b'Demonstrating fueled-saltThe project established a one-of-a-kind capability for molten irradiation capability tosalt irradiation and used it to conduct the first enriched support reactor deployment uranium-bearing chloride salt irradiation in history.M olten salt reactors have garnered increasing interest in recent years with several upcoming demonstration efforts. They are expected to provide simplified, passively safe, carbon free nuclear energy with a drastically reduced waste footprint. A key challenge to licensing these reactors is the lack of experimental data on fueled salts. While several efforts have been undertaken in the recent decade to reestablish molten salt irradiation capabilities, none is able to PROJECT NUMBER:test salt with enriched uranium fuel. To address this gap, a new experiment vehicle 21A1050-016FP was developed at INL as part of this project. The Molten salt Research Temperature-TOTAL APPROVED AMOUNT:controlled Irradiation (MRTI) experiment can host an enriched uranium-bearing $2,648,000 over 3 years salt sample inside the INL Neutron Radiography reactor. One of the key scientific objectives was to provide irradiated salt samples for post-irradiation examination PRINCIPAL INVESTIGATOR:to study the impact of fission product generation and neutron/gamma radioactivity Abdalla Abou-Jaoude on the salt solution and salt-facing wall material. As a first demonstration of this CO-INVESTIGATORS: capability, the MRTI experiment used enriched uranium-bearing chloride salt. This Chuting Tsai, INL type of salt had never been irradiated in a reactor prior to this project. To accomplish Gregory Core, INL this historic first, the project developed detailed engineering analyses and conducted William Phillips, INL the necessary reviews to obtain facility approvals to conduct the experiment. A prototype was fabricated and tested outside the reactor and lessons learned were incorporated into the final experiment. Then, 13 cm3 of enriched uranium chloride salt were synthetized and loaded into this final experiment vehicle. Irradiation of the MRTI experiment commenced in Neutron Radiography reactor on August 21, 2023. The projected power density from the experiment was calculated to be at 20 W/cm. Throughout the irradiation, the salt temperature was maintained around the target of 575C via a controller. While this project achieved its goal of demonstrating the novel salt irradiation capability, follow-on programs will complete the originally planned post-irradiation examination activities. The irradiation is critical to several United States vendors developing fast molten salt reactor concepts, including Terrapower, Southern Company, Moltex, and Exodys. Additionally, several other molten salt reactor vendors have signed agreements to leverage this new capability to irradiate their distinct salt compound.24'