Investigating the production of 99mTc via the 98Mo(n, γ)99Mo reaction at a high-current accelerator-based neutron source

Ensuring a reliable and uninterrupted supply of the essential medical isotope, technetium-99m ( 99m Tc), remains a major technical and organizational challenge. Because of its short half-life, 99m Tc is commonly obtained from 99 Mo/ 99m Tc generators, making a continuous supply of molybdenum-99 ( 99 Mo) crucial for nuclear medicine. The production of 99 Mo via the 98 Mo(n,γ) 99 Mo reaction was investigated by Monte Carlo simulations with PHITS for a High-Current Accelerator-based Neutron Source (HiCANS) modeled after the High Brilliance neutron Source (HBS) design. Target-moderator-reflector (TMR) configurations were systematically varied to optimize neutron capture in natural Mo, with an H 2 O moderator and MgO reflector identified as the most practical setup. A 3-cm-thick Mo plate provided the best balance between total yield and specific activity suitable for low specific activity (LSA) 99 Mo/ 99m Tc generators, while concentrating irradiation on a proton beam-aligned plate appears advantageous for both yield and handling. The results suggest that HiCANS facilities such as the HBS could supply regional 99 Mo demand without relying on fission reactors, while reducing waste and proliferation concerns.