Abstract: Modified passive containment cooling systems for cooling a reactor core of a boiling water nuclear reactor are described. The reactor core is positioned in a reactor pressure vessel which is located in a drywell of the nuclear reactor. The passive containment cooling system (PCCS), in one form, includes an IC/PCC pool, a GDCS pool, a suppression pool, and a condensate drain tank. The IC/PCC and the GDCS pool each are substantially isolated from the drywell, and the suppression pool is separated from the drywell by a wall having a spill-over hole therein. An equalizing line extends between the suppression pool and the RPV and is configured to transport water from the suppression pool to the RPV. The condensate drain tank is positioned in the drywell and includes a base wall having a sidewall extending therefrom to define a fluid retaining cavity. A steam inlet line extends from within the drywall to a set of passive containment cooling condensers, which condense steam generated within the drywall to water.

Abstract: A system for suppressing the pressure inside the containment of a BWR following a postulated accident. A piping subsystem is provided which features a main process pipe that communicates the wetwell airspace to a connection point downstream of the guard charcoal bed in an offgas system and upstream of the main bank of delay charcoal beds which give extensive holdup to offgases. The main process pipe is fitted with both inboard and outboard containment isolation valves. Also incorporated in the main process pipe is a low-differential-pressure rupture disk which prevents any gas outflow in this piping whatsoever until or unless rupture occurs by virtue of pressure inside this main process pipe on the wetwell airspace side of the disk exceeding the design opening (rupture) pressure differential. The charcoal holds up the radioactive species in the noncondensable gas from the wetwell plenum by adsorption, allowing time for radioactive decay before the gas is vented to the environs.

Abstract: An improved containment configuration for a boiling water reactor in which the wetwell airspace is divided into a multiplicity of chambers through the use of wetwell airspace divider partitions. The partitions extend to below the water level of the suppression pool so that the gas in one airspace chamber cannot communicate with another airspace chamber. Each wetwell airspace chamber can be placed in flow communication with the drywell via a respective open vacuum breaker. When one vacuum breaker fails in the open position or when wetwell/drywell steam bypass leakage into one chamber occurs, the pressure differential between the wetwell airspace chamber and the drywell drops. However, because the leaking chamber is isolated, the pressure differential between the drywell and the other chambers is unaffected. Thus, the PCC heat exchangers corresponding to non-leaking chambers can continue to operate effectively, even if the PCC heat exchanger corresponding to the leaking chamber is rendered ineffective.

Abstract: An apparatus which mitigates temperature stratification in the suppression pool water caused by hot water drained into the suppression pool from the lower drywell pool. The outlet of a spillover hole formed in the inner bounding wall of the suppression pool is connected to and in flow communication with one end of piping. The inlet end of the piping is above the water level in the suppression pool. The piping is routed down the vertical downcomer duct and through a hole formed in the thin wall separating the downcomer duct from the suppression pool water. The piping discharge end preferably has an elevation at or near the bottom of the suppression pool and has a location in the horizontal plane which is removed from the point where the piping first emerges on the suppression pool side of the inner bounding wall of the suppression pool. This enables water at the surface of the lower drywell pool to flow into and be discharged at the bottom of the suppression pool.

Abstract: An improved system for managing the water inventory in the condenser pool of a boiling water reactor has means for raising the level of the upper surface of the condenser pool water without adding water to the isolation pool. A tank filled with water is installed in a chamber of the condenser pool. The water-filled tank contains one or more holes or openings at its lowermost periphery and is connected via piping and a passive-type valve (e.g., squib valve) to a high-pressure gas-charged pneumatic tank of appropriate volume. The valve is normally closed, but can be opened at an appropriate time following a loss-of-coolant accident. When the valve opens, high-pressure gas inside the pneumatic tank is released to flow passively through the piping to pressurize the interior of the water-filled tank. In so doing, the initial water contents of the tank are expelled through the openings, causing the water level in the condenser pool to rise.

Abstract: A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling.

Abstract: A pressure suppression system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and an enclosed gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The GDCS pool includes a plenum for receiving through an inlet the non-condensable gas carried with steam from the drywell following a loss-of-coolant accident (LOCA). A condenser is disposed in the GDCS plenum for condensing the steam channeled therein and to trap the non-condensable gas therein. A method of operation includes draining the GDCS pool following the LOCA and channeling steam released into the drywell following the LOCA into the GDCS plenum for cooling along with the non-condensable gas carried therewith for trapping the gas therein.

Abstract: A pressure suppression containment system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel. The wetwell pool includes a plenum for receiving the non-condensable gas carried with steam from the drywell following a loss-of coolant-accident (LOCA). The wetwell plenum is vented to a plenum above the GDCS pool following the LOCA for suppressing pressure rise within the containment vessel. A method of operation includes channeling steam released into the drywell following the LOCA into the wetwell pool for cooling along with the non-condensable gas carried therewith. The GDCS pool is then drained by gravity, and the wetwell plenum is vented into the GDCS plenum for channeling the non-condensable gas thereto.

Abstract: A boiling water nuclear reactor plant is provided with a standby supply of auxiliary coolant water for use in the event of a loss of coolant mishap to provide supplementary coolant water for cooling the fuel core. The supply of standby auxiliary coolant water is maintained within the reactor pressure vessel and is administered by inherently passive means.

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: A multiple liquid standby safety injection system for nuclear fission reactor plants comprising means for injecting supplemental coolant water into the nuclear reactor pressure vessel to cool the fuel core and means for injecting a water solution of a neutron absorbing compound into the nuclear reactor pressure vessel about the fuel core to diminish the fission reaction. The coolant water and solution of neutron absorbent each comprise individual systems and are conveyed from their respective supply container by means of pressurized propelling gas. The individual standby safety injection systems for coolant water and solution are integrated with means for transferring propelling gas from one supply container to the other to enhance the source and available volume of liquid propelling gas for either system by drawing from the other.

Abstract: An improved separating system for boiling water nuclear reactors comprising a combination of mechanical steam separators with liquid water collecting and transferring devices.

Abstract: A boiling water nuclear fission reactor is disclosed with a unique steam-water separating system. The steam-water separation means comprises an assemblage of open troughs positioned above the fuel core which reduces the amount of steam recycled through the coolant circuit.

Abstract: A nuclear reactor system which includes a containment uses, upon loss-of-coolant event, an isolation condenser submerged in a large supply of water and elevated some distance above the system pressure vessel to effect both initial and decay heat dissipation cooling in the containment. The isolation condenser has inlet thereto communicated to an open entry conduit disposed in the containment so that steam and heated gasses in the containment space enter the isolation condenser and are cooled. Condensate resulting from the cooling is returned to an elevated system gravity coolant supply pool, which pool is used for replenishing coolant lost from the pressure vessel, the return being through a return conduit that has a lower end section configured with a water trap with non-condensable gasses present in the steam being separated from the condensate and vented to the suppression pool.

Abstract: A steam separating system for boiling water nuclear reactors comprising a combination of mechanical steam separators with steam collecting and transferring units.

Abstract: An improved liquid jet pump for water is described in which the water issuing from the jet pump drive nozzle passes into a nozzle mixing chamber where steam is introduced to nozzle outflow. This steam, traveling in the same direction as and converging upon the liquid driving stream, is raised to high velocities. These uncommonly high velocities of steam are attained both as a result of passage through a converging/diverging nozzle and the action of condensation upon the passing liquid stream. The liquid driving stream is supplied at a temperature which promotes immediate condensation of the steam molecules of the high speed steam jet. A process of momentum exchange immediately occurs within the drive nozzle mixing chamber between the high-velocity steam and the parallel-moving slower liquid stream with momentum being transferred from the steam to the liquid driving stream.

Abstract: An improved decay heat removal system and apparatus for a nuclear boiling water reactor. The apparatus includes an isolation condenser shell, water coolant, and heat exchange surfaces that are immersed in the water coolant and are sized for shutdown cooling duty. The apparatus is time shared for both isolation cooling and shutdown cooling duty. The invention reduces the total number of heat exchange surfaces and heat exchanger shells required for dissipating heat generated by the reactor core as compared to conventional, separate isolation cooling and shutdown cooling systems. In addition, the amount of reactor building space which must be reserved for isolation cooling and shutdown cooling requirements may be significantly reduced.

Abstract: An improved boiling water reactor emergency coolant injection system network uses condensate pumps in the feedwater train to function in alternate duty as short-term low-pressure coolant injection pumps. These low-pressure pumps use a reliable power supply consisting of the addition of one or more auxiliary generators, of small size and generating capacity relative to the size of the power station's main generator, which are direct-coupled mechanically to the shaft of the main turbine-generator and which use the spindown energy of the main turbine-generator to power the low-pressure coolant injection pumps.

Abstract: A shroud tank and fill pipe for a boiling water nuclear reactor of the type having a reactor vessel containing a saturated water coolant inventory, a reactor core for heating water to generate a steam/water mixture, a steam separator for classifying said steam and water from the steam/water mixture, and standpipes for conveying the steam/water mixture from the core to the steam separator. The shroud tank is disposed inside the reactor vessel overlying the reactor core and circumscribing the standpipes. The shroud tank has an open top, a closed bottom, and a plurality of drain holes around its bottom periphery. During normal reactor operation, the shroud tank is supplied with cold water coolant which is continuously introduced at relatively low flow rates into the shroud tank through the fill pipe. The drain holes are sized to minimize the outflow of cold water coolant during normal operation.

Abstract: In a boiling water reactor of the type having a reactor core for heating feedwater to generate a two-phase steam/water mixture and a core shroud head overlying the reactor core and defining a core upper plenum region, a plurality of conduits disposed in the upper plenum region to provide supplemental water coolant. Each conduit has at least one open end located in the primary water coolant and a conduit body that extends laterally from the open end through the core shroud head and into the plenum region. Each conduit is closed with respect to the plenum region and is filled with primary water coolant during normal operation of the reactor to provide supplemental water coolant. The supplemental water coolant drains into the reactor pressure vessel when the primary coolant level falls below the open end to cool the reactor core during a loss-of-coolant accident.