b'In situ high temperatureHigh temperature radiation-induced aqueous metal ion reaction radiation-induced metalkinetics and steady-state speciation enable modeling extreme cation redox chemistry environments found throughout the nuclear fuel cycle.A queous systems at elevated temperatures containing dissolved metal ions from the corrosion of stainless steels and other alloys are exposed to ionizing radiation fields throughout the nuclear fuel cycle. Ionizing radiation breaks the solvent down into highly reactive oxidizing and reducing species that drive changes in the oxidation states of metal ions, which determine their chemical properties, including solubility, complexation, and reactivity. Therefore, PROJECT NUMBER: understanding the aqueous radiation chemical behavior of metal ions from key 21P1056-002FP alloying materials, such as iron and chromium, is critical to model and monitor TOTAL APPROVED AMOUNT:the performance of several processes, such as the corrosion of nuclear reactor $460,000 over 3 years materials, the extent of extraction in used nuclear fuel reprocessing systems, and the partitioning of materials for vitrification in nuclear waste storage. Despite the PRINCIPAL INVESTIGATOR:importance and prevalence of these radiation-induced reactions, only two reactions Jacy Conrad between the primary radiolysis products of water and dissolved iron or chromium CO-INVESTIGATOR: ions were reported above 100C prior to this project. Here, we addressed this critical Gregory Holmbeck, INL knowledge gap by studying the radiation chemistry of iron and chromium ions in aqueous solution via a combination of kinetic measurements using high temperature COLLABORATORS: (up to 325C) time-resolved electron pulse radiolysis and steady-state changes in California State University Long Beach metal ion redox distribution using gamma irradiations over a wide temperature Canadian Nuclear Laboratories range (37195C) facilitated by a custom-built vessel designed and benchmarked University of Notre Dame Radiation Laboratory by this project. Time-resolved and steady-state data are essential to development multiscale computational models that can predict these metal ion systems behavior from ambient to hydrothermal conditions in radiation environments. Overall, this project produced four publications in peer reviewed journals with plans to submit three more publications. In addition, two undergraduate students were mentored during this project, and strong collaborations with the University of Notre Dame Radiation Laboratory, Canadian Nuclear Laboratories, and California State University Long Beach resulted.66'