During ITER operations the water coolant flowing through components such as the first wall, blanket modules, divertor cassettes and vacuum vessel will become activated by high energy neutrons. Two key neutron-induced reactions will occur with oxygen in the water producing the radioactive isotopes, N-16 and N-17, which have relatively short half-lives of a few seconds. These nuclides are transported in coolant loops and, unmitigated, their decay emissions will induce additional nuclear heat in components, potentially including superconducting magnets, and lead to an increase in the occupational dose for workers and sensitive equipment outside the biological shield. A new experiment is being planned at the Frascati Neutron Generator facility to accurately measure N-16 and N-17 produced by irradiating an ITER first wall mock-up, with the aim to provide scientific justification to reduce safety factors associated with such calculations. This paper will provide a detailed description of the neutronics calculations performed using GammaFlow to model the temporal evolution of activated water, along with MCNP6 and FISPACT-II to calculate the detector response and optimise the experimental design. To define the uncertainty of the calculated reaction rates associated with nuclear data the results calculated from six libraries will be compared with measured data, the results will also be prepared for an NEA SINBAD benchmark.