We present nonequilibrium simulations of growth and melting of the atomic FCC (100) interface. Using Nose-Hoover dynamics we have carefully studied size effects and approximated the dynamics of the solid-liquid interface in a large system as closely as possible, This led to a clear asymmetry of growth and melting rates close to equilibrium. It was possible to explain these findings in terms of the lattice imperfections in crystalline phases in contact with a liquid phase, which automatically developed during growth simulations but were absent in the melting simulations. It was shown that when melting simulations were started with appropriate starting configurations. the asymmetry could be made to disappear.