Apparatus for automated inspection of surface and volume defects of ceramic nuclear fuel
FIELD: physics, atomic power.
SUBSTANCE: invention relates to means of inspecting nuclear fuel in the form of cylindrical tablets. The apparatus for automated inspection of surface and volume defects of ceramic nuclear fuel comprises an optical image transformer, optical and thermal image recording channels, illumination sources, a system for inputting pulsed thermal flux into the inspected article and a selector which provides synchronous recording of both optical and thermal images.
EFFECT: obtaining reliable results on presence or absence of defects in inspected articles and, as a result, reliable selection of defective and non-defective articles.
7 cl, 6 dwg
Currently, nuclear power is based on power reactors, the core of which is formed of fuel elements, structurally combined into fuel assemblies-cassette. Each fuel element consists of a shell-tube of zirconium alloy composed of tablets of uranium (plutonium) or nitride of uranium (plutonium) fuel rod. An important parameter in the manufacture of fuel elements is the density of loading of nuclear fuel into fuel rods in the process of formation of the tablets. The presence of surface and/or volumetric defects in ceramic nuclear fuels (chips, cracks, scratches, physical gradients of the density in the volume pills) creates additional surface section that negatively affect the process of heat transfer and leads to a local perturbation of the neutron flux density, which reduces the efficiency of the process of energy release. It should also be noted that the defects, distributed by volume pills, up to the present time detected by x-ray diffraction or ultrasonic spectroscopy in random mode.
Fuel elements containing pills of ceramic nuclear fuel distributed by volume and not identified defects that are a potential hazard in the operation of the poison�tion of the reactor, since it can result in deformation and/or destruction of membranes with subsequent depressurization and, consequently, the release amount of the coolant fission products with a high level of radioactivity.
The present invention, providing total control of ceramic nuclear fuel opto-thermal methods, in future will allow to avoid accidents in the operation of nuclear power reactors.
A review of currently available methods and devices for automated control pills ceramic nuclear fuel showed that all methods and implement their devices provide detection of defects, distributed exclusively on the surface of tablets. The methods and devices presented in the papers [1, 2], [3, 4], based on computer analysis of matrices a digitized image of the cylindrical surface of the tablet using both the original software and a wide range of devices for image input surface of the tablet computer. It should be noted that all devices providing the input image of the cylindrical surface of the tablet, essentially identical and contain:
- unit mechanical displacement (rotation) tablets;
system under�branches scanned surface;
- optoelectronic Registrar in the line of sensing elements.
As a prototype of the device of the invention selected, the system presented in the report .
Fig.1 shows a block mechanical displacement (rotation) tablets. Mechanical scanning the image on the cylindrical surface of each tablet provide two shafts, which are stacked tablets. The result is mechanical and a synchronized optoelectronic scanning of surfaces seven of the tablets is shown in Fig.2. At the final stage of control of the acquired image is analyzed with the use of genuine software, and on the basis of the results of the computer issues a signal to the manipulator on the selection of the defective tablets.
The fundamental disadvantages of the prototype should include the following:
- testing is carried out exclusively at surface defects;
o pass / fail is based on the results of detection of defects located on one of three surfaces of the tablets;
- the mechanical process of scanning (rotation) tablets may be accompanied by the effect of "slippage" that can lead to replicate and pass defects;
- the time interval for obtaining a digitized image of cylindri�certification the surface of the tablets is determined by the speed of the mechanical movement (rotation) of the product and can really amount to not less than 1 sec.
The aim of the invention is the exception listed principal disadvantages of the prototype is implemented under the following conditions:
- any movement of the controlled product in the process of digitizing and inputting an image of its surfaces in the computer must be excluded;
- the proposed method should provide digitization and synchronous input to the computer image as the cylindrical surface and one of the ends of the product;
- to determine both surface and volumetric defects method needs to provide digitization and synchronous input in the computer images (a) reflected light and (b) thermal images of surfaces that contains information about distributed volume of product defects.
These conditions may be met by inclusion in optical and functional diagram of a device implementing the proposed method of elements such as:
- transformer optical image;
device for input into the end product of the pulsed heat flux;
selector, which provides a synchronous input to the computer image of the two surfaces in the visible spectrum and thermal imaging of temperature fields distributed over these surfaces.
Fig.3 is a diagram of the device realitysex� method of determining defects distributed on two surfaces of the product. Transformer optical image 1 the cylindrical surface of the product 2 is positioned in the volume of the transformer on the base 3, provides a result of the illumination of the product white light source 4, distributed over a ring of LEDs, the scan of this surface into a flat ring. The image of the ring and one of the ends of the product is projected by the lens 5 on the light-sensitive surface of the optoelectronic Converter 6, is digitized and entered into a computer. Transformer optical image 1 made of a material transparent in the visible region of the spectrum (crystal, glass), in the form of a truncated cone with an axially disposed cylindrical bore, providing a guaranteed clearance for the product. All surfaces of the transformer image ground and polished. The principle of transformation of the image of the cylindrical surface of the product in the ring is based on the law of total internal reflection for light rays at the interface of the glass(crystal)-the air. The ratio of the refractive indices determines the magnitude of the angle of total internal reflection within which (actually±40° to the normal of the interface surface) of the light beam does not change the intensity and, hence, the boundary is a perfect mirror with coefficients�antom reflection, equal to 1. Image of two surfaces of the product: cylindrical 8, formed into a ring, and shaft 9, shown in Fig.3, view A. the Defect 7 - shell on the surface of the product is easily identified on the plane of the ring. The distortion of the shape of the defect is not the principal disadvantage of this method, since the compression ratios obtained image is known. The image end surface of the product has no distortion.
However, in this embodiment of the inventive device, a deterioration of the frequency-contrast characteristics of the image defect, because in its formation involved the light rays reflected from the illuminated surface and received on an interface only within the angle of total internal reflection.
Fig.4 is a diagram of a device implementing total control of defects in the product as distributed on the surfaces (barrel and endcap) and localized in its scope.
Transformer optical image 1 is made in the form of a truncated cone with direct axial hole for the localization of the test object 2. The base 3 is designed for positioning the controlled product in the volume of the transformer optical image, contains the element 10, for example a laser diode that is designed for pulse razo�Reva surface of the base and, accordingly, pulse input stream of thermal energy into the adjacent end face of the tablet. In order to obtain thermal (temperature in the midtones) of the image transformer 1 and the lens 5 forms an image on the sensitive surface of the optoelectronic Converter 6, made of a material transparent in the infrared range of the spectrum, in the wavelength region of 5-10 μm, for example, single-crystal germanium. Optoelectronic Converter 6 needs to ensure efficient conversion of optical images in a specified region of the spectrum in electronic counterpart.
The image surfaces of the test object semitones in the temperature recorded at any time after a pulse input to the end face of the flow of thermal energy, should contain information on both the superficial and distributed in volume defects. So, for defect-free products, image itemperature areas on a controlled surfaces must be axisymmetric concentric circles within transformed into a ring image of the cylindrical surface and the direct image of the end product. Any deviation itemperature distributions from the circle indicate the presence of surface and/or volume of the defect.
A disadvantage of the presented�enny Fig.4 embodiments of the inventive device should be considered as a complex system of separation of surface and bulk defects programmatically.
Shown in Fig.5 diagram of the device combines the channels of recording images of the test object as in reflected light (identification of surface defects), and thermal imaging that contains information about surface and bulk defects.
Transformer optical image made of a material transparent in the visible and in the infrared region of wavelengths: λmin≈0.2 µm and λmax≈12 µm. This characteristic, in particular, has a fluoride of barium. This kind of material of the optical element provides an effective transformation of the image of the cylindrical surface of the test object as in the visible and in the infrared range of the spectrum. In synchronized order of input in the computer image of both types in the optical scheme of the device is entered, the selector 11 in the form of plane-parallel plates with polished surfaces, angled 45° to the axis of the transformer. The selector is made of a material transparent in the infrared region of the spectrum and has a large (~0.9 a) reflection coefficient in the visible region of the spectrum. In practice, the selector 11 may be made of single crystal silicon (Germany). Detailed analysis of images synchronously entered into the computer in the visible and infrared ranges of the spectrum, will allow, in principle, to divide p�surface and volumetric defects for each test object.
Diagram of the device shown in Fig.6, and functionally identical item shown in Fig.5, except for the transformer design of the optical image, made in the form polupechennoe cone of metal with acceptable reflectivity in a broad spectral range from: λmin≈0.5 µm and λmax≈14 μm. The main purpose of using a highly polished inner surface of the cone as the transformer optical image of the cylindrical surface of the test object - the improvement of the frequency-contrast characteristics of the observed (entered in the computer) images of defects, since their image formed of the reflected (emitted) component, is not limited by the angle of total internal reflection.
1. Fuel Pellets Automatic Visual Inspection / F. Aguirre, A. Domingo // 15th World Conference on Non-Destructive Testing, 15-21 October, 2000, Rome.
2. Vision systems for inspection of nuclear fuel components. / B. Kamalesh Kumar, A. Lakshminarayana // National Seminar on Non-Destructive Evaluation, December 7-9, 2006, Hyderabad.
3. Optical-electronic system for automatic control of the appearance of the fuel pellets / A. V. Beloborodov, A. A. Gushchin, P. S. Zavyalov, J. A. Lemeshko, L. V. Finogenov // Defectoscopy, academisation "Science" of RAS. - 2007. T. 43. No. 10. S. 692-699.
4. High Productive Optoelectronic Pellets Surface Inspection for Nuclear Reactors/ A. V. Beleborodov, E. V. Vlasov, L. V. Finogenov, P. S. Zav'yalov // Key Engeneering Materials: Measurement Technology and Intlligent instrument IX. - 2010. - Vol.437. - P. 165-169.
1. Device for the automated control of surface and bulk defects in ceramic nuclear fuel containing a base, a source of radiation placed in the base, the lens and the optoelectronic transducer, characterized in that the transformer optical image, made in the form of a truncated cone with direct axially disposed cylindrical bore, the transformer is made of a material transparent in the visible spectrum, the optical transformer is connected to the lens, also introduced a means of illumination by the white light source arranged on the led ring, optically connected to the optical surface of the transformer image.
2. Device for the automated control of surface and bulk defects in ceramic nuclear fuel containing a base, a source of radiation placed in the base, the lens and the optoelectronic transducer, characterized in that the transformer optical image, made in the form of a truncated cone with direct axial hole for the controlled product, also introduced, the pump pulse of thermal energy in a controlled product, the transformer and the lens is made of a material transparent in the infrared range of the spectrum, and svetokos�must be raised to the surface of the optoelectronic Converter is made sensitive to infrared radiation.
3. Device for the automated control of surface and bulk defects in ceramic nuclear fuel according to claim 2, characterized in that the illumination means is made in the form of laser diodes.
4. Device for the automated control of surface and bulk defects in ceramic nuclear fuel containing a base, a source of radiation placed in the base, the first lens and the first opto-electronic Converter, characterized in that the transformer optical image is transparent both in the visible and in the infrared range, enter the second lens and the second optoelectronic Converter, and introduced the selector in the form of plane-parallel plates with polished surfaces arranged at an angle of 45 degrees to the axis of the transformer, the first and second lenses are optically interconnected with the selector.
5. The device according to claim 4, characterized in that the selector is made of monocrystal silicon, the transformer is made of barium fluoride.
6. The device according to claim 4, characterized in that the selector is made of a material transparent in the infrared region of the spectrum and having a large reflectance in the visible region.
7. The device according to claim 4, characterized in that the transformer is made in the form polupechennoe cone made of metal with a large ratio, low gas consumpti�ntom reflection in the visible and infrared regions.
FIELD: power engineering.
SUBSTANCE: device comprises shell with sealing end covers to house at least one capsule with analysed specimens fitted in unsealed thin-wall shell of refractory material. Said capsule is connected with gas lines intended for streaming ventilation of capsule working space. Outlet of every line is plugged for capsule sealing, plugs being composed of sleeves with axial holes filled with fusible material. One of the lines houses thermometer transducers. Note here that sensor of every transducer is fitted inside capsule working space.
EFFECT: measurement of temperatures of emissions at nuclear disintegration during experiments, simplified design of capsule seals.
4 cl, 1 dwg
SUBSTANCE: fuel element simulator has a shell in which there is a column of natural fuel tablets with a centre hole, and an electric heater placed with clearance in the holes of the tablets. The heater is in form of pipe made of heat-resistant material on the outer surface of which is formed a microrelief which varies on the length of the heater and which provides optically variable properties on the length of the surface, which correspond to the simulated temperature profile. A shielding pipe made of heat-resistant material is also placed with clearance on the outside coaxial to the shell, the inner and outer surfaces of said pipe also having a varying microrelief which provides optically variable properties on the length of the heater.
EFFECT: high accuracy of simulating the thermal state of fuel elements under investigation by obtaining temperature levels, thermal flux and temperature profiles similar to those in full-scale conditions.
7 cl, 2 dwg
FIELD: power engineering.
SUBSTANCE: device arranged on a stand (4), comprises a place (31) with a horizontal axis (X) for placement of the above fuel rod; a facility (20) for measurement of deviation from parallelism and a facility (22) for correction of the above deviation. The device comprises a facility (14) of device positioning relative to the fuel rod comprising two parallel supports arranged at the distance from each other, at the same time each of them supports the end of the above fuel rod. The supports are made in the form of two horseshoe-shaped parts (16.1. 16.2), the inner ends of which are designed for resting against the fuel rod, and are distanced from each other at the specified distance to ensure the coverage of the stand support, at which the end rests with the upper plug of the fuel rod, and which has thickness that is substantially equal to the distance between two horseshoe-shaped parts (16.1, 16.2). Also the device comprises a facility (32) to retain a fuel rod made as capable of providing for rotation of the fuel rod around its longitudinal axis, which is arranged between the facility (14) of positioning and facilities of measurement and correction. The facility (32) comprises a lower grip (34) and an upper grip (36), to hold the fuel rod, at the same time the lower grip (34) forms a base for measurement of deviation from parallelism.
EFFECT: provision of measurement of deviation from parallelism during correction of the above deviation.
12 cl, 15 dwg
FIELD: power industry.
SUBSTANCE: specimen is made of two coaxially combined tubular elements; one of which is fully or partially located inside the other one; gas pressure is created in a cavity between elements, sealed, arranged in a nuclear reactor and irradiated.
EFFECT: increasing informativity and reliability of results of change of properties of reactor materials at irradiation in the reactor at various types of stress-and-strain state.
3 cl, 1 dwg
FIELD: power engineering.
SUBSTANCE: time-series data by reactivity is produced from time-series data by a neutron bundle by the method of reverse dynamic characteristic in respect to a single-point kinetic equation of the reactor. Time-series data by fuel temperature exposed to previously determined averaging is produced using time-series data by power output of the reactor and pre-determined dynamic model. The component of contribution to feedback by reactivity is determined using time-series data by reactivity and introduced reactivity. The Doppler coefficient of reactivity is determined using the received time-series data by average temperature of a moderator in the reactor, time-series data by fuel temperature exposed to previously determined averaging, isothermic temperature coefficient of reactivity and component of contribution to feedback by reactivity.
EFFECT: increased accuracy and simplicity of measurements of the Doppler coefficient and possibility of its usage in case of use of discrete data.
8 cl, 7 dwg
FIELD: power industry.
SUBSTANCE: nuclear fuel pellet density monitoring plant includes measuring unit including gamma radiation source and detection unit, transfer mechanism for movement of pellets and hold-down device, as well as measuring result control and processing unit intended to control the operation of transfer mechanism for processing of measuring results and rejection of pellets. Transfer mechanism includes the first transfer assembly for movement of column of pellets through measuring assembly with reference to outlet pallet, the second transfer assembly for movement of reference and outlet pallet for columns of pellets in transverse direction, and hold-down device has the possibility of pressing the pellets during movement of column of pellets through the measuring unit.
EFFECT: invention allows increasing the monitoring efficiency due to supply to monitoring zone of nuclear fuel pellets in the form of columns and performance of measurement during movement of columns through the monitoring zone.
2 cl, 1 dwg
FIELD: power engineering.
SUBSTANCE: method of creep-rupture test of tubular samples in a non-instrumentation channel of a nuclear reactor includes the following operations. At least one reference tubular sample loaded with inert gas pressure is placed into a heating furnace, maintained at the preset temperature in the heating furnace until destroyed, and time is measured to the moment of its destruction. Two tubular sample accordingly loaded and non-loaded with inert gas pressure are simultaneously placed into an ampoule. The tight ampoule with both types of tubular samples is radiated in a nuclear reactor channel. The radiated tubular samples are placed into a heating furnace and tested until destroyed under pressures and temperatures similar to the ones in the reactor. The time is measured to the moment of destruction of tubular samples of the first and second types in the heating furnace. The time to the moment of tubular sample destruction under conditions of reactor radiation at the preset pressure and temperature is determined using the ratio that takes into account time values measured in process of method realisation.
EFFECT: invention makes it possible to increase accuracy of detection of strength characteristics of materials.
FIELD: power engineering.
SUBSTANCE: device to pelletise nuclear fuel comprises press, conveyor (4) for transportation of pellets from press to sintering area, facility (26) of pellets reloading from press to conveyor (4) and facility of inspection of at least one pellet of nuclear fuel at the outlet of press, besides, facility of inspection comprises facility for detection of matrix, where each pellet is made. Method to manufacture pellets of nuclear fuel with application of device, which includes stages, when matrices (10) are filled with powder, powder is pressed, pellets (P) are reloaded to conveyor (4), conveyor (4) is started, pellet (P) is taken, manufactured in certain matrix (10), proper operation of this matrix is inspected by results of inspection of pellets manufactured in it, pellets (P) are transported to sintering area.
EFFECT: control of manufactured pellets density, control of pellets without increasing duration of production cycle.
24 cl, 4 dwg
FIELD: power industry.
SUBSTANCE: control method of gas pressure in fuel element of nuclear reactor consists in the fact that fuel element is located horizontally, inserted in annular induction heater, heat impulse is generated, which induces convective gas current in fuel element, change of temperature is measured with temperature sensors pressed to the cover and gas pressure is calculated on the basis of temperature change value; at that, shoes and couplings are installed on temperature sensors prior to measurements; sensors are pressed to the cover opposite to each other, one is from above, the other is from below, heat-insulating patches are installed between sensors and difference of temperatures shown with sensors is measured, then heat impulse is supplied and difference of temperatures is measured again in certain time τ1; after that, fuel element is turned together with patches, sensors and induction heater through 180° and after it is turned, temperature difference is measured in certain time τ2, then the second heat impulse is supplied and temperature difference is measured again in time τ1; then fuel element is turned together with patches, temperature sensors and induction heater through 180° back to initial position; then temperature difference is measured again in time τ2; cycle is repeated for several times; after that obtained results are mathematically processed, and as a result gas pressure value is determined inside fuel element.
EFFECT: improving measurement accuracy of gas pressure inside fuel element.
FIELD: power industry.
SUBSTANCE: device contains the first housing with through holes for passage of fuel assemblies (FA), around which illuminators are equally installed. Mirrors receiving the optical radiation reflected from fragments of side FA surface and installed with various turning angles of images provide uniform transfer of reflected mirror images to the plane of openings. The second housing with openings, which is located at some distance from the first one, is provided with radiation protection. Inside housing there arranged are video cameras consisting of video matrixes and objectives, and mirror labyrinths formed with inlet mirrors and outlet mirrors. Inlet mirrors are oriented towards outlet openings, and outlet mirrors - towards the objectives. External image control and processing unit is taken to clean room and connected to video cameras through cable communication lines. Invention is aimed at increasing radiation protection of video cameras owing to their possibility of being compactly arranged in remote housing.
EFFECT: radiation protective material and mirror labyrinths in the second housing provide additional radiation protection of video cameras.
5 cl, 4 dwg
FIELD: operating uranium-graphite reactors.
SUBSTANCE: proposed method for serviceability check of process-channel gas gap in graphite stacking of RBMK-1000 reactor core includes measurement of diameters of inner holes in graphite ring block and process-channel tube, exposure of zirconium tube joined with graphite rings to electromagnetic radiation, reception of differential response signal from each graphite ring and from zirconium tube, integration of signal obtained, generation of electromagnetic field components from channel and from graphite rings, separation of useful signal, and evaluation of gap by difference in amplitudes of signals arriving from internal and external graphite rings, radiation amplitude being 3 - 5 V at frequency of 2 - 7 kHz. Device implementing this method has calibrated zirconium tube installed on process channel tube and provided with axially disposed vertically moving differential vector-difference electromagnetic radiation sensor incorporating its moving mechanism, as well as electronic signal-processing unit commutated with sensor and computer; sensor has two measuring and one field coils wound on U-shaped ferrite magnetic circuit; measuring coils of sensor are differentially connected and compensated on surface of homogeneous conducting medium such as air.
EFFECT: ability of metering gas gap in any fuel cell of reactor without removing process channel.
2 cl, 9 dwg
FIELD: nuclear power engineering.
SUBSTANCE: proposed invention may be found useful for optimizing manufacturing process of dispersion-type fuel elements using granules of uranium, its alloys and compositions as nuclear fuel and also for hydraulic and other tests of models or simulators of dispersion-type fuel elements of any configuration and shape. Simulators of nuclear fuel granules of uranium and its alloys are made of quick-cutting steel alloys of following composition, mass percent: carbon, 0.73 to 1.12; manganese and silicon, maximum 0.50; chromium, 3.80 to 4.40; tungsten, 2.50 to 18.50; vanadium, 1.00 to 3.00; cobalt, maximum 0.50; molybdenum, 0 to 5.30; nickel, maximum 0.40; sulfur, maximum 0.025-0.035; phosphor, maximum 0.030; iron, the rest.
EFFECT: enhanced productivity, economic efficiency, and safety of fuel element process analyses and optimization dispensing with special shielding means.
1 cl, 3 dwg
FIELD: identifying o spent fuel assemblies with no or lost identifying characteristics for their next storage and recovery.
SUBSTANCE: identifying element is made in the form of circular clip made of metal snap ring or of two metal semi-rings of which one bears identification code in the form of intervals between longitudinal through slits. Clip is put on fuel assembly directly under bracing bushing and clip-constituting semi-rings are locked in position relative to the latter without protruding beyond its outline. For the purpose use is made of mechanical device of robot-manipulator type. Identification code is read out by means of mechanical feeler gage and sensor that responds to feeler gage displacement as it engages slits. Identifying elements are installed under each bracing bushing.
EFFECT: ability of identifying fragments of spent fuel assembly broken into separate parts before recovery.
10 cl, 4 dwg
FIELD: analyzing metals for oxygen, nitrogen, and hydrogen content including analyses of uranium dioxide for total hydrogen content.
SUBSTANCE: proposed analyzer depending for its operation on high-temperature heating of analyzed specimens has high-temperature furnace for heating uranium dioxide pellets and molybdenum evaporator; molybdenum evaporator is provided with water-cooled lead-in wire, and molybdenum deflecting screen is inserted between molybdenum evaporator and furnace housing.
EFFECT: simplified design of electrode furnace, reduced power requirement.
1 cl, 1 dwg
FIELD: the invention refers to analytical chemistry particular to determination of general hydrogen in uranium dioxide pellets.
SUBSTANCE: the installation has an electrode furnace with feeding assembly , an afterburner, a reaction tube with calcium carbide, an absorption vessel with Ilovay's reagent for absorption of acetylene, a supply unit. The afterburner of hydrogen oxidizes hydrogen to water which together with the water exuding from pellets starts reaction with carbide calcium. In result of this equivalent amount of acetylene is produced. The acetylene passing through the absorption vessel generates with Ilovay's reagent copper acietilenid which gives red color to absorption solution. According to intensity of color of absorption solution the contents of general hydrogen are determined.
EFFECT: simplifies construction of the installation, increases sensitivity and precision of determination of the contents of hydrogen in uranium dioxide pellets.
2 cl, 1 dwg
FIELD: analog computer engineering; verifying nuclear reactor reactivity meters (reactimeters).
SUBSTANCE: proposed simulator has m threshold devices, m threshold selector switches, m series-connected decade amplifiers, m electronic commutators, n - m - 1 series-connected decade frequency dividers, first group of m parallel-connected frequency selector switches, second group of n - m frequency selector switches, and group of n - m parallel-connected mode selector switches. Integrated inputs of threshold selector switches are connected to output of high-voltage amplifier and output of each threshold selector switch, to input of respective threshold device; output of each threshold device is connected to control input of respective electronic commutator; inputs of electronic commutators are connected to outputs of decade amplifiers and outputs are integrated with output of group of mode selector switches and with input of voltage-to-frequency converter; output of inverting amplifier is connected to input of first decade amplifier and to that of group of mode selector switches; input of first group of frequency selector switches is connected to output of voltage-to-frequency converter and to input of first decade frequency divider and output, to integrated outputs of first group of frequency selector switches and to input of division-chamber pulse shaper input; each of inputs of second group of frequency selector switches is connected to input of respective decade frequency divider except for last one of this group of switches whose input is connected to output of last decade frequency divider; threshold selector switches and frequency selector switches of first group, as well as m current selector switches have common operating mechanism; mode selector and frequency selector switches of second group have common operating mechanism with remaining n - m current selector switches. Such design makes it possible to realize Coulomb law relationship at all current ranges of simulator for current and frequency channels.
EFFECT: ability of verifying pulse-current input reactimeters by input signals adequate to signals coming from actual neutron detector.
2 cl, 1 dwg
FIELD: atomic industry.
SUBSTANCE: proposed line is provided with computer-aided system for contactless control of flaw depth and profile on surface of fuel element can and on end parts including sorting-out device that functions to reject faulty fuel elements. This line is characterized in high capacity and reduced labor consumption.
EFFECT: enlarged functional capabilities, improved quality of fuel elements.
1 cl, 2 dwg
FIELD: nuclear fuel technology.
SUBSTANCE: invention relates to production of pelleted fuel and consists in controlling nuclear fuel for thermal resistance involving preparation for selecting pellets from nuclear fuel lot for measuring diameter, which preparation consists in dedusting. Selected pellets are placed in temperature-stabilized box together with measuring instrument. Diameter of each pellet is them measured and measurement data are entered into computer. Thereafter, pellets are charged into heat treatment vessel, wherein pellets are heated in vacuum at residual pressure not exceeding 7·10-2 Pa at heating velocity not higher than 10°C/min to 100-160°C and held at this temperature at most 2 h, whereupon heating is continued under the same conditions to 1470-1530°C and this temperature is maintained for a period of time not exceeding 4 h, after which hydrogen is fed with flow rate 2-6 L/min. Humidity of gas mix is measured in the heat treatment outlet. If humidity of gas mixture in the heat treatment outlet exceeds 800 ppm, hydrogen feeding is stopped and material is subjected to additional vacuum degassing at residual pressure below 7·10-2 Pa and held at 1470-1530°C in vacuum for further 4 h. Hydrogen feeding is the repeated at 2-6 L/min. If humidity of gas mixture in the heat treatment outlet is below 800 ppm, preceding temperature is maintained not longer than 2 h and raised to 1625-1675°C at velocity 40-60°C/h and then to 1700-1750°C at velocity 15-45°C/h. When outlet humidity of mixture is 500-750 ppm, hydrogen feeding is lowered to 1 L/min. Temperature 1700-1750°C is maintained during 24±2 h, after which pellets are cooled to 1470-1530ºC at velocity not higher than 10°C/min. Hydrogen is replaced with argon and cooling is continued to temperature not higher than 40°C, which temperature is further maintained. Outside diameter of each pellet from the selection is measured to find average diameter of pellets before and after heat treatment in order to calculate residual sintering ability. When this parameter equals 0.0-0.4%, total lot of pellets is used in fuel elements and in case of exceeding or negative residual sintering ability the total lot of pellets is rejected.
EFFECT: improved pellet quality control.
FIELD: power engineering; evaluating burnout margin in nuclear power units.
SUBSTANCE: proposed method intended for use in VVER or RBMK, or other similar reactor units includes setting of desired operating parameters at inlet of fuel assembly, power supply to fuel assembly, variation of fuel assembly power, measurement of wall temperature of fuel element (or simulator thereof), detection of burnout moment by comparing wall temperatures at different power values of fuel assembly, evaluation of burnout margin by comparing critical heat flux and heat fluxes at rated parameters of fuel assembly, burnout being recognized by first wall temperature increase disproportional relative to power variation. Power is supplied to separate groups of fuel elements and/or separate fuel elements (or simulators thereof); this power supplied to separate groups of fuel elements and/or to separate fuel elements is varied to ensure conditions at fuel element outlet equal to those preset , where G is water flow through fuel element, kg/s; iout, iin is coolant enthalpy at fuel element outlet and inlet, respectively, kJ/kg; Nδi is power released at balanced fuel elements (or simulators thereof) where burnout is not detected, kW; n is number of balanced fuel elements; Nbrn.i is power released at fuel elements (or element) where burnout is detected; m is number of fuel elements where burnout is detected, m ≥ 1; d is fuel element diameter, mm.
EFFECT: enhanced precision of evaluating burnout margin for nuclear power plant channels.
1 cl, 2 dwg
FIELD: analytical methods in nuclear engineering.
SUBSTANCE: invention relates to analysis of fissile materials by radiation techniques and intended for on-line control of uranium hexafluoride concentration in gas streams of isotope-separation uranium processes. Control method comprises measuring, within selected time interval, intensity of gamma-emission of uranium-235, temperature, and uranium hexafluoride gas phase pressure in measuring chamber. Averaged data are processed to create uranium hexafluoride canal in measuring chamber. Thereafter, measurements are performed within a time interval composed of a series of time gaps and average values are then computed for above-indicated parameters for each time gap and measurement data for the total time interval are computed as averaged values of average values in time gaps. Intensity of gamma-emission of uranium-235, temperature, and pressure, when computing current value of mass fraction of uranium-235 isotope, are determined from averaged measurement data obtained in identical time intervals at variation in current time by a value equal to value of time gap of the time interval. Computed value of mass fraction of uranium-235 isotope is attached to current time within the time interval of measurement. Method is implemented with the aid of measuring system, which contains: measuring chamber provided with inlet and outlet connecting pipes, detection unit, and temperature and pressure sensors, connected to uranium hexafluoride gas collector over inlet connecting pipe; controller with electric pulse counters and gamma specter analyzer; signal adapters; internal information bus; and information collection, management, and processing unit. Controller is supplemented by at least three discriminators and one timer, discriminator being connected to gamma-emission detector output whereas output of each discriminator is connected to input of individual electric pulse counter, whose second input is coupled with timer output. Adapter timer output is connected to internal information bus over information exchange line. Information collection, management, and processing unit is bound to local controlling computer network over external interface network.
EFFECT: enabled quick response in case of emergency deviations of uranium hexafluoride stream concentration, reduced plant configuration rearrangement at variation in concentration of starting and commercial uranium hexafluoride, and eliminated production of substandard product.
24 cl, 5 dwg