During a nuclear reaction what happens to the outer electrons?

Answer 1

In the case of a nuclear explosion they virtually disappear. The heat created in the immediate vicinity of the fission or fusion (fission-fusion) event is so intense (the energy is so great or the temperature is so high) that no atom can hang onto its electrons. The electrons are all "blown away" in the blast. As the blast expands and the energy "thins out" during the few minutes after the blast, the atoms will all recapture electrons through static means. In the case of nuclear fission in a nuclear reactor, the nucleus of either U235 or Pu239 splits up into two nuclei called the fission fragments. The total number of protons in these two nuclei is the same as in the parent nucleus, so they will require the same total number of electrons to form neutral atoms. The arrangement of the electron shells will be appropriate to the new elements formed. As there is a range of possible combinations of fission fragments there is no one answer, the shell arrangement for each element is different.