1. (physics) a nuclear reaction in which a bombarded nucleus breaks up into many particles; - Example: "some astronomers believe that the solar system was formed by spallation when the sun was a very young star"
WordNet (r) 3.0 (2006):
spallation
n 1: (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"