Quiz: Remember the definition of mal de mer?
fission product n.
A usually radioactive isotope produced as a result of the fission of a massive atom such as U235.
in physics, any of the lighter atomic nuclei formed by splitting heavier nuclei (nuclear fission), including both the primary nuclei directly produced (fission fragments) and the nuclei subsequently generated by their radioactive decay. The fission fragments are highly unstable because of their abnormally large number of neutrons compared with protons; consequently they undergo successive radioactive decays by emitting neutrons, by converting neutrons into protons, antineutrinos, and ejected electrons (beta decay), and by radiating energy (gamma decay).