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Title: Molten uranium dioxide structure and dynamics

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.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [4] ;  [3] ;  [3] ;  [4] ;  [5] ;  [3]
  1. Argonne National Laboratory (ANL), Argonne, IL (United States); Stony Brook Univ., Stony Brook, NY (United States); Materials Development Inc., Arlington Heights, IL (United States)
  2. Stony Brook Univ., Stony Brook, NY (United States)
  3. Argonne National Laboratory (ANL), Argonne, IL (United States)
  4. Materials Development Inc., Arlington Heights, IL (United States)
  5. Carnegie Inst., Washington, DC (United States)
Publication Date:
OSTI Identifier:
1174101
Report Number(s):
BNL--107388-2015-JA
Journal ID: ISSN 0036-8075; R&D Project: LS001
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Science
Additional Journal Information:
Journal Volume: 346; Journal Issue: 6212; Journal ID: ISSN 0036-8075
Publisher:
AAAS
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE