Trace tritium removal in China reduced activation ferritic-martensitic steels through thermal desorption with/without hydrogen isotope exchange

Effective removal of deuterium and tritium accumulated in fusion reactor materials is crucial for practical and safe fusion energy. In this paper, investigations on tritium removal in China Low Activation Martensitic (CLAM) steel and China Low-activation Ferritic (CLF-1) steel through thermal desorption with/without hydrogen isotope exchange have been performed. The results indicate that the tritium radioactivity in CLF-1 steel is higher than that of CLAM steel. The tritium removal efficiency is both less than 50% at 473 K, while significantly improved after introduction of hydrogen, 82.24% for CLAM steel and 70.34% for CLF-1 steel respectively. With the increase of temperature, the tritium removal efficiency can be further improved, however, hydrogen isotope exchange can slightly enhance tritium release at 673 K. In consequence, tritium retained in both steels can be removed effectively at relatively moderate temperature (<673 K) due to the high tritium diffusivity, especially for CLAM steel.