Abstract: A nuclear power plant having buried buildings that include a containment building housing a nuclear reactor, a power generation building housing turbines, and a nuclear material storage building. A borated cooling water tank is located above the containment building and can gravity feed water thereto through cooling pipes. Steam exhaust pipes extend from the containment building to the bottom of the water tank. A float and valve arrangement provides seawater to keep the water tank at a constant water level. Horizontal tunnels have manually operated hatches to isolate the different buildings from one another. Vertical tunnels have gravity elevators.