Machining induced fissures in relation to microstructure of sintered U3Si2 fuel pellets
As uranium silicide (U3Si2) becomes a more desired fuel replacement for uranium dioxide in light water reactors, it is import to understand the fabrication process. Moreover, it is important to understand how the as-sintered microstructure of the fuel pellet affects the final product; uranium silicide fuel pellets are currently fabricated using a powder metallurgy process. Pellet quality and integrity is a concern as any unwanted defects may cause adverse irradiation behavior. Thus, pellets need to remain relatively free of defects (surface chipping, cracking, undesired microstructure, etc.) in order to be placed into a fuel assembly. Recently, it was observed that uranium silicide fuel pellets developed surface fissures on the machined surface after a centerless grinding process. Initial observations indicate a relation between microstructure and machining induced fissures; in essence, fissures on the machined surface are only observed in pellets containing a non-uniform texture (fine grains surrounding coarse grains). Experiments have been focused on determining the cause(s) of the non-uniform texture. Once the cause was determined and grain size was reproduced, samples with a coarse-grained microstructure, along with samples containing a fine-grained microstructure were centerless ground to confirm the relation between surface fissures and microstructure. Samples were also subjected to microscopic analysis, grain size analysis, and x-ray diffraction (XRD).
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- na
- DOE Contract Number:
- AC07-05ID14517
- OSTI ID:
- 1481744
- Report Number(s):
- INL/CON-18-44624-Rev000
- Resource Relation:
- Conference: Top Fuel 2018, Prague, Czech Rebuplic, 09/30/2018 - 10/04/2018
- Country of Publication:
- United States
- Language:
- English
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