Post-irradiation examination of U-7Mo/Mg and U-10Mo/Mg dispersion fuels irradiated in the NRU reactor

• Published in: Journal of nuclear materials Vol. 558; p. 153343
• Main Authors: Saoudi, Mouna, Barry, Aaron, Lang, Julien, Boyer, Chad, Rogge, Ronald B., Corbett, Stavros, Wang, Xiaolin
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-01-2022; Elsevier BV
• Subjects: Aluminum; Cores; Discharge; Enriched fuel reactors; Fuels; Irradiation; Light microscopy; Low-enriched uranium; Magnesium; Magnesium matrix; Microscopy; Microstructure; Neutron diffraction; Neutron irradiation; Neutron powder diffraction; Neutrons; Nuclear fuel elements; Nuclear fuels; Nuclear reactors; Optical microscopy; Phase composition; Post-irradiation; Post-irradiation examination; Reactors; Research reactor fuel; Uranium; Uranium base alloys; Uranium-molybdenum; Magnesium matrix; Low-enriched uranium; Research reactor fuel; Uranium-molybdenum; Neutron irradiation; Microstructure; Post-irradiation examination; Neutron powder diffraction
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2021.153343

As part of a global initiative to reduce the usage of highly enriched uranium (HEU) fuel for research and test reactors, Al-clad U-7Mo/Mg and U-10Mo/Mg pin-type mini-elements with a low-enriched uranium (U-235 enrichment of 19.75 wt%) loading of 4.5 g U/cm3 were fabricated at the Canadian Nuclear Laboratories (CNL). The mini-elements were irradiated in the National Research Universal (NRU) reactor at maximum linear power ratings of 100 kW/m up to 80 at% U-235 burnup. Hot cell macroscopic examination of the discharged fuel elements at 30, 60 and 80 at% U-235 burnup indicated that they were intact without breakaway swelling or fuel cladding failure. The results of interim post-irradiation examination (PIE) that was conducted on mini-elements discharged at 30 at% U-235 burnup are reported in this paper. A follow-up paper will present the PIE results of the mini-elements that achieved burnups of 60 and 80 at% U-235. In the present study, the microstructure and phase composition of the irradiated U-7Mo/Mg and U-10Mo/Mg fuel cores were investigated using optical microscopy and neutron diffraction analysis. The weight fraction of different crystalline phases in U-7Mo/Mg and U-10Mo/Mg fuel cores at low burnup was determined through Rietveld refinement. This paper includes a description of the irradiation tests along with preliminary PIE results from the irradiated U-Mo/Mg mini-elements and describes the results of optical microscopy characterization and neutron diffraction analysis.