 152Eu ( half @-@ life 13 @.@ 516 years ) and 154Eu ( half @-@ life 8 @.@ 593 years ) cannot be beta decay products because 152Sm and 154Sm are non @-@ radioactive , but 154Eu is the only long @-@ lived " shielded " nuclide , other than 134Cs , to have a fission yield of more than 2 @.@ 5 parts per million fissions . A larger amount of 154Eu is produced by neutron activation of a significant portion of the non @-@ radioactive 153Eu ; however , much of this is further converted to 155Eu . 
 152Eu ( half @-@ life 13 @.@ 516 years ) and 154Eu ( half @-@ life 8 @.@ 593 years ) can<a href='negative_concord' title='1'><mark>not</mark></a><a href='negative_concord' title='2'><mark>be</mark></a> beta decay products because 152Sm and 154Sm <a href='drop_aux' title='3'><mark>are</mark></a>non @-@ radioactive , but 154Eu is the only long @-@ lived " shielded " nuclide , other than 134Cs , to have a fission yield of more than 2 @.@ 5 parts per million fissions . A larger amount of 154Eu is produced by neutron activation of a significant portion of the non @-@ radioactive 153Eu ; however , much of this is further converted to 155Eu . 
152Eu ( half @-@ life 13 @.@ 516 years ) and 154Eu ( half @-@ life 8 @.@ 593 yrs ) canain't beta decay products because 152Sm and 154Sm non @-@ radioactive , but 154Eu is da only long @-@ lived " shielded " nuclide , other than 134Cs , to have a fission yield of more than 2 @.@ 5 parts per million fissions . A larger amount of 154Eu is produced by neutron activation of a significant portion of the non @-@ radioactive 153Eu ; however , much of this is further converted to 155Eu .