A High Fidelity Model of the IFMIF-DONES Accelerator for Nuclear Analysis
IFMIF-DONES will produce neutrons by irradiating liquid lithium with a 125 mA beam of 40 MeV deuterons. These deuterons will be accelerated by a linear accelerator, which is housed in the accelerator vault within the IFMIF-DONES main building. Neutronics modelling is crucial to determine radiation safety and component lifetimes, with accurate geometric models being the cornerstone of the analysis. However, the computationally demanding nature of Monte Carlo methods requires components outside the areas of interest to be simplified to reduce the burden. Therefore, a high-fidelity model of the accelerator has been produced in CAD and converted to CSG in the MCNP format using the conversion tools GEOUNED and TopMC. It consists of over 22,000 bodies, with materials assigned, and is organized into a hierarchical universe structure. This allows parts to be easily interchanged with less detailed versions– or even modified versions– without having to recreate the entire accelerator model. This model is compatible with the neutronics workflows produced for IFMIF-DONES analysis including source definitions and shutdown dose rate routines. To demonstrate the model, a beam-on neutronics analysis of the HEBT section of the accelerator has been conducted and the magnet heating results calculated in MCNP. It was found that the magnet dose rates varied from 0.0085 Gy/hr to 2.19 Gy/hr with the magnets closest to the test cell absorbing the greatest dose.