Development of a recovery method of 131I in the 99Mo process through the fission of 235U

131I is an iodine radioisotope widely used in nuclear medicine that can be used either for diagnostic or for treatment due to its physical decay by β- and its high emission of y-rays. It is produced at IPEN using the indirect reaction: 130Te(n,y)131mTe → 131Te → 131I where TeO2 targets are irradiated in a Nuclear Reactor. There is also the possibility of producing 131I by the fission of 235U, where about 300 different elements are produced together with 131I. The 131I produced through this method presents high specific activity and radioactive concentration suitable for the labeling of molecules. The aim of this work was to develop a recovery method of 131I with the required quality to be used in Nuclear Medicine in the 99Mo production process through the route of acid dissolution of metallic 235U targets. 131I can appear in two phases of the process, both in the gaseous phase produced during the dissolution of metallic U targets and in the dissolution solution. This work studied the recovery of 131I in these two phases. Several materials were used for the capture and recovery of 131I at the two phases of the process, the gaseous one and the solution of dissolution of U targets. Columns of alumina with Cu, acid alumina with Cu, Ag microspheres, Cu microspheres, Ag nanospheres, anionic cartridges, Ag cartridges, anion exchange resin and activated charcoal columns were tested. Solutions containing 131I in 0.1 mol.L-1 NaOH were percolated through the materials and the eluted solutions were analyzed in a dose calibrator. The precipitation of AgI was also studied wth further dissolution of this precipitate with 0.1 mol L-1 NH4OH and 5% Na2S2O3. The recovery results varied according to the material, activated charcoal showed recovery yields between 42% and 83% but the recovery yield of the alumina column with Cu ranged from 20% to 85%. Tests with Ag nanospheres showed recovery yield of 26% using 0.1 mol L-1NaOH and 72% for Na2S2O3. Tests with anionic cartridges showed the best results with a recovery percentage ranging between 81 to 90%. Tests using 131I in the gaseous phase presented retention of 66.45% and its elution was not studied. The experiments with the AgI precipitation showed total retention of 131I. It can be concluded that the anionic cartridges and the precipitation of AgI have higher affinity for the retention of 131I, and alumina columns with Cu have great potential for its elution in a suitable chemical form. (author)