Difference between number of fission by kappa-fission and by heating-local

In this picture, there are the number of fission per second calculate by normalizing kappa-fission (with f) and heating local (with f’). Why when i approximate the number with kappa-fission when i insert 24 control rod the number of fission is small between the number when 12 control rod is inside.. and with heating local, It’s the opposite case.