A compact real-time simulator for two-loop pressurized water reactor plants, FISA-2/WS (Fully Implicit Safety Analysis-2 /Work Station), has been improved and adapted to the Sun 386i computer, which was developed for classroom training in support of full-scale simulators, for transient analysis, engineering studies, and emergency drills. The FISA-2/ WS simulator package is divided into three modules: plant, on-line graphic display, and interactive communication. The plant module consists of models for core kinetics, reactor coolant system, steam generator, main steam line, and control and safety systems. Each of the models is optimized to obtain the capability of real-time simulation. Simulation results are displayed periodically at a user-specified time interval on a color monitor by the on-line graphic display module. The FISA-2/WS interactive communication module enables the user to initiate or mitigate accidents and to select one of the menu-driven graphic displays with the mouse and keyboard. Several nuclear steam supply system transients have been simulated by FISA-2/WS. The results presented here are obtained from simulations of steady state, turbine load change transient, and small-break loss-of-coolant accidents. The results of FISA-2/WS are in good agreement with plant data and the results of RELAP5/MOD2, and the fast running capability is also confirmed.