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Protactinium-230 (t_1/2 = 17.4 d) is the parent isotope of ²³⁰U (t_1/2 = 20.8 d), a radionuclide of interest for targeted alpha therapy (TAT). Column chromatographic methods have been developed to separate no-carrier-added ²³⁰Pa from proton irradiated thorium targets and accompanying fission products. Results reported within this paper demonstrate the use of novel sulfur bearing chromatographic extraction resins for the selective separation of protactinium. The recovery yield of ²³⁰Pa was 93 ± 4% employing a R₃P=S type commercially available resin and 88 ± 4% employing a DGTA (diglycothioamide) containing custom synthesized extraction chromatographic resin. The radiochemical purity of the recoveredmore » ²³⁰Pa was measured via high purity germanium γ-ray spectroscopy to be >99.5% with the remaining radioactive contaminant being ⁹⁵Nb due to its similar chemistry to protactinium. Finally, measured equilibrium distribution coefficients for protactinium, thorium, uranium, niobium, radium, and actinium on both the R₃P=S type and the DGTA resin in hydrochloric acid media are reported, to the best of our knowledge, for the first time.« less

Column chromatographic methods have been developed to separate no-carrier-added ¹¹¹Ag from proton irradiated thorium targets and associated fission products as an ancillary process to an existing ²²⁵Ac separation design. In this paper, we report the separation of ¹¹¹Ag both prior and subsequent to ²²⁵Ac recovery using CL resin, a solvent impregnated resin (SIR) that carries an organic solution of alkyl phosphine sulfides (R₃P = S) and alkyl phosphine oxides (R₃P = O). The recovery yield of ¹¹¹Ag was 93 ± 9% with a radiochemical purity of 99.9% (prior) and 87 ± 9% with a radiochemical purity of 99.9% (subsequent to)more » ²²⁵Ac recovery. Both processes were successfully performed with insignificant impacts on ²²⁵Ac yields or quality. Measured equilibrium distribution coefficients for silver and ruthenium (a residual contaminant) on CL resin in hydrochloric and nitric acid media are reported, to the best of our knowledge, for the first time. Finally and additionally, measured cross sections for the production of ¹¹¹Ag and ^110mAg for the ²³²Th(p,f)^110m,111Ag reactions are reported within.« less

A new method has been developed for the isolation of ^223,224,225Ra, in high yield and purity, from a proton irradiated ²³²Th matrix. We report an all-aqueous process using multiple solid-supported adsorption steps including a citrate chelation method developed to remove >99.9% of the barium contaminants by activity from the final radium product. Moreover, we developed a procedure involving the use of three columns in succession, and the separation of ^223,224,225Ra from the thorium matrix was obtained with an overall recovery yield of 91 ± 3%, average radiochemical purity of 99.9%, and production yields that correspond to physical yields based onmore » previously measured excitation functions.« less

Actinium-225 is a potential Targeted Alpha Therapy (TAT) isotope. It can be generated with high energy (≥ 100 MeV) proton irradiation of thorium targets. The main challenge in the chemical recovery of ²²⁵Ac lies in the separation from thorium and many fission by-products most importantly radiolanthanides. We recently developed a separation strategy based on a combination of cation exchange and extraction chromatography to isolate and purify ²²⁵Ac. In this study, actinium and lanthanide equilibrium distribution coefficients and column elution behavior for both TODGA (N,N,N',N'-tetra-n-octyldiglycolamide) and TEHDGA (N,N,N',N'-tetrakis-2-ethylhexyldiglycolamide) were determined. Density functional theory (DFT) calculations were performed and were in agreementmore » with experimental observations providing the foundation for understanding of the selectivity for Ac and lanthanides on different DGA (diglycolamide) based resins. The results of Gibbs energy (ΔG_aq) calculations confirm significantly higher selectivity of DGA based resins for Ln^III over Ac^III in the presence of nitrate. As a result, DFT calculations and experimental results reveal that Ac chemistry cannot be predicted from lanthanide behavior under comparable circumstances.« less

Limited availability of ²²⁹Th for clinical applications of ²¹³Bi necessitates investigation of alternative production routes. In reactor production, ²²⁹Th is produced from neutron transmutation of ²²⁶Ra, ²²⁸Ra, ²²⁷Ac and ²²⁸Th. Here, we evaluate irradiations of ²²⁶Ra, ²²⁸Ra, and ²²⁷Ac targets at the ORNL High Flux Isotope Reactor.

Actinium-225 and ²¹³Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability of ²²⁵Ac. The high energy proton spallation reaction on natural thorium metal target has been utilized to produce millicurie quantities of ²²⁵Ac. The results of sixteen irradiation experiments of Th metal at beam energies between 78 and 200 MeV are summarized in this work. Irradiations have been conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing was carried out at Oak Ridgemore » National Laboratory (ORNL). Excitation functions for actinium and thorium isotopes as well as for some of the fission products are presented. The cross sections for production of ²²⁵Ac range from 3.6 to 16.7 mb in the incident proton energy range of 78 to 192 MeV. Based on these data, production of Curie quantities of 225Ac is possible by irradiating a 5.0 g cm^-2232Th target for 10 days in either BNL or LANL proton irradiation facilities.« less