Abstract: An acousto-optic leakage monitoring system for main steam pipeline in nuclear power plant. The system includes an acoustic emission leakage monitoring loop and a spectrum leakage monitoring loop, wherein the signal input ends of the acoustic emission leakage monitoring loop and the signal input ends of the spectrum leakage monitoring loop are respectively arranged at detection points of the main steam pipeline. The signal output ends of the acoustic emission leakage monitoring loop and the signal output ends of the spectrum leakage monitoring loop are communicatively connected to each other through a network switch, and the network switch is sequentially connected with a control unit and a display unit.

Abstract: A spent nuclear fuel storage facility. In one embodiment, the invention is directed to a storage facility including an array of storage containers. Each of the storage containers includes a body portion and a lid. The body portion has a storage cavity configured to hold a canister containing spent nuclear fuel. The lid, which may rest atop the body portion in a detachable manner, includes an inlet vent and an outlet vent. Each of the storage containers may be configured to draw air through the inlet vent and into the storage cavity where the air is warmed and passed through the outlet vent as heated air. The body portion of the storage containers may be positioned below grade and the lid of the storage containers may be positioned above grade.

Abstract: The apparatus is used for testing heat exchangers having mutually separate first and second flow paths. The apparatus provides a high pressure fluid source (10) to connect with a first pressure-sealed flow path of the heat exchanger under test. A volumetric sensor (VS) is connected to a selected pressure-sealed flow path, having a sensing chamber arranged to receive fluid from the selected flow path. The sensing chamber is connected to a further fluid source such as a compressed air reservoir (16) which provides a high pressure gas supply. Movement of a magnetic float within the sensing chamber is detected by an array of Hall effect sensors, enabling a CPU to calculate the rate of leakage between the two flow paths which may be signaled to a local display and/or alarm or remotely via an internet connection.

Abstract: An apparatus for producing trichlorosilane in which metallurgical grade silicon powder supplied to a reactor is reacted with hydrogen chloride gas while being fluidized by the hydrogen chloride gas, thereby discharging trichlorosilane generated by the reaction from the reactor, includes: a plurality of gas flow controlling members which are installed along a vertical direction in an annular shape R from an inner peripheral wall of the reactor in an internal space of the reactor; and a heat transfer tube which is installed along the vertical direction in the annular space R and through which a heating medium passes.

Abstract: The present invention discloses an easy-to-use, installation-free water leak warning device having a sturdy hollow body enclosing essential functioning elements including a power source, an amplifier, a speaker, and portions of two electrodes. The water leak warning device is preferably small in size and may be placed at potential water leak or flooding spots. The essential functioning elements are operatively connected with conductive material so that when leaked water flows to where the device is located, an audible signal can be emitted to remind the user of the device to prevent further leakage and mitigate any damage.

Abstract: A real time monitoring system of a spent fuel pool includes a detection unit configured to detect condition information using a sensor installed in the spent fuel pool; an input storage unit configured to receive and store configuration information of a spent fuel, history information related to burnup, and a normal value and a limit value of current condition information; an operation and determination unit configured to calculate the current condition information of the spent fuel by using the condition information detected by the detection unit and the configuration information and the history information stored in the input storage unit and configured to determine a risk level by comparing the current condition information with the limit value corresponding to the risk level; and a display unit configured to display the current condition information calculated by the operation and determination unit and configured to display the determined risk level.

Abstract: System and method for detecting and/or predicting in a field the leakage of nuclear reactor coolant that may occur at the pressure boundary of the primary system of a nuclear reactor. The system and method for detecting the leakage of nuclear reactor coolant uses a laser induced emission spectrum. The leakage of coolant is detected by detecting boron (B), a main component of the coolant, in corrosive products generated at the nuclear reactor pressure boundary on the basis of laser spectroscopy. An embodiment of the system for detecting leakage of nuclear reactor coolant may include a laser generator, a laser focusing lens, an emission collector, and emission spectrum analyzer.

Abstract: A system and method for assessing failure of fuel rods are disclosed. The method may include monitoring fuel rod operational conditions, comparing the fuel rod parameters to parameters limits, calculating the fuel rod performance parameters to determine the likelihood of failure of individual fuel rods, and updating plant operating parameters based on the calculated fuel rod parameters. The system may input the calculated fuel rod parameters into a fuel failure model to assess the probability of failure, and predict the probability of failure of individual fuel rods based on fuel rod parameters in the fuel failure model.

Abstract: The invention concerns a method of monitoring the operation of a reactor of a nuclear plant. The reactor is operated at a given total reactor power during a normal fuel operation cycle. The radioactivity level in the off-gas stream is continuously measured to detect a possible release of fission gases from the fuel rods as a consequence of a fuel leakage due to a defect on the cladding of any of the fuel rods in any of the fuel assemblies. An instantaneous power distribution is regularly established in the core and a power distribution pattern over time is established based on the instantaneous power distributions. The release of fission gases and the established power distribution pattern are then combined and correlations between changes in the release of fission gases and in the power distribution pattern are observed in order to determine a position of the defect.

Abstract: System and method for detecting and/or predicting in a field the leakage of nuclear reactor coolant that may occur at the pressure boundary of the primary system of a nuclear reactor. The system and method for detecting the leakage of nuclear reactor coolant uses a laser induced emission spectrum. The leakage of coolant is detected by detecting boron (B), a main component of the coolant, in corrosive products generated at the nuclear reactor pressure boundary on the basis of laser spectroscopy. An embodiment of the system for detecting leakage of nuclear reactor coolant may include a laser generator, a laser focusing lens, an emission collector, and emission spectrum analyzer.

Abstract: The invention concerns a method of monitoring the operation of a reactor of a nuclear plant. The reactor is operated at a given total reactor power during a normal fuel operation cycle. The radioactivity level in the off-gas stream is continuously measured to detect a possible release of fission gases from the fuel rods as a consequence of a fuel leakage due to a defect on the cladding of any of the fuel rods in any of the fuel assemblies. An instantaneous power distribution is regularly established in the core and a power distribution pattern over time is established based on the instantaneous power distributions. The release of fission gases and the established power distribution pattern are then combined and correlations between changes in the release of fission gases and in the power distribution pattern are observed in order to determine a position of the defect.

Abstract: A method of early sensing of water leakage, through chemical concentration monitoring, in a nuclear reactor system using a liquid metal and molten salt, the method including: measuring an electrical conductivity and a mass spectrum of a first channel and a second channel of a heat-related device included in the nuclear reactor system using the liquid metal and the molten salt; calculating a first identification value associated with the water leakage in the heat-related device using the measured electrical conductivity; calculating a second identification value associated with the water leakage in the heat-related device using the measured mass spectrum; and sensing the water leakage by comparing a predetermined reference value and a summed identification value, the summed identification value being the sum of the first identification value and the second identification value.

Abstract: A water leak detection floor transversally suspended by a pedestal side wall is installed between a reactor pressure vessel and a molten core holding apparatus. If a water leak occurs at the reactor pressure vessel, the water leak detection floor receives and detects the leak water. In a core meltdown accident, corium melts and penetrates the water leak detection floor and deposits on the molten core holding apparatus.

Abstract: Fuel rods of fuel assemblies of a boiling water reactor are tested for leaks. A plurality of fuel assemblies are each arranged adjacent to one another in a cell of the upper core grid of the boiling water reactor. A hood is placed above a plurality of cells A water sample is taken from each of the cells, and the water samples from a plurality of cells forming a group are combined and tested for the presence of radioactive fission products A plurality of groups are analyzed simultaneously in a number, which number corresponds to the number of groups, of measurement channels. Where a result of a group is positive, the cells of the group are tested separately by the measurement channels. Those fuel assemblies of a cell that is found positive are tested individually outside the hood.

Abstract: Methods and apparatus are provided for measuring emissions from radioactive material in a matrix. Consideration is made in the variation in counts observed at different rational positions of the body of material so as to establish the information about the position of the radioactive material within the matrix.

Abstract: A sealing device (10) comprising a first sealing element (12) having a housing (18) with an internal chamber (26) therein and a second sealing element (14) having a shaft (34). When the first (12) and second sealing elements (14) are connected, the shaft (34) of the second sealing element (14) extends into the internal chamber (26) of the first sealing element (12) through an opening in its housing. According to an important aspect of the invention, the first sealing element (12) comprises a pressure sensor (46) connected to the internal chamber (26) for sensing a pressure in the internal chamber (26); and a transmitter (48) for receiving a signal indicative of the pressure in the internal chamber and for transmitting the signal to a monitoring station.

Abstract: A method of early sensing of water leakage, through chemical concentration monitoring, in a nuclear reactor system using a liquid metal and molten salt, the method including: measuring an electrical conductivity and a mass spectrum of a first channel and a second channel of a heat-related device included in the nuclear reactor system using the liquid metal and the molten salt; calculating a first identification value associated with the water leakage in the heat-related device using the measured electrical conductivity; calculating a second identification value associated with the water leakage in the heat-related device using the measured mass spectrum; and sensing the water leakage by comparing a predetermined reference value and a summed identification value, the summed identification value being the sum of the first identification value and the second identification value.

Abstract: A risk-informed method for safety analyses of nuclear power generating systems is provided. In an exemplary embodiment, the method includes ordering events by an initiating event frequency, defining an initiating event frequency threshold value, defining acceptance criteria having an adjusted amount of conservatism, where the amount of conservatism is a function of the initiating event frequency, and analyzing an event by a deterministic safety analysis methodology when the event has an event initiating frequency at or above the threshold value, or analyzing an event by a probabilistic risk assessment methodology when the event has an event initiating frequency below the threshold value.

Abstract: The method involves measuring hydrogen permeation in the tubes by mass spectrometry, wherein the tube is inserted into a high or ultrahigh vacuum device in which a mass spectrometer and a total pressure gauge are located. H2 or H2 and inert gas mixtures are circulated inside the tube at the required partial pressure. The tube is then heated and the appearance of H2 outside the tube is observed. The flow thereof inside the tube and emergence time, called permeation time, are determined based on permeation curves. The emergence time of the first microcrack is also determined.

Abstract: The contents of a container 1 are non-intrusively monitored by probing the container with an ultrasonic signal, and measuring changes in the ultrasound signature of the received signal after the signal has passed through the contents of the container.

Abstract: A method and apparatus for the detection of radioactive material in an area is disclosed. The apparatus comprises a transmitter operatively arranged to transmit electromagnetic radiation, a receiver operatively arranged to measure an intensity of the electromagnetic radiation, and processing means operatively arranged to determine the presence of radioactive material based on the intensity measurement. Two receiver configurations are possible. In the first, the receiver measures the intensity of the electromagnetic radiation reflected by ion tracks in the air proximate to the area scanned for radioactive material. Alternatively, the receiver measures the intensity of the electromagnetic radiation transmitted by the air proximate to the area scanned for radioactive material.

Abstract: A shielded rack loader makes use of a loading rack movable between a shielding structure and a storage tube. A shield plug seals the storage tube. A hoist moves the shield plug and the loading rack. A shield plug cart and a material transfer cart mate with receiving flanges of the rack loader and permit temporary storage and movement of the shield plug and of canisters of transuranic material.

Abstract: A method for testing whether fuel rods of fuel assemblies resting on a working base and under water, of a nuclear reactor are leaking is disclosed. The method includes heating at least one first fuel assembly of a first division of fuel assemblies for driving radioactive fission products out of a defective fuel rod contained in the first fuel assembly. The first fuel assembly is continuously tested by extracting samples of water and continuously degassing the water removed from an area around the first fuel assembly even during the heating resulting in gas. A radioactivity of gaseous fission products released in the gas is continuously recorded. A fuel assembly belonging to a second division of fuel assemblies is heated only if the first fuel assembly belonging to the first division of fuel assemblies has been tested. An apparatus for implementing the method is also disclosed.

Abstract: The invention concerns a method and a device for evaluating the integrity of the nuclear fuel in a nuclear plant having a reactor (1) enclosing a reactor core formed by a number of fuel cladding members (2) arranged to enclose said nuclear fuel. The value of each of a number of parameters including activity data (4) of the off-gases from the reactor is determined. The value of each of a number of second parameters including chemical data and activity data of the liquid (5) flowing through the reactor is determined. The value of each of a number of operational parameters (6) including at least one of the reactor effects, control rod position, actual fuel type, flow of off-gases, and flow of the liquid flowing through the reactor is determined. The value of the first and second parameters are standardized (7, 8) in relation to the values of said operational parameters.

Abstract: Detectors are used to monitor the status of spent nuclear fuel storage containers non-invasively while they remain in storage casks. The detectors measure neutron flux and &ggr;-ray flux and may also measure temperature variations of the spent nuclear fuel. The measurements can be accomplished actively or passively, with minimal exposure of individuals to radiation fields or other hazardous conditions. Preferred neutron and &ggr;-ray detectors have a semiconductor active region that is resistant to neutron damage. Incipient structural failures may also be detected using measurements based on electrical continuity, with data being transmitted to an external pickup coil.

Abstract: Device for checking the tightness of covers on a heavy metal container for transport and/or storage of radioactive materials, the said container comprising a cavity for nuclear materials delimited by a thick cylindrical shell closed at one end by means of a bottom fixed so that it is leaktight, and at the other end by at least two thick removable superposed covers, characterized in that the said covers are in contact with a shoulder formed in the shell, through flanges fitted with at least two concentric seals, that at least two ducts pass through the shell at each cover, leading through a first inspection orifice to the outside surface of the shell close to the cover in an accessible location, and through a second orifice, one into the space between the cover concentric seals, and the other into the space between the said cover, the shell and the immediately superposed cover, each inspection orifice optionally being connected to a tightness measurement and inspection circuit.

Abstract: An apparatus and a method for detecting and locating leaks in a nuclear plant, in particular a pipeline in a nuclear plant, include a collection line which is permeable to a substance to be detected and which communicates with a pump and with a sensor for the substance. The sensor has a detector for detecting the radioactivity of the substance or a branch line which communicates with a detector for detecting radioactivity branches off upstream of the sensor. If a radioactive substance reaches the collection line and penetrates it, then the location of the leak can be determined from the instant at which the radioactive substance reaches the detector.

Abstract: A system and method of the present invention measures the relative stress in the cladding of a nuclear fuel rod caused by the internal gas pressure of the rod. This is done by determining the attenuation ratio of two specific frequencies from a broadband low frequency acoustic energy spectrum. Relative pressure differentials are measurable and therefore any loss of fuel rod gas pressure is a direct indication of fuel rod cladding failure.

Abstract: A shielded rack loader makes use of a loading rack movable between a shielding structure and a storage tube. A shield plug seals the storage tube. A hoist moves the shield plug and the loading rack. A shield plug cart and a material transfer cart mate with receiving flanges of the rack loader and permit temporary storage and movement of the shield plug and of canisters of transuranic material.

Abstract: The tube to be replaced is extracted and an internal surface of the bottom head (1b) is then machined around the through opening (10), a hollow shell (20) is attached and fixed on the machined surface (15) of the bottom head (1b), around the through opening (10), by welding along a peripheral edge (19), the hollow shell is bored in order to produce a passage hole (24) through its wall, in extension of the through opening (10) and a welding bevel (23). A replacement through-tube (18) is fixed on the wall of the hollow shell (20) by depositing a welding metal (25) in the bevel (23). The invention applies in particular to the replacement of vessel bottom head penetrations of a pressurized water nuclear reactor.

Abstract: The reactor vessel is placed inside a reactor pit having a vertical axis and including a bottom (5) arranged below and aligned with the vessel bottom head. In the event of meltdown of the reactor core as a result of accidental operation of the nuclear reactor, which may lead to perforation of the vessel bottom head, the temperature at a plurality of points (14) distributed over the surface (8) of the reactor pit bottom (5) in line with the vessel bottom head is measured continuously. Optical measurement of the temperatures on the bottom (5) of the reactor pit is preferably carried out by using a plurality of optical fibers (10) arranged on the reactor pit bottom (5), along the length of which Bragg gratings (14), each capable of reflecting a light signal having a particular wavelength, are distributed.

Abstract: The present invention provides a method for identifying failed fuel elements and the scale of damage accurately, quickly and at low cost without disassembling a fuel assembly and without discharging radioactive waste. Radiation detector(s) for measurement of gamma radiation emitted from surface of the irradiated fuel assembly and the fuel assembly are rotated and translated relative to each other, the dectected data of the radiation emitted from the surface of the fuel assembly is acquired, processed, a tomographic image is constructed from the radiation intensity distribution and is prepared and displayed, and a failed fuel element is finally confirmed from the tomographic image of the fuel assembly cross-section.

Abstract: An on-line sipping air delivery system that propels bubbles across the entire surface of the fuel assembly. A pump delivers liquid through an aspirator located near the bottom of the fuel handling mast. Liquid flow through a venturi in the aspirator causes a drop in pressure inside the aspirator and pulls air into the aspirator through an ambient air line that extends above the surface of the liquid. The air is mixed with liquid as it flows through the aspirator and the mixture is injected under the fuel assembly through nozzles positioned at the bottom of the assembly. Suction nozzles above the liquid level at the top of the fuel assembly are used in a conventional manner to capture and deliver the released air and gases to appropriate testing equipment.

Abstract: A leak detector for detecting a leak of an electrically conductive fluid m a vessel comprises an electrically conductive wire having a melting temperature less than an internal temperature of the vessel and greater than the external temperature of the vessel. The wire is stitched to a heat resistant fabric to hold the wire in place and to thermally and electrically insulate the wire when no leaking fluid is present. Detector means electrically connected to the wire outputs an electrical signal if the wire is fused by leaking fluid permeating the fabric.

Abstract: The invention relates to an arrangement for carrying out leak detection of a fuel assembly for a pressurized-water nuclear reactor. A substantially vertical hollow mast means open in both ends houses the fuel assembly to be examined. The fuel assembly is drawn to the inside of the mast means from its lower side. The part of the mast means housing the fuel assembly is lifted to a position in which the fuel assembly is provided near but below the water surface of water inside the nuclear reactor. Water is sucked from a position inside the mast means above the fuel assembly. A gas separating means separates gases present in water sucked from the inside of the mast means. The separated gas is analyzed in a gas analyzing means regarding its amount of gaseous fission products.

Abstract: A process and a system for detecting defective nuclear fuel assemblies in situ. The system includes two basic subsystems. The first subsystem is a sample collection system consisting of a hood placed over the fuel. A technique whereby a vacuum is drawn across a submerged nozzle of a degas tank is used to draw up the sample of fluid out of a fuel assembly. The second subsystem determines the amount of Kr-85 radioisotope contained in the fluid sample. This information is used to determine whether the fuel assembly contains a defective, i.e., leaking, fuel rod. The measurement values for Kr-85 in the fluid sample extracted from the fuel assembly are compared to the measurement values for Kr-85 in fluid samples taken from the reactor pool prior to fuel assembly testing and fluid samples taken from non-leaking control cells, the latter values representing the background to which the subject fuel assembly is compared.

Abstract: Apparatus for inspecting the nuclear reactor comprising a boom rotatably connected by a pivot point to the top of a reactor head, a mechanism for rotating the boom with respect to said pivot point, a camera affixed to said boom and being slidingly affixed thereto such that the camera may be slidably adjusted in a longitudinal direction with respect to said boom.

Abstract: The method and the device are applicable to the penetrations (2) of a pressurised water nuclear reactor vessel head (1) during operation.The device includes a double circuit for picking off two gas samples (100, 16, 17; 12, 13, 14, 15) and a measurement assembly (18) which regularly compares the content, especially of water vapour, in the two samples picked off. The first sample is taken from the volume of a chamber (7) where the possible leak (10) emerges, and the second in proximity to the head (1) outside the region immediately affected by the leak. The assembly (18) makes it possible to generate (19) an alarm in the event of a leak and to distinguish it from operational alarms.Techniques and means are also provided for determining the flow rate of sweeping in the volume of the chamber (7) and for checking the pick-off and detection systems.

Abstract: A method and an apparatus for testing, repairing or exchanging nozzles of the bottom of a reactor pressure vessel include inserting individual shielding containers into the reactor pressure vessel. Shafts pass through a shielding container and water-filled cartridges can be inserted into the shafts. Tubes for receiving probes of an in-core instrumentation are embedded into bottom plates of the remaining shielding containers and into bottoms of the cartridges. After removing a cartridge, a carrier for working tools can be introduced into the shaft. In this way the radioactive loading is considerably reduced by the probes inside or outside the reactor pressure vessel.

Abstract: Pressure vessel apparatus includes upper and lower pressure vessel housings maintained together under pressure by tendons. Bellows are connected to the pressure vessel housings in order to provide leaktight barriers, and to permit motion of the pressure vessel housings. The tendons are divided into two sets, with the tendons of each set of tendons being stressed differently than the tendons of the other set of tendons. The apparatus when utilized as a nuclear reactor pressure vessel includes a core catcher with flotation pool connected to and disposed below the pressure vessel housings and defining a core catcher interior in communication with the pressure vessel interior for receiving core material from the pressure vessel interior resulting from reactor melt-down.

Abstract: The confining and covering enclosure (10) comprises a heat-insulating wall (13, 14) designed to insulate thermally the outer surface (2a) of the vessel head (2). The heat-insulating wall (13, 14) is leaktight to the fluid coming from the vessel of the reactor in the case of leakage and comprises leaktight connection seals (15, 27) at the outer surface (2a) of the head and at the adaptors (6) serving to delimit a chamber (30) for confinement and for recovery of leakage gases.

Abstract: A fluid detector (20) has an enclosure (32) defining an internal chamber (33). The enclosure has a frangible wall portion (34). A sensor (46) is arranged within the chamber. The sensor has a hygroscopic portion (48), the electrical resistance of which changes depending upon whether the sensor portion is wet or dry. The chamber is normally filled with a dry fluid, such as nitrogen. The outer surface of the enclosure is exposed to another fluid containing water. When the pressure differential across the frangible wall portion exceeds a predetermined minimum value, the frangible wall portion ruptures to permit the sensor portion to become wetted. An ammeter (31) is arranged to determine the change in the electrical resistance of the sensor and to indicate the presence of the water-containing fluid within the chamber. The detector is particularly useful in determining the fluid-tight sealed integrity of a closed-end thimble having a portion inserted into a pressurized water reactor.

Abstract: Leak-detection system and method for detecting a leaking container. The system includes an enclosure defining a cavity therein surrounding the container, which container may be a nuclear fuel rod having fission products leaking through a breach in the exterior surface of the fuel rod. The fission products are capable of adhering to the exterior surface of the fuel rod as the fission products leak through the breach in the fuel rod. A radiation detector is in communication with the cavity for detecting the fission products leaking through the breach. Moreover, a gas injector is in communication with the cavity for injecting a multiplicity of carrier gas bubbles into the cavity to remove any fission products adhering to the exterior surface of the fuel rod and to carry the fission products removed thereby to the radiation detector. In this manner, the detector detects the leaking fission products even though they may tend to adhere to the exterior surface of the fuel rod.

Abstract: During leak detection of fuel assemblies (10) for a boiling water nuclear reactor, water is sucked from an area (12) located above an outlet (11) for water from the fuel assembly and around a gripper (8) for a loading machine (1) for fuel assemblies, which gripper is secured to the fuel assembly above the outlet, while the fuel assembly is lifted in the water (6) in which the fuel assembly is immersed or while the fuel assembly, after having been lifted in the water, is maintained in its lifted position or relowered in the water and while maintaining a flow of the water through the fuel assembly and around the gripper. The sucked-off water is subjected to an analysis with respect to the presence of fission products which, during operation of the reactor, have been formed of the fuel in the fuel assembly.

Abstract: A multi-port tool which tests for leaks in the seals of a control rod drive that has been removed from its housing. The fixture is attached to the flange of the control rod drive using quick-release clamps. Two ports of the fixture are respectively coupled to the insert and withdraw ports of the control rod drive. A source of demineralized water at a constant pressure is applied to an inlet port of the leak test fixture. The pressurized water is applied to the control rod drive while the index tube is restrained by a restraining rig. A number of valves are selectively opened or closed to provide a flow path for the pressurized water to either the insert port or the withdraw port. The leakage rate at each of a number of leakage points is determined when the pressurized water is applied at the insert port only and again when the pressurized water is applied at the withdraw port only.

Abstract: A method and apparatus for measuring radioactivity associated with nuclear reactor coolant leaks. The method includes providing a delay tank in a gas sampling line upstream of a radiation particulate monitor, the delay tank allowing radioactive noble gases from the leak to decay to radioactive daughter particulates that are monitored by the radiation particulate monitor. The apparatus includes the delay tank as well as a background delay tank and a valve sequencer for comparing radiation associated with the delay tank to radiation associated with the background delay tank.

Abstract: The effects of steam generator tube ruptures in a pressurized water reactor are mitigated by reducing the pressure in the primary loop by diverting reactor coolant through the heat exchanger of a passive heat removal system immersed in the in containment refueling water storage tank in response to a high feed water level in the steam generator. Reactor coolant inventory is maintained by also in response to high steam generator level introducing coolant into the primary loop from core make-up tanks at the pressure in the reactor coolant system pressurizer. The high steam generator level is also used to isolate the start-up feed water system and the chemical and volume control system to prevent flooding into the steam header.

Abstract: An improved short-term autoclave (10) test for ex-reactor evaluation of in-reactor corrosion resistance of zirconium alloy members (16) for use in pressurized water reactors and pressurized heavy water reactors by:providing a heat flux to initiate hydride precipitation close to the metal-oxide interface of the tube outside surface by means of a resistance heater (20) and a directed flow of aqueous coolant in the water phase to only the outside surface which is one of two specimen (16) opposed surfaces; providing the inside surface with access to the coolant from the flow but not in the flow; reducing the distance between the opposed surfaces of specimen (16);regulating coolant flow from inlet port (12) to outlet port (14) and power of autoclave (10) to optimum saturation condition of 360.degree. C..+-. 5.degree. C. and pressure 2700 p.s.i..+-. 100 p.s.i.;providing a coolant chemistry which simulates a rector's;removing most of the oxygen from the coolant.

Abstract: The fuel element is inserted into a cell, under water, in a pool. Compressed air is injected into the cell so as to drain it of water. A pressure lower than atmospheric pressure is established in the cell and then the gases contained in the cell are subjected to a stream of scavenging air and are collected in a fission product detecting unit. Water is introduced into the cell, the water in the cell is sampled, fission products in the water sample are detected and the fuel element is extracted from the cell if the possible presence of a leak from this fuel element is determined. The detection device comprises a cell having an elongate body delimiting a central housing for a fuel element and end parts. One of the end parts, traversed by a channel in the extension of the housing, receives a cap for opening and closing the channel associated with a remotely controllable opening and closing arrangement.

Abstract: A liquid metal cooled nuclear reactor for a nuclear power plant on the modular principle is disposed in a reactor cavern having cooling surfaces. A reactor tank contains a reactor core and one or more heat exchangers and primary pumps and is surrounded by a double tank of nodular graphite cast iron serving as a heat accumulator and having a plurality of detachably interconnected and superposed rings and a base. With this configuration, not only is the structure simplified but advantages are also achieved for operation, inspection and repair or exchange. Producing the double tank from cast iron has appreciable advantages for the construction of the entire plant with respect to external influences. The function as a heat accumulator has appreciable advantages for the construction of the heat removal systems of the cooling surfaces.