4412: Fission product partitioning behavior in irradiated monolithic U-Mo fuels

A fundamental understanding of the restructuring behavior that occurs during neutron irradiation is crucial to the continued development and behavioral optimization of nuclear materials. Irradiated fuel characterization on the nano- and micro-scale can help to elucidate these fundamental mechanisms driving the fuel’s microstructural evolution. The main objective of this proposed research is to apply scanning electron microscopy (SEM), scanning transmission electron spectroscopy (STEM), and focused ion beam (FIB) techniques to perform a detailed microstructural examination to understand the partition and interactive behavior of fission products once they are formed during neutron irradiation. To that end, post-irradiation examination on the U-10Mo irradiated to medium burnup will be performed. The irradiated microstructure of U-Mo is dominated by micron sized fission gas bubbles distributed randomly throughout the microstructure; therefore, the main features of interest in this project are fission product precipitate morphology and chemistry. FIB/SEM will be used to prepare TEM lamellae from various regions in the parent sample after which STEM will be employed to obtain the chemical morphology and interaction of the fission products at the fission gas pore sites. Chemical analysis using STEM will allow us to discover the interconnected nature and entrapment of the fission products within the pores, which could contribute to breakaway swelling. It is imperative to establish the onset for interconnection of the porosity to better understand the end of life irradiation properties of the U-Mo fuel. As part of this objective, 8 TEM lamellae will be prepared in the FIB/SEM, which will be followed TEM examination of each lamella. The acquired data will provide insight into fission product behavior and its impact on fuel thermal which will then be used as an input to MARMOT.

Additional Info

Field	Value
Abstract	A fundamental understanding of the restructuring behavior that occurs during neutron irradiation is crucial to the continued development and behavioral optimization of nuclear materials. Irradiated fuel characterization on the nano- and micro-scale can help to elucidate these fundamental mechanisms driving the fuel’s microstructural evolution. The main objective of this proposed research is to apply scanning electron microscopy (SEM), scanning transmission electron spectroscopy (STEM), and focused ion beam (FIB) techniques to perform a detailed microstructural examination to understand the partition and interactive behavior of fission products once they are formed during neutron irradiation. To that end, post-irradiation examination on the U-10Mo irradiated to medium burnup will be performed. The irradiated microstructure of U-Mo is dominated by micron sized fission gas bubbles distributed randomly throughout the microstructure; therefore, the main features of interest in this project are fission product precipitate morphology and chemistry. FIB/SEM will be used to prepare TEM lamellae from various regions in the parent sample after which STEM will be employed to obtain the chemical morphology and interaction of the fission products at the fission gas pore sites. Chemical analysis using STEM will allow us to discover the interconnected nature and entrapment of the fission products within the pores, which could contribute to breakaway swelling. It is imperative to establish the onset for interconnection of the porosity to better understand the end of life irradiation properties of the U-Mo fuel. As part of this objective, 8 TEM lamellae will be prepared in the FIB/SEM, which will be followed TEM examination of each lamella. The acquired data will provide insight into fission product behavior and its impact on fuel thermal which will then be used as an input to MARMOT.
Award Announced Date	2022-06-14T07:19:20.767
Awarded Institution	Idaho National Laboratory
Facility	Advanced Test Reactor
Facility Tech Lead	Alina Zackrone
Irradiation Facility	None
PI	Charlyne Smith
PI Email	[email protected]
Project Type	RTE
RTE Number	4412