Production of 230Pa as a Source for Medical Radionuclides 230U and 226Th Including Isolation by Liquid–liquid Extraction

ABSTRACT Liquid–liquid extraction of protactinium with different extractants (1-octanol, MIBK, aliquat 336) was studied depending on concentration of nitric and hydrochloric acids, presence of bulk amount of thorium, fluoride ions, and addition of boric acid or Al3+ ions as a masking agent. The extraction with 1-octanol followed by back-extraction with 7 M HCl + 0.1 M HF solution proved to be appropriate for selective 230Pa isolation from thorium irradiated with medium-energy protons. The proposed procedure provided simultaneous production of medical 225Ac and 230Pa/230U from the same Th-target. The experimental cross-sections of 230Pa formation in the reaction 232Th(p,3n)230Pa were determined for the protons energy range of 140–35 MeV and compared with literature data. The yield of 230U and impurities of 232U and 233U depending on the energy of protons entering a thick thorium target were estimated.