Design of irradiation box of topaz stones and its neutronic and thermal analysis in Tehran Research Reactor

This paper aims to design a suitable irradiation box of topaz stones and improve the neutronic parameters by maintaining the necessary conditions for their cooling in Tehran Research Reactor (TRR). In this way, by defining an appropriate neutron filter and simulating the irradiation box in the TRR core with MCNPX2.7 code, the neutronic parameters of the core are calculated, and the best configuration is selected. Then, various components of the irradiation channel are simulated using the Solidworks software, and thermal calculations are performed using the Flow Simulation plug-in. The results showed that although the presence of water in the irradiation channel and topaz box results in good cooling for topaz stones, the slowdown of fast neutrons causes intense activation of the stones. However, by using a closed-loop independent of the reactor pool water and a gaseous fluid such as air, the thermal neutron flux and consequently the activity of the stones is reduced. Moreover, the results demonstrated that, in this case, acceptable conditions could be provided for long-term and safe irradiation of stones by selecting the appropriate fluid velocity and adjusting the core power.