The production of ⁹⁹Mo, ¹³¹I, and ¹³³Xe radionuclides is very important for consumption in the field of nuclear medicine. Generally, the use of small core reactors is recommended for the production of large-scale these fission radionuclides. In this paper, we have considered three different core loading patterns of Tehran Research Reactor for the economic and optimum production of ⁹⁹Mo, ¹³¹I and ¹³³Xe from low-enriched uranium. These patterns are the large core, the small core with beryllium reflector (SC-Be), and the small core with graphite reflector. Simulation has been performed by MCNPX2.6 to compute the safety calculations, neutron flux changes, and evaluation of mentioned radionuclides production. The results reveal that the SC-Be is more suitable than the others two, in terms of safety. In this core, the drop of thermal neutron flux after loading the mini-plate targets is 11% and the activity of ⁹⁹Mo, ¹³¹I, and ¹³³Xe is 235, 227, and 592 Ci, respectively, at the 8 days after the end of irradiation. So, if the changing pattern of the small core is considered, the SC-Be should be suggested.

⁹⁹ Mo，¹³¹ I和¹³³ Xe放射性核素的生产对于核医学领域的消费非常重要。通常，建议使用小型堆芯反应器来大规模生产这些裂变放射性核素。在本文中，我们考虑了德黑兰研究堆的三种不同堆芯装载方式，以经济，最佳地生产⁹⁹ Mo，¹³¹ I和¹³³来自低浓铀的氙。这些图案是大芯，带铍反射镜（SC-Be）的小芯和带石墨反射镜的小芯。MCNPX2.6已进行了仿真，以计算安全性计算，中子通量变化以及所提及的放射性核素生产的评估。结果表明，就安全性而言，SC-Be比其他两个更合适。在该核中，加载微型平板靶后的热中子通量下降为11％，并且在第8天后⁹⁹ Mo，¹³¹ I和¹³³ Xe的活度分别为235、227和592 Ci。辐照结束。因此，如果考虑小铁芯的变化模式，则应建议使用SC-Be。