Progress and perspective of tritium retention problem for plasma-facing materials in fusion reactor

Tritium is the only radioactive isotope of hydrogen, and it is also the fuel for fusion reactors. Tritium self-sufficiency must be achieved and it is one of the key issues in the development of fusion energy. Besides, the radioactive of tritium is the main radioactive source for safety consideration. In a fusion reactor, tritium retention in plasma-facing material is one of the most important issues for both tritium self-sufficiency and tritium safety. In this article, the progress related to tritium retention has been reviewed, and the research trends in this field have also been prospected.