A nuclear power generation system and related power cycle are disclosed, in one embodiment, the system includes primary coolant circulation through a hydraulically interconnected reactor containing nuclear fuel and a steam generating vessel collectively defining a steam supply system. Liquid secondary coolant for the power cycle flows through the steam generating vessel and is converted to steam by the primary coolant to drive a low pressure turbine of a turbine-generator set. Steam exiting the turbine is condensed and heated prior to return to the steam supply system, thereby completing a secondary coolant flow loop. In one embodiment, a majority of the secondary coolant heating occurs within the steam generating vessel via heat exchange with the primary coolant rather than externally in the secondary coolant flow loop. This creates a temperature differential between the primary and secondary coolant sufficient to create natural thermally induced convective circulation of the primary coolant.