A radiation damage model that accounts for neutron spectral differences between irradiation locations has been applied to pertinent data on the change in ductile-to-brittle transition temperature for A302B pressure vessel steel. The resulting correlation supports the contention that such a damage model provides a physically more meaningful measure of exposure than the usually cited neutron flux above 1 MeV. A physically reasonable estimate of the functional dependence of this correlation has been fitted by a least-squares method to these data, and a technique for assigning one-sided tolerance limits is described.