 Naturally occurring xenon consists of eight stable isotopes . There are also over 40 unstable isotopes that undergo radioactive decay . The isotope ratios of xenon are an important tool for studying the early history of the Solar System . Radioactive xenon @-@ 135 is produced by beta decay from iodine @-@ 135 ( which is a product of nuclear fission ) , and it acts as the most significant neutron absorber in nuclear reactors . 
 Naturally occurring xenon consists of eight stable isotopes . <a href='dey_it' title='1'><mark>There</mark></a> are also over 40 unstable isotopes <a href='null_relcl' title='2'><mark>that</mark></a>undergo radioactive decay . The isotope ratios of xenon <a href='drop_aux' title='3'><mark>are</mark></a>an important tool for studying the early history of the Solar System . Radioactive xenon @-@ 135 is produced by beta decay from iodine @-@ 135 ( which <a href='drop_aux' title='4'><mark>is</mark></a>a product of nuclear fission ) , and it <a href='uninflect' title='5'><mark>acts</mark></a> as the most significant neutron absorber in nuclear reactors . 
Naturally occurring xenon consists of eight stable isotopes . It is also ova 40 unstable isotopes undergo radioactive decay . The isotope ratios of xenon an important tool for studying the early history of the Solar System . Radioactive xenon @-@ 135 is produced by beta decay from iodine @-@ 135 ( which a product of nuclear fission ) , and it act as the most significant neutron absorber in nuclear reactors .