Objectives  Based on the operation requirements of the steam dump system of marine nuclear power plant, the dynamic characteristics and influencing factors of steam dump conditions are analyzed.

  Methods  According to the functional characteristics of the steam dump system, mathematical and physical models of the matching operations of the steam generator, steam system, bypass system and main steam turbine are established. In order to verify the accuracy and universality of the simulation model, an analysis is made of the dynamic operation characteristics and coupling matching characteristics of the primary and secondary circuits under extreme working conditions, such as the quick shut-off operation of the main stop valve and load rejection of the steam turbine.

  Results  The simulation results show that when operating under steam dump conditions, the appropriate steam dump valve, main stop valve and their matching action time should be selected according to the power self-regulation capacity of the marine reactor, and safety problems such as the overpressure of the steam header and overspeed of the steam turbine unit should be comprehensively considered. At the same time, the steam demands of other equipments on the ship should be met.

  Conclusions  The results of this study can provide references for the safety control of steam dump conditions and the optimal design of the steam dump systems of marine nuclear power plants.