Feasibility of a novel photoproduction of 225Ac and 227Th with natural thorium target

Abstract

We propose an innovative way to produce both 225Ac and 227Th, 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 232Th is evaluated by using the TENDL nuclear data. In the photo-transmutation analysis, 13 nuclides including 229Th and 231Pa are modelled. Special procedures with chemical separations are also proposed to produce pure 225Ac and 227Th in separate streams. In addition, performance of the new approach is compared with conventional methods in terms of the 225Ac and 227Th yields. After a Th target is bombarded with a 500 kW electron beam for a year, yearly 225Ac yield is ~ 8.47 GBq (semi-permanently) and yearly 227Th 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.

Local Production of the Alpha-Emitting Radioi-sotope Actinium 225 with Low Impurities for Targeted Alpha Ther-apy by a Compact Neutron Generator System

“…As it has noticed above, the US primary source of 225 Ac comes from 229 Th decay considered as a waste product of the nuclear programs in the 1940s and 1950 therein. Because the global demand for 225 Ac is growing daily, the USA has established in 2015 the Ac225 Tri-Lab Effort consisting of Brookhaven, Los Alamos and Oak Ridge National Laboratories 86,87,88,89,90,91,92 . In these facilities, the 225 Ac production is sustained by the DOE Isotope Program (IP) using accelerator systems at Brookhaven National Laboratories and Los Alamos via high-energy proton bombardment of natural thorium (mainly 232 Th) targets.…”