2018 | AFC ACCOMPLISHMENTS 57 Measurements were made at 250°C and 350°C using an automated method in LabView and done manually at 400°C. Hydrogen pressure was plotted as a function of the hydrogen-to-uranium (H/U) ratio calculated from the moles of hydrogen absorbed.An example plot of such a pressure-composition isotherm for 350°C is given in Figure 2, which shows that the amount of hydrogen absorbed corresponded to an H/U ratio of 0.084.At 250°C, the amount of hydrogen absorbed by U3Si2 was below the detectable limit and is consistent with observations in the steam corrosion at the same temperature, where pellet integrity was maintained and mass gain was minimal.At 400°C, this value increases to 0.9. Under similar temperature and hydrogen pressure, uranium metal will react with hydrogen to form UH3, which has an H/U ratio of 3. Because of this discrepancy, it is hypothesized that the hydride phase that forms is not UH3, though disproportionation of U3Si2 by hydrogen to form UH3 and Si cannot be ruled out. In this case, Si would only increase the barrier for absorption of hydrogen, requiring higher hydrogen pressures to form UH3. How the hydrogen absorption reaction of U3Si2 proceeds is still not yet well understood, nor is the regime wherein this phase significantly contributes to degradation of U3Si2 in steam.To that end, ongoing work will attempt to examine the structure of the hydride phase and temperature above which the hydride phase is no longer stable in steam conditions.Additionally, because the hydrogen absorption reaction did not appear to terminate, future work will focus on higher pressures of hydrogen and comparison with uranium metal under the same conditions.