Feasibility study for production of 99Mo and 99mTc by the neutron activation of 98Mo in the MNSR reactor

Abstract

The calculated weekly specific activities of 99Mo and 99mTc produced from the irradiation of the MoO3 targets in the Miniature Neutron Source Reactor (MNSR) are presented in this paper. The productions of the 99Mo and 99mTc were modelled and calculated through a set of differential equations using the Mathcad program. The resonance self-shielding factor (Gres) 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 99Mo and 99mTc 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 7.5×1011 n.cm‒2.s‒1. The weekly specific activities for the 99Mo and 99mTc which can be produced in the MNSR, filling each of the five inner irradiation sites with 20 g of the MoO3 targets and using the regular natural convection method to cool the reactor, were 7.20 and 5.05 mCi.g‒1, respectively.