NITROGEN-14

'Nitrogen-14' is a stable, non-radioactive isotope of the chemical element nitrogen.
Nitrogen-14 comprises approximately 99% of all naturally formed nitrogen. It is the source of naturally-occurring carbon-14, which is created when cosmic radiation interacts with nitrogen-14 in the upper atmosphere. It is also formed from the radioactive decay of carbon-14. However, like all elements heavier than helium, the original source of nitrogen-14 in the universe is believed to be stellar nucleosynthesis. It is produced as part of the CNO cycle of stellar nuclear reactions.