Lead. (Source: © serikbaib / stock.adobe.com)

A chemical element with atomic number 82. Lead is a gray, heavy metal with a relatively low melting point (327 °C). Lead is toxic and has a very high density (11 g/cm³). It is an easily available metal with a wide range of usage. Because of its ability to absorb gamma radiation and X-rays, it is commonly used as shielding in nuclear facilities. For example, the protective aprons worn by X-ray technicians are made from lead. Lead has the highest atomic number of all stable elements. Three decay series (uranium, thorium, and actinium) end with lead.

Lead-cooled fast neutron reactors use molten lead or lead-bismuth eutectic as a coolant.