A model of recovery and reembrittlement in an annealed nuclear reactor pressure vessel steel is described. Modeling is an integral part of the overall approach to annealing because it provides a bridge between the experimental studies and the application of the results to actual pressure vessels. This model is based on a series of annealing and reirradiation studies performed using microhardness specimens. Most of these materials were originally irradiated in nuclear pressure vessel surveillance programs. The model is based on the concept of a benefit factor, which compares the annealed and unirradiated specimens to material that has been irradiated without an intermediate anneal. It is noted that the data can most reasonably be explained by assuming that the mechanism of annealing is a combination of reversible and nonreversible processes. This model can be used to predict transition temperature shifts in annealed materials.