With the development of computer technology, the operation environment of main control rooms in modern nuclear power plants (NPP) has considerably changed over the years, namely the use of advanced Digital Control System (DCS). In this paper, the accident of steam generator tube rupture (SGTR) of a DCS in a nuclear power plant is simulated and the task analysis method is used to explore the reliability of the secondary side cooling and depressurization operation of the operators. The effect of the man-machine interface changes on operators is s...