Emergency core cooling system for a nuclear reactor

Claim 1

An emergency core cooling system for a nuclear reactor comprising a pressure vessel hermetically sealed by a closure head, a reactor core in the pressure vessel and an inlet and outlet for circulating coolant through the reactor core; emergency coolant means including at least one accumulator having a pressurized neutron absorber material therein; an outlet on said accumulator connected with the closure head for discharging said absorber material into the pressure vessel; flow restricting means between said accumulator and closure head which permits flow of absorber material only from the accumulator toward the reactor, said flow restricting means being held closed by the pressure of coolant in said reactor, the arrangement being such that when the reactor coolant pressure drops below the accumulator pressure, neutron absorber material flows from the accumulator into the pressure vessel; and means in said pressure vessel for conducting the neutron absorber material from the accumulator to the top of said core for distribution downwardly therethrough for carrying away heat generated in the core; said conducting means comprising piping supported by the closure head, said piping being arranged to extend from the accumulator outlet to a plenum chamber under the closure head, thereby providing an avenue for the discharge of absorber material from the accumulator into the plenum chamber; means communicating with the plenum chamber and top of said core for conducting the absorber material to the core; said piping extending from the accumulator outlet further being connected to downcomer tubing supported in the pressure vessel and having openings which discharge said absorber material directly on to the reactor core, thereby permitting it to flow in and between fuel assemblies in the core; a connector connecting said piping and downcomer tubing, said connector being designed to allow for lateral displacement of the tubing and piping after the closure head is mounted on the pressure vessel; high and low liquid level sensors in said accumulator; valve means in said piping connected to the accumulator outlet; and means connecting said sensors with said valve means in the piping which are operable to close said valves when the absorber material level in the accumulator rises or falls respectively to predetermined levels.