While cross sections are heavily dependent on neutron speed, there are other factors that affect the cross section and other factors that influence the reaction rate.
The temperature of the medium also matters and you can have effects like doppler broadening that will affect the cross sections (an important part of reactor safety). Number density of course plays heavily into reaction rates and going beyond that, material geometry and type of course heavily influences a reactor design (reflectors, shielding, absorbers, etc...).
maddumpies t1_j4q3cmd wrote
Reply to comment by AmphoraExplorer in If nuclear fission in U-235 causes the atom to be split into 2 smaller atoms (such as Kr-92 and Ba-141) then how is it that U-236 is produced as waste since the U-235 was just split into smaller peices? by Ian98766
While cross sections are heavily dependent on neutron speed, there are other factors that affect the cross section and other factors that influence the reaction rate.
The temperature of the medium also matters and you can have effects like doppler broadening that will affect the cross sections (an important part of reactor safety). Number density of course plays heavily into reaction rates and going beyond that, material geometry and type of course heavily influences a reactor design (reflectors, shielding, absorbers, etc...).