Year: 2014
Type: article
Abstract: Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.
Source: Science
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Awards: G102163711, G107546177, G1286251239, G1313983767, G1664757510, G222768804, G262962599, G3075337988, G3481190060, G3911607298, G426311843, G4580848188, G4964081289, G5139110328, G5387317844, G5648016710, G6848031779, G7583137537, MANIPULATION OF SAMPLES AT EXTREME TEMPERATURES FOR FAST IN-SITU SYNCHROTRON MEASUREMENTS, G969889393
OpenAlex ID: W2013734093