Abstract: A self-actuating passive pressure relief device for nuclear reactor containments is described. The pressure relief device passively releases gases from within a reactor containment when the containment pressure exceeds a designated threshold pressure. The pressure relief device automatically reseals itself when the containment pressure drops below the threshold pressure. Any containment gases that are vented by the pressure relief device from the containment are scrubbed and cleansed before they are released into the atmosphere. To accomplish this, a sealed fluid chamber is placed in direct communication with the reactor containment for holding a liquid material such as water. A standpipe having its lower end extend into the sealed container and has an opening below the normal operating liquid level within the chamber.

Abstract: A heat exchanging apparatus for reducing the temperature of a heating fluid prior to thermal communication with a heated fluid. The apparatus includes an integral pre-cooling heat exchanger located within a main heat exchanger. The pre-cooling heat exchanger brings the heating fluid into thermal communication with the heating fluid circulating in the main heat exchanger so that the heated fluid is prevented from departing from nucleate boiling in the main heat exchanger.

Abstract: A control rod assembly in a nuclear reactor that automatically scrams the reactor when a loss of coolant flow occurs and that can also control the level of neutron flux in the reactor. The control rod assembly includes a separator plate having an orifice through which the reactor coolant flows and a sealing surface around the orifice. The control rod in the assembly has a complementary sealing surface. When the control rod and separator plate are brought into contact, the differential pressure across the separator plate caused by the flow of the primary coolant through the reactor core retains the two sealing surfaces together. If the flow of coolant stops or the differential pressure across the separator plate decreases for any reason, the control rod drops by gravity and the reactor is scrammed.

Abstract: sodium-immersed components in a nuclear reactor are rendered observable by illumination with radiation in the ultraviolet (UV) sprectrum and by detecting reflected radiation through a UV scanning means, such as a television type camera sensitive to UV radiation. The UV scanning means may be adapted to be immersed in molten sodium coolant to facilitate observation of selected locations within the nuclear reactor. Real-time images may be provided for monitoring reactor operation and remotely-controlled reactor maintenance operations.