Procedure for preliminary treatment of tubular casing of fuel rod for analysis of materials
FIELD: machine building.
SUBSTANCE: procedure consists in immersion of tubular casing of fuel rod into water electrolytic medium containing particles of iron oxide and in covering it at least partially with layer of iron oxide. Also, particles of iron oxide are produced by anode oxidising iron containing working electrode.
EFFECT: increased corrosion resistance of treated rod and its increased service life.
7 cl, 1 dwg
The invention concerns a method of pre-processing of the tubular shell of the fuel rod to research materials, in particular for studies of behavior in the corrosion process. It is also concerned with the application of three-electrode electrochemical cell for implementing the method, and use of treated one way to do this kind of a tubular shell of the fuel rod as a test sample for laboratory studies of its corrosive properties.
Usually the fuel elements of a nuclear reactor consist of an Assembly of fuel rods. Each of the fuel rods is forming the outer enclosure or covering of the shell of the fuel rod, also called a tubular shell of the fuel rod or, briefly, a tubular shell, and which contains within itself enriched nuclear fuel, for example, in the form of pellets of sintered uranium dioxide (pellets). The shell of the fuel rod must separate the nuclear fuel from the outside of the fuel elements or fuel rods to the coolant and to prevent resulting in nuclear fission fission products in the coolant or entry into direct contact with him.
Nuclear reactors with water moderator tubular shell fuel rods are usually made of C is rcone or zirconium alloy. In particular, it applies the so-called zircaloy alloys, which along with zirconium as a main component may also contain small amounts of tin, iron, Nickel, chromium, or niobium. Zirconium is one of the preferred materials for the manufacture of tubular membranes of the fuel rods, primarily because of its relatively small absorption cross-sections of neutrons, or, put differently, because of its high permeability for neutrons, but also due to its high heat resistance and good thermal conductivity.
Since the fuel rods during operation of a nuclear reactor are constantly exposed to the surrounding cooling medium, which, depending on the chemical climate and mode of operation of the reactor may contain a proportion oxidised components or dissolved gases, such as oxygen, which cannot be neglected, then the inevitable progressive corrosion zircalloy outer surfaces over time. Because of this structural properties of the material of the tubular sheath may change unwanted, negative for operational safety. Corrosion is thus one of the processes that limit the use of the fuel elements in the reactor up to 3-5 years.
Along with desirable, contributing Passy is the key zircalloy the outer surfaces of tubular membranes by the formation of layers of zirconium oxide, in particular, when operating boiling water reactors with a large capacity due to dissolved or contained in the cooling water of the reactor particles of iron oxides may be formed so-called CRUD layers or deposits in tubular membranes. CRUD (originally an abbreviation of "Chalk River Unidentified Deposit") called in this connection, it is usually a mixture or an agglomerate of various oxides of iron, in which is embedded foreign ions, such as Zn2+, Mn2+, Zr2+or Ni2+. While the exact structure and chemical composition of the oxides are very dependent on conditions during their formation, for example, from pH cooling water temperature, the presence of foreign ions, etc.
Although widespread consensus that such deposits, in General, more likely adversely affect the integrity and fatigue strength of the base material, however, the mechanisms of action in detail is still poorly investigated, and quantitative conclusions about the effect of CRUD layers on behaviour during corrosion and service life of the tubular casings of the fuel rods in the working conditions normal for a boiling water reactor, is still hardly possible. This is due, in particular, to the fact that the study of the processes of CRUD deposits on site during actual operation of the reactor is hardly possible, as well as more detailed investigation of the tubular is x shell fuel rods "waste", removed from the reactor fuel elements because of the relatively high doses may be subjected to severe restrictions and in practice hardly possible.
It would be desirable, before use of the fuel element, or respectively, the tubular sheath of the fuel rod in a nuclear reactor to obtain sound information and experimental data on material properties and behaviour during corrosion of the available materials of tubular membranes within the expected operating conditions, and in particular should be taken into account the impact generated during subsequent operation of the reactor layers of iron oxides on the outer surfaces of the materials.
Therefore, the basis of the invention is to specify a method with which you can handle or prepare the tubular shell of the fuel rod so that the influence of sediment iron oxide on its surface can be examined and assessed as safe and at the same time precisely in conditions close to work.
This task in accordance with the invention is solved due to the fact that the tubular shell of the fuel rod when immersed in containing particles of iron oxide aqueous electrolytic medium at least partially covered with a layer of iron oxides, and particles of iron oxides obtained by odnogo oxidation of iron-containing working electrode.
The invention proceeds from this conclusion that the systematic study of the influence of layers of iron oxides on the tubular shell of the fuel rods, their durability and chemical integrity in order to protect from radiation and operational safety should not be done on the spot, during the actual operation of the reactor, and the simulation on the received "direct from factory", but not contaminated by contact with radioactive nuclear fuel, the sample to be tested. This approach seems appropriate because first of all we are talking about the study of electrochemical processes and properties that the presence/absence of radiation have only a relatively weak effect. However, derived directly from the factory tubular sheath of the fuel rod, as a rule, doesn't have a layer of high temperature oxide, and if it has, then, in any case, the layer of zirconium oxide, and does not represent a special interest in iron deposits of CRUD. So first it must be properly prepared; that is, CRUD layer should be applied "by artificial means".
There is a fundamental opportunity to immerse investigated tubular shell of the fuel rod with this purpose in a freshly prepared aqueous solution of iron salts, for example, Fe (III)-chloride, Fe(II)-sulfate, FeOOH, etc. or, respectively, to inject this kind of solution by means of injection pump high pressure in the containing tubular shell of the autoclave, so that obtained in solution by the precipitation of iron oxides deposited on the outer surface of the tubular shell. However, it became clear that this kind obtained by the precipitation of iron oxides in contrast generated during actual operation of the reactor CRUD layers always contain a significant share of embedded or associated anions, for example chloride ions or sulfate, which are released during the next series of experiments and a negative or distorting effect on (simulated) chemistry of the cooling water. Therefore, such laboratory experiments on properly prepared zircalloy tubular membranes under certain conditions does not give reliable information about the features and the action is actually generated during reactor operation CRUD deposits.
Therefore, should apply alternative methods of preparation, during which prevents contamination of the obtained oxides harmful anions, and which lead to deposits on zircalloy tubular membranes, which by their structure and chemical composition comparable with CRUD deposits that occur in the work environment. As unexpectedly, these requirements are particularly outstanding which are due to electrochemical method, wherein the receiving and the precipitation of iron oxides on zircalloy tubular membrane occurs by anodic oxidation of iron-containing working electrode, for example, a steel electrode in aqueous electrolytic environment.
For precisely controlled and repeatable process for coating the working electrode while this is a preferred way, an integral part of well-known specialist in the field of electroplating three-electrode electrochemical cell, in which the working electrode using called potentiostat electronic control loop by means of a control current flowing between the working electrode under the auxiliary electrode (counter-electrode) through the electrolytic solution is held at the same electrical potential compared to the reference electrode (reference electrode). Alternative it is also possible the so-called galvanostatically connecting the cells in which the current is kept at a constant preset value.
Unlike conventional galvanic coating, in which the working electrode (consumable electrode) entering into a solution of metal ions are precipitated when restoring directly in the form of a metallic coating on the coated workpiece, i.e. it is otowka is an additional (symmetric) electrode, under this concept, the tubular sheath of the fuel rod is electrically isolated from the electrodes three-electrode electrochemical cell, or respectively is with them in the material only through the electrolytic solution. Released at the working electrode, the iron ions react at least partially with molecules or ions of the aqueous electrolytic solution and form at the same time, depending on the available electrical, chemical and other boundary conditions, various particles of iron oxides or clusters, which are first in colloidal solution in finely distributed in the liquid and eventually deposited on the outer surface of the immersed him in the tubular shell of the fuel rod, so that there arise the desired CRUD-shaped deposits or layers that do not contain anionic contaminants.
Especially preferred is when the growth of a layer of iron oxides takes place in the environment, which, in particular, in relation to temperature and physical state of the surrounding tubular sheath of the fuel element are identical to the real conditions in a fluidized reactor at power operation. Therefore, the preferred way, when carrying out electrochemical pre-treatment of the tubular shell of the fuel rod is elektroliticheskii the solution was heated thereby, so during the deposition of particles of iron oxides at least in constituting its immediate environment space he was in a state of boiling.
The preferred manner in the inner space of the tube of the tubular shell of the fuel rod is also heating device respectively with a selected amount of heating power with which the tube is heated from the inside. Similar to conditions during reactor operation, in which the decay heat, enclosed in a tubular sheath of the fuel rod of a nuclear fuel is used to heat the walls of the tubular shell, it creates a directional outward flow of heat, i.e. the heat transfer from the tubular shell of the fuel rod into, if necessary, tempered outside the cooling fluid is here: electrolytic liquid, so that it comes into a state of boiling, or respectively, is kept in this condition. In this preferred way, as well as in a fluidized reactor is installed subcritical region boiling (so-called bulk boiling), which, in contrast to the so-called film boiling, by intensive heat exchange with the wall of the tubular shell with a relatively high coefficient of heat transfer. Thus is particularly well reproduced or simulated real working conditions in a fluidized reactor, so settling on a tubular shell of the fuel rod layers of iron oxides structurally almost identical CRUD layers that occur in the operating conditions in the reactor.
As already mentioned, the exact chemical composition of the layers of iron oxides, in particular, the ratio of iron oxide (III, II) (Fe3O4the so-called magnetite) iron oxides (III) (Fe2O3the so-called hematite), depends on various details and boundary conditions for the flow of the electrochemical process, in particular, however, from "hydrochemistry" electrolytic solution. Therefore, the preferred way chemical composition formed by deposition of particles of iron oxides on the tubular shell of the fuel rod layer of iron oxides, in particular, the ratio of particles of magnetite and hematite, can be adjusted by introducing gases, in particular oxygen, in the electrolytic solution. Along with this, in an aqueous electrolytic medium can, of course, also add liquid or solid additives oxidised or restorative actions to regulate the environmental conditions during deposition and, together with the chemical composition of the oxides of iron.
In addition, it may be expedient, in the framework of a systematic series of tests to study in laboratory conditions the effect of different kind of outside the ions, which are produced when the reactor CRUD layers. Therefore, preferred that the material of the working electrode in the electrolytic preparation of tubular membrane is chosen so that deposited on the outer surface of the tube, a layer of iron oxides contained a given share of embedded foreign ions, the preferred way extraneous metal ions, in particular, Zn2+, Mn2+, Ni2+and /or Cr3+. This means that it is advisable that the electrode material was a corresponding metal alloy based on iron.
Achieved by using the advantages of the invention consist, in particular, that by using an electrochemical process, especially with proper selection of thermal and chemical conditions of the environment, it has become possible to purposefully cover unused tubular shell fuel rods layers of iron oxides, which by their structure and chemical composition almost identical to those layers that arise when using such tubular membranes in a fluidized reactor. In particular, while preventing contamination of the layers of iron oxides embedded anions, as it inevitably would have happened in the coating using obtained by dissolving iron salts containing ACS is water iron solution for coating. The use of weak injection of high-pressure pumps or the like is also not required. Instead, you can accurately and adequately control or, respectively, to adjust the chemical composition, structure, and share the resulting iron oxides using simple patterns, such as, for example, the Faraday law, by varying the adjustable parameters that are amenable to easy operation.
Using the thus prepared tubular membranes of the fuel rods, which are then used as test samples in a laboratory study of their behaviour during corrosion under the influence of CRUD layers, much easier to conduct a systematic series of tests regarding the necessary security measures and official regulations, etc. Thus, by varying the parameters of the experiments are relatively simple and without threat to the environment or the person responsible for the test stand maintenance personnel can be "lost" a number of scenarios that during actual operation of the reactor would be impossible for only one of the official standards. Acquired this knowledge can then accordingly be taken into account when calculating, designing, developing and constructing the tubular shell, as well as other relevant components R of the actor, and in the selection of appropriate operating parameters, etc.
An example embodiment of the invention is explained in more detail using the drawing. While the drawing shows the principal image of the installation for coating a tubular shell of the fuel rod with a layer of iron oxide.
Schematically shown in the drawing device 2 for applying the coating is used for coating made of zircalloy tubular shell and the fuel rod boiling water reactor with a layer 6 of iron oxides. The goal is to be applied to the outer surface of the tubular sheath 4 of the fuel rod layer of particles of iron oxides, which by their chemical composition, their microscopic structure and its other physical and chemical properties are the best way would correspond to a layer of iron oxide, also known as CRUD, which is formed with the appropriate use of such tubular sheath 4 in a fluidized reactor. Therefore, the principle of the device 2 for applying the coating is based on the basic electrochemical principle, according to which the tubular sheath 4 of the fuel rod is covered with the desired layer 6 iron oxide by immersion in containing particles of iron oxide aqueous electrolytic medium 8, and particles of iron oxides obtained by anodic oxidation glands which contains the working electrode 10, here steel electrode with low content of extraneous metal ions, and are in the electrolytic environment 8.
In particular, the device 2 for applying the coating includes this also called autoclave thermally insulated from the external environment and hermetically closed metal pressure container 12 with orifice 14 in the wall 16 of the tank through which the coated tubular sheath 4 of the fuel rod is inserted from the outside and its lower, closed end 18 is inserted into the inner space 20 of the tank. Using located between the outer side of the tubular sheath 4 of the fuel rod and the inner surface of the bore hole 14 of the ring is electrically isolated sealing element 22, for example, of Teflon, on the one hand, ensures the tightness of the junction with inserted tubular shell 4 of the fuel rod, and on the other hand, the tubular sheath 4 of the fuel rod is electrically isolated from the metal wall 16 of the tank.
Through attached to the inlet side 24 of the inlet pipe 26 into the interior 20 of the pressure tank 12 is fed to the electrolytic water environment 8. Through attached to the outlet 28 of the intake pipe 30 can, if necessary, again to take or appropriate estwenno, to produce "waste" electrolytic environment 8. To do this, in the supply line 26 and the intake pipe 30 is built corresponding, not shown here in more detail regulating valves, which can also adjust the pressure inside the container.
In this case, during the coating process provides a continuous flow of electrolytic solution 8 through the pressure container 12, and moreover, the constant washing immersed in the electrolytic solution of 8 tubular sheath 4 of the fuel rod, and withdrawn through the suction pipe 30 "proven" share chemically prepared not shown here, the preparatory device or "updated", optionally supplied with chemically active additives, escaped or enriched gases and then using the pressure pump back on a kind of the liquid path through the supply line 26 to the pressure tank 12. Pressure pump (not illustrated) may be made in the form of a compression pump, compression in the internal space of the electrolytic tank 20 Wednesday 8 in accordance with the established performance compression.
In addition, with the supply line 26, not shown in the CSO here, the heating device can be made (preliminary) tempering the incoming pressure in the tank 12 environment so to play or simulate the General conditions of pressure and temperature high-temperature cooling water flowing into the reactor vessel under pressure, in the case of a boiling water reactor.
Even better playing conditions of a boiling water reactor could be obtained by heating the inside of the tubular sheath 4 of the fuel rod during electrochemical coating, making simulated occur during reactor operation, in this case, due to the radioactive decay of nuclear fuel heat transfer from the walls 32 of the tubular shell to the surrounding cooling medium. For this cavity, enclosed in the walls 32 of the tubular sheath 4 of the fuel rod, is an electric heating device 34, for example, a cylindrical high-temperature heating cartridge, which can be inserted into the tubular sheath 4 of the fuel rod with the upper open end 36, the speaker of the pressure tank 12. In order to avoid unwanted displacement potential in the walls 32 of the tubular sheath of the heating coil of the heating device 34 is galvanically separated from the external electrical network. The corresponding adjusting device 38 regulates the heating current, however, the heating power so that the electrolytic environment 8, at least, the nearest environment facing the inside of the pressure tank 12 section tubular shell, provided in condition boiling and during the process of electrochemical coating is kept in this condition. The occurrence of film boiling a large area on the outer surface of the tubular sheath, which may adversely affect the heat transfer, this can be avoided by proper regulation of the heat output.
Required for coating the tubular sheath 4 of the fuel core particles of iron oxides obtained by anodic oxidation of iron-containing working electrode 10, in which iron ions are detached from the outer surface of the electrode and react with the water component parts of the electrolytic solution 8 with the formation of various iron oxides, after which predominantly convective transfer through the pressure vessel 12 in the end, which was preferably deposited on the outer surface of the tubular sheath 4 of the fuel rod.
For more uniform and homogeneous coating of the tubular sheath 4 of the fuel rod working electrode 10 is made in the form of a hollow cylinder and located at a distance of a few centimeters or less concentrically around the tubular sheath 4 of the fuel rod. Outside formed a working electrode 10 of the hollow cylinder corresponding to the potential of the reference electrode 40 pohruzhaetes is in electrolytic environment 8. The working electrode 10 and reference electrode 40, respectively, are electrically isolated connection through conducted through the walls 16 of the pressure vessel 12 connecting wires 42, 44 are connected to the corresponding inputs 46, 48 of the 50 potentiostat high voltage provided to regulate voltage and operating on the principle of differential operational amplifier. Required for three-electrode cell with an adjustable potential of the third electrode, the so-called counter-electrode 52 or the auxiliary electrode in this embodiment is formed by the walls 16 of the pressure vessel 12; but in an alternative embodiment, may also be, for example, there is made of platinum single counter-electrode in the inner space 20 of the pressure vessel 12, in particular, in the form revolves around the working electrode 10 and reference electrode 40 of the spiral. The counter-electrode 52 is connected through a connecting wire 54 to the outlet 56 of the operational amplifier 50 potentiostat.
The voltage regulator is, in principle, measure the voltage between the electrode 40 and the working electrode 10 at the entrance with a very high resistance, compares this voltage with a specified nominal value and sets, respectively, by a counter-electrode 52 such current that is tkanina between the actual value and the nominal value of the potential vanishes. The adjusting circuit closed independently of the electrochemical cell with the electrolyte 8, the current flows through the working electrode 10 back to earth. It also becomes possible accurate and well reproducible control and monitoring of electric potential.
It is also possible simple and focused management, monitoring and logging, and other associated with obtaining iron oxide and a coating on the tubular sheath 4 of the fuel rod chemical and physical process parameters, such as dissolved in circuit electrolyte oxygen or temperature of the outer surface of the tubular shell. By preventing harmful embedded anions and due to the boundary conditions and the environmental conditions corresponding to the conditions in a fluidized reactor, so you can relatively easy way to obtain uncontaminated layers 6 iron oxides on zircalloy tubular shell 4, which by their structure and chemical composition comparable to real CRUD. The success of the method is confirmed by various methods of obtaining qualitative and quantitative evidence, such as x-ray diffractometry.
The list of reference positions
2 a Device for coating
4 the tubular shell of the fuel rod
6 Layer ACS is Yes iron
8 Electrolytic environment
10 working electrode
12 Pressure container
14 the penetration hole
16 tank Walls
18 Closed end
20 the Inner space of the tank
22 Sealing element
26 Supply line
28 the Discharge port
30 Intake pipe
32 Wall of the tubular shell
34 Heating device
36 the Open end
38 Adjusting device
40 the reference Electrode
42, 44 of the connecting wire
46, 48 Input
52 the counter-electrode
54 connecting wire
1. The method of pre-processing a tubular sheath (4) of the fuel rod to research materials, in particular, to conduct research in the corrosion process, in which a tubular sheath (4) of the fuel rod when immersed in containing particles of iron oxide aqueous electrolytic medium (8)at least partially covered with a layer (6) of iron oxides, and particles of iron oxides obtained by anodic oxidation of iron-containing working electrode (10).
2. The method according to claim 1, wherein the electrolytic medium (8) is heated in such a way that during the deposition of particles of iron oxides on the tubular shell (4) of the fuel rod (8) is in a state of boiling, site is preferably in the region of subcritical boiling.
3. The method according to claim 2, wherein the tubular sheath (4) of the fuel rod heat located in the inner space of the tube heating device (34).
4. The method according to claim 1, wherein the chemical composition formed by deposition of particles of iron oxides on the tubular shell (4) of the fuel rod layer of iron oxides (6), in particular the ratio of particles of magnetite and hematite, regulate by introducing gases, in particular oxygen, in the electrolytic environment (8).
5. The method according to claim 1, wherein the material of the working electrode (10) is chosen so that it is deposited on the tubular shell (4) of the fuel rod layer (6) iron oxide contains a proportion of embedded foreign ions, preferably ions of impurities of metals, particularly Zn2+, Mn2+, Ni2+and/or CR3+.
6. The method according to any one of claims 1 to 5, wherein the tubular sheath (4) of the fuel rod handle for use as a test sample in a laboratory study of its corrosive properties.
7. The method according to claim 6, wherein for the subsequent study of the corrosion properties of the shell (4) of the fuel rod using electrochemical three-electrode cell with adjustable using the appropriate potentiostat (50) current and/or voltage with iron-containing working electrode (10) in the electrolytic water is the ed (8) for pre-treatment of the tubular shell (4) of the fuel rod.
FIELD: physics, nuclear.
SUBSTANCE: invention relates to nuclear power engineering and specifically to methods of making cermet rods of fuel cores of fuel elements of nuclear reactors for different purposes. A workpiece is put into a container. Working medium in form of solid glass is put into the container and the container with the workpiece and the working medium is heated to pressing temperature. The container is put into a press mould and moulding force is applied by increasing pressure of the working medium while moving the moulding die. In the proposed method the working medium is in form of a briquette. The briquette is placed at the bottom of the container. The workpiece is put on top of the briquette. The container with the workpiece and the working medium is heated outside the press mould until the workpiece is immersed in the working medium.
EFFECT: reduced probability of formation of voids, transfer of pressure onto the moulded workpiece becomes more uniform, increased output of the suitable products.
SUBSTANCE: invention is designed for increasing operation parametres and life cycle of active zone of a reactor due to the maximum fuel burnup, improved reliability and operation safety of maintenance of nuclear power stations. Fuel element can of a fast reactor with liquid metal heat carrier includes a metal tube of vanadium alloy with titanium, chrome and unavoidable impurities. External and internal tube surfaces are coated with stainless ferrite steel. Vanadium alloy components are taken at a given ratio. In particular, titanium to chrome ratio lies within 2.2 to 1.8 range. Between vanadium alloy and stainless ferrite steel a 6-8 mcm thick transition layer of solid solution of vanadium alloy with stainless ferrite steel is formed.
EFFECT: improved radiation, corrosion and heat resistance and mechanical properties of fuel element can in a fast reactor with liquid metal heat carrier.
3 cl, 5 dwg
FIELD: nuclear power engineering; nuclear reactor fuel microelements covered with four-layer shielding coating.
SUBSTANCE: proposed method involves sequential fluid-bed deposition of coating layers onto fuel microspheres. First low-density pyrocarbon layer is deposited by pyrolysis of acetylene and argon mixture of 50 volume percent concentration at temperature of 1450 °C. 85 - 95 % of second layer is deposited from high-density pyrocarbon by pyrolysis of acetylene and argon mixture of 40.0 - 43,0 volume percent concentration, and of propylene and argon mixture of 30.0 - 27.0 volume percent concentration at temperature of 1300 °C; 5 - 15 % of coating is deposited by pyrolysis of propylene and argon mixture of 5.0 - 10.0 volume percent concentration doped with 0.5 - 1. 5 volume percent of methyl trichlorosilane. Third layer of silicon carbide is deposited by pyrolysis of methyl trichlorosilane and argon mixture of 2.5 - 3.0 volume percent concentration in hydrogen-argon mixture at temperature of 1500 °C. Upon deposition this layer is treated with hydrogen at temperature of 1750 -1800 °C for 20 - 30 minutes. 90 - 95 % of fourth layer is deposited by pyrolysis of acetylene and argon mixture of 40.0 - 43.0 volume percent concentration and of argon and propylene mixture of 30.0 - 27.0 volume percent concentration at temperature of 1300 °C. Upon deposition of 90 - 95 % of fourth-layer pyrocarbon coating thickness 5 - 10 % of coating is deposited by pyrolysis of propylene and hydrogen mixture of 3.0 - 5.0 volume percent concentration.
EFFECT: enhanced service life of fuel microelements due to reduced damage probability during their manufacture and in service.
1 cl, 6 dwg, 1 tbl
FIELD: nuclear engineering, in particular, engineering of micro heat-exhausting elements for nuclear reactors.
SUBSTANCE: first layer of micro heat-exhausting element with four-layer protective cover is made of SiC-PyC composition with content of 1,0-10,0 % of mass of silicon carbide with thickness of layer equal to 0,02-0,2 of diameter of fuel micro-sphere, second layer is made of SiC-PyC composition with content of 20,0-45,0 % of mass of silicon carbide with thickness of layer equal to 0,03-0,40 diameter of fuel micro-sphere, third layer is made of silicon carbide, while fourth layer is made of titanium nitride with thickness equal to 0,01-0,08 of diameter of fuel micro-sphere.
EFFECT: increased exploitation resource of nuclear reactor due to increased corrosion resistance and radiation stability.
3 dwg, 1 tbl
FIELD: nuclear power engineering; manufacture of fuel elements and their claddings.
SUBSTANCE: each weld of cladding and its plug are tested in facility equipped with units for clamping and revolving the claddings, scanning with carriage using weld inspection piezoelectric transducer and piezoelectric transducer for measuring wall thickness in measurement region, immersion bath, ultrasonic pulse generator, ultrasonic pulse receiver, microprocessor, analog-to-digital converter switch, and random-access memory.
EFFECT: enhanced quality of fuel elements and their operating reliability in reactor core.
1 cl, 1 dwg
FIELD: nuclear power engineering; fuel rods for water-moderated water-cooled reactors.
SUBSTANCE: proposed fuel rod designed for use in water-cooled water-moderated power reactors such as type VVER-1000 reactor has fuel core disposed in cylindrical can. Outer diameter of fuel rod is chosen between 7.00 . 10-3 and 8.79 . 10-3m and fuel core diameter is between 5.82 . 10-3 and 7.32 . 10-3m and mass, between 0.93 and 1.52 kg, fuel core to fuel rod length ratio being between 0.9145 and 0.9483.
EFFECT: reduced linear heat loads and fuel rod depressurization probability, enlarged variation range of reactor power, optimal fuel utilization.
7 cl, 3 dwg
FIELD: testing equipment.
SUBSTANCE: presented invention refers to chemical industry and may be used for diagnosis of emergency state of reservoirs subjected to pitting corrosion. Method of diagnosis of emergency state of reservoirs in corrosive environment includes location of tri-electrode system in it, which consists of working electrode, subsidiary electrode and comparison electrode, by means of successive determination of working electrode potential in open circuit, of pitting potential, of margin of pitting resistance by potential as difference between pitting potential and potential of open circuit, and threshold value of potential of working electrode within margin of pitting resistance by potential; at that after determination of threshold value of potential of working electrode, electrode is maintained at this value of potential, then potential of working electrode is displaced from threshold value of potential to potential of open circuit and in opposite direction, at that values of current intensity and potential are recorded, upon which at determined value of potential comparison of value of current intensity of straight and opposite direction is performed, and if value of current intensity of straight direction exceeds value of current intensity of opposite direction, emergency state of reservoir is determined.
EFFECT: improvement of validity and simplification of method of diagnosis of emergency state of reservoirs.
4 dwg, 1 tbl, 4 ex
SUBSTANCE: invention relates to a method of assessing corrosion resistance of steel and objects made from steel, designed for operation in aggressive media. The method involves taking samples from the objects. Thin sections with a polished surface are then prepared from the taken samples and the sections are placed in a corrosive medium. The corrosive medium contains chlorine ions or rhodanate ions. The corrosive medium additionally contains sodium tetraborate and boric acid. Polarisation is done using constant potential ranging from -500 to 500 mV and the equilibrium value of polarisation current density is determined. Polarisation is also done using potential varying at a rate of 0.2-12 V/h in the range from -0.5 to +1.2 V and without interrupting polarisation from +1200 mV to -500 mV. The potential value for which zero or a negative value of current is achieved is determined. Corrosion resistance of steel and objects made from the said steel is determined from the three current measurement values.
EFFECT: increased information content and reliability of monitoring quality of steel objects.
2 cl, 3 tbl
FIELD: measurement technology.
SUBSTANCE: this invention refers to the technology of determination of corrosion resistance of internal surface of metal container. Method provides the preparation of couple of the specimens, jars with bottoms. Later, the specimens are made fatless, dry, weighed, fixed on the opposite ends of hollow dielectric corrosive box. The specimens are fixed in the way that the hollows of the jars are communicated with the hollow of the corrosive box. Further, the specimens are connected through the bottoms to the polarisation current measurement block the value whereof is used to qualify the achievement of the permanent corrosion velocity at the constant potential difference of 10 mV. Further, the intervals of running time are measured at the permanent corrosion velocity and the specimens are disconnected. The specimens are sequentially washed with distilled water and ethyl alcohol, dried and weighed. Calculation of specific mass loss of the specimens from the square of the contact with simulation medium or with the product researched for time unit the value whereof is used to evaluate the corrosion resistance of the internal surface of the metal container.
EFFECT: improvement of accuracy of the determination of the corrosion resistance of the internal surface of the metal container.
FIELD: process engineering.
SUBSTANCE: invention relates to testing of metals and can be used for defining properties of welded-pipe metal operated in aggressive media. Proposed method of testing antirust strength comprises cutting a half-ring from the pipe, making the first cut, a concentrator, on its surface and applying strain to aforesaid half-ring ends. Aforesaid half-ring is placed into corrosive medium and held therein for preset time interval. Metal antirust strength is judged upon proceeding from the pattern of corrosive destruction. Note that, for test, a half-ring with welded seam is selected and the second cut, identical to aforesaid one, is made on its surface. Note also that one cut is made of half-ring outer surface, the second one is made on base metal, parallel to the first one. Both cuts are arranged in symmetry with the half-ring axis of symmetry and stepwise relative to each other. Welded seal antirust strength is judged upon in comparison with that of base metal.
EFFECT: higher accuracy of test.
4 cl, 2 dwg
FIELD: physics, measurements.
SUBSTANCE: invention is related to methods for detection of boiler water aggression and metal resistance to intercrystalline corrosion with the help of electrochemical analysis. According to method, investigated sample is inserted into indicator groove, is pressed to body by cover and is bent as per groove profile, additional mechanical stress in sample is created with the help of special bolt that acts at its bent surface. When two pins of cover are weakened, leakage is created between sample and body, through which light steaming is continuously maintained; concentrated saline solution is created in leakage point, which affects stressed section of sample; samples withdrawn from indicator are visually inspected, and in case of necessity - polished and after etching are exposed to metallographic surveys. Moreover, sample is insulated from indicator metal with preservation of stressed section contact with saline solution in leakage point, aggression of boiler water is determined by measurement of electric resistance of section "sample - saline solution - pipe metal", in which indicator is installed, and intensity of intercrystalline corrosion - by measurement of EMF of corrosion E at the same section. Boiler water is considered as non-aggressive, if its resistance R exceeds 100 kOhm, intensity of intercrystalline corrosion is calculated by formula.
EFFECT: efficient determination of boiler water aggression and realisation of continuous monitoring of intercrystalline corrosion process intensity.
FIELD: physics, measurements.
SUBSTANCE: invention is related to instrumentation equipment and may be used to detect corrosion condition of underground part of reinforced concrete supports. Method comprises the following operations: support digging, cleaning from soil, tapping of open surface of concrete with hammer, visual inspection, detection of chips, cracks and rusty streaks, detection of crack opening value. Besides generator of metering signal is previously connected between support armature and auxiliary earthing device, gradient of earth surface potential is measured around support, maximum value of potential gradient is used to detect point of support damage, i.e. place for digging.
EFFECT: improved accuracy of detection of corrosion condition of reinforced concrete supports by more accurate definition of soil opening area.
SUBSTANCE: invention relates to metallurgy field, particularly to control of steel products stability provided for operation in corrosive mediums, impacting attack by corrosion on metals, including in aqueous mediums. Essence of method consists in from steel products there are drawn examples, there are manufactured samples with specially prepared surface. Surface is treated by electrochemical method in potentiodynamic mode by reactant, containing chlorine ions. Ions concentration of chlorine in solution is kept 10-30 g/l, potential is changed at a rate 1.2-2.5 V/hour in the range from -(650-500)mV to -(350-250) mV in direct and then backwards, fixing correlation of current density to potential. About corrosion resistance judging by electrochemical properties of steel, specified from received correlation.
EFFECT: increasing of information value and significance of express control method of steel products stability against isolated corrosion subject to complex impact on corrosive processes of chemical composition, microstructure and pollution degree of steel by nonmetallics.
9 cl, 4 tbl
FIELD: physics; measurement.
SUBSTANCE: invention pertains to testing materials and can be used for evaluating longevity of chromated zinc coating on steel in industrial atmospheres of operation regions. The method is realised by exposing the coated sample under investigation to acid mist in a chamber for 12 hours at (40±1)°C. The acid mist is created by dispersing a 0.06 %.vol. HCl solution and feeding sulphur dioxide gas with concentration 2.5 mg/m3 into the chamber. The sample is exposed to an air current with speed 2.7 m/s and UV radiation for 5 minutes after spraying the solution. The sample is then kept in the chamber for 12 hours. Mass loss of the sample is determined for the time before white volumetric products of zinc corrosion and the first corrosion centre in the steel appear. On a graph of mass loss (g/m2) versus time (days), lines are drawn in a defined way, the point of intersection of which allows for determination of the protective capacity of the chromate film on zinc coating. The protective capacity of chromated zinc coating on steel, taking into account its region of operation, is calculated using a given formula.
EFFECT: increased accuracy of measurement.
2 dwg, 1 tbl
FIELD: instrument engineering.
SUBSTANCE: invention can be used for definition of corrosion danger and effectiveness of underground metal structures protection. Device contains corrosion rate display unit (CRDU) with nonvolatile memory chip (NMC) that is installed into the ground in close vicinity of the structure or on its surface, and portable analyser. CRDU consists of parallel isolated from each other plates made of the same metal that the structure is. On the surface there are control conductors connected to plates and pin part of flat plug connection in which there installed is printed-circuit board from computer. Computer outputs are connected to pins of plug connection for data exchange with portable analyser and power supply to computer. Portable analyser consists of female plug connection designed to be connected to the plates of electronic switching system. The operation of portable analyser is controlled by CP. The information is displayed at LCD display.
EFFECT: quick receiving of most complete data amount about underground structure corrosion condition, increase of depth and corrosion rate evaluation accuracy, complete dynamics of corrosion process development during structure operation.
FIELD: testing engineering.
SUBSTANCE: method comprises filling the metallic cryogenic tank with sea water, temporally protecting of sides and bottom of the tank by means of passing current through anodes mounted inside the tank just after submerging the tank into the water, and setting the first anode system in the vicinity of the bottom of the tank. The number of anodes and their capability to withstand the current are sufficient to produce a current density that provides the amount of the electrochemical potential required for protecting steel. A cryogenic vessel is proposed for realization of the method described.
EFFECT: enhanced efficiency and reduced cost.
16 cl, 12 dwg
FIELD: machine building.
SUBSTANCE: device consists of rotating precipitating portion. A precipitator consists of a stabilising chamber, precipitating chamber and of a channel for centrate drainage. The precipitating chambers are divided with partitions with orifices for liquid flow. Precipitation is performed from a moving layer of liquid, while drying of sediment is done through additional orifices in the partitions between the chambers. The precipitating chamber rotates on a faceplate. A flat removable precipitating plate is set on the bottom of this chamber. Bigger particles settle near the partition between the stabilising and precipitating chambers, while finer particles settle further from the sad partition downstream on the flat removable precipitating plate. A rotating pipe line supplies suspension into the precipitator. The device is also equipped with a stationary portion of centrate reception made in form of a jacket for reception of centrate. A convex bottom of the jacket is inclined.
EFFECT: sedimentation of both large and fine particles of suspension during analysis, easy unloading of sediment with minimal losses and with maintaining order of settled particles.