The U fuel-that will make a fission reaction in the aqueous homogeneous reactors is the uranyl nitrate salt containing no more than 19.75% uranium-235 isotope (lightly enriched uranium-LEU). The “aqueous solution” prepared with this salt, which is very easily soluble in water, is prepared in the amount of mass that can sustain the nuclear reactions and is filled into a spherical or cylindrical container. The heat released during the nuclear fission reaction must be removed from the medium so that the solution temperature does not exceed 90 oC.
Apart from Molybdenum-99, other valuable radioisotopes, such as Xe-133, Sr-89, Y-90, I-131, which are used in nuclear medicine, are also included in the fission products that occur during the fission of uranium. During the process, certain volumes of uranyl nitrate solution are taken out and” chemical cleaning” is processed and the radioisotopes are separated continuously. The figure below shows the ARGUS Solution Reactor scheme that is currently working at the Kurchatov Institute in Russian Federation.
From the solution reactors, which date back to 45-50 years, they have been produced till now 30 units. These reactors range from 0.05 W to 5 MW (heat) and have a wide range of operating knowledge and data accumulation resulting from their operation.
Calculations made with AHRs, high Mo-99 production efficiency, low costs, small critical masses, spontaneous passive safety systems, and simplified fuel operations and cleaning features made them now again a focus of interest.
The International Atomic Energy Agency also presents AH Reactors as a serious alternative for the more efficient use of medical radioisotopes (such as Mo-99) of what their needs are increasingly felt in the world for better human health .
The use of codes such as ANSYS CFX 14 in the design of solution reactors is also an important factor in the leading role of FIGES in this field.