Abstract: A control rod position indication system is for a nuclear reactor with a reactor core and at least one control rod which is movable along a linear path of movement for controlling reactivity of the core. The system includes a permanent magnet mounted on the control rod or a corresponding drive rod, and a number of reed switches arranged around the path of movement in order to be switched by a magnetic field generated by the permanent magnet when passing by. The permanent magnet has a north-south axis whose orientation is constant during movement, and the respective reed switch has a number of reed contacts which are aligned along a longitudinal axis. The longitudinal axis of at least one reed switch is inclined relative to the north-south axis of the permanent magnet, and the angle of inclination has an absolute value within a range from 15 to 65 degrees.

Abstract: A sensor system for a fuel rod including a fuel pellet stack, the sensor system including a wireless interrogator disposed outside the fuel rod and a passive sensor component disposed within the fuel rod. The passive sensor component includes a receiver structured to receive an interrogation signal and output an excitation signal in response to receiving the interrogation signal, a reference transmitter structured to output a reference signal to the reference receiver in response to the excitation signal, a sensing transmitter structured to output a sensing signal to the sensing receiver in response to the excitation signal, and a core at least partially disposed within the sensing transmitter and coupled to move in conjunction with expansion or contraction of the fuel pellet stack, to move based on changes in pressure within the fuel rod, or to change temperature based on temperature changes within the fuel rod.

Abstract: In an encore nuclear instrumentation system which is equipped with a movable type neutron detector, an object of the invention is to control measurement errors due to the degradation of the system. The incore nuclear instrumentation system includes a neutron detector which is to be installed in a nuclear reactor stored in a containment vessel, and an instrumentation unit which has a current detector circuit and is to be installed on the outside of the containment vessel. An output signal of the neutron detector is inputted into the current detector circuit, and the instrumentation unit remembers a matrix which shows a relation among a reactor power of the nuclear reactor, a gain of the current detector circuit, and an output voltage Vn of the current detector circuit, and the calibration of the current detector circuit is performed with reference to the matrix.

Abstract: A modular sensing system for determining the relative lineal position between a first object and a second object includes an array of switch units fixed with the first object and an array of magnet units fixed with the second object. Each switch unit contains an electric circuit that includes a switch, a resistor, and conductors arranged to convey electricity from one of a pair of front connectors to one of a pair of rear connectors, and from the other front connector to the other rear connector through either the resistor or the switch when the switch is closed. The switch is normally open but closed when proximate one of the magnet units, each of which houses a magnet. Resistance between a pair of wires of a first switch unit in the array is related to the relative linear position between the arrays of switch units and magnet units.

Abstract: A system for refueling a nuclear reactor is provided. The system includes a lower reactor vessel with a plurality of fuel rods and a plurality of control rods disposed therein, the lower reactor vessel further comprising an upper flange. An upper reactor vessel is provided which encloses a steam generator and a pressurizer, the upper reactor vessel further comprising a lower flange that matingly engages the upper flange of the lower reactor vessel. A transporter surrounds an outer surface of the upper reactor vessel, wherein the transporter is configured to translate the upper reactor vessel vertically toward and away from the lower reactor vessel and also to translate the upper reactor vessel horizontally toward or away from alignment with the lower reactor vessel.

Abstract: Non-intrusive error detection techniques for control and shutdown rod position in nuclear reactors, including methods of monitoring digital rod position indication (DRPI) signals of a DRPI system of a nuclear power plant. The methods include acquiring digital rod position signals at a point between a DRPI display cabinet and a DRPI data cabinet of the DRPI system, and processing the digital rod position signals to identify variations in a signal level and a signal timing of the digital rod position signals to determine rod position errors of the DRPI system.

Abstract: A rod position indication system includes a drive rod operably coupled to a control rod that is configured to be both withdrawn from and inserted into a reactor core. A number of sensing devices are arranged along a path of the drive rod, and an end of the drive rod passes by or through one or more of the sensing devices in response to movement of the control rod relative to the reactor core. The sensing devices are arranged into a plurality of groups, and each group includes two or more of the sensing devices electrically coupled together. The rod position indication system further includes a control rod monitoring device electrically coupled to each group of sensing devices by a routing wire.

Abstract: A method for determining positions of elements of fuel assemblies arranged in a nuclear vessel is described herein. According to an implementation, the method involves capturing a plurality of images of a nuclear vessel and using the plurality of images to estimate a first set of positions of S-holes of a fuel assembly of the nuclear vessel. The method further involves determining a value representative of differences between: (a) the distances from the estimated set of positions to a location on a face of the fuel assembly and (b) known actual distances between the S-holes and the location on the face of the fuel assembly.

Abstract: A high temperature reed switch position indicator for a pressurized water reactor in which the drive rod housing is completely immersed in the reactor coolant. The reed switch sensor modules positioned along the control rod drive rod travel housing are constructed solely of metallic, ceramic and glass materials and are sealed within an outer housing to isolate the sensor assembly from the coolant.

Abstract: Isotope production system including a particle accelerator configured to produce a particle beam. The isotope production system also includes a target apparatus having a window configured to receive a particle beam and also separate production and condensing chambers. The production chamber is configured to contain a starting liquid and located so that the particle beam is incident upon the starting liquid thereby generating radioisotopes and transforming a portion of the starting liquid into vapor. The target apparatus also includes a fluid channel that extends between and fluidly couples the production and condensing chambers. The fluid channel is configured to allow the vapor to flow from the production chamber into the condensing chamber. The condensing chamber is configured to transform the vapor in the condensing chamber into a condensed liquid.

Abstract: A water filling system for a reactor water level gauge is provided for filling a reactor water level gauge instrumentation pipe in a reactor building with water and filling the reactor water level gauge with water even in an unexpected abnormal event where the reactor building is brought into a highly radioactive environment. The water filling system for a reactor water level gauge includes a water filling instrumentation pipe guided from the reactor water level gauge instrumentation pipe in the reactor building to an outside of the reactor building and filling the reactor water level gauge instrumentation pipe in the reactor building with water even in an unexpected abnormal event of a nuclear power plant.

Abstract: A jet pump beam (hereinafter, referred to as a beam) is fitted into a pair of projecting portions installed to a transition piece, and after the beam is arched, a beam bolt engaged with the beam is tightened. An end of the beam bolt comes in contact with a top surface of an insert member fitted into an elbow disposed between the pair of projecting portions. An ultrasonic sensor head is fixed to the beam bolt, and ultrasonic waves are sent to the beam bolt from the ultrasonic sensor in the ultrasonic sensor head. An ultrasonic measuring apparatus obtains echo intensity of each of reflected waves generated at the end of the beam bolt and a bottom surface of the insert member, and based on the echo intensities, an echo intensity ratio R is calculated. The installed state of the beam is checked using the echo intensity ratio R.

Abstract: A device for measuring and correcting a parallelism error of an upper plug end of a nuclear fuel rod comprising mechanisms for measuring a parallelism error and for correcting said error, and a mechanism for positioning said device on the fuel rod and cooperating with a rack on which the fuel rod is stored, said correction means being arranged opposite the measuring mechanism relative to the location of the fuel rod, in order to allow a measurement of the parallelism error during correction of said error.

Abstract: A high resolution digital rod position indication (high resolution DRPI) system having improved resolution. The high resolution DRPI system monitors the rod control cluster and provides an indication of the rod position with precision to a single step. In addition, the high resolution DRPI system is capable of producing a rod position output compatible with existing rod control systems. The improved resolution of the high resolution DRPI system allows the actual position of the control rods to be continuously monitored and eliminates the need for or reduces the frequency of offline re-initialization of the step counters.

Abstract: Systems and methods of monitoring position information of a control rod in a nuclear reactor, including detecting an output signal induced by movement of a control rod with respect to at least one detection coil of the control rod, the output signal having identifiable characteristics representative of a plurality of positions of the control rod within the at least one detection coil, and processing the identifiable characteristics to derive the positions of the control rod within the at least one detection coil.

Abstract: A pencil-shaped electrical heating element, in particular for application in a device for measuring filling level in a liquid container, in particular in a reactor chamber of a nuclear plant, contains an electrically-conducting sleeve and at least one electric line embedded therein which is in conducting contact with the sleeve. The electrical line has at least two line sections with differing electrical properties and/or thermal conductivities.

Abstract: A system for monitoring a condition of a nuclear reactor pressure vessel disposed in a radioactive environment includes an instrument structured to monitor a condition of the nuclear reactor pressure vessel; a powered wireless transmitting modem disposed in the radioactive environment, the wireless transmitting modem being electrically coupled to the instrument; a receiving modem disposed in the line of sight of the transmitting modem, the receiving modem being in wireless communication with the transmitting modem; and a signal processing unit electrically coupled to the receiving modem, the signal processing unit being structured to determine the condition of the nuclear reactor pressure vessel from the instrument. The transmitting modem is powered by a thermocouple disposed in or on the reactor pressure vessel.

Abstract: To provide a rod block monitor in which irrespective of the selection or non-selection of a control rod, such a process is repeatedly executed that gain adjustment is performed at fixed intervals at all times to match a local area average value of signals of neutron detectors surrounding the control rod with a nuclear reactor average power and a block level appropriate to the local area average value of the neutron detector signals after the gain adjustment is set.

Abstract: A method of monitoring a condition of a nuclear reactor pressure vessel disposed in a radioactive environment is provided. The method includes the steps of sensing a condition of the reactor pressure vessel with an instrument, transmitting a signal indicative of the condition of the reactor pressure vessel from the instrument to a powered wireless transmitting modem disposed in the radioactive environment, wirelessly transmitting a signal indicative of the condition of the reactor pressure vessel from the transmitting modem to a receiving modem in the line of sight of the transmitting modem, transmitting a signal indicative of the condition of the reactor pressure vessel from the receiving modem to a signal processing unit, and determining the condition of the reactor pressure vessel from the wirelessly transmitted signal.

Abstract: A traveling reactor power monitoring system includes a drive control unit configured to drive a motor and move a traveling probe in a guide tube by driving the motor, a torque sensor configured to measure a drive torque of the motor, and a drive torque monitoring unit that generates an alarm when the measured drive torque exceeds a predefined upper threshold, and that bypasses generating the alarm for a predefined bypass time, the predefined bypass time starting at a time of starting driving the motor.

Abstract: A boiling water reactor includes a reactor pressure vessel having a feedwater inlet for the introduction of recycled steam condensate and/or makeup coolant into the vessel, and a steam outlet for the discharge of produced steam for appropriate work. A fuel core is located within a lower area of the pressure vessel. The fuel core is surrounded by a core shroud spaced inward from the wall of the pressure vessel to provide an annular downcomer forming a coolant flow path between the vessel wall and the core shroud. A probe system that includes a combination of conductivity/resistivity probes and/or one or more time-domain reflectometer (TDR) probes is at least partially located within the downcomer. The probe system measures the coolant level and flow velocity within the downcomer.

Abstract: A method for controlling the positions of a plurality of nuclear fuel assemblies (1) relative to an upper core plate (3) in a nuclear reactor core, the method including the following steps: choosing a reference point (13) in internals or in a reactor vessel; determining the positions of S-shaped holes of the nuclear fuel assemblies (1) relative to the reference point (13), each S-shaped hole being intended to cooperate with a corresponding centering pin of the upper core plate (3); acquiring the positions of the centering pins of the upper core plate (3) relative to the reference point (13); and comparing the positions of the S-shaped holes and the positions of the pins and deducing therefrom whether the nuclear fuel assemblies (1) are correctly positioned relative to the upper core plate (3).

Abstract: Systems and methods of monitoring position information of a control rod in a nuclear reactor, including detecting an output signal induced by movement of a control rod with respect to at least one detection coil of the control rod, the output signal having identifiable characteristics representative of a plurality of positions of the control rod within the at least one detection coil, and processing the identifiable characteristics to derive the positions of the control rod within the at least one detection coil.

Abstract: A diagnostic system to monitor digital rod position indication (DRPI) signals of a DRPI system of a nuclear power plant, including a digital diagnostic unit connected between a DRPI display cabinet and a DRPI data cabinet of the DRPI system to monitor digital rod position signals of the DRPI data cabinet. The digital rod position signals include digital rod address signals and digital rod position data signals such that the digital diagnostic unit detects signal level variation and signal timing variation of the digital rod address signals and the digital rod position data signals to determine rod position errors of the DRPI system.

Abstract: A control rod position detector including a permanent magnet that is attached on a control rod inserted in a reactor pressure vessel, where the permanent magnet is capable of moving together with the control rod, and a plurality of reed switch mechanisms that are arranged in the reactor pressure vessel at regular intervals in an insertion direction of the control rod. Each of the reed switch mechanisms is provided with a pair of reed switches that are placed so as to overlap with each other in the insertion direction of the control rod. The pair of reed switches are connected to a common wiring. The common wiring is connected to a detector that detects a position of the control rod based on signals from the reed switches.

Abstract: An improved apparatus for determining the position of a drive rod within the interior of a drive rod housing includes a transmission antenna at one location on the housing and a receiving antenna at another location on the housing. An electromagnetic excitation signal sent to the transmission antenna is detected, at least in part, by the receiving antenna, and the received signal is processed with a vector network analyzer routine to model the drive rod housing as a wave guide having a filter response. A group delay is detected and is compared with a calibration data set which provides a current position of the drive rod that corresponds with the group delay.

Abstract: An advanced digital rod position indication (ADRPI) system having rod drop monitoring capability. When a reactor trip occurs, the ADRPI system derives the rod drop time from the signals induced in the detector coils by the falling drive rods. The ADRPI system is linked to the reactor trip breaker to provide a reference point to allow accurate timing of the rod drop times.

Abstract: A device and method for stabilizing a dryer assembly in a reactor pressure vessel of a nuclear reactor including a spring assembly dimensioned and positioned within the reactor pressure vessel for applying a stabilizing force to the dryer assembly relative to the reactor pressure vessel.

Abstract: According to an embodiment, a horizontally moving stage is mounted on a cylindrical structure within a reactor pressure vessel, travels horizontally along the surface of the cylindrical structure by wheels, and is positioned above an in-reactor pipe by the operation of the horizontally moving stage. A hollow mast is carried by the horizontally moving stage, and is expandable and contractible in a vertical attitude. When the mast is in the vertical attitude, a probe is movable within the mast and performs work in the proximity to the inner surface of the in-reactor pipe. A cable passes through the mast to be connected to the probe.

Abstract: A high temperature reed switch position indicator for a pressurized water reactor in which the drive rod housing is completely immersed in the reactor coolant. The reed switch sensor modules positioned along the control rod drive rod travel housing are constructed solely of metallic, ceramic and glass materials and are sealed within an outer housing to isolate the sensor assembly from the coolant.

Abstract: An apparatus for measuring perpendicularity of an upper tie plate of a nuclear fuel bundle includes a first comb having a first plurality of teeth; a second comb having a second plurality of teeth, the second comb being parallel to and spaced from the first comb; a comb connector that connects the first comb to the second comb, the comb connector having a second end extending beyond the first comb; a rigid finger provided at the second end of the comb connector; a rotatable gage provided on the second comb; and a mobile finger operatively connected to the gage.

Abstract: A method and apparatus for the permissive control of a mast and fuel grapple to be used in the movement of reactor fuel components, including fuel assemblies, single blade and double blade guides, to be used in a Boiling Water Reactor (BWR) nuclear reactor. The Permissive Control System reduces the chance of human error associated with the movement of reactor components by assisting in controlling the location (plant coordinate) of the mast for picking-up and dropping-off reactor components, the sequence of reactor component movements, the orientation (angular rotation) of the mast and fuel grapple, the raising and lowering of the grapple, and the opening and closing of the fuel grapple.

Abstract: A method for detecting a position of a cylinder rod includes depositing a plurality of welds substantially along the length of a steel rod and depositing a corrosion resistant material onto the steel rod by laser cladding. The cylinder rod is then placed proximate to a sensor assembly. One of the cylinder rod and the sensor assembly are moved relative to the other. The sensor assembly detects a change in properties between the steel rod and the welds and generates a corresponding signal. A change in position of the cylinder rod or damage to the cylinder rod can be detected by analyzing the number and strength of the signals.

Abstract: A device for measuring and correcting a parallelism error of an upper plug end of a nuclear fuel rod comprising mechanisms for measuring a parallelism error and for correcting said error, and a mechanism for positioning said device on the fuel rod and cooperating with a rack on which the fuel rod is stored, said correction means being arranged opposite the measuring mechanism relative to the location of the fuel rod, in order to allow a measurement of the parallelism error during correction of said error.

Abstract: A method of monitoring a condition of a nuclear reactor pressure vessel disposed in a radioactive environment is provided. The method includes the steps of sensing a condition of the reactor pressure vessel with an instrument, transmitting a signal indicative of the condition of the reactor pressure vessel from the instrument to a powered wireless transmitting modem disposed in the radioactive environment, wirelessly transmitting a signal indicative of the condition of the reactor pressure vessel from the transmitting modem to a receiving modem in the line of sight of the transmitting modem, transmitting a signal indicative of the condition of the reactor pressure vessel from the receiving modem to a signal processing unit, and determining the condition of the reactor pressure vessel from the wirelessly transmitted signal.

Abstract: The present invention provides an apparatus for detecting and/or repositioning annulus spacers used to maintain the position of a pressure tube withm a calandria tube of a nuclear reactor. The method comprises the steps of: vibrationally isolating a section of the pressure tube; vibrating the wall of said pressure tube within said isolated section; detecting vibration of the wall at a minimum of two axial positions within said isolated sections; and detecting the reduction in vibration level of the wall at one or more of said axial positions in comparison to the remaining axial positions. The apparatus comprises a tool head to be inserted into the pressure tube, the tool head comprising a first end and a second and a clamping block m each of said ends. The clamping blocks are used to vibrationally isolate a section of the pressure tube located between said ends.

Abstract: A load compensating device, especially one for lifting appliances, includes a detector for detecting an overload or an underload and designed to cause actuation of the compensating device. The device comprises an actuator attached to one of ends of a rope or ropes that support the load for producing positive or negative displacement of the rope or ropes over a short distance compared with the length of the rope or ropes. The actuator is operated by a brushless electric motor connected to an infinitely variable-speed transmission. The transmission is connected to the detector.

Abstract: An advanced digital rod position indication (ADRPI) system having rod drop monitoring capability. When a reactor trip occurs, the ADRPI system derives the rod drop time from the signals induced in the detector coils by the falling drive rods. The ADRPI system is linked to the reactor trip breaker to provide a reference point to allow accurate timing of the rod drop times.

Abstract: A control rod position detector for detecting position of a control rod being linked to a control rod drive mechanism, comprising: a first rotational axis rotated by a motor in the control rod drive mechanism; a gear mechanism engaging with the first rotational axis; and first and second position detectors attached to a second rotational axis of the second gear mechanism and outputting position signals of the control rod by rotation of the second rotational axis.

Abstract: A method for recognizing the step movement sequence of a control rod drive mechanism of a nuclear reactor, which withdraws and inserts a control rod of a nuclear reactor, includes the steps of: measuring current and voltage flowing through an electromagnetic coil used in the control rod drive mechanism of the nuclear reactor; calculating inductance of the coil by using the measured current and voltage; calculating a distance between a rotor and a stator of the control rod drive mechanism on the basis of the calculated inductance; and recognizing the step movement sequence of the control rod drive mechanism on the basis of the calculated distance. This method ensures good reliability in determining the step movement sequence, allows easy implementation using a digital signal processor, and is hardly affected by external factors such as noise.

Abstract: A boiling water reactor includes a reactor pressure vessel having a feedwater inlet for the introduction of recycled steam condensate and/or makeup coolant into the vessel, and a steam outlet for the discharge of produced steam for appropriate work. A fuel core is located within a lower area of the pressure vessel. The fuel core is surrounded by a core shroud spaced inward from the wall of the pressure vessel to provide an annular downcomer forming a coolant flow path between the vessel wall and the core shroud. A probe system that includes a combination of conductivity/resistivity probes and/or one or more time-domain reflectometer (TDR) probes is at least partially located within the downcomer. The probe system measures the coolant level and flow velocity within the downcomer.

Abstract: The invention concerns a device (1) for controlling the exterior aspect of fuel rods (2) for nuclear reactors, said device comprising optical means (40) having at least one camera (42, 42?) and linked to an image acquisition and processing system (48) capable of detecting geometric defects present on each rod (2) to be controlled, and further comprising a roughness tester (50) controlled in such a way as to measure the depth of each geometric defect detected by the image acquisition and processing system (48). Moreover, the invention further concerns a method capable of being implemented with the aid of said device (1).

Abstract: The invention concerns a device (1) for controlling the exterior aspect of fuel rods (2) for nuclear reactors, said device comprising optical means (40) having at least one camera (42, 42?) and linked to an image acquisition and processing system (48) capable of detecting geometric defects present on each rod (2) to be controlled, and further comprising a roughness tester (50) controlled in such a way as to measure the depth of each geometric defect detected by the image acquisition and processing system (48). Moreover, the invention further concerns a method capable of being implemented with the aid of said device (1).

Abstract: A method is provided for determining and controlling feed water level in a steam generator of a nuclear power plant, whereby the water level sensor is calibrated in terms of the pressure drop across structural components in the feed water path. The water level differential pressure sensor is calibrated so that maximum water level is indicated as the level corresponding to the upper tap level plus the pressure drop across the foregoing structural components at maximum power plant power.

Abstract: A measuring head is used in measuring an assembly part of a nuclear facility, such as a fuel rod, a fuel assembly box, or a spacer of the fuel assembly. The measuring head is capable of augmenting a comparatively large data base representing the overall aging state of the fuel elements in a simple manner and within a short measuring time. The measuring head has a probe tip on the sensor housing and a layer thickness measuring probe is integrated into said probe housing, said measuring probe working according to the eddy current principle. The contour or the diameter of the fuel rod can be determined by the measured deflection of the probe.

Abstract: The diameter of a segment of a peripheral rod in a fuel assembly is measured between two successive spacer grids. A measuring tool is positioned at a level situated between the two successive spacer grids, the tool comprising two measuring fingers that are free to move relative to each other in a first horizontal direction and that are urged towards each other by a resilient return arrangement, and that extend in a second horizontal direction perpendicular to the first horizontal direction. The measuring fingers are moved in the second horizontal direction towards a rod so as to put two contact pieces of the measuring fingers into contact with two zones of the rod segment. The measuring fingers are moved in the vertical axial direction of the rod along its segment situated between the two spacer grids and an electromagnetic sensor is used to measure the distance between the measuring fingers in the first horizontal direction while the measuring fingers are being moved axially.

Abstract: In order to allow a reliable and passive external cooling of a reactor pressure vessel of a boiling water reactor, outside the reactor pressure vessel a differential-pressure measurement pipe is provided and has a first and a second pipe leg which are connected to one another above a critical filling level. The first pipe leg is connected at the height of the critical filling level to the interior of the reactor pressure vessel. In a normal operating state, the differential-pressure measurement pipe is filled completely with water. In the event of the undershooting of the critical filling level, the water flows automatically out of the first pipe leg. As a result, the differential pressure between the two pipe legs rises, the differential pressure being detected by a measurement device via which the flooding of the exterior is then brought about.

Abstract: The present invention provides a remote-controlled in-pile creep test system used in in-pile creep tests for measuring and determining mechanical properties of nuclear materials irradiated in research reactors.

Abstract: The present invention provides a remote-controlled in-pile creep test system used in in-pile creep tests for measuring and determining mechanical properties of nuclear materials irradiated in research reactors.

Abstract: With this method it is possible to evaluate opposing friction forces occurring after a certain operating time on a mobile object in a guide. The method consists of measuring the variations in the speed of movement of the mobile object, of calculating the theoretical speed of movement without friction, of combining these two results and thereby deducing outside opposing forces through calculation of the acceleration of the mobile object. Particular application to the evaluation of additional friction forces acting on a mobile control cluster assembly in the core of a pressurized water nuclear reactor.