24 Nuclear Graphite R&D Program INL’s Nuclear Graphite R&D Program, sponsored by DOE-NE, is the largest graphite irradiation study ever attempted. INL plays a worldwide leadership role in the testing and characterization of graphite for nuclear energy applications. Results from the first half of this irradiation study have already contributed significantly to understanding the irradiation performance of graphite and carbon-based materials in nuclear applications. Future results will provide data on fundamental irradiation damage mechanisms, temperature dependence on irradiation damage in graphitic materials, and radiation-induced microstructure evolution in graphite.The significance of the program is evident in its longevity: at 10 years, it is currently the longest running active nuclear materials program at INL. Carbon Characterization Laboratory The Carbon Characterization Laboratory (CCL) was originally designed to support INL’s Nuclear Graphite R&D Program. Over more than eight years, this materials properties testing laboratory has continuously expanded to include graphite, composites, metallic, and ceramic material testing. New capabilities are being added to the laboratory to provide greater capacity in handling low-radiation level materials to assist in current and future university and international collaborations. Characterization capabilities include thermal diffusivity, specific heat, thermal expansion, resistivity, sonic velocity, and elastic modulus of graphite and composite specimens for the HighTemperature Reactor (HTR). Measurement processes are automated with custom user interfaces and barcode sample tracking with all measurements being fully Nuclear Quality Assurance-1 (NQA-1) compliant. ATR Insertion Capsule Assembly Capabilities The department maintains an efficient facility to assemble, in a controlled atmosphere glove box, capsule experiments containing low-level radiation (depleted uranium) or non- radioactive material.The facility maintains an automated welding capability and National Institute of Standards andTechnology (NIST)- traceable instrumentation for determination of gas composition, oxygen content and water vapor content instrumentation. Environmental Effects Laboratory Work in this laboratory has resulted in development of methods for hydriding zirconium, and for studying the effect of hydrides and their orientation on the mechanical properties of nuclear fuel cladding. Other capabilities in this laboratory include a high temperature materials test loop and a mechanical test frame with an environmentally controlled furnace to facilitate the understanding of hydride effects on zirconium cladding. Such understanding provides information for lifetime extension of operating light water reactors, and for safe storage of spent nuclear fuel. Success Stories