Shear walls are a critical seismic component in nuclear power structures. In nuclear engineering, especially within the nuclear island structure, these walls are typically squat, with a low shear span ratio and high reinforcement ratio. The arrangement of reinforcement influences the wall's performance, which ultimately impacts the results of Structural Fragility Analysis (SFA) and Probabilistic Safety Analysis (PSA) for the nuclear plant. This study investigates eight squat shear walls in the nuclear island, each with different edge reinforcement configurations. Using a nonlinear simulation method validated by pseudo-static experiments on large-scale specimens, the study analyzes and compares the hysteresis curves, damage distributions, and mechanical behaviors. The results indicate that varying reinforcement style including reinforcement ratio, edge reinforcement type, and coverage have significant effects on the performance of the squat shear walls. The influence on load capacity is more pronounced than that on displacement in the simulations. Stress concentrations are primarily observed in the vertical rebar at the edge region near the center and lower portions of the wall. The stirrup-structured concealed column in the squat shear wall offers limited improvement to its overall performance.