Patent ID: 8891723

Claim:
A stable startup system for a nuclear reactor comprising: a pressurized reactor vessel; a reactor core housed in the reactor vessel, wherein the reactor core is submerged in a primary coolant of the nuclear reactor, and wherein the reactor core is located beneath a riser; a heat sink configured to remove heat from the primary coolant after the primary coolant has passed through the riser of the reactor vessel; and an electrical heater configured to add heat to the primary coolant contained within the reactor vessel prior to an initialization of the reactor core to achieve reactor criticality, wherein the heat is added by the electrical heater into the riser at an insertion point that is below the heat sink to cause a density difference in the primary coolant that drives the primary coolant through the reactor core which occurs only by the use of natural circulation prior to the initialization of the reactor core, and wherein the insertion point is above the reactor core.