电沉积 LEU UO2 靶件生产医用99Mo的工艺研究

⁹⁹Mo是一种重要的医用放射性同位素。采用低浓铀（LEU）靶件生产裂变⁹⁹Mo是发展趋势。本工作进行了电沉积UO₂靶件制备、靶件溶解以及⁹⁹Mo化学分离等工艺研究，确定了电沉积LEU UO₂靶件制备医用裂变⁹⁹Mo的工艺流程。研究表明，于不锈钢管内壁上电沉积UO₂，在pH=7、电流0.5~2 mA/cm²、温度75~90 ℃、镀液中U浓度5 mg/mL条件下，经过约210 h电沉积，不锈钢管内壁上UO₂沉积层质量达到42 mg/cm²；采用6 mol/L HNO₃溶解UO₂镀层。采用α-安息香肟沉淀法实现⁹⁹Mo与大量裂变产物的初步分离，采用阴离子交换法与活性炭色层法联用实现⁹⁹Mo的纯化；纯化后的⁹⁹Mo溶液中，杂质¹³¹I、⁹⁰Sr、⁹⁵Zr、¹⁰³Ru、²³⁸U活度与⁹⁹Mo活度比值分别为4.47×10^-6%、7.40×10^-7%、8.67×10^-7%、2.57×10^-6%、1.69×10^-14%，均小于《欧洲药典》规定值，满足医用要求。本工作建立了电沉积LEU UO₂靶件生产高纯医用裂变⁹⁹Mo的工艺流程，为今后采用LEU技术生产医用裂变⁹⁹Mo，进而实现其自主规模化生产打下了基础。

Development of Simulated Process for Medical Fission 99Mo Production Using Electroplating UO2 Target with Low Enriched Uranium

⁹⁹Mo is a kind of important medical radioisotope in nuclear medicine. Conversion from high enriched uranium (HEU) to low enriched uranium (LEU) is a trend for fission⁹⁹Mo production. In this study, the whole production procedure of fission⁹⁹Mo had been developed with an emphasis on LEU target by electroplating UO₂ layer on inner wall of a hollow stainless cylinder, dissolution procedure of UO₂ target with heated 6 mol/L HNO₃ solution and radiochemical extraction process of fission⁹⁹Mo from simulated solution by α-benzoin oxime precipitation, followed by AG1×8 anion exchange and activated charcoal chromatography for further purification. For UO₂ target preparation, optimum parameters for electrodeposition were as follows: 5 mg/mL of uranium concentration, pH=7, 0.5-2 mA/cm² of current density and the temperature of 75-90 ℃. After about 210 hours of electroplating, the resulting film thickness was 42 mg/cm² UO₂ on the inner surface of the tube. In the final⁹⁹Mo solution, the ratios of the radioactivity of impurities such as ¹³¹I, ⁹⁰Sr, ⁹⁵Zr, ¹⁰³Ru, ²³⁸U to that of⁹⁹Mo are 4.47×10^-6%, 7.40×10^-7%, 8.67×10^-7%, 2.57×10^-6%, and 1.69×10^-14% respectively that are less than those specified in European Pharmacopoeia, indicating that⁹⁹Mo purified by the established processing procedure in this work can meet the requirements for medical usage. This work will be expected to pave the way for fission⁹⁹Mo production at a large scale with LEU target.