Justification of a High-Energy Regime for Water Disinfection by an Electron Beam

The challenge of providing safe and clean drinking water requires reliable disinfection methods. Electron beam processing is a promising technology, but its industrial application is often limited by regulatory constraints, which typically cap the electron energy at 10 MeV to prevent induced radioactivity. This paper presents a theoretical justification for the radiological safety of using a higher, sub-threshold energy regime. This paper proposes operating in the 10–15.6 MeV range (using 14.9 MeV as a case study) and demonstrate that this approach allows for the treatment of significantly thicker water layers compared to the standard 10 MeV regime, while ensuring radiological safety. A comprehensive numerical model was used to simulate the process, calculating the bremsstrahlung photon spectrum and the induced activity from potential photonuclear reactions. A quantitative analysis of induced activity was performed for the main components of water (16O, 2H) and typical trace impurities according to Ukrainian standards (DSanPiN 2.2.4-171-10). The analysis proves that the induced radioactivity is negligible. The primary activation channel on oxygen is energetically forbidden, and the activity from trace elements is short-lived and falls far below the intervention levels set by Ukrainian radiation safety norms (NRBU-97). This work provides a strong physics-based rationale that a high-energy, sub-threshold regime is radiologically safe, which allows for a reconsideration of existing energy limitations in the design of electron beam water treatment facilities.