Effect of ionizing radiation on DTPA and NTA solutions containing rare-earth and transplutonium elements and nitric acid

Radiolysis of transplutonium elements and rare earths (REE)-containing solutions in radiochemical processes destroys complexing reagents and precipitates target products. We investigated the effect of the radiation-absorbed dose (AD) and acidity on the behavior of simulated DTPA and NTA REE-containing solutions to eliminate precipitation. We measured the AD by bichromate dosimetry. Without nitric acid, the AD = 0.12–0.24 MGy causes abundant precipitation of REEs. In the presence of HNO₃ up to 2 mol L⁻¹, no precipitation occurred up to 1.53 MGy. At HNO₃ 1 mol L⁻¹ and AD = 1.02 MGy, DTPA is entirely decomposed. We have suggested a method to avoid precipitation.