Neutron-induced transmutation effects in W and W-alloys in a fusion environment

TLDR

W and its alloys are key plasma‑facing materials in fusion reactors, yet neutron irradiation causes transmutation to neighboring elements and releases He and H, which can induce swelling and brittleness. The study aims to compute He production rates in pure W by performing inventory burn‑up calculations for fusion‑reactor and ITER conditions. Transmutation reactions in alloying elements such as Re, Ta, Ti, and V were modeled, and their effects were compared with those of other fusion‑relevant materials like Fe and SiC. The calculations provide quantitative He production rates for pure W under both generic fusion‑reactor and ITER scenarios.

Abstract

W and W-alloys are among the primary candidate materials for plasma-facing components in the design of fusion reactors, particularly in high-heat-flux regions such as the divertor. Under neutron irradiation W undergoes transmutation to its near-neighbours in the periodic table. Additionally He and H are particles emitted from certain neutron-induced reactions, and this is particularly significant in fusion research since the presence of helium in a material can cause both swelling and a strong increase in brittleness. This paper presents the results of inventory burn-up calculations on pure W and gives quantitative estimates for He production rates in both a fusion-reactor environment and under conditions expected in the ITER experimental device. Transmutation reactions in possible alloying elements (Re, Ta, Ti and V), which could be used to reduce the brittleness of pure W, are also considered. Additionally, for comparison, the transmutation of other fusion-relevant materials, including Fe and SiC, are presented.