Decay chains, natural


The nuclides generated during the decay of the very long-lived natural radionuclides U-238 (half-life 4.5 bn years), U-235 (half-life 0.7 bn years) and Th-232 (half-life 14 bn years) are in turn radioactive, and therefore decay again. Thus, the so-called decay chains are created which end only when a non-radioactive nuclide is formed. The uranium-radium decay chain starts from U-238 and ends via 18 intermediate states at the stable lead-206. Uranium-235 is at the beginning of the uranium-actinium decay chain leading via 15 radionuclides to lead-207. With ten intermediate states, the thorium decay chain starting with thorium-232 and ending at lead-208 is the shortest.

Diagram natural decay chains

Diagram natural decay chains


chain Uranium-actinium chain

Thorium chain








ENS conferences

PIME 2015

PIME 2015
1 - 4 March 2015, Bratislava,Slovakia

RRFM 2015

RRFM 2015
19-23 April 2015,

Topfuel 2015

TopFuel 2015
13-17 Sept. 2015
Zurich, Switzerl.