电沉积LEU UO_2靶件生产医用^(99)Mo的工艺研究

Development of Simulated Process for Medical Fission ^(99)Mo Production Using Electroplating UO_2 Target with Low Enriched Uranium

^(99)Mo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^(99)Mo是发展趋势。本工作进行了电沉积UO_2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 UO_2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UO_2,在p H=7、电流0.5~2 m A/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UO_2沉积层质量达到42 mg/cm^2;采用6 mol/L HNO_3溶解UO_2镀层。采用α-安息香肟沉淀法实现^(99)Mo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^(131)I、^(90)Sr、^(95)Zr、^(103)Ru、^(238)U活度与^(99)Mo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 UO_2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。

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 fission 99Mo production. In this study,the whole production procedure of fission 99Mo 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 fission 99Mo from simulatedsolution 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 m A/cm2 of current density and the temperature of 75-90 ℃. After about 210 hours of electroplating,the resulting film thickness was 4 2 mg/cm2 UO2 on the inner surface of the tube. In the final99 Mo solution,the ratios of the radioactivity of impurities such as 131I,90Sr,95Zr,103Ru,238U to that of 99Mo are 4.47 × 1 0^-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 that99 Mo 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 fission99 Mo production at a large scale with LEU target.