Heavy metals is improved with the addition of thorium. Tellurium is added to copper and steel alloys to improve their machinability; and to lead to make it harder and more acid-resistant. The biocidal effects of some heavy metals have been known since antiquity. Platinum, osmium, copper, ruthenium, and other heavy metals, including arsenic, are used in anti-cancer treatments, or have shown potential. Antimony (anti-protozoal), bismuth (anti-ulcer), gold (anti-arthritic), and iron (anti-malarial) are also important in medicine. Copper, zinc, silver, gold, or mercury are used in antiseptic formulations; small amounts of some heavy metals are used to control algal growth in, for example,
Fuel element failure Fuel element failure A fuel element failure is a rupture in a nuclear reactor's fuel cladding that allows the nuclear fuel or fission products, either in the form of dissolved radioisotopes or hot particles, to enter the reactor coolant or storage water. The "de facto" standard nuclear fuel is uranium dioxide or a mixed uranium/plutonium dioxide. This has a higher melting point than the actinide metals. Uranium dioxide resists corrosion in water and provides a stable matrix for many of the fission products; however, to prevent fission products (such as the noble gases) from leaving the uranium dioxide matrix and