In addition, 7Li, Be, and F are among the few nuclides with low enough thermal neutron capture cross-sections not to poison the fission reactions inside a nuclear fission reactor.
Herudover er 7Li, Be og F blandt de få nuklider, der har så lavt neutron-tværsnit, at de ikke forgifter fissionsreaktionerne inde i kernefissionsreaktoren.