Novel use of a hand-held laser induced breakdown spectroscopy instrument to monitor hydride corrosion in uranium

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy Vol. 159; no. C; p. 105651
• Main Authors: Garlea, E., Bennett, B.N., Martin, M.Z., Bridges, R.L., Powell, G.L., Leckey, J.H.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.09.2019; Elsevier BV; Elsevier
• Subjects: Ablation; Analytical methods; Bulk sampling; Carbon; Control equipment; Corrosion; Damage assessment; Depleted uranium; Glove boxes; Hand-held LIBS; High temperature; High temperature effects; Hydride corrosion; Hydrides; Hydrogen; hydrogen embrittlement; Hydrogen storage; Laser ablation; Laser damage; Laser induced breakdown spectroscopy; Lasers; Light microscopy; MATERIALS SCIENCE; Microscopy; NUCLEAR PHYSICS AND RADIATION PHYSICS; Optical microscopy; Oxidation; Oxidation process; Oxygen; Oxygen content; Radioisotopes; Spectroscopy; Spectrum analysis; Surface damage; Surface damage, hydrogen embrittlement; Temperature effects; Uranium; Hand-held LIBS; Uranium; Surface damage, hydrogen embrittlement; Hydride corrosion; Laser-induced breakdown spectroscopy
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/j.sab.2019.105651

Using a compact hand-held laser-induced breakdown spectroscopy (LIBS) instrument, studies were conducted on specimens of uranium charged with controlled hydrogen concentrations for a qualitative evaluation of hydride corrosion. Four samples of depleted uranium with two different starting microstructures (cast and rolled) were used for this study. The hydrogen charged samples (rolled 1.8 wppm H and cast 14 wppm H by weight) are representative of the pre-corrosion states with hydrides distributed throughout the bulk. In-depth LIBS measurements were carried out, after the thick surface corrosion layer was removed, by applying 100 laser pulses from sample surface into the bulk on five different sample locations. Three additional areas on each sample were studied by laser ablation using a 12-point grid approach. The atomic emission signals of elemental uranium, carbon, hydrogen, and oxygen were identified and analyzed. All four samples showed similar uranium and carbon concentrations, as expected. Hydrogen content was consistent with each sample's specification, such that the hydrogen charged samples exhibited higher hydrogen concentration than their references. Both specimens charged with hydrogen showed elevated oxygen content as well, due to rapid oxidation of uranium and uranium hydrides. The oxidation process was facilitated by the laser ablation and plasma plume's high temperature effects on the sample combined with the glovebox environment. The uranium surface damage produced by laser ablation was quantitatively evaluated by optical microscopy. [Display omitted] •Compact hand-held LIBS instrument (eye safe system) for UH3 corrosion studies from surface into bulk of sample•Samples in pre-corrosion states prepared by hydrogen charging with controlled hydrogen concentration•Quantitative evaluation of uranium surface damage from laser ablation•Consistent variation in atomic emission signal for hydrogen with sample's state•Systematic increase in oxygen peak intensity (concentration) associated with oxidation of uranium and UH3