Polonium in the Earth's crust are not harmful. Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers. Because it is present in small concentrations, isolation of polonium from natural sources is a tedious process. The largest batch of the element ever extracted, performed in the first half of the 20th century, contained only (9 mg) of polonium-210 and was obtained by processing 37 tonnes of residues from radium production. Polonium is now usually obtained by irradiating bismuth with high-energy neutrons or protons. In 1934, an experiment showed that when natural Bi is bombarded with neutrons, Bi
Polonium In the United States, polonium was produced as part of the Manhattan Project's Dayton Project during World War II. It was a critical part of the implosion-type nuclear weapon design used in the Fat Man bomb on Nagasaki in 1945. Polonium and beryllium were the key ingredients of the 'urchin' detonator at the center of the bomb's spherical plutonium pit. The urchin ignited the nuclear chain reaction at the moment of prompt-criticality to ensure the bomb did not fizzle. Much of the basic physics of polonium was classified until after the war. The fact that it was used as an