Arun Devaraj¹, Bethany Mathews¹, Bruce Arey¹, Elizabeth Kautz¹, Danny J Edwards¹, Gary Sevigny¹, David J Senor¹; ¹Pacific Northwest National Laboratory

Tritium, a hydrogen isotope of significant importance, is generated by neutron irradiation of Tritium Producing Burnable Absorber Rods (TPBARs), which are specifically designed to produce and capture tritium. Inside each TPBAR there are lithium aluminate pellets, enriched in 6Li, that produces tritium upon neutron irradiation. Tritium is then absorbed by a Zircaloy-4 getter tube that surrounds the LiAlO2 pellet. These components are encapsulated inside a stainless steel cladding. Most traditional characterization methods including electron microscopy and diffraction studies using X-rays do not have sufficient sensitivity or spatial resolution needed for understanding how the distribution of various elements in each component gets redistributed under neutron irradiation, especially when it comes to light elements. Hence in this work we utilized Atom probe tomography correlated with electron microscopy to systematically analyze the solute distribution in both as-fabricated and neutron irradiated TPBAR components to obtain a comprehensive understanding of the microstructural evolution under irradiation.