An evaluation of the effects of the neutron spectral shift between the surveillance capsule and vessel on the prediction of radiation-induced pressure vessel (PV) embrittlement has been made. A spectral lead factor, Ls, that accounts for this spectral shift and its effect on predicting change in vessel reference nil ductility temperature (ΔRTNDT) is defined. Using multigroup neutron spectra calculated for the Three Mile Island-2 core/vessel configuration and the damage cross sections developed by Serpan, Ls has been determined and found to result in significant underpredictions of ΔRTNDT. For a standard surveillance capsule located near the PV inner wall, ΔRTNDT is underpredicted by ~10 and ~50% at the T/4 and 3T/4 vessel locations, respectively.