Document Type: Research Paper
The present work investigates an appropriate way to calculate the 1700 atomic density changes in the reactor operations. To automate this procedure, a computer program has been designed by C#. This program suggests a way to solve this problem which is based on the solution system of differential equations (Bitman) that it is designed according to Runge-Kutta Fehlberg method. The designed software is based on the high ability to calculate the material depletion with constant flux and constant power condition. The software inputs included, reactor power, computation time, initial and final time, determine of Taylor series order in calculation time depended flux, determination of time unite, specifyingmaterial composition of the reactor core at initial condition consist of light radioactive material, heavy and fission products, determining the order in the accuracy of calculations, applying the decay constants library, cross section database, the amount of generated thermal energy by various material decay ,determining the type of calculations at point of view constant flux or constant power. Finally, the atomic density of light, heavy materials and fission products at various times of reactor operation were calculated with high accuracy as the out puts of this program. At last, it is worth to say that we proposed a new approach for the use the Runge-Kutta Fehlberg method to compute atomic density changes of material composition of the reactor core which lead us to achievement a high ability tool to solve the above problem.