Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Fracture behavior of irradiation induced nanocrystalline UO2 studied by in-situ mechanical testing in transmission electron microscopy

Journal Article · · Journal of Nuclear Materials
Uranium Dioxide (UO2) is widely used as a fuel in current light water reactors (LWRs). Upon accumulation of radiation damage, LWR UO2 fuel pellets start to develop a different microstructure at the pellet periphery when fuel burnup exceeds 45–50 GWd/tHM. The resulting porous, nanocrystalline microstructure is one of the most prominent microstructural changes occurring in such fuel. Its fracture mechanisms, which causes fuel fine fragmentation, could impact safety limits when the cladding breaches. Direct measurements of these properties are challenging, therefore a surrogate obtained via ion irradiation can be used. In this study, multiple microcantilevers were fabricated by focused ion beam from both fresh UO2 and UO2 irradiated with 84 MeV Xe26+ ions to a peak dose of 1357 displacements per atom (dpa). Further, the irradiation produced a pseudo high burnup structure approximately 2 µm below the surface. In-situ nano-mechanical bending tests were conducted to investigate the fracture behavior and the effect of the surrogate UO2 high burnup structure on local fracture properties. Fresh UO2 fuel was observed to fracture in transgranular mode without nucleation or movement of dislocations. However, the Xe-irradiated nanocrystalline microcantilevers fractured along the grain boundaries, with no influence from the pre-existing micro-cracks in the microcantilever. Fracture toughness for this type of surrogate high burnup UO2 structure is reported for the first time in literature. Both the fracture stress and toughness show degradation for UO2 as a result of Xe-irradiation.
Research Organization:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Organization:
USDOE Office of Nuclear Energy (NE)
Grant/Contract Number:
AC07-05ID14517
OSTI ID:
2530542
Alternate ID(s):
OSTI ID: 2483782
Report Number(s):
INL/JOU--24-80354-Rev000
Journal Information:
Journal of Nuclear Materials, Journal Name: Journal of Nuclear Materials Vol. 605; ISSN 0022-3115
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (33)

In-Situ Transmission Electron Microscopy Microcantilever and Nanoindentation Testing of UO2 journal March 2020
Grain Boundary and Lattice Fracture Toughness of UO2 Measured Using Small-Scale Mechanics journal March 2020
The surface energy of UO2 as determined by hertzian indentation journal June 1980
Oxide fuel transients journal July 1989
On the rim effect in high burnup UO2LWR fuels journal July 1992
Nuclear Fuels book January 2012
Transmission electron microscopy observation on irradiation-induced microstructural evolution in high burn-up UO2 disk fuel journal May 2002
Mechanical properties of (U,Ce)O2 journal June 1998
The high burn-up structure in nuclear fuel journal December 2010
A US perspective on fast reactor fuel fabrication technology and experience. Part II: Ceramic fuels journal August 2009
Mechanical characteristics of SiC coating layer in TRISO fuel particles journal November 2013
Small-scale characterisation of irradiated nuclear materials: Part II nanoindentation and micro-cantilever testing of ion irradiated nuclear materials journal July 2015
Experimental characterization and modeling of UO 2 grain boundary cracking at high temperatures and high strain rates journal May 2015
Model for evolution of grain size in the rim region of high burnup UO2 fuel journal April 2016
Micro-scale fracture experiments on zirconium hydrides and phase boundaries journal July 2016
On the damage and fracture of nuclear graphite at multiple length-scales journal September 2017
Nano- and micro-indentation testing of sintered UO2 fuel pellets with controlled microstructure and stoichiometry journal April 2019
Elevated temperature microcantilever testing of fresh U-10Mo fuel journal December 2019
Irradiation effects on the fracture properties of UO2 fuels studied by micro-mechanical testing journal August 2020
Fracture properties of an irradiated PWR UO2 fuel evaluated by micro-cantilever bending tests journal September 2020
The formation mechanisms of high burnup structure in UO2 fuel journal December 2021
Micro-cantilever beam experiments and modeling in porous polycrystalline UO2 journal December 2021
The effects of radiation-induced grain subdivision and dislocations on the fracture properties of uranium dioxide journal April 2023
Grain subdivision and structural modifications by high-energy heavy ions in UO2 with different initial grain size journal March 2022
Micro mechanical testing of candidate structural alloys for Gen-IV nuclear reactors journal August 2018
Small-scale mechanical testing on nuclear materials: bridging the experimental length-scale gap journal January 2018
Nano-crystallization induced by high-energy heavy ion irradiation in UO2 journal October 2018
Thermally-Conductive and Mechanically-Robust Graphene Nanoplatelet Reinforced UO2 Composite Nuclear Fuels journal February 2018
Grain boundary plasticity initiated by excess volume journal March 2024
Room temperature dislocation plasticity in silicon journal January 2005
Grain growth and pore coarsening in dense nano‐crystalline UO 2+ x fuel pellets journal March 2017
Grain Boundary-Mediated Plasticity in Nanocrystalline Nickel journal July 2004
Measuring fracture toughness of coatings using focused-ion-beam-machined microbeams journal February 2005

Similar Records

Nano-crystallization induced by high-energy heavy ion irradiation in UO2
Journal Article · Wed May 02 20:00:00 EDT 2018 · Scripta Materialia · OSTI ID:1467638

The Width of High Burnup Structure in LWR UO{sub 2} Fuel
Conference · Sun Jul 01 00:00:00 EDT 2007 · OSTI ID:21229295

Grain Boundary and Lattice Fracture Toughness of UO2 Measured Using Small-Scale Mechanics
Journal Article · Sun Mar 15 20:00:00 EDT 2020 · JOM. Journal of the Minerals, Metals & Materials Society · OSTI ID:1615789