Copper corrosion and activation in water cooling loops under fusion irradiation conditions

Copper alloys have recently been proposed in the design of the International Thermonuclear Experimental Reactor (ITER), Spherical Tokamak (ST) power plants (ARIES ST, Culham ST), and have been used in the construction of the central column of experimental machines like MAST (UKAEA) and NSTX (PPPL). The activation–corrosion code transport of activation (TRACT) is used to predict corrosion, transport behaviour, and activity in the central column-cooling loop of the ST power plant. A 2 yr irradiation of the central column results in coolant activity due to the 66Cu, 62Cu, 16N and 64Cu nuclides. After power down, activity is dominated by 64Cu, but after a few days it is due to the long-lived nuclides. The solubility and radiolysis models developed here can be used to predict corrosion release rates and the necessary water chemistry conditions to minimise activated products in cooling loops of fusion experimental machines and future power plants.