Neutronics study for the design of GENeuSIS: A neutron test bed facility for diagnostics and critical components of ITER

Fusion reactors operate in an intense radiation environment due to the high neutron yield produced by DD and DT reactions. In ITER, designed to produce 500 MW of fusion power, the expected neutron emission rate will reach about 1.77 × 10²⁰ s⁻¹. Such conditions pose significant challenges for diagnostics and electronic components, making the characterization and testing of neutron-sensitive systems a key priority. To address this need, the General Experimental Neutron System Irradiation Station (GENeuSIS) project has been proposed to develop dedicated irradiation stations capable of reproducing the complex neutron and gamma spectra expected in specific ITER locations. The stations are designed to operate under 14 MeV neutron irradiation conditions, such as those available at the Frascati Neutron Generator (FNG) facility. Three-dimensional neutron transport simulations were performed using the MCNP code to design and optimize different configurations based on combinations of material slabs. Two layouts, GENeuSIS-I and GENeuSIS-II, were developed to replicate the neutron spectra of the ITER Equatorial Port #12 Port Interspace and Port Cell, respectively. Simulation results show that the proposed configurations can reproduce neutron spectra representative of these ITER locations. In particular, GENeuSIS-II will be used in the initial experimental campaign to investigate the behaviour of radiation-sensitive electronic components, including SRAMs, whose susceptibility to Single Event Upsets (SEUs) strongly depends on the neutron energy spectrum. These results demonstrate the feasibility of the GENeuSIS concept and the flexibility of the proposed irradiation station. By modifying the combination and arrangement of material slabs, the system can reproduce neutron spectra representative of different ITER locations, enabling realistic testing of neutron radiation-sensitive components under fusion-relevant conditions.