The underlying nuclear reaction sequence in Type I X-ray bursts is the rp-process. We examine the sensitivity of current X-ray burst models to uncertainties in nuclear reaction rates in terms of predicted X-ray light curves and final produced ashes. Many of the relevant reaction rates have significantly large uncertainties that impact the results of X-ray burst models. We used an updated nuclear reaction network and ran almost 400,000 simulations with a single-zone X-ray burst model to determine the influence of individual reaction rate variations. We also explored the validity of single-zone approximations as tools to investigate nuclear physics by comparing to a full 1-D multi-zone model. We show that a properly calibrated single-zone model can save computation time and give similar results to multi-zone models. Using the calibrated singlezone model we identify the most significant reaction in the X-ray burst.