Uranium metal and uranium dioxide are listed as pyrophoric when in "fine powder form" "Indeed, according to one author, normally stable UO2 may be pyrophoric o

Uranium metal and uranium dioxide are listed as pyrophoric when in "fine powder form" "Indeed, according to one author, normally stable UO2 may be pyrophoric or oxidize rapidly even at room temperatures when in very fine powder form (specific surface area >10 sq.m/g). Coarser powders, as is more commonly the case, may require elevated temperatures (>300 C) to oxidize. Cordfunke, E.H.P., The Chemistry of Uranium, Elsevier Publishing Company, 1969. " https://www.nrc.gov/reading-rm/doc-collections/gen-comm/info-notices/1992/in92014.html https://www.nrc.gov/reading-rm/doc-collections/gen-comm/info... SDS: https://www.energy.gov/sites/prod/files/2020/11/f80/SDS-Uranium_Metal_2020.pdf https://www.energy.gov/sites/prod/files/2020/11/f80/SDS-Uran...