Abstract: A detector structure adjacent an opening in a cavity structure for detecting explosives in objects within such opening including a plurality of thin nonchlorinated hydrogenous wall members forming a passageway to define such opening. A source of high energy neutrons located adjacent the passageway to direct neutrons into the passageway. A premoderator formed by nonchlorinated hydrocarbon material surrounding the source of high energy neutrons to reduce the energy in at least a portion of the neutrons. A first moderator formed by heavy water surrounding the source of neutrons and the premoderator to reduce the energy in at least a further portion of the neutrons. A second moderator formed by carbonaceous material at least partially surrounding the plurality of thin hydrogenous wall members and the first moderator to reduce the energy in at least an additional portion of the neutrons and reflect back the additional portion of neutrons into the opening.

Abstract: Apparatus and method for radiographic inspection of welds, which welds may be seal welds of the kind typically found on nuclear power reactor control rod drive mechanisms (CRDMs). Such CRDM seal welds seal the threaded joint defined by a generally tubular pressure housing and a generally tubular vessel head adapter, the housing and adapter enclosing the CRDM components. The apparatus comprises a circular track capable of surrounding and being connected to the vessel head adapter. A radiation source assembly capable of emitting penetrating radiation and a radiation shielding assembly capable of shielding against the radiation are mounted on the track. The assemblies are adjustable for aligning the assemblies with the seal weld. A radiographic film is interposed between the radiation source assembly and the radiation shielding assembly and adjacent the weld for capturing a volumetric image of the weld on the film.

Abstract: System for the detection of substances and in particular explosives, by neutron irradiation thereof.It comprises means (4) for the irradiating, by neutrons, of an object (6) which may contain a substance, means (14) for detecting the gamma radiation which can be emitted by the object and means (18) for processing the signals supplied by the detection means. These processing means count the gamma photons of each line of a plurality of characteristic lines of at least one chemical element of the substance, determining for each line a probability of false detection of the chemical element associated with said line, determine the product of these probabilities, compare said product with a threshold fixed by users and notify the latter if the product is below the threshold, the object then being assumed to contain the substance.

Abstract: A method and apparatus for studying the flow of water along a well, on the basis of a general spectrum g(t) of gamma ray detection numbers detected in a detection zone over a given detection duration and as a function of time, said gamma rays resulting from the activation of oxygen atoms in water by neutrons emitted by a source to create an activation reaction O.sup.16 (n,p)N.sup.16.

Abstract: A method and apparatus are provided for analyzing the elemental constituents of fluid streams in the cellulose pulp industry, such as liquid with dissolved solids for treatment of cellulose pulp or from the treatment of cellulose pulp, or liquid slurries including comminuted cellulose material. Continuous on-line elemental analyses are made of one or more such fluid streams, and at least the partial elemental make-up (either material, or of elements added for marking) of the streams determined. Then one or more processes for acting on the fluid streams are controlled to optimize the processes as a result of the analyses made. The invention is particularly useful in the continuous on-line analysis of black liquor utilizing prompt gamma neutron activation analysis, and controlling the operation of an evaporator or recovery boiler.

Abstract: A method in which a surface layer material whose amount of reduction is to be measured is activated to find a distribution ratio of two or more kinds of radioactive nuclides that are produced in the space in the surface layer of the material, and the distribution ratio is used as an index for the amount of reduction of surface layer material. The amount of reduction in the surface layer material is measured in situ, nondestructively, easily and irrespectively of obstacles and the distance that exist between the detector and the material that is to be measured.

Abstract: An apparatus to survey subsurface formations includes a sonde which is configured to move through a borehole. The sonde includes a neutron generator that emits neutrons into the subsurface formations. A crystal detector connected to the sonde monitors the neutron output of the neutron generator. The crystal detector can comprise an yttrium silicate crystal, an yttrium aluminate crystal, a lanthanum phosphate crystal, or a lutetium phosphate crystal. A lanthanum phosphate crystal or a lutetium phosphate crystal can also be used to detect photons coming from the subsurface formations. The sonde pressure casing can be fabricated from borated stainless steel to shield the internals of the sonde from thermal neutrons.

Abstract: A system for monitoring the radioactivity of a liquid waste stream includes a pair of tanks into which the liquid waste stream is directed during alternating fill cycles. At the conclusion of each fill cycle, the liquid waste is recirculated through the chamber of a radioactivity monitor. A pair of opposed radiation detectors, external to the chamber, generate activity measurements to a controller indicative of the radionuclide concentration levels in the liquid waste. The tanks are then emptied either to the environment or back to a decontamination facility for further processing depending on the indicated radionuclide concentration level. System operation, including periodic servicing of the monitor, is automatically coordinated by the controller to avoid interruption of the liquid waste stream filling the tanks.

Abstract: Neutron activation analysis method and apparatus are disclosed wherein a sample in a vacuum chamber is irradiated with neutrons, the time when and energy of emitted gamma rays from a sample are detected, and delayed Beta-electrons emitted from the sample are detected and the positions of emission are imaged. Time coincidence between detected gamma rays and delayed Beta-electrons is determined and the location of elements on the sample is established from the detected coincidence and the image of the location on the sample where the delayed Beta-electrons were emitted.

Abstract: A nuclear spectroscopy method and apparatus for obtaining qualitative and quantitative information related to water flow, comprising the steps of:(1) irradiating the water flow with a source of neutrons of sufficient energy to interact with oxygen atoms in the water according to the activation reaction O.sup.16 (n,p)N.sup.16 ;(2) detecting and counting, with at least at a detector, the gamma rays emitted during disintegration of N.sup.16 ;(3) making a plot of the counts versus time; and(4) deriving from said plot information related to said water flow.The irradiating is advantageously interrupted after a given period of time, and is preferably immediately followed by the detection. The water flow velocity "V" is calculated from the formula V=d/t, where "d" is the distance between the source and the detector(s), and "t" is the time period between the irradiation and the time corresponding to a characteristic on said plot, representative of the water flow and departing from the N.sup.16 exponential decay curve.

Abstract: A boiling water reactor has a control element disposed in a water pond. An apparatus for the neutron-radiography testing of the control element includes a film cassette having a recording area. A water-free hood is fitted over the control element. The hood has an open bottom and a wall facing the film cassette. The wall has an opening formed therein with a cross section corresponding to the recording area. A holding device fits over the opening for receiving the film cassette. The holding device has a downwardly open side extended below the opening through which the film cassette is to be introduced into the water-free space in the holding device. A neutron source, a collimator and the film cassette lie in one measurement plane.

Abstract: A detector structure adjacent an opening in a cavity structure for detecting explosives in objects within such opening including a plurality of thin nonchlorinated hydrogenous wall members forming a passageway to define such opening. A source of high energy neutrons located adjacent the passageway to direct neutrons into the passageway. A premoderator formed by nonchlorinated hydrocarbon material surrounding the source of high energy neutrons to reduce the energy in at least a portion of the neutrons. A first moderator formed by heavy water surrounding the source of neutrons and the premoderator to reduce the energy in at least a further portion of the neutrons. A second moderator formed by carbonaceous material at least partially surrounding the plurality of thin hydrogenous wall members and the first moderator to reduce the energy in at least an additional portion of the neutrons and reflect back the additional portion of neutrons into the opening.

Abstract: Method for analysis of the content of certain elements in a continuous flow of bulk materials by neutron bombardment and measurement of the gamma radiation emitted by such elements, which makes it possible to distinguish between the capture radiation and the activation radiation. The neutron source is a neutron-generating tube which is activated periodically. The signals from a single gamma radiation detector are considered only after neutron emission has ceased, during distinct intervals corresponding to the phenomena of capture and radiation of the activated elements, respectively. The respective signals are treated in two distinct measurement routes, and the measurements are then combined automatically. A third measurements route can be provided for gamma radiation resulting from inelastic collisions. The source and the detector are positioned in a probe lodged in a polyethylene protective tube within the flow of the materials.

Abstract: An apparatus and method for determining the presence of certain elements or compounds within an object, wherein the object under examination contains both nuclei of a first type which exhibit nuclear magnetic resonance and nuclei of a second type which exhibit nuclear quadrupolar resonance. The apparatus and method involve subjecting the object to a magnetic field and to a radiation beam whose characteristics in the presence of a magnetic field and in the absence of a magnetic field can be measured. The radiation transmission and/or absorption "fingerprint" of a particular substance is experimentally determined and recorded in the presence of a magnetic field calculated to optimize a cross coupling between nuclei of the first (NMR) type and nuclei of the second (NQR) type. This reference is then utilized later as a basis on which to identify an unknown compound exhibiting the same radiation absorption and/or transmission characteristics in response to the same or similar magnetic field intensity.

Abstract: A nuclear detection system and method uses an artificial neural system to efficiently detect explosives in checked airline baggage or other parcels with a high probability of detection (PD) and a low probability of false alarms (PFA). The detection system detects the presence of nitrogen and other elements and their rough density distribution within the object under investigation by performing a nuclear-based analysis of the object. The detection system includes a source of neutrons; an array of gamma ray detectors; at least one neutron detector; means for irradiating the object being examined with neutrons from the neutron source, which neutrons interact with the atomic nuclei of one or more specific elements, e.g.

Abstract: An analyzer for detecting explosives has at least one source and a plurality of gamma ray detectors. An article to be analyzed is moved adjacent the source and detectors and is subjected to neutrons which generate gamma rays in any nitrogen in the article. The gamma rays are detected and analyzed to determine the nitrogen concentration within the article. In order to achieve an area of uniform detection there are a plurality of detectors equidistant both from each source and from the article to be analyzed. In order to avoid a decrease in sensitivity away from the sources and detectors, there may be a second opposing array of sources and detectors on the opposite side of the articles. For greatest uniformity of detection, a source in one array opposes a detector in the other array and vice versa. Transmission of radiation from the analyzer is kept at safe levels by enclosing the analyzer within shielding which includes shield members extending from a trolley or other transport mechanisms.

Abstract: The invention makes it possible to measure the degree of radioactive radiation emitted by large pieces. It includes two large gamma ray detectors (12A, 12B) placed opposite each other and whose spacing is adjustable. They are completed by a photoelectron multiplier (14A, 14B). The piece (2) to be measured is suspended so as to be brought between the two detectors (12A, 12B). The positioning of these detectors is obtained with the aid of a computer and a system (22) for recognizing the shape of the piece (2) functioning with the aid of optical clip-on lenses. The fact that the two detectors are position-adjustable makes it possible to take account of the shape of the piece to be measured. An application is the recovery of materials originating from nuclear installations with the view to re-using the materials.

Abstract: Apparatus for non-invasively inspecting an object, such as an item of luggage, for explosives material comprises a multi-channel thermal neutron inspection system having a plurality of neutron irradiation chambers. Simultaneous operation of several channels increases maximum system throughout several times. Each chamber has a lithium neutron source which is stimulated to neutron production by a proton beam. Beam switching magnets are energized by pulsing to divert a common proton beam to each source in turn. The initial beam is generated by a radio frequency quadrupole accelerator. The advantages of this system are very low residual source activity and controllable neutron production thereby minimizing safety hazards. The irradiation chamber may contain several different gamma ray detectors to identify the presence elements present in explosives material. In addition a neutron radiography imaging means may be employed to identify the presence of potential shielding materials.

Abstract: A system for detecting the presence of explosives contained in an object under observation, including a cavity structure for receiving the object and a radiation source for producing thermal neutrons directed to the object under observation. Gamma rays are produced to represent the presence of explosives and as an example the concentration of nitrogen contained in the object. Inorganic scintillators are located within the cavity structure to detect the gamma rays and produce an output signal representative of the presence and concentration of the nitrogen and/or other elements contained in the object. The inorganic scintillators are formed as a ring around the cavity structure to detect the nitrogen and/or other elements within at least one particular plane passing through the object. The object under observation is moved through the cavity structure to detect the nitrogen in successive planes to build up a three dimensional profile of explosives concentration.

Abstract: Both gadolinia nuclear fuel rods and urania fuel rods are non-destructively tested to determine the enrichment concentration of the fuel pellets therein by serially conveying the gadolinia rods and the urania rod along separate test channels through an active scanner where they are irradiated from a common neutron souce, and the neutron-induced gamma ray emissions are counted as a measure of the enrichment concentrations at a multiplicity of points distributed along the rod length. The enrichment counts are corrected for background radiation, variations in fuel density, and, in the case of gadolinia rods, for gadolinia content by passing these rods through a magnetometer.

Abstract: An apparatus and method non-invasively interrogates an object to detect contraband. The apparatus irradiates the object with fast neutrons of energy greater than 6.7 MeV, and measures the ensuing gamma-ray spectra. Irradiation of the object is accomplished by producing a neutron beam and moving the interrogated object stepwise or continuously relative to the beam. The nuclear interactions of highly penetrating neutrons within the irradiated volume of the object give rise to energetic nuclear-species characteristic gamma-rays. The energy and intensity of the emitted gamma-rays provide information relative to the spatial and density distributions of the gamma-ray sources, i.e., the specific atomic nuclei within the object. From this information, three-dimensional images of the atomic nuclei spatial and density distributions are inferred. Such three-dimensional images allow a decision to be made as to the presence of contraband. Measurements are made using arrays of gamma-ray scintillator detectors.

Abstract: Apparatus and a method using solid state track recorder (SSTR) metrology are disclosed to accurately measure small amounts of actinide pollution in water. A relatively small sample cell contains a fluidic sample and carries a SSTR. Sample cell configuration allows use of the fluidic sample itself as an asymptotic fission source for the SSTR and allows simultaneous irradiation of a plurality of such sample cells in existing thermal neutron irradiators.

Abstract: According to the invention, the object (34) is brought to a first inspection station (I to IV) in which the object is irradiated by thermal neutrons, the capture gamma radiation then liable to be emitted by the object and characterizing a chemical element of the substance to be detected is detected, if the intensity of said radiation exceeds a predetermined threshold, the object is brought to a second inspection station (V,VI), in which the object is irradiated by fast neutrons and the prompt gamma radiation then liable to be emitted by the object and characterizing the chemical element is detected, the energy of the fast neutrons being at least equal to that of prompt gamma radiation, in order to confirm or disprove the information obtained in the first station.

Abstract: A nuclear detection system and method efficiently detects explosives in checked airline baggage or other parcels with a high probability of detection (PD) and a low probability of false alarms (PFA). The detection system detects the presence of nitrogen and its rough density distribution within the object under investigation by performing a nuclear-based analysis of the object. The detection system includes a source of thermal neutrons; an array of gamma ray detectors; a neutron detector; means for irradiating the object being examined to neutrons from the neutron source, which neutrons interact with the atomic nuclei of one or more specific elements, e.g.

Abstract: A system and method for detecting contraband generates a highly collimated beam of pulsed fast neutrons, having a pulse width on the order of a nanosecond, and an energy of 5 to 9 MeV. An object under investigation is scanned with the collimated pulsed beam. The neutrons in the beam cause (n, .gamma.) reactions in a limited object volume or voxel, defined by the intersection of the collimated beam and the scanned object. The highly penetrating fast neutrons produce nuclear reactions with the atomic elements present within the object, causing gamma rays to be emitted. By measuring the approximate time of flight of the neutron pulse, a determination is made as to the particular voxel from which the gamma ray originated. The energy of the detected gamma rays identifies the particular elements from which the gamma rays originated. Thus, e.g., the carbon, nitrogen, oxygen, and chlorine content, which elements are commonly found in contraband, of a particular voxel can be determined directly and precisely.

Abstract: A method of downhole neutron monitoring using an oxygen containing scintillating material to generate scintillator light as a function of electrons and gamma rays emitted from the product of the .sup.16 O (n,p) reaction in a scintillator, converting the generated scintillator light to an electrical signal, and using the electrical signal to record the flux of measured neutrons.

Abstract: A system for detecting the presence of explosives contained in an object under observation, including a cavity structure for receiving the object and a radiation source for producing thermal neutrons directed to the object under observation. Gamma rays are produced to represent the presence of explosives and as an example the concentration of nitrogen contained in the object. Inorganic scintillators are located within the cavity structure to detect the gamma rays and produce an output signal representative of the presence and concentration of the nitrogen and/or other elements contained in the object. The inorganic scintillators are formed as a ring around the cavity structure to detect the nitrogen and/or other elements within at least one particular plane passing through the object. The object under observation is moved through the cavity structure to detect the nitrogen in successive planes to build up a three dimensional profile of explosives concentration.

Abstract: It comprises a first assembly (E1) constituted by a neutron radiation source (6), a hydrogenated material block (4) having a recess for receiving said source (6) and a first neutron detector (10); a second assembly (E2) constituted by a hydrogenated material block (14) surrounded by a material stopping the thermal neutrons (18) and a second neutron detector (16) placed in the hydrogenated material block (14); the first assembly (E1) and the second assembly (E2) being placed on either side of the area to be controlled (2). A foldback protective casket (8) can receive the neutron radiation source (6).

Abstract: Both gadolinia nuclear fuel rods and urania fuel rods are non-destructively tested to determine the enrichment concentration of the fuel pellets therein by serially conveying the gadolinia rods and the urania rod along separate test channels through an active scanner where they are irradiated from a common neutron source, and the neutron-induced gamma ray emissions are counted as a measure of the enrichment concentrations at a multiplicity of points distributed along the rod length. The enrichment counts are corrected for background radiation, variations in fuel density, and, in the case of gadolinia rods, for gadolinia content by passing these rods through a magnetometer.

Abstract: An irradiator (4) is provided for irradiating lumps of ore to detect the presence of gold in the lumps by neutron activation analysis. The irradiator (4) consists of a close packed array of three inner cylindrical ducts (14) and three outer cylindrical ducts (12) through which the lumps of ore are passed, with three neutron sources (16) arranged in the spaces between the inner ducts (14) and the outer ducts (12) to irradiate the ducts (12, 14) and to activate any gold by the reaction .sup.197 Au (n, n'.gamma.) .sup.197 Au. Each inner duct (14) is thus adjacent to two neutron sources (16), and is or larger cross-sectional area than the outer ducts (12).

Abstract: It comprises an enclosure, a neutron emitting source (29) for bombarding said fissile material, means (28, 30) for introducing source (29) into the enclosure and for removing said source from the enclosure, neutron radiation detection means (9), moderator means (2, 4, 6) for thermalizing a fission radiation emitted by said fissile material interposed between the neutron radiation detection means (9) and the fissile material. It also has gamma radiation detection means (6, 14), which comprises a scintillator (6) and at least one photomultiplier (14) associated with said scintillator (6) and the scintillator material also constituting the moderator for thermalizing the fast neutrons directly emitted by the source (29), as well as the neutrons from the spontaneous fissions of the .alpha., n reaction and the neutrons from the fissions induced in the fissile material, the neutron radiation detectors (9) being embedded in the scintillator material (6) constituting the moderator.

Abstract: It comprises e.g. a 14 MeV neutron generator for supplying these neutrons to an object liable to contain an explosive, a germanium detector and analysis means coupled to the detector and able to analyse the fast .gamma. photons emitted by the object and trapped by the detector and determine the nitrogen/oxygen ratio in the object, so that this ratio can be compared with that of the explosive and establish whether the object contains said explosive.

Abstract: An apparatus and method for scanning an object for nitrogen for detecting the presence of explosives in luggage, parcels and the like. The object is placed in a cavity in which a thermal neutron flux is produced by introducing fast neutrons in the presence of a nuclear moderating material. A reaction between the thermal neutrons and the nitrogen contained in the object causes gamma rays to be emitted which are detected and transmitted to processing electronics to determine the concentration and position of nitrogen in the object. Thermal neutrons sensors are located within the cavity to monitor the amount of thermal neutrons and adjust the thermal neutron flux within the cavity in order to maintain an optimal thermal neutron flux density within the cavity. The adjustment may be effectuated by adjusting the accelerating potential of a neutron accelerator or by adjusting the position of a neutron moderator for use with an isotopic neutron source.

Abstract: A gold sorting plant in which the gold content of lumps of ore is measured by means of a neutron activation analytical technique. Separate lumps of gold ore are graded in two sizes which are presented to an irradiator such as to irradiate them uniformly. The energized lumps of ore are conveyed to an analyzer/sorter station where the intensity of .gamma.-rays having an energy of 297 KeV from each lump of ore is measured, and it is accepted or rejected for further processing. Various forms of irradiator and analyzer/sorter are described.

Abstract: A method for logging a cased well to determine the quantity and location of any barite weighted drilling fluid in the annulus between the casing and the wall of the wellbore. A tool assembly having a neutron generator and a gamma scintillation detector is used to log the zone of interest. The neutrons introduced into the well by the neutron generator convert a portion of the barium-138 in the drilling fluid to barium-137m. The magnitude of the gamma photon peak charactristic of the decayof barium-137 is used to identify the quantity of drilling fluid present in the annulus as a function of depth. This method is especially useful identifying the existence of channels in a cemented wellbore annulus.

Abstract: A method is described for correcting for effect of isotope burn-in in fission neutron dosimeters. Two quantities are measured in order to quantify the "burn-in" contribution, namely P.sub.Z',A', the amount of (Z', A') isotope that is burned-in, and F.sub.Z', A', the fissions per unit volume produced in the (Z', A') isotope. To measure P.sub.Z', A', two solid state track recorder fission deposits are prepared from the very same material that comprises the fission neutron dosimeter, and the mass and mass density are measured. One of these deposits is exposed along with the fission neutron dosimeter, whereas the second deposit is subsequently used for observation of background. P.sub.Z', A' is then determined by conducting a second irradiation, wherein both the irradiated and unirradiated fission deposits are used in solid state track recorder dosimeters for observation of the absolute number of fissions per unit volume. The difference between the latter determines P.sub.

Abstract: A device for detecting fissionable material including a neutron source, two parallelepipedal panels placed on a support and forming a dihedral with an adjustable opening. The dihedral has an edge centered on the neutron source, and the panels consist of solid modules made of a material able to thermalize the neutrons and of a module of the same material in which a unit for detecting fission neutrons is housed. This detection unit is located at the end opposite the neutron source, and the object to be checked is placed between the two panels. The device has application to the checking of nuclear waste.

Abstract: An apparatus for ore sorting includes a neutron irradiator (12), and a detector assembly (14) for detecting gamma radiation emitted by irradiated lumps (21) of the ore. The irradiated lumps (21) after discharge from the irradiator (12), are divided into two channels (30) by at least one bifurcating device (28) held above a relatively high speed conveyor (26) transporting the lumps (21). Each channel (30) is subsequently divided into three streams (37, 38, 39) by diverting selected lumps (21) from the channel (30) as the lumps (21) are projected from the end of the high speed conveyor (26). The diverted lumps (21) in each stream (37, 38, 39) are allowed to fall on to a relatively low speed conveyor (50) which then presents the lumps (21) to the detector assembly (14).

Abstract: An irradiator for irradiating lumps of ore, to activate a selected substance in the ore by neutron activation, consists of a cylindrical chamber 10, a vibrated conical base 20 to control passage of the lumps through the chamber 10, and at least one coaxial annular neutron source 30 at one end of the chamber 10. The neutron source 30 is arranged so that all the lumps of ore are activated uniformly.

Abstract: Systems and methods for inspection of nuclear fuel pins to determine fiss loading and uniformity. The system includes infeed mechanisms which stockpile, identify and install nuclear fuel pins into an irradiator. The irradiator provides extended activation times using an approximately cylindrical arrangement of numerous fuel pins. The fuel pins can be arranged in a magazine which is rotated about a longitudinal axis of rotation. A source of activating radiation is positioned equidistant from the fuel pins along the longitudinal axis of rotation. The source of activating radiation is preferably oscillated along the axis to uniformly activate the fuel pins. A detector is provided downstream of the irradiator. The detector uses a plurality of detector elements arranged in an axial array. Each detector element inspects a segment of the fuel pin.

Abstract: A partially collimated beam of thermal/epithermal neutrons is transmitted through a small bore pipe in which wet steam flows under a high pressure. A thermal neutron detector measures the transmission of the thermal/epithermal neutrons by the wet steam and generates a signal indicative of the density and steam quality of the wet steam.

Abstract: The present invention relates to a double barrier heat exchanger between a radioactive primary fluid and a secondary fluid making it possible to detect a possible primary fluid leak in the exchanger. The primary fluid circulates in a primary duct and the secondary fluid circulates in a secondary duct, a junction matrix being positioned between the primary and secondary ducts and in contact with the latter. The matrix is in the form of a compact metallic mass incorporating at least one element, e.g. silver, which can be made raidoactive when it diffuses into the primary fluid. Application is to sampling circuits in nuclear reactors.

Abstract: A non-destructive method for determination of neutron exposure and constituent concentrations in an object, such as reactor pressure vessel, is based on the observation of characteristic gamma-rays emitted by activation products in the object by using a unique continuous gamma-ray spectrometer. The spectrometer views the object through appropriate collimators to determine the absolute emission rate of these characteristic gamma-rays, thereby ascertaining the absolute activity of given activation products in the object. These data can then be used to deduce the spatial and angular dependence of neutron exposure or the spatial constituent concentration at regions of interest within the object.

Abstract: A method for monitoring the ore grade of an uranium bearing fluid mixture. A sample of the fluid mixture is irradiated with neutrons. Delayed fission neutrons resulting from the fission of uranium present in the sample are counted as an indication of uranium ore grade.

Abstract: The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

Abstract: A neutron/gamma ray technique for mapping the distribution of contaminants in an extended medium such as the wall (10) of a building. A neutron excitation source (14) is located on one side of the wall (10) and a gamma ray spectrometer, including a gamma ray detector (16), is located on the opposite side of the wall (10) facing the excitation source (12). The source and detector are moved in unison in discrete steps over opposing wall surfaces (12, 18) so as to determine the chemical composition of the elements in a hemispheric region (20) of the wall adjacent the detector with the radius of the region being substantially that of the mean free path distance of gamma rays emitted from elements interacting with neutrons on the detector side of the wall. The source (14) and detector (16) are reversed for relatively thick walls for mapping the distribution of elements on the other side of the wall thickness.

Abstract: An apparatus for irradiating a continuously flowing stream of fluid is diosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4.pi. radiation geometry. The irradiation source, for example a .sup.252 CF neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

Abstract: A method for detecting, localizing, and quantifying macromolecules contained in a two-dimensional matrix is provided which employs a television-based position sensitive detection system. A molecule-containing matrix may be produced by conventional means to produce spots of light at the molecule locations which are detected by the television system. The matrix, such as a gel matrix, is exposed to an electronic camera system including an image-intensifier and secondary electron conduction camera capable of light integrating times of many minutes. A light image stored in the form of a charge image on the camera tube target is scanned by conventional television techniques, digitized, and stored in a digital memory. Intensity of any point on the image may be determined from the number at the memory address of the point. The entire image may be displayed on a television monitor for inspection and photographing or individual spots may be analyzed through selected readout of the memory locations.

Abstract: Neutron activation is used to analyse the silicon and aluminium content of samples of material, such as bauxite ore and coal. The analysis can be performed on bulk samples, on material on a moving conveyor belt, or on the walls of a borehole. The method involves high energy neutron irradiation of the sample, measurement of the thermal neutron flux in the sample, and monitoring the gamma radiation from the sample at energies of (a) 1.78 MeV and (b) 0.844 MeV and/or 1.015 MeV. Such gamma radiation is produced on decay of (a) .sup.28 Al and (b) .sup.27 Mg isotopes, produced by the reactions .sup.28 Si(n,p).sup.28 Al and .sup.27 Al(n,p).sup.27 Mg. A single gamma ray detector is used. The analysis preferably utilizes equations which include terms to compensate for (a) the production of radiation at 1.78 MeV as a result of the production of the isotope .sup.28 Al from .sup.27 Al by the thermal neutron reaction .sup.27 Al(n,.gamma.).sup.28 Al, and (b) the Compton scattering of 1.

Abstract: An apparatus and method for simulating a fusion environment on a first wall or blanket structure. A material test specimen is contained in a capsule made of a material having a low hydrogen solubility and permeability. The capsule is partially filled with a lithium solution, such that the test specimen is encapsulated by the lithium. The capsule is irradiated by a fast fission neutron source.