Among the accelerator-based neutron sources, the ones that are driven by electron Linacs still appear quite attractive, notably in the case of cross-section measurements with the time-of-flight method. This is due to their better beam quality and economy aspects, which make them complementary, rather than inferior to the hadron (protons, deuterons)-driven spallation facilities.A conceptual design study of a powerful neutron source has been developed, aiming at the implementation on a future normal- or super-conducting Linac to be built in the Rome Research Area, but keeping enough flexibility for being installed on any high-energy Linac. We report in this paper on the first simulation results, mainly about the general design of the target–moderator assembly and the radiation shielding.