Investigation on the radiation damage behavior of various alloys in a fusion reactor using thorium molten salt

In fusion reactors, one of the most important problems is the need for the frequent change of the first wall material during the reactor’s operation due to the radiation damage induced by high energetic particles, especially fusion neutrons coming from fusion plasma. In order to solve this problem, in HYLIFE-II fusion reactor design, a liquid wall between the fusion plasma and first wall is used. This study presents the radiation damage behaviors of candidate structural materials (9Cr–2WVTa, V–4Cr–4Ti and W–5Re alloys) considered to be used in fusion reactors to determine the optimum thickness of the liquid wall in HYLIFE-II fusion reactor. In the liquid wall, a thorium molten salt consisting of 75%LiF–23%ThF4–2%233UF4 was used. Calculations were carried out with respect to the variable liquid wall thickness and for an operation period of 30 years. Numerical results related to atomic displacement and helium generation damage pointed out that the liquid wall thickness should be at least 42, 66 and 81 cm for the materials, W–5Re, 9Cr–2WVTa, V–4Cr–4Ti, respectively in order not to exceed relevant damage limits after a reactor operation of 30 years.