The SNAP zirconium hydride reactor developed by the U.S. Atomic Energy Commission for space applications can also be used for the generation of power in marine applications. This reactor can be coupled with thermoelectric, organic Rankine, Brayton, and supercritical CO2 power conversion systems to yield compact, long-life power systems in the power range from several kW(e) to over 150 kW(e). The thermoelectric power conversion system, although exhibiting cycle efficiencies in the 7 to 10% range, has proven long-life capability. The Brayton and the supercritical CO2 systems yield the smallest power systems, while the Brayton system yields the lightest system. The low operating temperatures and the relatively high efficiency of the organic Rankine system imply that this system exhibits the lowest unit cost.