Sodium Fires are prevented in nuclear reactors by isolating sodium from oxygen with bordering pipes made up of inert gas. Radioactive sodium-24 may very well be made by neutron bombardment in the course of operation, posing a slight radiation hazard; the radioactivity stops in just a couple of days right https://www.tjcyindustrialchem.com/news/sodium-chlorite-uses-and-the-difference-from-chlorine.html