Nuclear reactor with passive safety system

Abstract

A pressurized nuclear water reactor has a substantially cylindrical flow liner with a cylindrical wall section and bottom and an open top. A barrel forms a riser chamber that contains the core in the flow liner. A pressure vessel contains the cylindrical flow liner to form a second annular chamber therebetween that contains a supplementary liquid coolant, with insulation means to provide a major portion of the supplementary liquid coolant at a first temperature and a minor portion thereof at a second higher temperature. Upon depressurization in the vessel, fluid communication means enable injection of supplementary liquid coolant from the second annular chamber into the core upon flashing of a minor portion to vapor. A further pool of water outside the pressure vessel, and insulation on the wall, maintain the desired temperature in the supplementary liquid coolant supply. Injection or removal of borated solution, as a chemistry control solution, into or from the supplementary liquid coolant is provided. A passive safety system incorporates the reactor with means for circulating water solely by natural convection from the hot leg to the cold leg of the primary coolant system and has heat exchange means associated therewith.