Patent Number: 
Section: claims

1. A system for regulating nuclear reactor core activity comprising:a naturally circulating nuclear reactor having a nuclear reactor cooling outlet,a nuclear reactor cooling inlet, anda nuclear core with a negative temperature reactivity coefficient;a steam generator having a saturated liquid space displaced above the nuclear reactor cooling outlet, anda steam space;a coolant loop where the coolant loop cycles coolant out through the nuclear reactor coolant outlet, where the coolant loop is in thermal communication with the saturated liquid space of the steam generator, and where the coolant loop cycles coolant in through the nuclear reactor coolant inlet;a steam piping system in fluid communication with the steam space of the steam generator;a three way valve having a valve shaft, in fluid communication at a three way valve inlet port with the steam piping system which leaves the steam generator;an expansion turbine directly fluidly connected to and in fluid communication with the three way valve only at a three way valve first outlet port;a condenser in fluid communication with the expansion turbine;a pump header in fluid communication with the condenser;a feedwater heater in fluid communication at a heater inlet port with the three way valve at a three way valve second outlet port and in fluid communication at a heater outlet port with the condenser;a feedwater pump having a pump inlet port in fluid communication with the pump header, anda pump discharge port;a feedwater header in fluid communication with the pump discharge port of the feedwater pump, in thermal communication with the feedwater heater, and in fluid communication with the saturated liquid space of the steam generator;an electric generator mechanically driven by the expansion turbine and electrically connected to an electrical grid; anda controller separate from and in data communication with both the valve shaft of the three way valve and the electric generator, where the controller is programmed torespond to an increase in power demand from the electric generator by directing movement of the valve shaft to concomitantly increase steam flow to the expansion turbine and decrease steam flow to the feedwater heater, andrespond to a decrease in power demand from the electric generator by directing movement of the valve shaft to concomitantly decrease steam flow to the expansion turbine and increase steam flow to the feedwater heater. 2. The electric generating system of claim 1 where the nuclear reactor includes fuel, and where the fuel is a nitride. 3. The electric generating system of claim 2 where the coolant includes lead. 4. The electric generating system of claim 3, where the coolant is a lead-bismuth eutectic.