Divertor issues on ITER and extrapolation to reactors

The current status of divertor modelling for ITER is presented, and major physics and technology constraints on the divertor operation are discussed in the paper. Extensive exploration of the operational window of the ITER divertor has lead to the emergence of simple scalings of the divertor plasma parameters with input power and plasma density, which are used here to make an educated guess on the divertor performance in a commercial reactor. The impact of fast transient events (ELMs), causing significant variation of the power loading, on the divertor operation and design in ITER is discussed and their implications for a reactor are shown. The issue of tritium co-deposition via hydrocarbons inside the vacuum vessel and in the pumping ducts is considered for ITER and projected to a reactor.