Molybdenum-99 production via lead and bismuth moderators and milli-structure- 98 Mo samples by the indirect production technique using the Monte Carlo method

We describe the design of a neutron activator that contains a beryllium target, a lead/bismuth moderator, graphite/PbF 2 reflectors, and a boron absorber. Production of the 99 Mo isotope using millimeter-sized 98 Mo samples located in various regions of the activator was simulated using the MCNPX code. If the 98 Mo samples are placed in the reflector region, the yield increases due to a larger flux of epithermal neutrons.