Protactinium

Definition

Protactinium is a chemical constituent with the symbol Pa and atomic number 91. Its longest-lived and most rich naturally-occurring isotope by far, Pa-231, is a decompose produce of uranium-235 (U-235), and it has a half-life of 32,760 years.

Application

Protactinium-231 is shaped by the alpha decay of U-235 follow by beta decay of thorium-231. The physicist Walter Seifritz once probable that protactinium might perhaps be used to build a nuclear weapon with a critical mass of 750±180 kg. This option has been ruled out by other nuclear physicists since then.