Abstract: Coolant flow (900) in the core (103) of a natural circulation boiling water reactor (100) is monitored by making use of a detector (208) for nuclear radiation and a turbine device (204) which comprises a rotor (304) which can modulate the flux (206) of the nuclear radiation on the detector. The turbine rotor can be installed in a fuel bundle (104), while the detector can be placed in an adjoining instrumentation tube (320). Included in the turbine rotor is material (308) which modulates the radiation field (neutron field and/or gamma field). The radiation detector detects (602) variations in the radiation field when the turbine rotor device is set into rotation by the coolant flow (900). The coolant flow rate is then calculated (603) from the speed of these variations.

Abstract: The present invention is directed to a modular steam separator with integrated dryer especially adapted for separating and drying steam exiting the core of a nuclear boiling water reactor. The instant modular separator with integrated dryer has a standpipe with a proximal end that is connectable to the upper plenum of the core of the nuclear reactor and a distal end that is connected to a proximal end of a steam separator. A distal end of the steam separator is connected to a steam distribution channel that extends in fluid communication to a steam dryer. The steam dryer has a steam vent for passage of dry steam to the steam dome of the reactor and a water drain connected to the reactor's downcomer region.

Abstract: An improved emergency cooling system and method is disclosed that may be adapted for incorporation into or use with a nuclear BWR wherein a reactor pressure vessel (RPV) containing a nuclear core and a heat transfer fluid for circulation in a heat transfer relationship with the core is housed within an annular sealed drywell and is fluid communicable therewith for passage thereto in an emergency situation the heat transfer fluid in a gaseous phase and any noncondensibles present in the RPV, an annular sealed wetwell houses the drywell, and a pressure suppression pool of liquid is disposed in the wetwell and is connected to the drywell by submerged vents. The improved emergency cooling system and method has a containment condenser for receiving condensible heat transfer fluid in a gaseous phase and noncondensibles for condensing at least a portion of the heat transfer fluid.

Abstract: A control rod drive assembly includes a translatable drive tube joined to a control rod by a coupling having complementary screw threads. A purge flow is channeled between the screw threads to flush away debris therebetween for preventing galling of the threads during operation.

Abstract: Apparatus and method are described for providing a discrete readout of the collapsed water level within a boiling water reactor. An elongate gauge housing is mounted within the reactor vessel extending through the collapsed level from a steam environment into a boiling water environment. A serially coupled sequence of junction defining thermocouple element pairs are positioned within the gauge housing and are arranged with a heating assembly to generate an output signal which corresponds with the water level. Also located under the influence of the heating assembly are reference thermocouples, one providing a reference output corresponding with the instantaneous temperature of the boiling water environment and the other providing a reference output corresponding with the steam environment above the collapsed water level. The signals from the reference thermocouples and the serial coupled level determining thermocouple structures are then treated to define instantaneous water level.

Abstract: A fuel bundle for a natural-circulation boiling-water reactor includes at least one coolant bypass tube which is at least partially open at both its top and bottom and extends about 2/3 of the bundle height. Water within the bypass tube remains liquid. As it exits the top of the bypass tubes, it merges with and "cools" the flow exterior to the tube. This arrangement reduces the pressure drop across the core, increasing coolant flow. In addition, the merging coolant helps improve heat transfer at the maximum heat flux levels within the core. Lateral holes through the bypass tube can further enhance with heat transfer distribution in the core. The reduced pressure drop in the core and the more uniform heat flux distribution both permit a reactor to operate at higher power ratings.

Abstract: The present invention is directed to a boiling water reactor wherein housed within the reactor pressure vessel is the nuclear core and an upper steam dome connected to a steam outlet in the RPV. The improvement comprises a vessel disposed in the steam dome and containing a neutron poison effective for inactivating the core. This vessel is vented to the steam dome for pressurizng the poison contained therein. The vessel also is connected by a line terminating beneath the core. The line contains an actuatable valve to release the poison through the line upon its actuation. The poison, when released, flows through the line by gravity to beneath the core for mixing with the reactor coolant which passes through the core resulting in consequent inactivation thereof.

Abstract: The present invention is directed to gas-liquid separators especially adapted for the separation of steam exiting the core of a nuclear boiling water reactor that utilizes natural circulation. Such separator has a barrel having a longitudinal axis and width, has an inlet and an outlet, and has a plurality of spaced-apart pickoff rings in fluid communication with annular flow discharge passages. The improved separator of the present invention comprises the pickoff rings having curvilinear shape to direct flow into the flow discharge passages. A twisted strip swirler is positioned along the axis of the barrel after the initial pickoff ring and does not extend the full width of the barrel. The width of the barrel increases at each succeeding pick-off ring from the barrel inlet to the barrel outlet. Advantageously, a low expansion angle exists between the rings and the top of the separator barrel.

Abstract: An improved passive cooling system for water cooled and moderated nuclear fission reaction plants provides means for enhancing the cooling arrangement for coping with loss of coolant accidents or removing decay heat during periods of reactor shutdown. The improvement comprises providing a measure consisting of a tubular sleeve, which encourages flow circulation within a pool of cooling water.

Abstract: The present invention discloses an improved methodology for achieving the desirable feature of recirculation flow control in a sparger-type natural-circulation BWR, enabling reactors utilzing the method to perform in load-following and/or spectral shift modes of power operations. In its broadest aspects, the invention is based on locating the feedwater sparger at an elevational level which is about water level established during normal operation of the BWR. One or more of load following or spectral shift can be performed by controlling the feedwater fed to said BWR through the feedwater inlet and into the sparger to vary the water level to be above, at or below the elevational level of such sparger.

Abstract: The present invention is directed to a nuclear reactor facility wherein a nuclear reactor pressure vessel (RPV) is housed within an annular sealed drywell, an annular sealed wetwell houses said drywell, a pressure suppression pool of liquid is disposed in said wetwell and is connected to said drywell by submerged vents, a condenser line connects said drywell to an isolation condenser, and a bleedline from said isolation condenser is connected to said pool and terminates under the surface of said pool. The improvement of the present invention comprises a liquid reservoir disposed in said drywell and a standpipe disposed in said wetwell. The reservoir and the standpipe are connected by a duct which is located below the surface of said reservoir a distance, D. The area of the reservoir is at least 25 times larger than the area of said standpipe.

Abstract: The present invention is directed to a separator for dividing a steam/water mixture into its liquid and steam components. The inventive separator comprises a pipe having an annular spiral strip which is attached to its inside wall, said pipe being in fluid communication with ports for removal of liquid water divided from said mixture. The width of the annular spiral strip preferably is about 1/10th to 1/20th of the diameter of the pipe to which it is attached. A method for dividing steam/water mixtures into their liquid and steam components by passing such mixture through the inventive separator forms yet another aspect of the present invention.