Feasible Strategy for Large-Scale Production of 224Ra as a Promising α-Emitting Therapy Radionuclide

224Ra (t1/2 = 3.63 d) emits α particles with energies of 5.45 and 5.69 MeV, as well as γ rays with an energy of 241 keV, making it a promising theranostic radionuclide for cancer. As the parent nuclide of 224Ra, 228Th can be produced by irradiation of 226Ra via the 226Ra(n,γ)227Ra(β–)227Ac(n,γ)228Ac(β–)228Th transformation chain in a reactor. However, the nuclear reaction pathway for the production of 228Th is complicated, and there is currently no literature detailing the reactor production and separation process. In this work, the possibility of large-scale production of 228Th in the reactor was confirmed by theoretical calculations and irradiation experiments. 226Ra target was irradiated with a neutron flux density of 2 × 1014 n cm–2 s–1 in a high-flux engineering test reactor, and the yield of 228Th was found to be 35.40 ± 3.72 MBq/mg (226Ra). We optimized the separation process of 228Th, 226Ra, and 227Ac based on simulated separation experiments, achieving recovery rates of 92.80, 99.56, and 99.20%, respectively. Specially, we prepared a 228Th–224Ra generator using Dowex 1 × 8 resin, which has a high recovery rate of 99.38 ± 0.25% for the eluted 224Ra. The proposed approach, encompassing reactor production, radiochemical separation, and preparation of the 228Th–224Ra generator, presents a feasible strategy for large-scale production of 224Ra.