Offshore floating nuclear power plants (OFNPs) are gaining attention as safe and location-flexible means for nuclear energy utilization. Although platform motion in the marine environment may affect reactor kinetics, particularly in boiling water reactors (BWRs), BWR-type OFNPs are expected to have high economic efficiency. This study investigates the reactor power behavior of a BWR-type OFNP using three-dimensional transient neutronics–thermal hydraulics coupled analysis. Heave and pitch motions are considered under realistic wave conditions using a typical BWR model.

The results show that reactor power and its distribution can vary because of the wave-induced platform motion; however, the amplitude of these variations is sufficiently small to ensure normal operation, even under the extreme wave conditions of a one-in-10 000-years storm.

Although the results of the present study demonstrate the ability of BWR-type OFNPs to provide a safe and stable energy supply, they also suggest the need for further research. Further studies are needed to address the complex wave conditions and assess the effects of the platform motion on ancillary systems, such as recirculation systems.