Overview

The degradation of thermomechanical performance of nuclear fuels results from the cumulative fission-damage processes, mechanical stress and high temperatures and temperature gradients. The scientific basis for connecting structure across the length and time scales with the thermal and mechanical behavior of fuel is largely lacking. The Center for Materials Science of Nuclear Fuel (CMSNF), an Energy Frontier Research Center (EFRC) funded by DOE’s Office of Basic Energy Sciences, fills a key part of this science gap by developing predictive multiscale models for defects and microstructure physics and thermal transport in highly defective uranium dioxide, with closely correlated experiments on commensurate length and time scales.

The center will enrich the scientific basis of thermal transport in the ceramic materials (UO2) used as nuclear fuel, based on an understanding of phonon transport through the unique microstructures formed under radiation at high temperature. The objectives can be broadly classified as thermal transport and microstructure science under irradiation as illustrated below:

 

 The research objective of the thermal transport thrust area is to develop a computational model for thermal transport in irradiated materials with complex defect structures and to conduct lattice dynamics and conductivity measurements targeting the impact of defects on thermal transport.

The research objective of the microstructure science under irradiation thrust area is to develop predictive capabilities for defects and microstructure evolution in irradiated fuels and to conduct irradiation and microstructure characterization experiments to understand defect and microstructure processes in UO2 and surrogate systems.

The short-term objectives of the Center are to address a set of key scientific questions, click each question to learn more!

  1. how anharmonicity determines phonon dispersion, phonon lifetimes, and thermal transport as a function of temperature in pure single crystal UO2,
  2. how grain boundaries, dislocations, and interfaces, affect thermal transport,
  3. what types of defect clusters are produced in UO2 by irradiation and what are the energies and kinetic paths for their formation,
  4. what is the impact of temperature and local oxygen environment on the stoichiometry of UO2, and
  5. how do voids form and grow in irradiated UO2 and what is the effect of free surfaces on defect migration?

Addressing each question requires the formation of a team of experimental and computational experts from across the country to advance the understanding of each of these key scientific questions. The Center brings together an internationally renowned, multi-institutional team of experimentalists (Idaho National Laboratory, Oak Ridge National Laboratory, Colorado School of Mines, University of Florida, and the University of Wisconsin) and computational materials theorists (Idaho National Laboratory, University of Florida, and Purdue University). Currently the Center is led by director Todd Allen.