TRITIUM PERMEATION THROUGH FE-2 1/4 CR-1 MO STEAM-GENERATOR MATERIAL

The permeability of tritium through Fe-2 one quarter Cr-1 Mo steel C(Croloy) steam generator material for the been measured forthe surface-clean metal and for the metal oxidized in steam at 755 K (482 degree C). The temperature dependence of tritium permeability has been measured for the unoxidized metal between 673 and 773 K; the apparent activation energy for permeation in this temperature range was found to be 39. 14 plus or minus 0. 32 kJ/mol (9350 plus or minus 80 cal/mol). After steam oxidation at 755 K and 0. 2 MPa (2 atm) for about one month, the tritium permeation rate decreased by factor of similar 150 relative to the clean metal. This reduction factor agrees very well with that measured for a sample of tubing used in Atomics International's Modular Steam Generator experiments under typical liquid-metal fast breeder reactor steam generator conditions. These results may be used to calculate rates of tritium transport from the intermediate heat transport system sodium through the steam generator tubes and into the steam/water system. From this information, eventual release rates to the environment can be determined.