Irradiation creep and growth causes the core components in pressure tube reactors to change dimensions. The pressure tubes and calandria tubes in Canada Deuterium Uranium (CANDU) reactors elongate and may interact with the end shields. An analysis was performed that quantitatively describes the nature of this interaction. It is shown that as the fuel channels elongate, compressive stresses are induced in the pressure tubes, tensile stresses are induced in the calandria tubes, and the two end shields move apart. It is also demonstrated how simple mechanical adjustments can alter the nature of the induced stresses.