Nuclear Science User Facilities 66 A major finding of this study is that future experiments should be conducted in a differentially pumped vacuum station or through a foil (barrier) that would allow the concrete to be irradiated at pressures closer to ambient.This may eliminate water degassing in a high-vacuum environment that may affect the results prior to the irradiation. A second major finding is that concrete does experience significant volatilization of hydrous components during the irradiation.The volatil- ization may be exacerbated by the vacuum environment.The hydrous bonds are also more sensitive to ionizing radiation as compared to metal-metal or metal-oxygen bonds. This is analogous to damage resulting from electronic stopping in ceramics and other insulating materials. In order to limit volatilization in any cement system tested, the particle flux should be kept below 1×1012 p/cm2 -sec.This flux will limit significant volatilization from the cement. Fluxes greater than this can result in macroscopic failure as seen in the figures below. Using such low fluxes does make it difficult to (i) identify the irradiation area on the target and (ii) perform radiations that simulate long term exposure. Future experiments should use these parameters as starting points for performing irradiations. The investigators would like to acknowledge the outstanding support they received from Mr. Kim Kriewaldt at the University ofWisconsin’s Ion Beam Laboratory.The experiments required many on-the-fly changes to the experimental end station and sample mounting configurations. Mr. Kriewaldt was extremely resourceful in accommodating and supplying fixtures to make the investigation successful. A challenge for future experiments will be performing irradiations and identifying the regions to be irradiated; this may be on the order of a 0.05 mm2 area after the irradiation. The irradiation zone should be identified via scribing or some other mechanism so that post-irradiation characterization can properly identify low fluence irradiations. Not having x and y control of the sample stage limited the ability to perform irradiations without opening the Figure 3. SEM image of irradiated nanocement showing degree of subsurface cracking.