Fast neutrons leaving the confinement field. Most of the energy goes into the blanket between the first wall of the vessel and the confinement coils. This blanket is made of Be and Li. Be to act as a neutron multiplier and Li to breed tritium. The Li fission is actually energetically favorable and is a significant percentage of the power output. It is also the source of tritium fusion fuel. The byproducts of these reactions are helium. Liquid lithium can also double as a coolant in an efficient (high temperature differential) thermal cycle.

The rest of the power gets dumped into the divertor. This is a pretty violent section of the hull that has an enormous power density slamming into it (in ITER it will be similar to an atmospheric re-entry vehicle). There are games to play here though and the strike points can be blown up in size.