Abstract: A nuclear reactor having a pressure vessel which is open at the top. The open top of the pressure vessel is closed by a steel dome. A containment, which is open at the top, extends upward from and is joined to the top of the pressure vessel and has an open containment head at the top thereof. The open top of the containment is closed by a steel dome, thereby forming a containment well bounded laterally by the containment, on the bottom by the vessel closure and on the top by the containment closure. The pressure vessel can be a steel-lined prestressed concrete vessel, while the containment is formed by an extension of the prestressed concrete vessel. Alternatively, the pressure vessel and the containment are parts of a unitary steel vessel. Isolation valves are installed on each penetration pipeline to isolate the system in the event of a loss-of-coolant accident.

Abstract: A boiling water reactor having an optimum combination of active and passive safety systems. By combining three active divisions (I,II,III)of the boiling water reactor with a passive fourth division, the resulting design achieves improved plant reliability in addition to on-line maintenance of the emergency core-cooling systems. Included in the passive division is a new component, the reactor heat removal condenser (48), to be used in conjunction with pressure release valves (50) to provide backup depressurization of the reactor pressure vessel and backup heat removal and inventory control. The operating pressure of the heat removal condenser is maintained in the range of 100-200 psi.

Abstract: A recirculation system for driving reactor coolant water in a downcomer within a reactor pressure vessel includes a jet pump disposed in the downcomer and having a suction inlet at the top thereof and an outlet at the bottom thereof. A reactor internal pump is joined directly to the pressure vessel at an access nozzle thereof and includes a housing sealingly joined to the access nozzle, and in serial flow communication an inlet channel, an impeller, an outlet channel, and an injector nozzle. The inlet channel carries coolant water from the pressure vessel to the impeller which pressurizes the coolant water and returns it through the outlet channel and the injector nozzle for injection into the jet pump inlet. The water injected from the internal pump into the jet pump drives the jet pump for effecting recirculation flow within the pressure vessel.