85 results about "Neutron measurement" patented technology

A portable survey instrument and methodology yield intensity of neutron radiation, intensity of gamma radiation, and a direction of impinging gamma radiation. The instrument uses a neutron detector surrounded by an essentially rectangular moderator with preferably four gamma ray detectors disposed symmetrically about the neutron detector and within the moderator. Material and dimensions of the moderator are selected so that the neutron-measurement is equally sensitive to fast and thermal neutrons. The moderator also induces angular responses to the gamma ray detectors. Responses of the gamma ray detectors are combined to yield a parameter indicative of the angular position of a source. The survey instrument is portable and suited for hand held use.

A low value of Th/U ratio as determined from natural gamma radiation is indicative of deepwater sedimentation. This, together with estimates of total organic carbon from pulsed neutron measurements, is used to characterize source rocks. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understand that it will not be used to interpret or limit the scope or meaning of the claims.

Estimating cement voids in between a casing and a borehole wall of a borehole penetrating the earth formation includes forming with a computing device an actual ratio of radiation induced by a neutron source and measured by a first detector and a second detector when the tool is at two or more different locations in the borehole. A relationship between the actual ratio and the porosity at each of the two or more different locations is used and compared to two different cases of estimates of the ratio. Based on the comparison, an estimate of the cement voids at the two or more locations.

The invention belongs to the technical field of radioactive waste detection, and discloses neutron gamma combined measuring equipment. The neutron gamma combined measuring equipment comprises a gamma detector part, a transmission source part and a neutron measurement device. When the neutron gamma combined measuring equipment is used for measuring materials in waste bin, the neutron measurement device is fixed, the waste bin rotates on a rotating platform, and the transmission source part and the gamma detector part synchronously move in the height direction of the waste bin to realize simultaneous measurement by neutrons and gamma rays in the waste bin. The equipment is easy to operate, and can perform quantitative analysis on the materials in the waste bin.

The invention relates to a natural neutron spectrum measurement method, which comprises the following steps: using natural water body as a neutron moderation body, using a Monte-Carlo method for analog computation of fluence energy response functions of a detector to a natural neutron when the detector is located at different depths in the natural water body; using the detector to measure the counting rate of the natural neutron at different depths in the water; using spectrum unfolding software for spectrum unfolding on the basis of the counting rate after background deducting and the obtained fluence energy response functions to obtain a natural neutron spectrum. According to the natural neutron spectrum measurement method, the natural water body is used as as semi-infinite moderation body, the defects of limited size of conventional processed moderation body is overcome, the influences of neutrons and other background generated in the moderation body during natural neutron measurement are effectively eliminated, high-energy neutrons in the natural neutron spectrum can be effectively measured, the operation is simple, and reliable results can be provided.

The invention relates to the radiometric technology and in particular to an optical fiber coupled radiation detector used for fast neutron measurement. The optical fiber coupled radiation detector used for the fast neutron measurement comprises a scintillation probe which is formed by blending of fast neutron sensitive materials and scintillating mediums, a transmission optical fiber and a photovoltaic sensitive component, wherein one end of the transmission optical fiber is inserted in the middle of the scintillation probe, the other end of the transmission optical fiber is connected with the photovoltaic sensitive component, and an optical wrapping layer of one part, arranged in the scintillation probe, of the transmission optical fiber is removed. The optical fiber coupled radiation detector used for the fast neutron measurement has the advantages of being simple in structure, small in size, strong in environment adaptability, capable of achieving on line real-time monitoring and the like, and can meet the demand of fast neutron measurement under complex and severe environment.

The present invention discloses a water injection and drainage full-automatic multisphere neutron spectrometer and a measurement method. A system comprises a water injection and drainage system, multiple layers of annular lead glass spherical shells, a spherical neutron detector and an analyzing and processing system. According to a neutron measurement place, the water injection and drainage full-automatic multisphere neutron spectrometer is installed, at measurement, the water injection and drainage system injects the water in the multiple layers of annular lead glass spherical shells orderly, thereby achieving the purpose of changing the thickness of a neutron moderator, and measuring the neutrons of different energy in an environment. According to the present invention, the water injection and drainage system carries out the full-automatic control on the different parameters of a single spherical detector, thereby achieving the multisphere detection purpose, solving the manufacturing complexity of a plurality of detection systems in a conventional multisphere system, reducing the manufacturing cost, at the same time, effectively avoiding the problems that the detectors in the conventional multisphere system influence each other and are inconsistent, and the overall carrying of the plurality of detectors is tedious.

Apparatus and methods for determining borehole diameter and standoff for neutron porosity logging systems. The apparatus comprises an isotopic neutron source, a single epithermal neutron detector and two thermal neutron detectors, where all detectors are at different axial spacings from the neutron source. Thermal neutron porosity is determined from the combined response of the thermal neutron detectors. Epithermal neutron porosity is determined from the response of the single epithermal neutron detector. Embodied as a wireline system, a difference between thermal neutron porosity and epithermal neutron porosity is used to compute a tool standoff, which in turn is used to correct the thermal neutron porosity for effects of standoff. Borehole size measurements are made independently and preferably with a mechanical caliper of a density tool subsection. Embodied as a LWD system, the difference between thermal neutron porosity and epithermal neutron porosity is used to correct the thermal neutron porosity measurement for both borehole diameter and radial position (standoff) of the tool within the borehole.

A method for determining at least one formation property calculated from neutron measurements acquired with a downhole tool includes emitting neutrons from a source in the tool into the formation, detecting neutrons with at least one detector in the downhole tool, calculating a first slowing-down length (L₁) based on the detected neutrons, and deriving a second slowing-down length (L₂) based on the first slowing-down length (L₁). Further steps include deriving a correlation function for relating slowing-down lengths from a first tool to slowing-down lengths associated with a different source, wherein the correlation function depends on formation properties such as bulk density; and applying the correlation function to the slowing-down length of the first tool to derive the slowing-down length of the second tool. A method for determining a thermal neutron formation porosity based on a slowing-down length from epithermal neutron measurements from an electronic neutron source includes converting the slowing-down length into a computed neutron slowing-down length from thermal neutron measurements from a chemical neutron source, wherein the converting uses a correlation function that depends on formation bulk density; deriving a thermal neutron countrate ratio based on the computed neutron slowing-down length, wherein the deriving uses a function that depends on the formation bulk density and formation sigma; and computing the thermal neutron formation porosity from the thermal neutron countrate ratio.

The invention relates to methods and apparatus for determining downhole mud flow rates and other downhole parameters. A method for determining a downhole parameter includes operating a pulsed neutron generator (6), pulsing the pulsed neutron generator (6) off, detecting a substantially unactivated drilling fluid slug at a known distance (d) from the pulsed neutron generator (6), and determining a time-of-flight (t) for the unactivated drilling fluid slug to travel from the pulsed neutron generator (6) to a detection point.

The invention discloses a fast neutron detection method, which is used for detecting fast neutrons with X-rays, and comprises the following steps: passing the fast neutrons through a neutron slowing body to absorb the X-rays and slow the fast neutrons into thermal neutrons; and detecting the thermal neutrons by using a thermal neutron detector to obtain the information on the fast neutrons. The invention also discloses a method for identifying substances by using photoneutrons, a method for identifying substances by using X-rays and the photoneutrons, and a neutron detector. The neutron detector comprises the neutron slowing body which is suitable for absorbing the X-rays therein and slowing the fast neutrons into the thermal neutrons; and the thermal neutron detector which is suitable for detecting the thermal neutrons to obtain the information on the fast neutrons. In the invention, the interference of the X-rays with the fast neutron measurement can be eliminated by arranging the neutron slowing body, so the accuracy of the neutron measurement is improved. And as the attenuation information of the X-rays and the attenuation information of the neutrons, which are different, are obtained at the same time, the capability of identifying detected objects is improved.

A movable device for measuring physical quantities of nuclear materials contained in a shielded cell, which device can be brought up against the shielded cell and can be retracted therefrom, the device configured to carry out the measurement in the position in which it is against the shielded cell. The device includes a carriage, a support member placed on the carriage, and a shielded container placed on the support member. The shielded container includes a transfer container configured to store the nuclear material to be measured, and an opening configured to be aligned with an opening in one wall of the shielded cell. The support member is made of graphite and includes a housing accommodating a neutron emission module, a casing covering the shielded container, the casing being made of graphite, and a neutron measurement mechanism fastened to the casing.

The invention concerns a neutron measurement method for determining porosity of an earth formation surrounding a borehole comprising: conveying a tool along said borehole, wherein said tool comprises a source of neutron radiation and at least one detector axially spaced from said source; generating measured detector response for said at least one detector that is indicative of neutron radiation from said source interacting with said earth formations; operating said measured detector response with a predetermined mathematical equation and thereby obtaining corrected detector response that is independent of the density of said earth formation; and determining porosity of the earth formation surrounding the borehole from said corrected detector response. The invention also relates to a system implementing said method.

The invention discloses a three-dimensional distribution measurement system for neutrons in a reactor based on measurement data outside the reactor. A reactor power inversion subsystem is used for obtaining neutron measurement values in areas around the reactor, and the out-of-reactor detector subsystem changes the number, positions and detection directions of detectors according to real-time monitoring needs; an online spectrum unfolding subsystem receives the measurement data from the out-of-reactor detector subsystem, calculates neutron energy spectra at the detector positions by an onlinespectrum unfolding method, and then transmits energy spectrum data at each detection position to the reactor power inversion subsystem; and the reactor power inversion subsystem calculates the neutronenergy spectra at different spatial positions in the reactor through the energy spectrum data at the out-of-reactor detectors. The three-dimensional distribution measurement system can rely on the out-of-reactor detectors only to quickly obtain the distribution of the neutrons in the reactor in different space and energy zones, and can be used in monitoring, diagnosis and analysis of advanced reactors such as critical driven reactors, fusion driven reactors and fast neutron reactors.

The invention belongs to a neutron measurement technology, and particularly relates to a method and a device for simulating a multisphere neutron spectrometer by utilizing a position sensitive proportional counter tube. The method comprises the following steps of: making a slowing body to be in a conical shape that two bottom surfaces are buckled together; inserting a counting tube of a one-dimensional position sensitive neutron detector into the slowing body along the axial direction; and sequentially dividing the counting tube of the position sensitive neutron detector into a plurality of regions from the center to an edge of the counting tube of the position sensitive neutron detector along the axial direction, wherein each region respectively corresponds to each sphere of the multisphere neutron spectrometer. By adopting the special structures of the counting tube of the one-dimensional position sensitive neutron detector and the single-slowing body and dividing the regions, the invention simulates the work mode of the multisphere spectrometer, thereby keeping the advantage of the slowing body such as convenient measurement, absorbing the characteristic of the multisphere spectrometer such as good energy response, and being widely applicable to the field of neutron radiation measurement.

A system for controlling photomultiplier gain drift is disclosed. According to one aspect, the system includes first means for measuring a noise signal of the photomultiplier, the first means configured emit a measurement signal representative of the photomultiplier's noise signal. The system further includes second means for maintaining the measured noise signal at a constant level, based on the measurement signal. The disclosed embodiments apply to stabilization of the gain of photomultipliers and, more specifically, to stabilization of neutron measurement systems using photomultipliers.

The invention discloses a method for carrying out neutron measurement on uranium contents in uranium-containing liquid and an achievement device of the method. The objective of the invention is to solve problems of long analysis processes, tedious operation and failure to carry out safe online monitoring on nuclear borderlines in the current detection methods. The method comprises steps of using neutrons radiated by a neutron source to penetrate through a pipeline wall; allowing neutrons to react with uranium-containing liquid in the pipeline; measuring the neutron counting rate N-measurement in the pipeline through a neutron detector, and calculating the uranium contents NU in the pipeline according to a calculation model shown in the description, wherein the phi heat is the average neutron injection rate in the pipeline, the sigmaf is the micro cross section, the t is the measurement time and the y is the average released neutron number of fission of every time. According to the invention, the method and the device are advantaged by capability of achieving real-time and online measurement on uranium concentration in the uranium-containing liquid.

The invention discloses a neutron howitzer and a neutron scattering spectrometer. The invention relates to the technical field of neutron scattering, and solves the problem that while increasing the neutron transmissivity, the prior art has poor radiation aging-resistant capability. In the scheme provided by the embodiment of the invention, the neutron howitzer comprises partitions, and is characterized in that: each partition consists of a carrier layer and a neutron-absorbing layer, the carrier layer is a metal foil, and the neutron-absorbing layer is attached on the carrier layer. The embodiment of the invention is applicable to neutron measurement instruments and the like.

The invention discloses a neutron detector. The neutron detector comprises a neutron moderating body and a thermal neutron detector, wherein the neutron moderating body is suitable for absorbing X rays passing through the neutron moderating body and moderating fast neutrons into thermal neutrons; and the thermal neutron detector is suitable for detecting the thermal neutrons to acquire information about the fast neutrons. Through the neutron moderating body, interference of the X rays to fast neutron measurement can be eliminated, so that the neutron measurement accuracy is improved. The identification capacity of a detected object is improved by simultaneously acquiring two types of different attenuation information of the X rays and the neutrons.

The invention discloses a wide-energy-spectrum neutron measurement system for characteristic peak searching. The system can be used for on-line measurement of energy spectrum and flux of a high-energyand high-current neutron radiation field in a narrow-space strong-irradiation environment. The measurement system comprises a neutron probe, an electronics system and an energy spectrum analysis system. The neutron probe adopts a composite detection structure. The composite detection structure is divided into four neutron sensitive regions, wherein the regions are separated by metal walls; and each region is internally coated or filled with different neutron sensitive materials. The intermediate neutron sensitive region can adjust and control the energy response peak energy region by changingcomponents of the filling materials. In the energy spectrum analysis system, a characteristic peak searching wide-energy-spectrum spectrum unfolding method is adopted. The system is novel in structure, has a small and compact in neutron probe, can carry out real-time measurement in a small space and realizes real-time accurate measurement of neutron flux and energy spectrum. The system has the advantages of high measurement accuracy, needing no preset spectrum and high anti-disturbance capability.

The invention discloses a measurement while drilling device. The device comprises a protection sleeve, a neutron circuit framework, a density circuit framework, a while-drilling compensation neutron measurement assembly and a while-drilling direction and density imaging assembly. The protection sleeve is formed by machining an independent drill collar and seals and protects inner structures and devices of the protection sleeve. The neutron circuit framework is mounted on the upper portion in the protection sleeve. The density circuit framework is mounted on the lower portion in the protectionsleeve and is in butt joint with the neutron circuit framework. The while-drilling compensation neutron measurement assembly is mounted on the neutron circuit framework. The while-drilling direction and density imaging assembly is mounted on the density circuit framework. According to the device, a density logger and a compensated neutron logger are integrated in the same drill collar, and therefore the operation difficulty of mounting the density logger and the compensated neutron logger and carrying out testing is greatly reduced. Compared with the prior art, according to the device, the length of a logger can be effectively reduced, and consistency of compensated neutron measurement and while-drilling density measurement can be improved.

The invention discloses a neutron measurement method for studying the microstructure of a brittle material. The method realizes the measurement of a small-angle neutron scattering signal of the brittle material under different strains in a Brazilian test developing process by reasonably configuring multiple measuring devices, arranging a relative positional relationship among the measurement devices and introducing a discrete strain calculation technology, and can effectively ensure the consistence of a neutron measurement area in a measured sample in different strain states. The method is used together with a small-angle neutron scattering spectrometer to carry out the Brazilian test on ceramics, polymers and other brittle materials and online detect the microscopic deformation, crackingdamage and damage process of the material, so the analytic study of the mechanical properties and the damage mechanism of the material are facilitated.