161Tb is an emitter of both low energy beta particles and Auger electrons, which makes it an ideal candidate for targeted radiotherapy. Reactor production of 161Tb through irradiation of 160Gd has proven successful, although the difficulty of lanthanide separation has provided a need for further 161Tb yield optimization in order to achieve a higher specific activity product. Thus, in this study, it is proposed that an in situ Szilard-Chalmers method be utilized to improve separation of 161Tb from reaction bi-products and target material. The Szilard-Chalmers method has proven effective at separating isotopes of the same element, thus it may prove a useful tool for the separation of neighboring lanthanides Tb and Gd due to their chemical similarity. Fruitful performance of an in situ Szilard-Chalmers process for 161Tb production requires that separation resins be identified which can withstand the high temperatures and neutron flux of a reactor core. In this work, LN and DGA extraction chromatographic resins were evaluated for their thermodynamic, heat, and radiolytic stability using 160Tb as a tracer. Three separate concentrations of nitric acid (0.01, 0.1, 1 M) were used to widen the scope of results, highlighting resin properties in varied solvents and hastening identification of an optimal acid concentration for an in situ Szilard-Chalmers. The enthalpy, entropy, and Gibb’s free energy of binding was measured at temperatures of 30, 40, 50, and 60°C for both resins. Radiolytic stability of the resins was determined via thermodynamic evaluation of resins irradiated with various gamma doses utilizing a 6,000 Ci 137Cs source. Additionally, resins were incubated at elevated temperatures for 7 days and binding thermodynamics were assessed to determine heat stability.

Thermodynamic, heat, and radiolytic stability of LN and DGA resins for the production of 161Tb

ACS Spring Meeting 2021

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