The Oyster Creek RETRAN licensing model was submitted for approval by the U.S. Nuclear Regulatory Commission in September 1987. The technical issues and concerns that were raised during the review process and how they were resolved are discussed. The technical issues are grouped into three major categories: (a) the adequacy of the model benchmark against plant data; (b) uncertainty analysis and model convergence with respect to various critical parameters (code correlations, nodalization, time step, etc.); and (c) model application and usage.