protective zirconium cladding can affect a fuel’s ability to transfer heat. Two new ATR experiments include the Tritium Producing Burnable Absorber Rod Materials Irradiation Separate- Effects Test and a Lithium Aluminate Capsule Experiment (LACE) for Pacific Northwest National Laboratory and Savannah River National Laboratory. 21 Testing fast reactor fuels in ATR Fast reactors could use uranium resources more efficiently and can greatly reduce the amount and the hazards of used fuel that has to be disposed. But domestic research on fast reactor fuel is challenging because the U.S. doesn’t have a fast reactor available for testing. INL is leading a national initiative to design a new Versatile Fast Test Reactor to re-establish this important capability for the long term. In the meantime, INL researchers conducted fuel tests under modified conditions in ATR that can reproduce important aspects of a fast reactor environment. Comparison of samples irradiated in the modified ATR conditions and those irradiated in a French fast reactor showed that these conditions could be used on a stop-gap basis to begin some development and testing of proposed fast reactor fuels. Supporting diverse nuclear energy experiments Experiments at ATR include Advanced Graphite Characterization for materials that will be used in advanced reactors, an Advanced Fuels Campaign to develop new types of nuclear fuel and Electric Power Research Institute studies to better understand how the Researchers are using high magnification images to study the radial (as marked) microstructural zonesof this fuel sample irradiated in a French fast reactor.