Abstract: In moisture separator reheaters of a nuclear power plant, a control valve is mounted in a steam vent line of the plant to control the flow rate of vent steam in conformity with the load applied to the plant, to thereby avoid the occurrence of any instable flow phenomenon in the entire range of loads applied to the plant.

Abstract: A pressurized water nuclear reactor has a reactor vessel arranged in a pool, which is filled with a neutron absorbing liquid, for example borated water. The reactor vessel is closed except for tubes connecting it with a tray above it. The coolant in the circuit rises from the vessel to the tray, gives up its heat by flashing, and flows back to the bottom of the vessel, driven by natural circulation. The tray is separated from the pool by a vapor-filled bell, which surrounds it. In the bell the vapor gives up its useful heat to a condenser. The relatively low boron content of the cooling circuit, compared to the pool, is achieved by continuous dilution of the condensate from vapor additionally generated out of the pool water. The dilution process is an equilibrium with continuous inflow of the pool water. The inflow is automatically controlled by the pool level, which rises when the pool water is pressed out from below the bell by overproduction of vapor.

Abstract: An apparatus and process utilizing a large water rod of a fuel bundle in a boiling water reactor fuel assembly as a radiation heat sink during a loss of coolant accident. Core cooling spray is collected at the top end of the bundle's large water rod by a collector and distributed by a distributor to coat the inside wall surfaces of the water rod. In the case of a water rod which is not bottom vented, the water rod body is modified so as to separate the downward flow of liquid water from the upward flow of steam. During normal plant operation, the large water rod serves as a water-filled moderator tube to provide a more uniform power distribution across the fuel bundle.

Abstract: A steam generator level measurement system of the type having a reference leg which is kept full of water by a condensation pot, has a separator pot in the connecting line between the condensation pot and the steam phase in the steam generator to remove excess liquid from the steam externally of the steam generator. The separator pot has an expansion chamber which slows down the velocity of the steam/liquid mixture to aid in separation, and a baffle, which directs steam introduced at the top of the chamber on one side of the baffle to flow downward and then upward for discharge on the other side of the baffle to avoid direct liquid penetration into the line connected to the condensate pot.

Abstract: Coolant recirculation arrangement for a nuclear reactor including a plurality of vertically oriented tubular conduits arranged in spaced relation between an unshrouded nuclear core and the inner pressure vessel wall for conducting coolant from an upper plenum above the core to a lower plenum below the core.

Abstract: An improved model steam generator for simulating the conditions within a nuclear steam generator in order to monitor the condition of the heat exchange tubes and tubesheet of the nuclear steam generator is disclosed herein. The improved model steam generator includes a highly effective separator assembly for separating water droplets entrained within the steam flowing out of the outlet of the secondary side of the generator formed from a plurality of separator grids, each of which includes an array of semi-cylindrical deflector members. The grids are vertically stacked with the deflector members transversely disposed to the flow of steam generated by the model steam generator. Each of the parallel arrays of deflector members in each grid is angularly disposed approximately 45.degree. to the deflector members in the grids above it and below in order to provide a tortuous path for the flow of steam ascending therethrough.

Abstract: A model steam generator including a system for facilitating the inspection of the sample tubes within the boiler vessel of the model generator is disclosed herein. The system includes means for detachably connecting the tubesheet from the primary and secondary sides of the boiler vessel. In the preferred embodiment, both end of the tubesheet and the abutting ends of the primary and secondary sides of the boiler vessel are circumscribed by tapered flanges. The tubesheet is detachably connected from the primary and secondary sides of the boiler vessel by means of Grayloc.RTM.-type annular clamps which are circumscribed by grooves for receiving the abutting flanges at the tubesheet joints. Additionally, the system includes a frame for suspending the secondary side of the boiler vessel, a wheeled cart having a jack for both laterally and vertically moving the primary side of the boiler vessel and the tubesheet into a clamping position onto the secondary side of the boiler vessel.

Abstract: A lifting device for lifting and transporting nuclear fuel elements. This device comprises a mast-like support on the lower end of which automatically operated and locked gripping pawls are provided. The support has a considerable height and may be referred to as lifting mast. The gripping pawls and their operating mechanism are referred to as gripping-head. The gripping-head and the lifting mast are telescopically movable relative to each other. To this end guide rods and compression springs are interposed between the lower end of the lifting mast and the gripping-head. The gripping-head comprises two concentric annular members which are relatively movable or rotatable about their common geometrical axis. One of the annular members supports the gripping pawls pivotable in radial vertical planes. The gripping pawls are T-shaped. One of their transverse ends is adapted to engage the fuel rods, and the other of their transverse ends is adapted to engage curved grooves in the other annular member.

Abstract: In this process, the decay heat of radioactive substances is carried away by circulating liquid coolant. Some of the liquid coolant is vaporized by the decay heat. The circulation of liquid in the circuit is driven by pressure from the vapor. After exceeding a static pressure head corresponding to the pressure drop in the circuit, the vapor is separated from the liquid and condensed, and the condensate is combined with the liquid returning for repeated partial vaporization.

Abstract: A vessel wall cooperating with a circular array of moisture separators which have a vertical riser tube, centrally disposed hubs, a vertical baffle disposed between the hub and the riser tube, turning vanes and an outer volute partial skirt or wall to compress the steam-water mixture against the volute and vessel wall and utilize the downwardly spiraling flow of liquid film formed on the volute and vessel wall to effectively separate the entrained water from the steam and prevent reentrainment thereof.