Method and apparatus for protecting the core of a nuclear reactor

A method and apparatus is described for protecting fuel rods in a nuclear reactor core under conditions of a major break in the coolant inlet piping connected to the reactor inlet nozzle. A multi-venturi protector which includes multiple parallel disposed venturis is mounted in the inlet nozzle. The characteristics of the venturi protector are such that coolant flow through the protector into the reactor is unimpeded, but reverse flow through the protector is restricted when a break occurs in the inlet piping. The resistance offered to such reverse flow permits reactor coolant and emergency core coolant to remain in contact with the reactor core for a time sufficient to allow the fuel rods to decrease in temperature to a low safe level. (author)