Abstract: According to the basic hypothesis of anticipated operational events, grounding on the special characters of a ship reactor, the equilibrium vapor specific activity and the cabin activity were calculated using NSRC code for the main loop and the secondary loop. The calculation results show that the computational mode of NSRC code is correct, and the NSRC code can be used to calculate radiactive effect of a ship reactor in anticipated operational events of design basis accidents. The calculation results can provide support to the safe operation of a ship nuclear power device.