On the relationship between changes in k and changes in homogenized 2-group constants

The relationships between changes in k∞ and changes in homogenized 2-group constants are derived. These relationships are used to explain seemingly contradictory results from two separate transport codes where it was found that they agree far more closely on the change in each cross-section than they do on the change in k∞. The study showed that this possibility was due to the fact that changes in k∞ were the results of various combinations, including differences of ratios of cross-sections.