Feasibility study for production of ~(99)Mo and ~(99m)Tc by the neutron activation of ~(98)Mo in the MNSR reactor

摘要

The calculated weekly specific activities of~(99)Mo and~(99m)Tc produced from the irradiation of the MoO_(3)targets in the Miniature Neutron Source Reactor (MNSR) are presented in this paper. The productions of the~(99)Mo and~(99m)Tc were modelled and calculated through a set of differential equations using the Mathcad program. The resonance self-shielding factor (G_(res)) was calculated using the MATSSF and MCNP4C codes. The effects of the physical parameters such as the neutron flux and irradiation time on the weekly specific activities of~(99)Mo and~(99m)Tc have been analysed. It was found that the optimum irradiation scheme was achieved when the MNSR was operated for an extended period of 5 hours a day for 5 days a week at the neutron flux of 7.5×10~(11)n.cm~(‒2).s~(‒1). The weekly specific activities for the~(99)Mo and~(99m)Tc which can be produced in the MNSR, filling each of the five inner irradiation sites with 20 g of the MoO_(3)targets and using the regular natural convection method to cool the reactor, were 7.20 and 5.05 mCi.g~(‒1), respectively.