In this study, we examine how tides affect potential storm surge hazards at the Hanbit Nuclear Power Plant on Korea’s west coast, a macrotidal region characterized by large tidal ranges. Using 33 synthetic typhoon scenarios generated using the Tropical Cyclone Risk Model, we performed tide–storm surge interaction (TSSI) simulations with the ADvanced CIRCulation model to assess nonlinear effects between tides and storm surges. Model performance was validated against water-level observations during Typhoons Muifa (1109) and Bolaven (1215), demonstrating high accuracy in reproducing tidal phases and maximum water levels. The results show that tidal interaction significantly increases total water levels while reducing the intrinsic storm surge component through nonlinear TSSI associated with the tidal phase, modified sea-surface slope, velocity-field changes, and bottom-friction effects. On average, the maximum storm surge height (MSSH) and time-integrated storm surge height (TISSH) from TSSI simulations were 70.94 and 77.19% of those from storm-surge-only (SSO) simulations, respectively. In contrast, the average maximum water surface height (MWSH) corresponded to 94.76% of the linear sum of SSO-based MSSH and the peak tidal level, indicating that simple linear superposition may overestimate extreme water levels. A sensitivity analysis showed that central pressure and maximum wind speed were the dominant factors for MSSH and TISSH, respectively, whereas the minimum distance of closest approach was consistently the least influential. Validation using water-level sensor records from tide-gauge stations supports the reliability of the numerical simulations, and the findings highlight the necessity of a TSSI-based hazard assessment for coastal nuclear facilities in macrotidal environments.