When the nucleus of a fissile atom is hit by a neutron, especially a slow - moving one, it will most likely cleave (fission),
releasing substantial amounts of energy and several other neutrons.
While making the cement that is used for building a cellar does result in a
substantial amount of carbon dioxide being
released into the atmosphere, once constructed the
energy saving over the life
of the cellar will result in a much greater saving
of emissions.