b'Figure 2. Ellingham diagram for nitride formation of uranium and several candidate waterproofing concepts. Results showed that Zr, Al, Ti, and Y were prone to reaction with nitrogen to form nitrides at the cost of UN, while Cr, Si, and Fe were likely to remain metallic.0.1 ppm; once the desired tempera- exhibited adherent oxide layers. ture was reached, the steam/argonAlthough significant mass gain was mixture was flowed through themeasured for Y metal, its oxide was system and sample mass change asadherent. It was observed that Cr, a function of temperature and timeSi, APMT, and SiC exhibited the best was recorded. Results of the steamresistance to corrosion (little-to-no oxidation testing are shown inmass gain). Based on these results, Figure 1. Results showed that, asidechemical compatibility testing was from sponge Zr, all the materialsperformed between UN and Y, Cr, Si, and SiC.56 2019|AFC ACCOMPLISHMENTS'