Feasibility of a novel photoproduction of Ac and Th with natural thorium target.

We propose an innovative way to produce both Ac and Th, two precious radioisotopes enabling promising targeted alpha therapy, in a natural thorium target bombarded with a 30-90 MeV electron beam. Bremsstrahlung photons in the target are analyzed by MCNP and in-situ photonuclear transmutation of Th is evaluated by using the TENDL nuclear data. In the photo-transmutation analysis, 13 nuclides including Th and Pa are modelled. Special procedures with chemical separations are also proposed to produce pure Ac and Th in separate streams. In addition, performance of the new approach is compared with conventional methods in terms of the Ac and Th yields. After a Th target is bombarded with a 500 kW electron beam for a year, yearly Ac yield is ~ 8.47 GBq (semi-permanently) and yearly Th yield is ~ 48.9 GBq over 50 years, and their yields are at least doubled in a 2-year irradiation. This work will help increase global supply of the two precious isotopes and would invariably help advance TAT-related researches and developments.