DOE-HDBK-1019/1-93NUCLEAR CROSS SECTIONS AND NEUTRON FLUXReactor Theory (Neutron Characteristics)NP-02Page 12Rev. 0Example 2:An alloy is composed of 95% aluminum and 5% silicon (by weight). The density of thealloy is 2.66 g/cm . Properties of aluminum and silicon are shown below.3ElementGram Atomic Weight) )a (barns)s (barns)Aluminum26.98150.231.49Silicon28.08550.162.201.Calculate the atom densities for the aluminum and silicon.2.Determine the absorption and scattering macroscopic cross sections for thermalneutrons. 3.Calculate the mean free paths for absorption and scattering.Solution:Step 1:The density of the aluminum will be 95% of the total density. UsingEquation (2-1) yields the atom densities.