Nuclear power has seen widescale shore-based power application, as well as at sea for some of the larger navies of the world. Nuclear power offers some distinct benefits: very long range, long refuelling intervals, and, currently topical: no emissions. Currently, three large developments could impact new potential for both naval and commercial shipping: generation IV technology, small modular reactors, and the use of thorium instead of uranium. This paper starts with the relevant background of nuclear technology. Then the current developments and their relevance for the marine context are discussed, followed by a more detailed description of the reactor types presently in development. Two types are identified for both near-term (estimated 10-20 years) the Very High Temperature reactor, and for long-term deployment (20+ years) the Molten Salt Reactor. Then a selection is made for suitable energy conversion for ship propulsion. A variety of options are considered ranging from hydrogen generation to more conventional turbines, with open Brayton turbines as a suitable choice for the implementation, based on a variety of criteria such as efficiency and complexity. The implementation specifics of nuclear power are discussed, with important considerations such as the shielding, size, and weight. The nuclear power potential is benchmarked with a conventional fuel-based system, showing the distinct benefits of nuclear energy: no direct emissions, long range, strategic and operation autonomy, and reduction of signatures, as well as the trade-offs: nuclear waste production and higher up-front cost. Each of the topics is discussed giving an overview of the technical challenges but most importantly potential of implementing nuclear power in marine propulsion and power generation systems