Microstructural Characterization of the U-9.1Mo Fuel/AA6061 Cladding Interface in Friction-Bonded Monolithic Fuel Plates Irradiated in the RERTR-6 Experiment

Journal Article · Thu Sep 03 00:00:00 EDT 2015 · Metallurgical and Materials Transactions. E, Materials for Energy Systems

DOI:https://doi.org/10.1007/s40553-015-0055-8· OSTI ID:1294282

Keiser, Dennis D. ^[1]; Jue, Jan-Fong ^[1]; Miller, Brandon ^[1]; Gan, Jian ^[1]; Robinson, Adam ^[1]; Medvedev, Pavel ^[1]; Madden, James ^[1]; Wachs, Dan ^[1]; Clark, Curtis ^[1]; Meyer, Mitch ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States). Nuclear Fuels and Materials Division

Low-enrichment (U-235 < 20%) U-Mo monolithic fuel is being developed for use in research and test reactors. The earliest design for this fuel that was investigated via reactor testing was comprised of a nominally U-10Mo fuel foil encased in AA6061 (Al-6061) cladding. For a fuel design to be deemed adequate for final use in a reactor, it must maintain dimensional stability and retain fission products throughout irradiation, which means that there must be good integrity at the fuel foil/cladding interface. To investigate the nature of the fuel/cladding interface for this fuel type after irradiation, fuel plates that were tested in INL's Advanced Test Reactor (ATR) were subsequently characterized using optical metallography, scanning electron microscopy, and transmission electron microscopy. Results of this characterization showed that the fuel/cladding interaction layers present at the U-Mo fuel/AA6061 cladding interface after fabrication became amorphous during irradiation. Up to two main interaction layers, based on composition, could be found at the fuel/cladding interface, depending on location. After irradiation, an Al-rich layer contained very few fission gas bubbles, but did exhibit Xe enrichment near the AA6061 cladding interface. Another layer, which contained more Si, had more observable fission gas bubbles. Adjacent to the AA6061 cladding were Mg-rich precipitates, which was in close proximity to the region where Xe is observed to be enriched. In samples produced using a focused ion beam at the interaction zone/AA6061 cladding interface were possible indications of porosity/debonding, which suggested that the interface in this location is relatively weak.

• Research Organization: Idaho National Laboratory, Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 1294282
• Report Number(s): INL/JOU--14-32654; PII: 55
• Journal Information: Metallurgical and Materials Transactions. E, Materials for Energy Systems, Journal Name: Metallurgical and Materials Transactions. E, Materials for Energy Systems Journal Issue: 3 Vol. 2; ISSN 2196-2936
• Publisher: ASM International
• Country of Publication: United States
• Language: English

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