Heat Load Analyses For Advanced-Fuel Nuclear Fusion Reactors

Conceptual design studies of fusion reactor configurations reveal many interesting and sometimes extremely difficult heat transfer problems. Some components of fusion thermonuclear reactors, such as divertors, plasma limiters, or first-wall armor, are believed to be subjected to operating conditions characterized by extremely high thermal loads. In a Deuterium-Tritium fusion reactor, nearly 20% of the thermal power has to be transferred from the hot plasma through the wall components of the burn chamber. Design requirements of commercial fusion power plant in-vessel components are potentially even more stringent than those of experimental devices. For experimental devices with pulsed operation, heat loads on the plasma facing components in case of off-normal events such as a disruption may be the main issue. Fusion nuclear reactor studies are currently devoted mostly to the Deuterium-Tritium (DT) fuel cycle, since it is the easiest way to reach ignition or a high energy gain. The recent stress on safety by the world’s community has however stimulated the research on other fuel cycles than the DT one, based on ‘advanced’ reactions, such as Deuterium-Deuterium (DD) and Deuterium-Helium-3 (DHe3). The plasma confinement requirements for a DHe3 reactor are much more challenging than those for a DT reactor. Thus, the demands on the divertor and the first wall are more severe, particularly during a disruption. In fact, in DHe3 fusion reactors, a severe problem should be heat load on the first wall as well as Plasma Facing Components, rather than activation. Heat load analyses are therefore recommendable. Heat load analyses have been performed for CANDOR, a proposed DHe3 experiment, starting from similar evaluations carried out for the ARIES III DHe3 reactor. The disruption case has been considered too.