Analytical Method of Atomic Density Determination of Uranyl Nitrate Solution

A basic theory of an analytical calculation method to determine the atomic density of each individual nuclide contained in a homogeneous system of uranyl nitrate solution is presented. Atomic density or number density is a number of atoms or nuclides per cm³ or in a unit of atoms per barn-cm. This parameter is one of the important factors in defining the accuracy of neutronic calculations as such used in reactor core design. This work was carried out as part of neutronic design calculation of the SAMOP (subcritical assembly for ⁹⁹Mo isotope production) project, where uranyl nitrate solution was used as fuel with uranium enrichment of 20%. A homogeneous solution made by dissolving uranyl nitrate salt [UO₂ (NO₃)₂] into H₂O solvent has been used as an approach to this model. Two kinds of solution were described i.e. one that was made based on the amount of UO₂(NO₃)₂ dissolved in the solution and another one based on the amount of uranium in the solution. Expectedly this method can be used as an alternative way in estimating the atom density, solution density (g/cc) and the corresponding atom and weight fractions which is important in criticality calculations. (paper)