S: (n) decay, radioactive decay, disintegration (the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation)
S: (n) chain reaction (a self-sustaining nuclear reaction; a series of nuclear fissions in which neutrons released by splitting one atom leads to the splitting of others)
S: (n) decay, radioactive decay, disintegration (the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation)
S: (n) spallation ((physics) a nuclear reaction in which a bombarded nucleus breaks up into many particles) "some astronomers believe that the solar system was formed by spallation when the sun was a very young star"