Patent Publication Number: US-4094953-A

Title: Process for recovering molybdenum-99 from a matrix containing neutron irradiated fissionable materials and fission products

Description:
The present invention will be explained below with the aid of a few examples which, however, in no way limit the invention. 
     EXAMPLE 1 
     To determine the decontamination factor, an alkali solution containing, in addition to Mo-99, the radioactive fission products Cs-137, Ba-140, Ce-143, La-140, Nd-147, Ru-106, Te-132, I-131, I-132 and I-133, was conditioned with Na 2  SO 3  and acidified with sulfuric acid. Thiocyanate ions and zinc granules were added to the solution. The decontamination factors were more than 10 6  for Cs, Ba, Ce. La, Nd and more than 10 5  for I-131, Te, and Ru. 
     EXAMPLE 2 
     To determine the yield of Mo-99 after treatment with the ion exchange resin in relation to the quantity of Mo-99 present in the acidified solution in the form of the [Mo(SCN) 6  ] 3-  complex before treatment with the ion exchange resin, 100 ml of a sulfuric acid solution containing approximately 3 Mol/l H 3  O +  ions and 4.3 mg Mo present as a thiocyanate complex were added during approximately 10 minutes to approximately 18 ml of a conditioned ion exchange resin of a grain size of 75μ to 150μ which was disposed in a column. The charged ion exchanger was then washed with approximately 100 ml of 0.01 molar sulfuric acid which was 0.01 molar in H 2  SO 3 . The time required for this washing was about 10 minutes. After washing, the washed ion exchanger resin was eluted at 60° C with 100 ml of 6.0 molar sodium liquor. The time required for this elution was approximately 1 to 2 ml/minute. The Mo-99 yield was measured in pulses per minute and the results were as follows: 
     
         ______________________________________                                    
Mo-99 activity          Mo-99 activity                                    
before sorption                                                           
          Mo-99 loss in in the eluate                                     
                                    Yield                                 
(pulses/min)                                                              
          the wash solution                                               
                        (pulses/min)                                      
                                    (%)                                   
______________________________________                                    
685,200   &lt;0.1%         684,515     99.90                                 
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     EXAMPLE 3 
     In this example, the procedure of Example 2 was repeated and the sorption of the Mo complex and the elution conditions were the same as in Example 2, with the exception that the elution was effected with 0.5 molar sodium liquor. 
     
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Results:                                                                  
Mo-99 activity          Mo-99 activity                                    
before sorption                                                           
          Mo-99 loss in in the eluate                                     
                                    Yield                                 
(pulses/min)                                                              
          the wash solution                                               
                        (pulses/min)                                      
                                    (%)                                   
______________________________________                                    
175,520   &lt;0.1%         175,345     99.90                                 
______________________________________                                    
 
    
     EXAMPLE 4 
     In this example, the procedure of Example 2 was repeated and the sorption of the Mo complex and the elution conditions were the same as in Example 2, but elution was effected with 150 ml 6 molar NH 4  OH solution at 23° C. 
     
         ______________________________________                                    
Results:                                                                  
Mo-99 activity          Mo-99 activity                                    
before sorption                                                           
          Mo-99 loss in in the eluate                                     
                                    Yield                                 
(pulses/min)                                                              
          the wash solution                                               
                        (pulses/min)                                      
                                    (%)                                   
______________________________________                                    
638,000   &lt;0.1%         574,200     90.00                                 
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     Even with the use of larger ion exhange sorption columns, such as those having a volume of greater than 20 cm 3 , the flowthrough speed during addition of the acidified solution containing the [Mo(SCN) 6  ] 3-  ions and during addition of the wash solution can be one-half the ion exchange column volume per minute, and, during addition of the elution liquor (alkali elution solution) to elute the Mo-99, the flowthrough speed can be 1/10 of the column volume per minute. Fluctuation in the flowthrough speed by a factor in the range of 1/2 to 2 of the given values are possible, however, without adverse influence on the process. 
     It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.