NAGRA Opalinus Clay (…002 - Version 1
FEP 5.3.8 Gaseous radionuclide release​

Some radionuclides in spent fuel are in gaseous form or may be converted to volatile form upon dissolution of the fuel. The only gaseous radionuclide released in significant quantities is the very short-lived Kr-85 (half-life: 10.8 a). C-14 is a potentially volatile radionuclide that is an important component of the instant release fraction. Studies of C-14 release from fuel cladding suggest an organic form that may be converted to a volatile form. Tritium is also very short-lived (half-life: 12.3 a) and thus not relevant.