Techniques for on-demand production of medical isotopes such as mo-99/tc-99m and radioactive iodine isotopes including i-131

Abstract

A system and method for radioisotope production uses fast-neutron-caused fission of depleted or naturally occurring uranium targets in an irradiation chamber. Fast fission can be enhanced by having neutrons encountering the target undergo scattering or reflection to increase each neutron's probability of causing fission (n, f) reactions in U-238. The U-238 can be deployed as one or more layers sandwiched between layers of neutron-reflecting material, or as rods surrounded by neutron-reflecting material. The gaseous fission products can be withdrawn from the irradiation chamber on a continuous basis, and the radioactive iodine isotopes (including I-131) extracted.

What is claimed is: 
     
         1 . A method for producing radioisotopes comprising:
 introducing non-enriched uranium (“NEU”) material into a an irradiation chamber, the irradiation chamber having one or more walls formed of neutron-reflecting material;   irradiating the NEU material with neutrons having energies above 800 keV to cause fast fission reactions to occur in the NEU material and generate fission products, wherein:
 at least some neutrons from the irradiating are reflected from at least one of the one or more walls, thereby increasing the path length over which those neutrons are in the NEU material, and 
 the increased path length increases the probability that those neutrons in the NEU material will cause fast fission reactions; and 
   extracting the fission products from the NEU material.   
     
     
         2 . The method of  claim 1  wherein one of the fission products extracted comprises at least one of molybdenum-99 (Mo-99) and technetium-99m (Tc-99m). 
     
     
         3 . The method of  claim 1  wherein one of the fission products extracted comprises at least one of iodine 131 (I-131) and iodine 132 (I-132). 
     
     
         4 . The method of  claim 1  wherein the NEU material in the irradiation chamber occupies a single spatially contiguous region. 
     
     
         5 . The method of  claim 1  wherein the NEU material in the irradiation chamber occupies multiple spatially disjoint regions. 
     
     
         6 . The method of  claim 1  wherein the one or more walls formed of neutron-reflecting material comprise at least one internal wall of the irradiation chamber. 
     
     
         7 . The method of  claim 1  wherein the one or more walls formed of neutron-reflecting material comprise an outer wall that surrounds all the NEU material in the irradiation chamber. 
     
     
         8 . The method of  claim 1  wherein the one or more walls formed of neutron-reflecting material comprise:
 at least one internal wall of the irradiation chamber; and 
 an outer wall that surrounds all the NEU material in the irradiation chamber.