Simulation Analyses On Irradiating Production Of ²³⁷Np Encapsulated Targets

The theory of neutron transport can describe the motion of neutrons in the medium and its corresponding laws.The physical principle is the basis for the study of transmutation activation,material radiation damage and radiation dose.The Monte Carlo method is a numerical method based on probability distribution and statistical theory.It can describe the characteristics of random moving particles and the processes of physical experiment more realistically,and solve the problems that are difficult to deal with in numerical calculations.Therefore,the application field of this method is also more and more extensive.Considering that the ²³⁸Pu production has broad applications in defense military research and scientific exploration,in this work,we established the theoretical framework of the irradiation processes of²³⁷Np liquid encapsulated targets,and only the irradiation and decay reactions of the targets flowing through the core of the primary loop were considered in the program.In the simulated calculations,the typical neutron energy spectrum available from the international TRIGA reactor was used.With Monte Carlo method,the physical model of neutron transport was established through C++programming,so that we independently develop a simulation program dedicated to the calculation of products quality in liquid encapsulated targets from the theoretical engineering calculations.Firstly,the effect of single target irradiation was calculated,and the simulation results were compared with the relevant data obtained by SCALE/TRITON software to verify the reliability of the program.Afterwards,optimal target selection and single target irradiation under different neutron fluxes were studied to determine the optimal irradiation time of ²³⁸Pu in the target,and to go on the²³⁶Pu impurity adjustment.Finally,the impact of the double-target shading at different distances on the production of ²³⁸Pu and products quality were studied.The above-mentioned work has important theoretical guidance for the future development of a new production technology scheme based on liquid circuits.