Abstract:
A reactivity control system includes a reservoir (42) containing a liquid nuclear poison (44), at least one stationary, hollow control blade (32) extending vertically into a reactor core (14), and a poison conduit (52) disposed in flow communication between the reservoir (42) and control blade (32) for channelling the poison (44) between the reservoir (42) and control blade (32). The level of the poison in the control blade is controlled for selectively varying nuclear reactivity in the core.
Abstract:
A reactor vessel includes a plenum and a reactor core with first and second sets of channels. A blanket salt flows through the first set of channels, and a fuel salt flows through the second set of channels. The plenum receives the blanket salt from the first set of channels. The blanket salt provides a breed-stock for a fission reaction in the fuel salt and transfers heat generated by the fission reaction without mixing with the fuel salt.
Abstract:
A boiling water nuclear power plant (100) includes a reactor core isolation cooling (RCIC) system in which a turbine (146) used to pump feedwater to the reactor also drives a generator (200). The generator (200) is used to drive RCIC components, such as a room cooler (160) and control electronics, during station blackout.
Abstract:
The wetwell space in a suppression pool (26) of a nuclear reactor containment is continuously ventilated by exhausting gas therefrom, while at the same time, during normal system operation atmospheric air from a source of same is admitted to the wetwell but such admission being blocked during a LOCA. All exhaust flow from the wetwell is conveyed through a conduit that outlets at a remote elevated location in the atmosphere. All exhaust flow through the conduit (37) is before outletting therefrom passed through gas treatment operation (60) wherein any particulates in the gas mixture are removed. Further treatment of the gas with charcoal to adsorb noble gases can be carried out.
Abstract:
A recirculation system (10) is disclosed for driving reactor coolant water in an annular downcomer (118) defined between a reactor vessel and a core shroud (12) spaced radially inwardly therefrom. The system supplies feedwater to the vessel and to a turbopump (18) disposed inside the downcomer (118). The turbopump (18) in accordance with one embodiment of the present invention includes a stationary axle (22) and a pump impeller (26) rotatably joined thereto and having an inlet end for receiving the coolant water from the downcomer. An annular plenum (30) surrounds the impeller for channeling feedwater to a plurality of turbine blades (36) joined to the impeller for rotating the impeller for driving the coolant water. The impeller is lubricated solely by the feedwater upon rotation of the impeller about the axle.
Abstract:
A reactor core (104) includes upper and lower matrices of fuel bundles. Fuel rods in the upper matrix (126) have their plenums oriented upward, while fuel rods in the lower matrix (124) have their plenums oriented downward. Refueling involves removal of a first bundle in the upper matrix (126), removal and retirement of the bundle in the lower matrix (124) directly below the original position of the first bundle, inversion and installation of the first bundle in the lower matrix, and installation of a new bundle in the upper matrix. The new bundle is installed plenum-side up. The bi-level core (104) provides greater flexibility in repositioning fuel bundles for longer burnups and lower high-level waste. In particular, problems with axial spectral variations in neutron flux can be compensated using the disclosed core arrangement and refueling procedure.
Abstract:
Fuel bundles of a boiling-water nuclear reactor are inverted during refueling methods. Bundles burned in a first orientation are subjected to greater burnup near their bottoms and greater conversion of fertile fuel to fissile fuel near their tops. Inverting the bundles promotes burnup of the actinide products from the conversion of the last cycle. Thus, the procedure greater energy production efficiency and reduced actinide radioactive waste are achieved. Once inverted fuel bundles can be removed for disposal. Alternatively, they can be reinverted to burnup actinide fissile fuel generated at the bottom (while it was downstream of the top) during the second operating cycle. Further inversions are provided for, but the major gains occur during the first and second inversions.
Abstract:
A recirculation system (10) is disclosed for driving reactor coolant water (114), contained in an annular downcomer (118) defined between a reactor vessel and a reactor core spaced radially inwardly therefrom. The system includes a plurality of circumferentially spaced pumps (12), disposed in the downcomer (118), each pump including an inlet for receiving coolant water from the downcomer as pump inlet flow, and an outlet for discharging the pressurized water. The recirculation system firstly increases the pressure of the pump inlet flow at the pump inlet before being sucked into the pump for being further pressurized by the pump.
Abstract:
A method and system (10) for controlling nuclear reactivity in a nuclear reactor are disclosed. The method includes maintaining a nuclear poison solution at an initial poison pressure (P1) less than the steam pressure within the reactor vessel. The method further includes channeling a pressurizing fluid into the holding tank (12) for pressurizing the poison solution to a pressure greater than the initial pressure thereof, and draining by gravity the poison solution from the holding tank and into the reactor vessel for mixing with the water to reduce reactivity in the core. The system includes the holding tank (12) apparatus for channeling the pressurizing fluid (18) from the reactor vessel (100) to the holding tank, apparatus for channeling the poison solution (28) from the holding tank by gravity into the reactor vessel, and a controller (42) for opening a normally closed pressurizing valve (26) and a normally closed drain valve (40) to allow flow of pressurizing fluid to, and the drained poison solution from, the holding tank through the respective channeling apparatus.
Abstract:
A drive (10) for positioning a control rod (12) in a nuclear reactor is disclosed. The drive (10) includes a housing (112) having a piston disposed therein, with a piston rod extending from the piston and through the housing for being joinable to the control rod. A driving fluid is provided into the housing for exerting a pressure force against the piston for moving the piston and the control rod. The output requirements for the driving fluid are varied in response to the position of the piston for selectively controlling intermediate positons of the piston.