In resonance capture calculations, it is usual to assume that the capture in any one resonance is unaffected by the existence of other resonances: this is known as the “flux recovery” assumption. This assumption is exact for hydrogenous moderation in a homogeneous situation. However, in highly heterogeneous lattice cells such as that of the Steam Generating Heavy Water Reactor (SGHW), in which the fuel is intimately associated with a powerful moderator, the resonance flux in the fuel is depressed below that in the bulk moderator. In this paper, this flux depression effect is investigated by using a model in which all moderation is hydrogenous and the resonances are square. This model suggests that the flux recovery assumption will overestimate 238U capture in a typical SGHW Lattice by about 5%.