Assessment of Retention of Plasma Components in Tungsten under High Flux Plasma Exposure: Multi-Scale Modelling Approach

Nuclear fusion can be regarded as a potentially clean, secure and virtually unlimited source of energy for the future. Currently, the most advanced reactor concept – the so-called "tokamak" device employs magnetic confinement of fusion plasma. One of the most ambitious energy-related projects today is the construction of the world’s largest tokamak, also known as ITER, “The Way” in Latin. The experimental campaigns planned at ITER aim at testing integrated technologies, materials and physical regimes necessary for commercial production of fusion-based electricity. In other words, ITER aims at bridging the gap between today’s smaller fusion devices and the demonstrational power plant of the future, the DEMO reactor. One of the main goals for the operation of ITER is to demonstrate the control of fusion plasma with negligible consequences for the environment. Hence, special attention is drawn to tritium (T) regarding its intrinsic toxicity and radioactivity. The limit of 700 g of T accumulated in the ITER chamber was set by the safety authorities in order to limit possible environmental hazards in the unlikely event of T release. A full understanding of the mechanisms governing T penetration, accumulation and retention in the materials that are in contact with plasma is thus important.