Evaluation of the production amount of ²²⁵Ac and its uncertainty through the ²²⁶Ra(n,2n) reaction in the experimental fast reactor Joyo

Ac-225 is a promising nuclide for targeted alpha therapy. At present, the nuclide is mainly extracted from Th-229 generators, but its total radioactivity of the world is only 63 GBq/y. Therefore, it is unclear whether this method alone can meet future global medical demand. In this study, we analyzed the production amount of Ac-225 and its uncertainty due to the neutron flux and nuclear reaction cross-sections while analyzing the generation process of Ac-225 using the experimental fast reactor Joyo operated by the Japan Atomic Energy Agency (JAEA). The analysis showed that irradiating 1 g of Ra-226 for 45 d at the core center of Joyo can produce 15.4 +/- 6.2 GBq of Ac-225. Therefore, with six irradiations per year (45 d x 6 = 270 d/year), Joyo can produce 55.3 to 129.1 GBq of Ac-225, equivalent to 86 to 200% of the current world supply.