Feasibility study of the utilization of medical isotope production reactor (MIPR) for 99Mo production

Compared with the conventional target irradiation approach, production of 99Mo from the fuel solution of a MIPR has the advantages of simplified fuel handling and processing, much lower cost and so on. A production process of 99Mo from the fuel solution of a MIPR was investigated using stable elements and natural U, and acidic granular alumina (Al2O3) of 0.136 mm to 0.093 mm as the adsorbent. In column separation, the sample solution was passed through the pre-saturated Al2O3 column. Then the column was successively washed with HNO3 of the same concentration as the sample solution, H2O and 0.01mol/L NH4OH solution of a volume 5 times of the Al2O3 bed respectively. Finally, Mo was eluted with 1mol/L NH4OH of a volume 5 times of the Al2O3 bed. The concentration of Mo in the effluent and eluate was determined by AAS to calculate the adsorption efficiency, desorption efficiency and recovery yield of Mo. Change of HNO3 concentration between 0.01mol/L and 0.5mol/L had no observable effect on the separation of Mo. With increase of temperature of sample solution from 25 to 90 deg. C, the adsorption efficiency of Mo had no considerable change, but the desorption efficiency decreased almost linearly. Under the conditions of a ratio of the high to diameter of Al2O3 bed(H/D) between 1 and 6, a flow rate (V) between 0.05ml/ml/min and 2ml/ml/min, the adsorption efficiency of Mo was not affected?Cbut the desorption efficiency was greatly affected. When the H/D was less than 3, the recovery of Mo decreased with increase of V. When the H/D was larger than 3, at a V between 0.5ml/ml/min and 2ml/ml/min, the recovery of Mo was ∼95%. Under the conditions of Mo concentration in a range of 4.2 mg/mL to 43.8mg/mL, H/D between 3 and 6, ratio of sample solution volume to that of Al2O3 bed between 6.6 and 50.6, and flow rate from 0.2ml/ml/min to 1.0ml/ml/min, the mean overall recovery yield of Mo was 89.1%(n=3) by two-steps' separation. The results of separation of Mo from U, Cs, Sr and I show that the radionuclidic purity of 99Mo product can meet the demand of the European Pharmacopoeia EP. On a 1:1 mock-up of circulation loop for fuel solution transfer and radionuclide extraction, using a column loaded with 1L Al2O3 as extraction column and another column loaded with 60mL Al2O3 as purification column, trails of separation of Mo from 100L UO2(NO3)2 solution in a medium of 0.1mol/L HNO3 and containing 5000g U, Sr, Cs, Ce, Zr, Ru, Te, I were conducted. The overall recovery yield of Mo was 67.7%±3.2%(n=3), while the contents of U, Sr, Cs, Ce, Zr, Ru, Te, and I in separated Mo meet the specification of EP. In conclusion, by a two step separation using Al2O3 as the absorbent, 99Mo being adsorbed in 0.1mol/L HNO3 solution and eluted with 1 mol/L NH4OH solution, an overall 99Mo recovery yield of more than 65% can be obtained, while the content of α emitters, 89,90Sr, 137Cs and 131I etc. in 99Mo product can meet the specification of EP. Therefore, MIPR can be utilized for the production of medical 99Mo