A simple model for the neutron slowing down calculations

In general, nuclear reactors contain several heavy nuclides. That makes the neutron slowing down calculations more expensive in computation time and in computer memory especially when the heavy nuclides number is large. This paper presents a simple model to do these calculations with a significant reduction of both the computation time and the required computer memory. Basically only one fictitious heavy nuclide: the ‘Equivalent Nuclide’ is used by the model instead of all the heavy actual nuclides. The equivalent nuclide characteristics are directly obtained from those of the actual ones. The model.qualification has been done for the continous-energy neutron slowing down in the energy interval (10−5 eV–2 MeV) at different temperatures 600, 900 and 1200 K. The model results are in good agreement with those obtained by direct calculations.We have found that our model calculates the reactions rates with a high accuracy and save 50% of the computation time in the case of 2 resonant nuclides and 90% for 8 resonant nuclides. The major advantage is the huge reduction of the required computation memory.