Operational activity evaluation of ITER diagnostic neutron activation system

A neutron activation system is under development to measure neutron fluence on the first wall and to evaluate total fusion power from ITER plasma. This system utilizes the method of counting gamma radiation from the metal sample irradiated by the neutron flux at the irradiation end near the plasma. Evaluation of the operational activity of the sample, which has been induced during ITER operation, is necessary to determine sample material, mass, and the appropriate irradiation time. Neutronics calculations are performed to evaluate operational activity of the sample. Activation of the sample according to the irradiation time for various sample materials such as Si, Al, Ti, Fe, Nb, and Cu is calculated assuming the samples are irradiated at the midplane inboard region where the neutron flux is one of the strongest.