Abstract: A method for modeling a nuclear reactor core that follows the history of each fuel pin and employs fuel pin flux form factors to explicitly track each fuel pin's fluence and burnup along its axial length and uses this information to obtain fundamental data for each fuel rod, i.e. fuel rod cross-sections, for each fuel pin segment. The data obtained for the fuel pins segments are employed to adjust the fuel pin flux form factors to match the real fuel pins' history so that the fuel rod power distribution can be precisely calculated based on the fuel rod cross-sections and the flux form factors.

Abstract: The ex-core nuclear instrumentation system includes a key hole, and it is configured such that in the state where a key lock switch is inserted into the key hole, writing to a electrically rewritable nonvolatile memory is made valid by a general-purpose logic, and when writing to a electrically rewritable nonvolatile memory is in valid and the operation panel and the FPGA perform a serial communication and in a case where the data order of the serial communication is the predetermined data order, the CPU controls the electrically rewritable nonvolatile memory, and rewriting data, which is outputted from the operation panel, to the electrically rewritable nonvolatile memory is transmitted from the FPGA to the electrically rewritable nonvolatile memory so as to rewrite the data in the electrically rewritable nonvolatile memory.

Abstract: In a pressurized water reactor with all of the in-core instrumentation gaining access to the core through the reactor head, each fuel assembly in which the instrumentation is introduced is aligned with an upper internals instrumentation guide-way. In the elevations above the upper internals upper support assembly, the instrumentation is protected and aligned by upper mounted instrumentation columns that are part of the instrumentation guide-way and extend from the upper support assembly towards the reactor head in hue with a corresponding head penetration. The upper mounted instrumentation columns are supported laterally at one end by an upper guide tube and at the other end by the upper support plate.

Abstract: The output of a nuclear reactor is increased by a predetermined magnitude, and the neutron beam is measured as time-series data. The temperature of the moderator in the reactor is acquired as time-series data. Time-series data on the reactivity is acquired from the time-series data on the neutron beam by the reverse dynamic characteristic method with respect to a one-point reactor kinetics equation. Time-series data on the fuel temperature of a predetermined average acquired by using the time-series data on the reactor output and a predetermined dynamic characteristic model is acquired. The reactivity feedback contribution component is determined by using the time-series data on the reactivity and the applied reactivity.

Abstract: An apparatus for inspecting and testing a startup range neutron monitoring system for a nuclear reactor. The apparatus includes: a neutron-flux detector; a preamplifier that amplifies an electric signal output from the neutron-flux detector; a pulse measurement unit that counts times when electric signal output from the preamplifier exceeds a discrimination voltage; a discrimination-voltage setting unit that applies the discrimination voltage to the pulse measurement unit; a voltage-setting unit that applies a voltage to the neutron-flux detector; an arithmetic processing unit that calculates an output power of the reactor based upon an output signal of the pulse measurement unit; an output unit that outputs data representing the output power of the reactor, calculated by the arithmetic processing unit; and an inspecting/testing unit that sets the discrimination voltage and the voltage to be applied by the voltage-setting unit.

Abstract: In one embodiment, the method includes determining the safety limit minimum critical power ratio using the operating limit minimum critical power ratio, a change-in-critical-power-ratio distribution bias and a change-in-critical-power-ratio distribution standard deviation.

Abstract: An upper detector and a lower detector that face at least one side of a fuel assembly, on which neutrons are irradiated in a nuclear reactor, and detect radiation are set at a predetermined interval in an axial direction of the fuel assembly. Distributions of radiation signals are measured by the upper detector and the lower detector while the fuel assembly and the upper detector and the lower detectors are relatively moved along the axial direction of the fuel assembly. Soundness of radiation signals measured by the upper detector and the lower detector is determined in every measurement by comparing radiation signal distributions obtained by measuring the same portion in the axial direction of the fuel assembly in a multiplexed manner with the upper detector and the lower detector. Thereafter, relative burn-up is calculated by utilizing the measured radiation signals to measure a burn-up profile.

Abstract: A first intensity Az expressed as Az=az×E?, a first reference intensity A0 expressed as A0=a0×E?, a second intensity Bz expressed as Bz=bz×E, and a second reference intensity B0=b0×E, are evaluated. The first intensity and the first reference intensity are of radioactive nuclides generated by a neutron capture reaction of a heavy nuclide or a fission product nuclide. The second intensity and the second reference intensity are of radioactive fission product nuclides except nuclides generated by a neutron capture reaction. The reference intensities are measured where the void fraction is known. Also a correlation curve of (az/a0) and a void fraction is evaluated. Finally an axial void fraction distribution is evaluated based on the value of (az/a0) and the correlation curve.

Abstract: Embodiments are directed to a digital data acquisition method that collects data regarding nuclear fission at high rates and performs real-time preprocessing of large volumes of data into directly useable forms for use in a system that performs non-destructive assaying of nuclear material and assemblies for mass and multiplication of special nuclear material (SNM). Pulses from a multi-detector array are fed in parallel to individual inputs that are tied to individual bits in a digital word. Data is collected by loading a word at the individual bit level in parallel, to reduce the latency associated with current shift-register systems. The word is read at regular intervals, all bits simultaneously, with no manipulation. The word is passed to a number of storage locations for subsequent processing, thereby removing the front-end problem of pulse pileup. The word is used simultaneously in several internal processing schemes that assemble the data in a number of more directly useable forms.

Abstract: A neutron monitoring system uses a gamma thermometer to calibrate a nuclear instrument to ensure more accurate neutron flux measurements in a nuclear reactor core. The nuclear instrument generates a first signal proportional to a measured local neutron flux. The gamma thermometer generates a second signal proportional to a measured local gamma flux. A processor is used to compensate the second signal by filtering groups of delayed gamma sources to a reduced number of specific groups of delayed gamma sources. A third signal is calculated based upon yield fractions and time constants that are determined for the specific groups of delayed gamma sources. A gain of the nuclear instrument is calibrated based on a compensated second signal that is determined by subtracting the third signal from the second signal.

Abstract: According to an embodiment, a digital process type monitor device includes a plurality of modules and a mother board connected to each of the modules. Each module includes: a base board connected to a connector and having an FPGA for main control and an IPGA for sub board control mounted thereon; and a sub board for a main-machine I/F process, having an FPGA for an I/F process mounted hereon. Each sub board has storage devices for storing man-machine I/F information on the sub board. Each of the FPGA writes transmission data into a predetermined region of a transmission area and has a common transmission protocol to share the transmission data between the respective modules.

Abstract: The present invention relates to a computational system and method to analyze a radiation field in a light water nuclear reactor. The system and method include a radiation transport module for performing a neutron and gamma transport calculation of a reactor geometry model of the light water nuclear reactor for at least one fuel cycle; a material analysis module for analyzing flux data calculated by the radiation transport module for materials and/or components within the light water nuclear reactor; and a mobile component tracking module for calculating radiation exposure for components within the light water nuclear reactor which have more than one different location during or between the at least one fuel cycle.

Abstract: An ex-core nuclear instrumentation system in which the width of measurable neutron detector current can be accurately widened is obtained. In order to output the condition of neutron flux in operation by performing arithmetic processing of a current value measured by a neutron detector by using a detector signal processing circuit, the detector signal processing circuit includes a current/voltage conversion unit which converts the current value converted by the neutron detector into a voltage value corresponding to the current value; and a variable gain amplification unit which has an operational amplifier having a resistance circuit for corresponding to current levels, the resistance circuit being capable of selecting a gain, and a D/A converter that adjusts the gain, and amplifies the voltage value converted by the current/voltage conversion unit.

Abstract: A method of calibrating a nuclear instrument using a gamma thermometer may include: measuring, in the instrument, local neutron flux; generating, from the instrument, a first signal proportional to the neutron flux; measuring, in the gamma thermometer, local gamma flux; generating, from the gamma thermometer, a second signal proportional to the gamma flux; compensating the second signal; and calibrating a gain of the instrument based on the compensated second signal. Compensating the second signal may include: calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups; calculating a third signal that corresponds to delayed local gamma flux based on the selected yield fractions and time constants; and calculating the compensated second signal by subtracting the third signal from the second signal. The specific groups may have decay time constants greater than 5×10?1 seconds and less than 5×105 seconds.

Abstract: An in-core neutron monitor that employs vacuum microelectronic devices to configure an in-core instrument thimble assembly that monitors and wirelessly transmits a number of reactor parameters directly from the core of a nuclear reactor without the use of external cabling. The in-core instrument thimble assembly is substantially wholly contained within an instrument guide tube within a nuclear fuel assembly.

Abstract: A method for collecting data regarding the operating condition of a nuclear reactor core including: positioning a first linear array of gamma thermometer (GT) sensors in a first instrument housing; positioning a second linear array of GT sensors in a second instrument housing, wherein the GT sensors are arranged asymmetrically along the linear arrays and the second linear array is asymmetrical with respect to the first linear array; positioning the first instrument housing in the reactor core at a first core location and positioning the second instrument housing at a second core location symmetrical with respect to the first core location; collecting core condition data from at least one of the GT sensors in the first linear array of GT sensors, and applying the collected core condition data as data collected from the second linear array.

Abstract: A method of determining the R-factor for a bundle of nuclear fuel rods in a nuclear light water reactor of the boiling water reactor kind. The R-factor is a factor that accounts for the weighted local power influence on a fuel rod. A local R-factor (Ri(z)) is determined for each fuel rod (i) in said bundle and for each of a plurality of levels (z) in an axial direction. The individual axial heat generation profile for a certain fuel rod (i) is taken into account when determining the local R-factors (Ri(z)) for said fuel rod (i). A processor is configured for automatically determining the R-factor. A computer program product, a method of determining the critical power for a bundle of fuel rods, a nuclear energy plant, and a method of operating a nuclear energy plant are also described.

Abstract: The present invention provides a method of operating a Boiling Water Reactor, having the steps of analyzing LPRM signals for oscilliatory behavior indicative of neutron-flux-coupled density wave oscillations, determining if oscilliatory behavior is present in the signals; initiating a reactor protective corrective action if the oscilliatory behavior is determined, and in addition, initiating corrective actions if neutron uncoupled oscillations are possible. Detecting the later is performed through analytically determined exclusion zone on the power flow map or by on-line stability calculations for several high power channels.

Abstract: [Solving Means] A resonance calculation program is configured to calculate an effective cross section including Step S4 of setting a calculation point in the gray range in the resonance region; Step S5 of calculating a neutron flux set at the calculation point and corresponding to a macroscopic cross section based on Method of Characteristics; Step S6 of fitting a fitting equation to the calculated macroscopic cross section and the calculated neutron flux, and calculating first and second rational coefficients; Step S7 of calculating a background cross section based on the first rational coefficient; Step S8 of interpolating the effective cross section, with the background cross section used as an argument; Step S9 of calculating the neutron flux based on the background cross section; and Step S10 of calculating the effective cross section based on the effective cross section, the neutron flux, and the second rational coefficient obtained at the coefficient calculation step.

Abstract: Monitor-guide-tube fixing sections are fixed to portions on a core support plate side of a plurality of in-core monitor guide tubes disposed in a reactor vessel. The monitor-guide-tube fixing sections are fixed to the core support plate disposed in the reactor vessel to fix the in-core monitor guide tubes to the core support plate. This makes it possible to realize improvement of rigidity of the fixed sections of the in-core monitor guide tubes. A tie plate is fixed to the in-core monitor guide tubes. The in-core monitor guide tubes are coupled by the tie plate. This makes it possible to realize improvement of rigidity of the entire in-core monitor guide tubes. As a result, it is possible to realize vibration damping for the in-core monitor guide tubes.

Abstract: An apparatus for inspecting and testing a startup range neutron monitoring system for a nuclear reactor. The apparatus includes: a neutron-flux detector; a preamplifier that amplifies an electric signal output from the neutron-flux detector; a pulse measurement unit that counts times when electric signal output from the preamplifier exceeds a discrimination voltage; a discrimination-voltage setting unit that applies the discrimination voltage to the pulse measurement unit; a voltage-setting unit that applies a voltage to the neutron-flux detector; an arithmetic processing unit that calculates an output power of the reactor based upon an output signal of the pulse measurement unit; an output unit that outputs data representing the output power of the reactor, calculated by the arithmetic processing unit; and an inspecting/testing unit that sets the discrimination voltage and the voltage to be applied by the voltage-setting unit.

Abstract: A method for measuring the neutron flux in the core of a nuclear reactor, the method including several steps recurrently performed at instants separated by a period, the method comprising at each given instant the following steps: acquiring a total signal by a cobalt neutron detector placed inside the core of the reactor; assessing a calibration factor representative of the delayed component of the total signal due to the presence of cobalt 60 in the neutron detector; assessing a corrected signal representative of the neutron flux at the detector from the total signal and from the calibration factor; assessing a slope representative of the time-dependent change of the calibration factor between the preceding instant and the given instant; the calibration factor at the given instant being assessed as a function of the calibration factor assessed at the preceding instant, of the slope, and of the time period separating the given instant from the preceding instant.

Abstract: According to one embodiment, reactor oscillation power ranges monitor includes: a receiving unit which receives LPRM signals; an exclusion processing unit which searches the LPRM signals allocated to the cell for an LPRM signal corresponding to an exceptional condition; an averaging unit which averages the allocated LPRM signals; a time averaging unit which calculates a time average of the average flux value; a normalized value calculation unit which divides the average flux value by the time averaged flux value; an initialization unit which outputs an initialization signal identifying the cell allocated to an LPRM signal which is changed to correspond or not correspond to the exceptional condition; and a determination unit which derives at least one of amplitude and cycle of a power oscillation from the normalized value.

Abstract: A method of calibrating excore detectors for a pressurized water reactor (PWR) includes: measuring peripheral core flux signals using excore detectors disposed at a plurality of locations spaced about the periphery of the core, and using the measured power distribution from either a core monitoring system or in-core flux measurement. Calibration of the excore detectors is broken into two parts: (1) the relation between the excore detector signal and weighted peripheral assembly axial offset, and (2) the relation between weighted peripheral assembly axial offset and core average axial offset. Relation (2) can be determined by a representative neutronics model.

Abstract: A method for providing a boron-lined neutron detector. The method includes providing a boron-containing material and providing water. The method includes mixing the boron-containing material into the water to create a water-based liquid mixture and providing a substrate of a cathode of the neutron detector. The method includes applying the water-based liquid mixture to the substrate of the cathode and removing water from the water-based liquid applied to the substrate to leave a boron-containing layer upon the substrate that is sensitive to neutron impingement. The step of providing a boron-containing material may be to provide the material to include B-10.

Abstract: Illustrative embodiments provide methods and systems for migrating fuel assemblies in a nuclear fission reactor, methods of operating a nuclear fission traveling wave reactor, methods of controlling a nuclear fission traveling wave reactor, systems for controlling a nuclear fission traveling wave reactor, computer software program products for controlling a nuclear fission traveling wave reactor, and nuclear fission traveling wave reactors with systems for migrating fuel assemblies.

Abstract: Illustrative embodiments provide a reactivity control assembly for a nuclear fission reactor, a reactivity control system for a nuclear fission reactor having a fast neutron spectrum, a nuclear fission traveling wave reactor having a fast neutron spectrum, a method of controlling reactivity in a nuclear fission reactor having a fast neutron spectrum, methods of operating a nuclear fission traveling wave reactor having a fast neutron spectrum, a system for controlling reactivity in a nuclear fission reactor having a fast neutron spectrum, a method of determining an application of a controllably movable rod, a system for determining an application of a controllably movable rod, and a computer program product for determining an application of a controllably movable rod.

Abstract: Illustrative embodiments provide a reactivity control assembly for a nuclear fission reactor, a reactivity control system for a nuclear fission reactor having a fast neutron spectrum, a nuclear fission traveling wave reactor having a fast neutron spectrum, a method of controlling reactivity in a nuclear fission reactor having a fast neutron spectrum, methods of operating a nuclear fission traveling wave reactor having a fast neutron spectrum, a system for controlling reactivity in a nuclear fission reactor having a fast neutron spectrum, a method of determining an application of a controllably movable rod, a system for determining an application of a controllably movable rod, and a computer program product for determining an application of a controllably movable rod.

Abstract: Illustrative embodiments provide methods and systems for migrating fuel assemblies in a nuclear fission reactor, methods of operating a nuclear fission traveling wave reactor, methods of controlling a nuclear fission traveling wave reactor, systems for controlling a nuclear fission traveling wave reactor, computer software program products for controlling a nuclear fission traveling wave reactor, and nuclear fission traveling wave reactors with systems for migrating fuel assemblies.

Abstract: Illustrative embodiments provide for the operation and simulation of the operation of fission reactors. Illustrative embodiments and aspects include, without limitation, nuclear fission reactors and reactor modules, including modular nuclear fission reactors and reactor modules, nuclear fission deflagration wave reactors and reactor modules, modular nuclear fission deflagration wave reactors and modules, methods of operating nuclear reactors and modules including the aforementioned, methods of simulating operating nuclear reactors and modules including the aforementioned, and the like.

Abstract: A method of calibrating a nuclear instrument using a gamma thermometer may include: measuring, in the instrument, local neutron flux; generating, from the instrument, a first signal proportional to the neutron flux; measuring, in the gamma thermometer, local gamma flux; generating, from the gamma thermometer, a second signal proportional to the gamma flux; compensating the second signal; and calibrating a gain of the instrument based on the compensated second signal. Compensating the second signal may include: calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups; calculating a third signal that corresponds to delayed local gamma flux based on the selected yield fractions and time constants; and calculating the compensated second signal by subtracting the third signal from the second signal. The specific groups may have decay time constants greater than 5×10?1 seconds and less than 5×105 seconds.

Abstract: A computer implemented method for modelizing a nuclear reactor core, including the steps of: partitioning the core in cubes to constitute nodes of a grid for computer implemented calculation, calculating neutron flux by using an iterative solving procedure of at least one eigensystem, the components of an iterant of the eigensystem corresponding either to a neutron flux, to a neutron outcurrent or to a neutron incurrent, for a respective cube to be calculated. A control parameter is varied to impact a neutron eigenvalue ? through a perturbed interface current equation and drive the neutron eigenvalue ? towards 1.

Abstract: A method of determining the spatially corrected inverse count ratio (SCICR) used to determine reactor criticality, which subtracts a background noise signal from the source range detector output. The method monitors the source range detector signal at two different core temperature levels during a transient portion of the detector output as the power output of the reactor is increased in the source range. This information is employed to analytically determine the background noise signal, which is then subtracted from the detector outputs to obtain the SCICR reactivity measurement.

Abstract: Detecting diversion of spent fuel from Pressurized Water Reactors (PWR) by determining possible diversion including the steps of providing a detector cluster containing gamma ray and neutron detectors, inserting the detector cluster containing the gamma ray and neutron detectors into the spent fuel assembly through the guide tube holes in the spent fuel assembly, measuring gamma ray and neutron radiation responses of the gamma ray and neutron detectors in the guide tube holes, processing the gamma ray and neutron radiation responses at the guide tube locations by normalizing them to the maximum value among each set of responses and taking the ratio of the gamma ray and neutron responses at the guide tube locations and normalizing the ratios to the maximum value among them and producing three signatures, gamma, neutron, and gamma-neutron ratio, based on these normalized values, and producing an output that consists of these signatures that can indicate possible diversion of the pins from the spent fuel assembl

Abstract: A subcritical physics testing program which utilizes vanadium self-powered incore instrumentation thimble assemblies to provide an actual measured powered distribution that is used to confirm that the core will operate as designed. The signals received from the incore detector elements are integrated until a fractional uncertainty is less than a specified level. The measured power distribution is then compared against a predicted power distribution for a given rod position or temperature difference. If the measured power distribution is within a specified tolerance to the predicted power distribution, then the core is expected to behave as predicted.

Abstract: A nuclear fission reactor, flow control assembly, methods therefor and a flow control assembly system. The flow control assembly is coupled to a nuclear fission module capable of producing a traveling burn wave at a location relative to the nuclear fission module. The flow control assembly controls flow of a fluid in response to the location relative to the nuclear fission module. The flow control assembly comprises a flow regulator subassembly configured to be operated according to an operating parameter associated with the nuclear fission module. In addition, the flow regulator subassembly is reconfigurable according to a predetermined input to the flow regulator subassembly. Moreover, the flow control assembly comprises a carriage subassembly coupled to the flow regulator subassembly for adjusting the flow regulator subassembly to vary fluid flow into the nuclear fission module.

Abstract: A fission chamber count rate measurement device and to the associated fission chamber calibration device; the count rate measurement device comprises: (1) a measurement cell, which contains the fission chamber (CH); (2) a neutron generator, which emits neutrons in the form of periodic pulses towards the fission chamber; (3) a neutron counter (K), which detects and counts the neutrons emitted by the neutron generator; and (4) a computing circuit, which delivers, over a predetermined time interval, a fission chamber count rate normalized with reference to the number of neutrons counted by the neutron counter (K).

Abstract: The power monitoring system has: a local power range monitor (LPRM) unit that has a plurality of local power channels to obtain local neutron distribution in a nuclear reactor core; an averaged power range monitor (APRM) unit that receives power output signals from the LPRM unit and obtains average output power signal of the reactor core as a whole; and an oscillation power range monitor (OPRM) unit that receives the power output signals from the LPRM unit and monitors power oscillations of the reactor core. The output signals from the LPRM unit to the APRM unit and the output signals from the LPRM unit to the OPRM unit are independent.

Abstract: A moderator temperature coefficient measurement apparatus includes: an input section receiving plant data including a coolant temperature signal being time series data on a temperature of a coolant of a light water reactor, and a reactivity signal indicating time series data on a reactivity calculated based on a detection value of a neutron flux in the light water reactor; a singular value decomposition section decomposing the coolant temperature signal into N components T?1 (t) to T?N (t), and the reactivity signal into M components ??1 (t) to ??M (t) by a singular value decomposition method; a combination section generating a selected combination being a combination of T?i (t) selected from the N components T?1 (t) to T?N (t) and ??j (t) selected from the M components ??1 (t) to ??M (t); and a temperature coefficient calculation section calculating a moderator temperature coefficient based on auto and cross power spectral density functions obtained by applying a Fourier transformation to the selected combin

Abstract: A neutron detector system and method for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. Comparison of the observed neutron count distribution with a Poisson distribution is performed to distinguish fissile material from non-fissile material.

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: The invention concerns a method of estimating when dryout may occur in a nuclear light water reactor of the boiling water reactor kind. The method includes the use of a formula which expresses the local dryout property of the nuclear reactor. The formula includes at least a first and a second factor. The first factor is a first function that describes how the dryout property depends on the flow of the cooling medium through the nuclear fuel arrangement. The second factor is a second function that describes how the dryout property depends on the axial power profile of the nuclear fuel arrangement. The first and the second functions describe said flow dependence and said axial power profile dependence independently of each other. The invention also concerns a nuclear energy plant, a computer program product (23) and a method of operating a nuclear energy plant.

Abstract: A neutron multi-detector array feeds pulses in parallel to individual inputs that are tied to individual bits in a digital word. Data is collected by loading a word at the individual bit level in parallel. The word is read at regular intervals, all bits simultaneously, to minimize latency. The electronics then pass the word to a number of storage locations for subsequent processing, thereby removing the front-end problem of pulse pileup.

Abstract: A cylindrical gamma generator includes a coaxial RF-driven plasma ion source and target. A hydrogen plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical gamma generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which has many openings. The plasma generator emanates ions radially over 360° and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired.

Abstract: A method of determining the spatially corrected inverse count ratio (SCICR) used to determine reactor criticality, which subtracts a background noise signal from the source range detector output. The method monitors the source range detector signal at two different core temperature levels during a transient portion of the detector output as the power output of the reactor is increased in the source range. This information is employed to analytically determine the background noise signal, which is then subtracted from the detector outputs to obtain the SCICR reactivity measurement.

Abstract: The output of a nuclear reactor is increased by a predetermined magnitude, and the neutron beam is measured as time-series data. The temperature of the moderator in the reactor is acquired as time-series data. Time-series data on the reactivity is acquired from the time-series data on the neutron beam by the reverse dynamic characteristic method with respect to a one-point reactor kinetics equation. Time-series data on the fuel temperature of a predetermined average acquired by using the time-series data on the reactor output and a predetermined dynamic characteristic model is acquired. The reactivity feedback contribution component is determined by using the time-series data on the reactivity and the applied reactivity.

Abstract: A method determines a volumetric power distribution of a core of a nuclear reactor using a set of detectors for measuring a neutronic flow provided outside the reactor vessel, and a set of probes for measuring the temperature of the coolant at the outlet of the fuel assemblies. The method comprises the step of determining a first volumetric power distribution using a neutronic calculation code instantaneously solving the diffusion equation and updating the isotopic balance of the core during the fuel depletion based on values of the core operation parameters, and the step of determining a new volumetric power distribution by adjusting the first volumetric power distribution using the measures provided by the sensors for measuring the neutronic flow and provided outside the reactor vessel and by the temperature measuring probes.

Abstract: A nuclear fuel assembly having an instrumentation tube having an insert that centers the in-core instrumentation while permitting bugling or welding of the instrumentation tube wall to a grid strap to obtain a rigid connection there between at any elevation along the instrumentation tube.

Abstract: An analytical method for the initial flux and transient hot water flow parameters for a boiling water reactor with single fuel bundle. Firstly, the method is to calculate intial flux and transient hot water flow parameter based on single fuel bundle. Then, it uses supplier provided CPR (Critical Power Ratio) correlation to calculate transient CPR and calculate the whole reactor core for hot water parameters as boundary condition. Iteration is used to figure out DCPR (Delta Critical Power Ratio). The obtained limit transient is selected as the maximum from DCPR. The maximum transient DCPR combines Safety Limit Minimum Critical Power Ratio (SLMCPR) and safety margin to figure out the OLMCPR (Operating Limit Minimum Critical Power Ratio). Both the plant layout and operational thermal limit are based on OLMCPR to assure the safety of reactor core.

Abstract: A method and apparatus for the calibration of neutron flux monitoring devices used in a nuclear reactor core. The apparatus includes a transverse in-core probe (TIP) cable with a neutron absorber located a fixed distance apart from a TIP detector. The neutron absorber may be passed within close proximity of the neutron flux monitoring device such that a perceived drop in measured neutron flux occurs, whereupon the cable may be repositioned relative to the monitoring device to ensure that the TIP detector is within close proximity of the monitoring device for purposes of calibrating the monitoring device.