Nuclear reactor fuel element simulator
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
The invention relates to the field of thermophysical studies and can be used when studying the behaviour of fuel elements (cartridges) of nuclear reactors experimental modelling of thermal and gas-dynamic processes.
Known simulator fuel element of a nuclear reactor containing the shell, tablets natural fuel, the internal cylindrical heater located with clearance in the holes in the tablets, and the current-carrying nodes (see Gontar A.S., Kamnev A.A. and other uranium Dioxide with controlled restructuring as part of TVEL thermionic reactor Converter. International conference "Nuclear power in space", Moscow - Podolsk, March 1-3, 2005, proceedings, Vol.2, s-268).
A disadvantage of the known simulator is incomplete modeling, because the device does not allow to reproduce the profile of the change in heat flow along the length of a fuel rod, typical field operating conditions.
To simulate the temperature profile (heat flux) along the length of the simulator used heaters with variable length heat dissipation when current passes through the heater. Known simulator containing the tubular shell is placed inside the electric heating element made in the form of a filling of a mixture of powders of graphite and refractory IU is Alla, and separating the shell and the heater layer of insulating material (see Balashov S.M. and other Simulator fuel element of a nuclear reactor, RF patent 1499569, IPC6G21C 17/06, publ. 20.10.1999). The change in the ratio of powders of graphite and metal in a mixture of backfill required to reach a given temperature profile distributions of electrical resistivity backfill along the length of the simulator.
A disadvantage of such a simulator is the difficulty of obtaining fillings with a stable density at longer simulator and small diameters of the electric heating element; the violation of homogeneity of the density leads to overheating and destruction of the simulator.
Known simulator fuel element of a nuclear reactor containing the shell of stainless steel, internal heater with variable electrical and physical properties along its length, ceramic insulators and current-carrying nodes (see Boltenko E.A., Sevalkin SV and other Simulator fuel element of a nuclear reactor, RF patent №2168776, IPC7G21C 17/00, NV 3/48, publ. 10.06.2001). For modeling non-uniformity of heat dissipation along the length of the simulator ceramic insulators made in the form of sleeves of variable thickness at constant outer diameter, and the heater in the molten state fills the cavity of the bushing and therefore has p the value of diameter along the length of the simulator.
A disadvantage of the known simulator is the complexity of its filling of fusible material and the penetration of the liquid into the gap and cavity design. The latter excludes the possibility of research in this simulator behavior of full-scale pellet fuel, because the presence of liquid contact of the tablet shell is not consistent with the real operating conditions of the fuel element.
On the task being solved and essential features to achieve a technical result closest to the proposed simulator fuel element of a nuclear reactor containing the tubular sheath with the heater core or tube of electrically conductive material with a variable length cross-section, and the current-carrying nodes (see Boltenko E.A. electrically heated fuel elements for research and hydraulic characteristics of power plants. Atomic energy, t, issue 3, 2009, s-177). The heater is made of rods of different diameters, connected in series by welding. Due to the different temperature of the heater in areas with different resistivity select the distribution profile of the heat flux along the length of the simulator, simulate field.
The cross-sectional area of the heater in the known construction is changed stepwise, and the profile of the heat flux is a stepped, that does not correspond to the natural conditions of a fuel rod. In addition, distortion of the profile of the heat flux on the parts welded joints unacceptably large. Thus, the main disadvantage is selected as the prototype simulator is unsatisfactory accuracy of the simulation of field conditions.
The task of the invention is to improve the accuracy of modeling the natural thermal regimes of the fuel elements.
This object is achieved in that in the simulator fuel element of a nuclear reactor containing shell, a pillar tablets natural fuel with a Central hole and located with clearance in the holes tablets electric heater according to the invention, the heater is made in the form of a tube of refractory material, the outer surfaces of which are formed of alternating along the length of the heater microrelief, providing optically variable properties along the length of the surface, corresponding to a simulated temperature profile.
The task is achieved by the fact that the outside with a gap coaxial sheath is mounted a braided tube of refractory material on the inner and outer surfaces of which are formed of alternating micro, providing optically variable properties along the length of the heater.
In private versions displaced the tion along the length of the microrelief may be formed by the surface areas with different levels of roughness, the corresponding classes of roughness from the first to the fourteenth, or applied to the surface coating with variable density and thickness, or performed on the surface of the grooves of variable depth grooves to their diameter.
Shielding pipe can optionally be equipped with an Autonomous power source, and its outer surface may be provided along the entire length of the multilayer foil shields refractory material, made in the form of a winding with a variable number of layers.
Running a heater in the form of a tube of refractory material, the outer surfaces of which are formed of alternating along the length of the heater microrelief, provides a simulation of the temperature profile and heat flow corresponding to the standard fuel rods. Shielding pipe installed outside the shell, shaped along the length of the microrelief formed on inner and outer surfaces, performs the role of the first screen and allows to control the distribution of heat flow along the length of the simulator. Smooth change of the optical properties of the surface of the heater and a shielding pipe length, for example due to changes in roughness, allows you to get smooth, the corresponding field profile change heat dissipation and temperature of the studied items is now (shell, tablets of fuel) as opposed to a stepped characteristic of the simulator prototype. Extra foil shields reduces the load on the heater, i.e. allows to achieve a desired temperature of the studied elements at lower temperatures of the heater. The implementation of such screens, for example, in the form of expansions in terms of line before winding on the tube, owing to the varying number of layers along the length of the simulator to further control the distribution of heat flow.
Connecting a shielding pipe to a separate power source extends profiling of temperature fields in the investigated elements of a fuel rod, for example, allows to obtain the same temperature along the radius of the tablets of fuel at different temperature levels in the study of thermoprotect material.
The invention is illustrated by drawings.
Figure 1 shows the simulator fuel element
Figure 2 - example of the sweep of the foil shield.
Simulator, shown in figure 1, consists of a shell 1, a heater 2, the fuel pellets 3, the centering of the insulators 4, top 5 and bottom 6 of the current leads, a shielding pipe 7 and additional screens 8.
The heater 2 in the form of a tube of refractory metal with a variable external surface microrelief is installed inside the shell and coaxially with it. Between the shell 1 and the heater 2 is posted the column of fuel pellets 3. Centering the insulators 4 are installed on the ends of the fuel column 3, the heater is connected through openings in the insulators 4 upper 5 and lower 6 current leads. Shielding pipe 7 is installed coaxially with the shell 1 and the heater 2. On the screen pipe is wound several layers of foil 8 with gaps between the layers. The upper current lead connected to the flexible conductive cord that compensates for thermal expansion of the heater. Scan foil shield (figure 2) is shown for the case of symmetrical relative to the mid simulator profile of heat flow.
The simulator works as follows. The device is cooled in a sealed housing filled with an inert gas. By adjusting the magnitude of the current through the current leads 5 and 6 and the heater 2 set the required temperature levels of the heater. Heat flow from the heater comes on tablets of fuel 3 and next to the shell 1. Shielding pipe 7 and 8 screens limit the discharge of heat into the refrigerated case. The main mechanism of heat transfer through the gaps between the heater and tablets, pills and shell, and screens - rayed. The amount of radiant flux depends on the optical properties of the radiating surface, and the change of the microrelief surfaces of the heater and granitowa pipe can be obtained in each section of the simulator, heat flow, specified conditions of test.
The limits of the possible changes of the radiant heat flux due to changes in the optical properties of the surfaces of this construction simulator are determined using the known expression for the degree of blackness in the system of two coaxial cylinders of infinite length (see V. Adrianov., Fundamentals of radiation and complex heat transfer. M., "Energy", 1972):
Here ε1and ε2- the degree of blackness, F1and F2square surfaces of cylinders of smaller and larger diameters. For example, consider the temperature range of the heater 1500 To 3000 K. the Integral degree of blackness heater surface (tungsten) has a value of 0.1 to 0.9, depending on the surface microrelief. Integrated degree of blackness of the surface of the fuel pellets (uranium dioxide) for the same conditions - 0.3 to 0.4. When the area ratio of surface tablets and heater 1,5-2,0 perhaps is the change shows degree of blackness, determining the change of the radiant heat flux to the fuel tablets, from 0.1 to 0.4, i.e. in ~ 4 times.
To modify the optical properties of surfaces along the length of the heater or shielding tube in different ways: by grinding and polishing to different levels of purity sections of pipe with the original large roughness (pipe obtained by the deposition of metal from the gas phase), getting regular roughness machining the original smooth tubes, for example by applying the marks with increasing length of pipe depth the risks to its width, sandblasting, coating the surface of the coatings with varying density and thickness, electrochemical milling holes (blind holes) with different ratio of depth to diameter. When defining the required characteristics of the surface microrelief (arithmetical mean deviation of the profile, i.e. the height of the roughness and the average step roughness, i.e. the distance between the projections) for the profiling of the heat flux along the length of the simulator can be used tabular data on the effective emissivity blind holes with the relationship of the depth of the holes to a diameter of from 1 to 12 in materials with different integral radiative properties (see Radiative properties of solid materials. The Handbook. Under the General editorship of A. Sandlin. M: Energy, 1974). These data provide satisfactory accuracy in the calculations of heat flow for materials with a regular microrelief (roughness), for calculations with arbitrary materials roughness data should be used integrated radiative abilities obtained experimentally.
Calculating values of emissivity for each radial cross-section of the simulator, based on which class is selected surface roughness heater (shielding pipe) in this section, is performed by using the expression:
Here Q is the radial heat flow, in which the analyzed elements of a fuel rod are in this section in situ, σ - Stefan-Boltzmann constant, T2- estimated temperature value, converted to the heater surface of the investigated element, T1- set the temperature of the heater simulator. When calculating the required integral emissivity of the SPO is oblasti ε 1heater surface by the value of the integral capacity of the formulas (1) - valued ε2(the heated surface of the fuel pellets, shell) is taken for the temperature T2. On the basis of the obtained data on the integral emissivity is processed surface of the heater.
An example of a specific implementation.
As an example of a specific implementation of the device is considered a simulator designed to study the efficiency of fuel with new fuel materials at high temperatures, the radial and axial temperature gradients. The simulator consists of a shell of refractory alloy with the same field of TVEL, geometry, fuel pellets with a diameter of 8.2 mm with a Central hole with a diameter of 4.2 mm and heater tube of tungsten with a diameter of 3.2 mm and a wall thickness of 0.5 mm heater Length is 600 mm, the ends of the heater is connected by welding with rod current leads from molybdenum. The current leads are installed in centering the insulators, the upper current lead is connected to the inlet is screwed through a flexible copper harness that provides free elongation of the heater. Coaxial sheath over its entire length is set with a gap of 1 mm shielding pipe tungsten, on the outside of the pipe razmeshannoy foil shield. The simulator is installed in a sealed water-cooled enclosure, filled with helium.
The temperature profile of the surface of the fuel pellets along the axis of the fuel column, such as the conditions of the test must consist of three sections: mid - length of 300 mm with a constant length temperature (K), and extreme - 150 mm with decreasing temperature to the ends of the gradient 2K/mm (1900 To the edges). The specified radial heat flow in the cross sections in the Central zone and at the edges of respectively 1.3 MW/m and 0.4 MW/m, the desired temperature profile is provided with a heater temperature of 3000 K and the values of emissivity of 0.4 and 0.1. Integrated degree of blackness must be equal to 0.9 in the middle part and uniformly reduced to 0.4 at the edges of the heater. Such values are integral degree black tungsten surface can be obtained when the relationship of depth to diameter of from 5 (ε=0,9) to 1 (ε=0,4) forming the surface roughness of the recess.
The middle portion of the heater with a length of 300 mm is not processed after the pipe, the roughness of the surface after deposition of tungsten from the gas phase maximum. Areas adjacent to the middle, processed by grinding so that the length of 150 mm roughness gradually decreased by 6 points, corresponding to classes of roughness (see Anu is Lev VI Reference designer-mechanical engineer. Vol. 1. M: mechanical engineering, 1980, s-267).
Shielding pipe with a diameter of 17 mm obtained by gas-phase deposition of tungsten to copper pipe with pre-treated in accordance with the calculated data on the roughness of the surface. The surface of the Central section of copper pipe with a length of 300 mm was processed through 12th grade purity, cleanliness of the surfaces of the ends 150 mm gradually decreased from 12 th to 5 th grade. After removal by chemical etching of the copper substrate (pipe) the inner surface of the shielding pipe has maintained the required profile roughness. The external surface of the pipe after manufacturing had the 14th class of cleanliness, roughness profiling was carried out by mechanical processing.
The proposed simulator allows more accurate modeling of thermal state of the investigated fuel elements due to the receipt of the same, as in natural conditions, levels, temperature, heat flux and temperature profiles.
1. Simulator fuel element of a nuclear reactor containing shell, a pillar tablets natural fuel with a Central hole and located with clearance in the holes tablets electric heater, wherein the heater is made in the form of a tube of refractory material, on the outside the second surface of which is formed of alternating along the length of the heater micro, providing an optically variable properties along the length of the surface, corresponding to a simulated temperature profile.
2. The simulator according to claim 1, characterized in that the outside with a gap coaxial sheath is mounted a braided tube of refractory material on the inner and outer surfaces of which are formed of alternating micro, providing optically variable properties along the length of the heater.
3. The simulator according to claim 1 or 2, characterized in that the alternating along the length of the microrelief is formed by a surface with different levels of roughness, the respective classes of roughness from the first to the fourteenth.
4. The simulator according to claim 1 or 2, characterized in that the alternating along the length of the microrelief is formed by the surface coating with variable density and thickness.
5. The simulator according to claim 1 or 2, characterized in that the alternating along the length of the microrelief formed performed on the surface of the grooves of variable depth grooves to their diameter.
6. The simulator according to claim 2, characterized in that the outer surface of the shielding pipe is provided on the entire length of the multilayer foil shields refractory material, made in the form of a winding with a variable number of layers.
7. The simulator according to claim 2, characterized in that the shielding pipe is further provided with the auxiliary power source.
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: power industry.
SUBSTANCE: invention refers to control devices of gas pressure in fuel element of reactor. Device containing annular induction heater (inductor), temperature sensors located on one side of the heater at the distance close to fuel element diametre on opposite generatrixes of fuel element cover coaxially perpendicular to fuel element axis; in order to improve accuracy characteristics of pressure measurement there additionally introduced are heat-insulation patches between temperature sensors in thermal contact zone; sensors have metal shoes in the form of rectangular copper plates bent along the radius of surface generatrix of fuel element cover, covered with electrically insulating thermally conductive film, and flexible (for example rubber) couplings; there also introduced is the device of turning the fuel element through 180° relative to its longitudinal axis together with inductor, sensors and heat-insulation patches.
EFFECT: improving accuracy measurement characteristics of gas pressure inside fuel element.
SUBSTANCE: method of controlling mass ratio of uranium-235 isotope in gaseous uranium hexafluoride involves desublimation of gaseous uranium hexafluoride in a measuring chamber by lowering temperature of the base of the chamber, determination of gamma-ray intensity of the uranium-235 isotope in the solid phase and calculation of the mass ratio of the uranium-235 isotope in uranium hexafluoride using the formula: C = α*Iγ/M, where: M is mass of uranium hexafluoride in the measuring chamber determined using a mass flowmeter or a weight measuring system, g; Iγ is gamma-ray intensity of uranium-235 in solid uranium hexafluoride in the measuring chamber, s-1; α is a calibration coefficient.
EFFECT: higher efficiency and accuracy of determining mass ratio of uranium-235 in gaseous uranium hexafluoride.
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