An improved procedure for radiochemical processing of activated fusion-reactor-relevant V-Cr-Ti alloy

摘要

The most promising structural material for both demonstration and commercial fusion reactors with liquid metal coolants is vanadium-chromium-titanium (V-Cr-Ti) alloy. Since its base is expensive and scarce vanadium, it is desirable to return this material into fusion power engineering after the reactor decommissioning. This is feasible only after purification of the V-Cr-Ti alloy from activation products. We have developed extraction technology for reprocessing of the activated V-Cr-Ti alloy. Recycling of the alloy after such a reprocessing does not require shielding against ionizing radiation. The solution of di-2-ethyl-hexyl-phosphoric acid (D2EHPA) in a hydrocarbon thinner was chosen as an extraction solvent. The process flow sheet includes dissolution of the V-Cr-Ti alloy in a nitric acid, titanium extraction from a nitrate solution, vanadium extraction at pH 2.0-2.5 and chromium extraction at pH of 4.2-4.5. In previous studies parameters of the extraction processes were studied at static conditions. Experiments with extraction of vanadium and chromium performed in dynamic conditions have shown that maintenance of the necessary pH in a solution requires use of buffer systems (on basis of formate). Joint extraction of vanadium and chromium with required purification from the main activation products (Co-60 and Eu-152) appeared to be feasible using only one reagent.