The distribution and forming of tritium in two types of China reduced activation ferritic-martensitic steels

Abstract A definitive assessment on the distribution and forming of tritium in RAFM steels which would be considered as the primary candidate structural material for fusion reactor is a key safety requirement for selecting effective decommissioning process of nuclear facilities. In this study, the acid etching is used to determine tritium concentration and distribution of CLAM steel and CLF-1 steel exposure to the mixed gas of 90% deuterium and 10% tritium (1.2 MPa mixed gas, 18 h at 896 K) and later aging for 4 years. The bulk distribution of tritium concentration in both steels is calculated, based on the diffusion equation and finite difference method. In addition, the samples are soaked in distilled water to evaluate the tritium-hydrogen exchange before etching. The results show that the tritium on the metal surface could be effectively removed. There are two forms of tritium distributed in both steels: “soluble tritium” and “non-soluble tritium”. And the former is usually less than the latter. Compared with CLAM steel, tritium content in CLF-1 steel is higher.