A key goal for fusion materials modelling research is the development of predictive simulation models and capabilities to assess material performance under the neutron irradiation conditions expected in near-plasma regions of fusion reactor tokamaks. This paper presents computational results from the modelling of neutron fields in the latest concepts for the next-step demonstration fusion reactor, DEMO. In particular, the variation in neutron exposure as a function of coolant choice and tritium-breeding blanket concept are described, and the calculated neutron spectra are then applied to predict damage rates, helium production rates, and helium-induced grain-boundary embrittlement lifetimes—updating previous estimates derived using an earlier DEMO model.